about summary refs log tree commit diff
path: root/compiler/rustc_codegen_llvm/src/intrinsic.rs
diff options
context:
space:
mode:
Diffstat (limited to 'compiler/rustc_codegen_llvm/src/intrinsic.rs')
-rw-r--r--compiler/rustc_codegen_llvm/src/intrinsic.rs2326
1 files changed, 2326 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_llvm/src/intrinsic.rs b/compiler/rustc_codegen_llvm/src/intrinsic.rs
new file mode 100644
index 00000000000..a0f9d5cf7cd
--- /dev/null
+++ b/compiler/rustc_codegen_llvm/src/intrinsic.rs
@@ -0,0 +1,2326 @@
+use crate::abi::{Abi, FnAbi, FnAbiLlvmExt, LlvmType, PassMode};
+use crate::builder::Builder;
+use crate::context::CodegenCx;
+use crate::llvm;
+use crate::type_::Type;
+use crate::type_of::LayoutLlvmExt;
+use crate::va_arg::emit_va_arg;
+use crate::value::Value;
+
+use rustc_codegen_ssa::base::{compare_simd_types, wants_msvc_seh, wants_wasm_eh};
+use rustc_codegen_ssa::common::{IntPredicate, TypeKind};
+use rustc_codegen_ssa::errors::{ExpectedPointerMutability, InvalidMonomorphization};
+use rustc_codegen_ssa::mir::operand::{OperandRef, OperandValue};
+use rustc_codegen_ssa::mir::place::PlaceRef;
+use rustc_codegen_ssa::traits::*;
+use rustc_hir as hir;
+use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, LayoutOf};
+use rustc_middle::ty::{self, GenericArgsRef, Ty};
+use rustc_middle::{bug, span_bug};
+use rustc_span::{sym, symbol::kw, Span, Symbol};
+use rustc_target::abi::{self, Align, HasDataLayout, Primitive};
+use rustc_target::spec::{HasTargetSpec, PanicStrategy};
+
+use std::cmp::Ordering;
+
+fn get_simple_intrinsic<'ll>(
+    cx: &CodegenCx<'ll, '_>,
+    name: Symbol,
+) -> Option<(&'ll Type, &'ll Value)> {
+    let llvm_name = match name {
+        sym::sqrtf32 => "llvm.sqrt.f32",
+        sym::sqrtf64 => "llvm.sqrt.f64",
+        sym::powif32 => "llvm.powi.f32",
+        sym::powif64 => "llvm.powi.f64",
+        sym::sinf32 => "llvm.sin.f32",
+        sym::sinf64 => "llvm.sin.f64",
+        sym::cosf32 => "llvm.cos.f32",
+        sym::cosf64 => "llvm.cos.f64",
+        sym::powf32 => "llvm.pow.f32",
+        sym::powf64 => "llvm.pow.f64",
+        sym::expf32 => "llvm.exp.f32",
+        sym::expf64 => "llvm.exp.f64",
+        sym::exp2f32 => "llvm.exp2.f32",
+        sym::exp2f64 => "llvm.exp2.f64",
+        sym::logf32 => "llvm.log.f32",
+        sym::logf64 => "llvm.log.f64",
+        sym::log10f32 => "llvm.log10.f32",
+        sym::log10f64 => "llvm.log10.f64",
+        sym::log2f32 => "llvm.log2.f32",
+        sym::log2f64 => "llvm.log2.f64",
+        sym::fmaf32 => "llvm.fma.f32",
+        sym::fmaf64 => "llvm.fma.f64",
+        sym::fabsf32 => "llvm.fabs.f32",
+        sym::fabsf64 => "llvm.fabs.f64",
+        sym::minnumf32 => "llvm.minnum.f32",
+        sym::minnumf64 => "llvm.minnum.f64",
+        sym::maxnumf32 => "llvm.maxnum.f32",
+        sym::maxnumf64 => "llvm.maxnum.f64",
+        sym::copysignf32 => "llvm.copysign.f32",
+        sym::copysignf64 => "llvm.copysign.f64",
+        sym::floorf32 => "llvm.floor.f32",
+        sym::floorf64 => "llvm.floor.f64",
+        sym::ceilf32 => "llvm.ceil.f32",
+        sym::ceilf64 => "llvm.ceil.f64",
+        sym::truncf32 => "llvm.trunc.f32",
+        sym::truncf64 => "llvm.trunc.f64",
+        sym::rintf32 => "llvm.rint.f32",
+        sym::rintf64 => "llvm.rint.f64",
+        sym::nearbyintf32 => "llvm.nearbyint.f32",
+        sym::nearbyintf64 => "llvm.nearbyint.f64",
+        sym::roundf32 => "llvm.round.f32",
+        sym::roundf64 => "llvm.round.f64",
+        sym::ptr_mask => "llvm.ptrmask",
+        sym::roundevenf32 => "llvm.roundeven.f32",
+        sym::roundevenf64 => "llvm.roundeven.f64",
+        _ => return None,
+    };
+    Some(cx.get_intrinsic(llvm_name))
+}
+
+impl<'ll, 'tcx> IntrinsicCallMethods<'tcx> for Builder<'_, 'll, 'tcx> {
+    fn codegen_intrinsic_call(
+        &mut self,
+        instance: ty::Instance<'tcx>,
+        fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
+        args: &[OperandRef<'tcx, &'ll Value>],
+        llresult: &'ll Value,
+        span: Span,
+    ) {
+        let tcx = self.tcx;
+        let callee_ty = instance.ty(tcx, ty::ParamEnv::reveal_all());
+
+        let ty::FnDef(def_id, fn_args) = *callee_ty.kind() else {
+            bug!("expected fn item type, found {}", callee_ty);
+        };
+
+        let sig = callee_ty.fn_sig(tcx);
+        let sig = tcx.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), sig);
+        let arg_tys = sig.inputs();
+        let ret_ty = sig.output();
+        let name = tcx.item_name(def_id);
+
+        let llret_ty = self.layout_of(ret_ty).llvm_type(self);
+        let result = PlaceRef::new_sized(llresult, fn_abi.ret.layout);
+
+        let simple = get_simple_intrinsic(self, name);
+        let llval = match name {
+            _ if simple.is_some() => {
+                let (simple_ty, simple_fn) = simple.unwrap();
+                self.call(
+                    simple_ty,
+                    None,
+                    None,
+                    simple_fn,
+                    &args.iter().map(|arg| arg.immediate()).collect::<Vec<_>>(),
+                    None,
+                )
+            }
+            sym::likely => {
+                self.call_intrinsic("llvm.expect.i1", &[args[0].immediate(), self.const_bool(true)])
+            }
+            sym::unlikely => self
+                .call_intrinsic("llvm.expect.i1", &[args[0].immediate(), self.const_bool(false)]),
+            kw::Try => {
+                try_intrinsic(
+                    self,
+                    args[0].immediate(),
+                    args[1].immediate(),
+                    args[2].immediate(),
+                    llresult,
+                );
+                return;
+            }
+            sym::breakpoint => self.call_intrinsic("llvm.debugtrap", &[]),
+            sym::va_copy => {
+                self.call_intrinsic("llvm.va_copy", &[args[0].immediate(), args[1].immediate()])
+            }
+            sym::va_arg => {
+                match fn_abi.ret.layout.abi {
+                    abi::Abi::Scalar(scalar) => {
+                        match scalar.primitive() {
+                            Primitive::Int(..) => {
+                                if self.cx().size_of(ret_ty).bytes() < 4 {
+                                    // `va_arg` should not be called on an integer type
+                                    // less than 4 bytes in length. If it is, promote
+                                    // the integer to an `i32` and truncate the result
+                                    // back to the smaller type.
+                                    let promoted_result = emit_va_arg(self, args[0], tcx.types.i32);
+                                    self.trunc(promoted_result, llret_ty)
+                                } else {
+                                    emit_va_arg(self, args[0], ret_ty)
+                                }
+                            }
+                            Primitive::F64 | Primitive::Pointer(_) => {
+                                emit_va_arg(self, args[0], ret_ty)
+                            }
+                            // `va_arg` should never be used with the return type f32.
+                            Primitive::F32 => bug!("the va_arg intrinsic does not work with `f32`"),
+                        }
+                    }
+                    _ => bug!("the va_arg intrinsic does not work with non-scalar types"),
+                }
+            }
+
+            sym::volatile_load | sym::unaligned_volatile_load => {
+                let tp_ty = fn_args.type_at(0);
+                let ptr = args[0].immediate();
+                let load = if let PassMode::Cast { cast: ty, pad_i32: _ } = &fn_abi.ret.mode {
+                    let llty = ty.llvm_type(self);
+                    self.volatile_load(llty, ptr)
+                } else {
+                    self.volatile_load(self.layout_of(tp_ty).llvm_type(self), ptr)
+                };
+                let align = if name == sym::unaligned_volatile_load {
+                    1
+                } else {
+                    self.align_of(tp_ty).bytes() as u32
+                };
+                unsafe {
+                    llvm::LLVMSetAlignment(load, align);
+                }
+                if !result.layout.is_zst() {
+                    self.store(load, result.llval, result.align);
+                }
+                return;
+            }
+            sym::volatile_store => {
+                let dst = args[0].deref(self.cx());
+                args[1].val.volatile_store(self, dst);
+                return;
+            }
+            sym::unaligned_volatile_store => {
+                let dst = args[0].deref(self.cx());
+                args[1].val.unaligned_volatile_store(self, dst);
+                return;
+            }
+            sym::prefetch_read_data
+            | sym::prefetch_write_data
+            | sym::prefetch_read_instruction
+            | sym::prefetch_write_instruction => {
+                let (rw, cache_type) = match name {
+                    sym::prefetch_read_data => (0, 1),
+                    sym::prefetch_write_data => (1, 1),
+                    sym::prefetch_read_instruction => (0, 0),
+                    sym::prefetch_write_instruction => (1, 0),
+                    _ => bug!(),
+                };
+                self.call_intrinsic(
+                    "llvm.prefetch",
+                    &[
+                        args[0].immediate(),
+                        self.const_i32(rw),
+                        args[1].immediate(),
+                        self.const_i32(cache_type),
+                    ],
+                )
+            }
+            sym::ctlz
+            | sym::ctlz_nonzero
+            | sym::cttz
+            | sym::cttz_nonzero
+            | sym::ctpop
+            | sym::bswap
+            | sym::bitreverse
+            | sym::rotate_left
+            | sym::rotate_right
+            | sym::saturating_add
+            | sym::saturating_sub => {
+                let ty = arg_tys[0];
+                match int_type_width_signed(ty, self) {
+                    Some((width, signed)) => match name {
+                        sym::ctlz | sym::cttz => {
+                            let y = self.const_bool(false);
+                            self.call_intrinsic(
+                                &format!("llvm.{name}.i{width}"),
+                                &[args[0].immediate(), y],
+                            )
+                        }
+                        sym::ctlz_nonzero => {
+                            let y = self.const_bool(true);
+                            let llvm_name = &format!("llvm.ctlz.i{width}");
+                            self.call_intrinsic(llvm_name, &[args[0].immediate(), y])
+                        }
+                        sym::cttz_nonzero => {
+                            let y = self.const_bool(true);
+                            let llvm_name = &format!("llvm.cttz.i{width}");
+                            self.call_intrinsic(llvm_name, &[args[0].immediate(), y])
+                        }
+                        sym::ctpop => self.call_intrinsic(
+                            &format!("llvm.ctpop.i{width}"),
+                            &[args[0].immediate()],
+                        ),
+                        sym::bswap => {
+                            if width == 8 {
+                                args[0].immediate() // byte swap a u8/i8 is just a no-op
+                            } else {
+                                self.call_intrinsic(
+                                    &format!("llvm.bswap.i{width}"),
+                                    &[args[0].immediate()],
+                                )
+                            }
+                        }
+                        sym::bitreverse => self.call_intrinsic(
+                            &format!("llvm.bitreverse.i{width}"),
+                            &[args[0].immediate()],
+                        ),
+                        sym::rotate_left | sym::rotate_right => {
+                            let is_left = name == sym::rotate_left;
+                            let val = args[0].immediate();
+                            let raw_shift = args[1].immediate();
+                            // rotate = funnel shift with first two args the same
+                            let llvm_name =
+                                &format!("llvm.fsh{}.i{}", if is_left { 'l' } else { 'r' }, width);
+                            self.call_intrinsic(llvm_name, &[val, val, raw_shift])
+                        }
+                        sym::saturating_add | sym::saturating_sub => {
+                            let is_add = name == sym::saturating_add;
+                            let lhs = args[0].immediate();
+                            let rhs = args[1].immediate();
+                            let llvm_name = &format!(
+                                "llvm.{}{}.sat.i{}",
+                                if signed { 's' } else { 'u' },
+                                if is_add { "add" } else { "sub" },
+                                width
+                            );
+                            self.call_intrinsic(llvm_name, &[lhs, rhs])
+                        }
+                        _ => bug!(),
+                    },
+                    None => {
+                        tcx.dcx().emit_err(InvalidMonomorphization::BasicIntegerType {
+                            span,
+                            name,
+                            ty,
+                        });
+                        return;
+                    }
+                }
+            }
+
+            sym::raw_eq => {
+                use abi::Abi::*;
+                let tp_ty = fn_args.type_at(0);
+                let layout = self.layout_of(tp_ty).layout;
+                let use_integer_compare = match layout.abi() {
+                    Scalar(_) | ScalarPair(_, _) => true,
+                    Uninhabited | Vector { .. } => false,
+                    Aggregate { .. } => {
+                        // For rusty ABIs, small aggregates are actually passed
+                        // as `RegKind::Integer` (see `FnAbi::adjust_for_abi`),
+                        // so we re-use that same threshold here.
+                        layout.size() <= self.data_layout().pointer_size * 2
+                    }
+                };
+
+                let a = args[0].immediate();
+                let b = args[1].immediate();
+                if layout.size().bytes() == 0 {
+                    self.const_bool(true)
+                } else if use_integer_compare {
+                    let integer_ty = self.type_ix(layout.size().bits());
+                    let a_val = self.load(integer_ty, a, layout.align().abi);
+                    let b_val = self.load(integer_ty, b, layout.align().abi);
+                    self.icmp(IntPredicate::IntEQ, a_val, b_val)
+                } else {
+                    let n = self.const_usize(layout.size().bytes());
+                    let cmp = self.call_intrinsic("memcmp", &[a, b, n]);
+                    match self.cx.sess().target.arch.as_ref() {
+                        "avr" | "msp430" => self.icmp(IntPredicate::IntEQ, cmp, self.const_i16(0)),
+                        _ => self.icmp(IntPredicate::IntEQ, cmp, self.const_i32(0)),
+                    }
+                }
+            }
+
+            sym::compare_bytes => {
+                // Here we assume that the `memcmp` provided by the target is a NOP for size 0.
+                let cmp = self.call_intrinsic(
+                    "memcmp",
+                    &[args[0].immediate(), args[1].immediate(), args[2].immediate()],
+                );
+                // Some targets have `memcmp` returning `i16`, but the intrinsic is always `i32`.
+                self.sext(cmp, self.type_ix(32))
+            }
+
+            sym::black_box => {
+                args[0].val.store(self, result);
+                let result_val_span = [result.llval];
+                // We need to "use" the argument in some way LLVM can't introspect, and on
+                // targets that support it we can typically leverage inline assembly to do
+                // this. LLVM's interpretation of inline assembly is that it's, well, a black
+                // box. This isn't the greatest implementation since it probably deoptimizes
+                // more than we want, but it's so far good enough.
+                //
+                // For zero-sized types, the location pointed to by the result may be
+                // uninitialized. Do not "use" the result in this case; instead just clobber
+                // the memory.
+                let (constraint, inputs): (&str, &[_]) = if result.layout.is_zst() {
+                    ("~{memory}", &[])
+                } else {
+                    ("r,~{memory}", &result_val_span)
+                };
+                crate::asm::inline_asm_call(
+                    self,
+                    "",
+                    constraint,
+                    inputs,
+                    self.type_void(),
+                    true,
+                    false,
+                    llvm::AsmDialect::Att,
+                    &[span],
+                    false,
+                    None,
+                )
+                .unwrap_or_else(|| bug!("failed to generate inline asm call for `black_box`"));
+
+                // We have copied the value to `result` already.
+                return;
+            }
+
+            _ if name.as_str().starts_with("simd_") => {
+                match generic_simd_intrinsic(
+                    self, name, callee_ty, fn_args, args, ret_ty, llret_ty, span,
+                ) {
+                    Ok(llval) => llval,
+                    Err(()) => return,
+                }
+            }
+
+            _ => bug!("unknown intrinsic '{}' -- should it have been lowered earlier?", name),
+        };
+
+        if !fn_abi.ret.is_ignore() {
+            if let PassMode::Cast { .. } = &fn_abi.ret.mode {
+                self.store(llval, result.llval, result.align);
+            } else {
+                OperandRef::from_immediate_or_packed_pair(self, llval, result.layout)
+                    .val
+                    .store(self, result);
+            }
+        }
+    }
+
+    fn abort(&mut self) {
+        self.call_intrinsic("llvm.trap", &[]);
+    }
+
+    fn assume(&mut self, val: Self::Value) {
+        self.call_intrinsic("llvm.assume", &[val]);
+    }
+
+    fn expect(&mut self, cond: Self::Value, expected: bool) -> Self::Value {
+        self.call_intrinsic("llvm.expect.i1", &[cond, self.const_bool(expected)])
+    }
+
+    fn type_test(&mut self, pointer: Self::Value, typeid: Self::Value) -> Self::Value {
+        // Test the called operand using llvm.type.test intrinsic. The LowerTypeTests link-time
+        // optimization pass replaces calls to this intrinsic with code to test type membership.
+        self.call_intrinsic("llvm.type.test", &[pointer, typeid])
+    }
+
+    fn type_checked_load(
+        &mut self,
+        llvtable: &'ll Value,
+        vtable_byte_offset: u64,
+        typeid: &'ll Value,
+    ) -> Self::Value {
+        let vtable_byte_offset = self.const_i32(vtable_byte_offset as i32);
+        let type_checked_load =
+            self.call_intrinsic("llvm.type.checked.load", &[llvtable, vtable_byte_offset, typeid]);
+        self.extract_value(type_checked_load, 0)
+    }
+
+    fn va_start(&mut self, va_list: &'ll Value) -> &'ll Value {
+        self.call_intrinsic("llvm.va_start", &[va_list])
+    }
+
+    fn va_end(&mut self, va_list: &'ll Value) -> &'ll Value {
+        self.call_intrinsic("llvm.va_end", &[va_list])
+    }
+}
+
+fn try_intrinsic<'ll>(
+    bx: &mut Builder<'_, 'll, '_>,
+    try_func: &'ll Value,
+    data: &'ll Value,
+    catch_func: &'ll Value,
+    dest: &'ll Value,
+) {
+    if bx.sess().panic_strategy() == PanicStrategy::Abort {
+        let try_func_ty = bx.type_func(&[bx.type_ptr()], bx.type_void());
+        bx.call(try_func_ty, None, None, try_func, &[data], None);
+        // Return 0 unconditionally from the intrinsic call;
+        // we can never unwind.
+        let ret_align = bx.tcx().data_layout.i32_align.abi;
+        bx.store(bx.const_i32(0), dest, ret_align);
+    } else if wants_msvc_seh(bx.sess()) {
+        codegen_msvc_try(bx, try_func, data, catch_func, dest);
+    } else if wants_wasm_eh(bx.sess()) {
+        codegen_wasm_try(bx, try_func, data, catch_func, dest);
+    } else if bx.sess().target.os == "emscripten" {
+        codegen_emcc_try(bx, try_func, data, catch_func, dest);
+    } else {
+        codegen_gnu_try(bx, try_func, data, catch_func, dest);
+    }
+}
+
+// MSVC's definition of the `rust_try` function.
+//
+// This implementation uses the new exception handling instructions in LLVM
+// which have support in LLVM for SEH on MSVC targets. Although these
+// instructions are meant to work for all targets, as of the time of this
+// writing, however, LLVM does not recommend the usage of these new instructions
+// as the old ones are still more optimized.
+fn codegen_msvc_try<'ll>(
+    bx: &mut Builder<'_, 'll, '_>,
+    try_func: &'ll Value,
+    data: &'ll Value,
+    catch_func: &'ll Value,
+    dest: &'ll Value,
+) {
+    let (llty, llfn) = get_rust_try_fn(bx, &mut |mut bx| {
+        bx.set_personality_fn(bx.eh_personality());
+
+        let normal = bx.append_sibling_block("normal");
+        let catchswitch = bx.append_sibling_block("catchswitch");
+        let catchpad_rust = bx.append_sibling_block("catchpad_rust");
+        let catchpad_foreign = bx.append_sibling_block("catchpad_foreign");
+        let caught = bx.append_sibling_block("caught");
+
+        let try_func = llvm::get_param(bx.llfn(), 0);
+        let data = llvm::get_param(bx.llfn(), 1);
+        let catch_func = llvm::get_param(bx.llfn(), 2);
+
+        // We're generating an IR snippet that looks like:
+        //
+        //   declare i32 @rust_try(%try_func, %data, %catch_func) {
+        //      %slot = alloca i8*
+        //      invoke %try_func(%data) to label %normal unwind label %catchswitch
+        //
+        //   normal:
+        //      ret i32 0
+        //
+        //   catchswitch:
+        //      %cs = catchswitch within none [%catchpad_rust, %catchpad_foreign] unwind to caller
+        //
+        //   catchpad_rust:
+        //      %tok = catchpad within %cs [%type_descriptor, 8, %slot]
+        //      %ptr = load %slot
+        //      call %catch_func(%data, %ptr)
+        //      catchret from %tok to label %caught
+        //
+        //   catchpad_foreign:
+        //      %tok = catchpad within %cs [null, 64, null]
+        //      call %catch_func(%data, null)
+        //      catchret from %tok to label %caught
+        //
+        //   caught:
+        //      ret i32 1
+        //   }
+        //
+        // This structure follows the basic usage of throw/try/catch in LLVM.
+        // For example, compile this C++ snippet to see what LLVM generates:
+        //
+        //      struct rust_panic {
+        //          rust_panic(const rust_panic&);
+        //          ~rust_panic();
+        //
+        //          void* x[2];
+        //      };
+        //
+        //      int __rust_try(
+        //          void (*try_func)(void*),
+        //          void *data,
+        //          void (*catch_func)(void*, void*) noexcept
+        //      ) {
+        //          try {
+        //              try_func(data);
+        //              return 0;
+        //          } catch(rust_panic& a) {
+        //              catch_func(data, &a);
+        //              return 1;
+        //          } catch(...) {
+        //              catch_func(data, NULL);
+        //              return 1;
+        //          }
+        //      }
+        //
+        // More information can be found in libstd's seh.rs implementation.
+        let ptr_align = bx.tcx().data_layout.pointer_align.abi;
+        let slot = bx.alloca(bx.type_ptr(), ptr_align);
+        let try_func_ty = bx.type_func(&[bx.type_ptr()], bx.type_void());
+        bx.invoke(try_func_ty, None, None, try_func, &[data], normal, catchswitch, None);
+
+        bx.switch_to_block(normal);
+        bx.ret(bx.const_i32(0));
+
+        bx.switch_to_block(catchswitch);
+        let cs = bx.catch_switch(None, None, &[catchpad_rust, catchpad_foreign]);
+
+        // We can't use the TypeDescriptor defined in libpanic_unwind because it
+        // might be in another DLL and the SEH encoding only supports specifying
+        // a TypeDescriptor from the current module.
+        //
+        // However this isn't an issue since the MSVC runtime uses string
+        // comparison on the type name to match TypeDescriptors rather than
+        // pointer equality.
+        //
+        // So instead we generate a new TypeDescriptor in each module that uses
+        // `try` and let the linker merge duplicate definitions in the same
+        // module.
+        //
+        // When modifying, make sure that the type_name string exactly matches
+        // the one used in library/panic_unwind/src/seh.rs.
+        let type_info_vtable = bx.declare_global("??_7type_info@@6B@", bx.type_ptr());
+        let type_name = bx.const_bytes(b"rust_panic\0");
+        let type_info =
+            bx.const_struct(&[type_info_vtable, bx.const_null(bx.type_ptr()), type_name], false);
+        let tydesc = bx.declare_global("__rust_panic_type_info", bx.val_ty(type_info));
+        unsafe {
+            llvm::LLVMRustSetLinkage(tydesc, llvm::Linkage::LinkOnceODRLinkage);
+            llvm::SetUniqueComdat(bx.llmod, tydesc);
+            llvm::LLVMSetInitializer(tydesc, type_info);
+        }
+
+        // The flag value of 8 indicates that we are catching the exception by
+        // reference instead of by value. We can't use catch by value because
+        // that requires copying the exception object, which we don't support
+        // since our exception object effectively contains a Box.
+        //
+        // Source: MicrosoftCXXABI::getAddrOfCXXCatchHandlerType in clang
+        bx.switch_to_block(catchpad_rust);
+        let flags = bx.const_i32(8);
+        let funclet = bx.catch_pad(cs, &[tydesc, flags, slot]);
+        let ptr = bx.load(bx.type_ptr(), slot, ptr_align);
+        let catch_ty = bx.type_func(&[bx.type_ptr(), bx.type_ptr()], bx.type_void());
+        bx.call(catch_ty, None, None, catch_func, &[data, ptr], Some(&funclet));
+        bx.catch_ret(&funclet, caught);
+
+        // The flag value of 64 indicates a "catch-all".
+        bx.switch_to_block(catchpad_foreign);
+        let flags = bx.const_i32(64);
+        let null = bx.const_null(bx.type_ptr());
+        let funclet = bx.catch_pad(cs, &[null, flags, null]);
+        bx.call(catch_ty, None, None, catch_func, &[data, null], Some(&funclet));
+        bx.catch_ret(&funclet, caught);
+
+        bx.switch_to_block(caught);
+        bx.ret(bx.const_i32(1));
+    });
+
+    // Note that no invoke is used here because by definition this function
+    // can't panic (that's what it's catching).
+    let ret = bx.call(llty, None, None, llfn, &[try_func, data, catch_func], None);
+    let i32_align = bx.tcx().data_layout.i32_align.abi;
+    bx.store(ret, dest, i32_align);
+}
+
+// WASM's definition of the `rust_try` function.
+fn codegen_wasm_try<'ll>(
+    bx: &mut Builder<'_, 'll, '_>,
+    try_func: &'ll Value,
+    data: &'ll Value,
+    catch_func: &'ll Value,
+    dest: &'ll Value,
+) {
+    let (llty, llfn) = get_rust_try_fn(bx, &mut |mut bx| {
+        bx.set_personality_fn(bx.eh_personality());
+
+        let normal = bx.append_sibling_block("normal");
+        let catchswitch = bx.append_sibling_block("catchswitch");
+        let catchpad = bx.append_sibling_block("catchpad");
+        let caught = bx.append_sibling_block("caught");
+
+        let try_func = llvm::get_param(bx.llfn(), 0);
+        let data = llvm::get_param(bx.llfn(), 1);
+        let catch_func = llvm::get_param(bx.llfn(), 2);
+
+        // We're generating an IR snippet that looks like:
+        //
+        //   declare i32 @rust_try(%try_func, %data, %catch_func) {
+        //      %slot = alloca i8*
+        //      invoke %try_func(%data) to label %normal unwind label %catchswitch
+        //
+        //   normal:
+        //      ret i32 0
+        //
+        //   catchswitch:
+        //      %cs = catchswitch within none [%catchpad] unwind to caller
+        //
+        //   catchpad:
+        //      %tok = catchpad within %cs [null]
+        //      %ptr = call @llvm.wasm.get.exception(token %tok)
+        //      %sel = call @llvm.wasm.get.ehselector(token %tok)
+        //      call %catch_func(%data, %ptr)
+        //      catchret from %tok to label %caught
+        //
+        //   caught:
+        //      ret i32 1
+        //   }
+        //
+        let try_func_ty = bx.type_func(&[bx.type_ptr()], bx.type_void());
+        bx.invoke(try_func_ty, None, None, try_func, &[data], normal, catchswitch, None);
+
+        bx.switch_to_block(normal);
+        bx.ret(bx.const_i32(0));
+
+        bx.switch_to_block(catchswitch);
+        let cs = bx.catch_switch(None, None, &[catchpad]);
+
+        bx.switch_to_block(catchpad);
+        let null = bx.const_null(bx.type_ptr());
+        let funclet = bx.catch_pad(cs, &[null]);
+
+        let ptr = bx.call_intrinsic("llvm.wasm.get.exception", &[funclet.cleanuppad()]);
+        let _sel = bx.call_intrinsic("llvm.wasm.get.ehselector", &[funclet.cleanuppad()]);
+
+        let catch_ty = bx.type_func(&[bx.type_ptr(), bx.type_ptr()], bx.type_void());
+        bx.call(catch_ty, None, None, catch_func, &[data, ptr], Some(&funclet));
+        bx.catch_ret(&funclet, caught);
+
+        bx.switch_to_block(caught);
+        bx.ret(bx.const_i32(1));
+    });
+
+    // Note that no invoke is used here because by definition this function
+    // can't panic (that's what it's catching).
+    let ret = bx.call(llty, None, None, llfn, &[try_func, data, catch_func], None);
+    let i32_align = bx.tcx().data_layout.i32_align.abi;
+    bx.store(ret, dest, i32_align);
+}
+
+// Definition of the standard `try` function for Rust using the GNU-like model
+// of exceptions (e.g., the normal semantics of LLVM's `landingpad` and `invoke`
+// instructions).
+//
+// This codegen is a little surprising because we always call a shim
+// function instead of inlining the call to `invoke` manually here. This is done
+// because in LLVM we're only allowed to have one personality per function
+// definition. The call to the `try` intrinsic is being inlined into the
+// function calling it, and that function may already have other personality
+// functions in play. By calling a shim we're guaranteed that our shim will have
+// the right personality function.
+fn codegen_gnu_try<'ll>(
+    bx: &mut Builder<'_, 'll, '_>,
+    try_func: &'ll Value,
+    data: &'ll Value,
+    catch_func: &'ll Value,
+    dest: &'ll Value,
+) {
+    let (llty, llfn) = get_rust_try_fn(bx, &mut |mut bx| {
+        // Codegens the shims described above:
+        //
+        //   bx:
+        //      invoke %try_func(%data) normal %normal unwind %catch
+        //
+        //   normal:
+        //      ret 0
+        //
+        //   catch:
+        //      (%ptr, _) = landingpad
+        //      call %catch_func(%data, %ptr)
+        //      ret 1
+        let then = bx.append_sibling_block("then");
+        let catch = bx.append_sibling_block("catch");
+
+        let try_func = llvm::get_param(bx.llfn(), 0);
+        let data = llvm::get_param(bx.llfn(), 1);
+        let catch_func = llvm::get_param(bx.llfn(), 2);
+        let try_func_ty = bx.type_func(&[bx.type_ptr()], bx.type_void());
+        bx.invoke(try_func_ty, None, None, try_func, &[data], then, catch, None);
+
+        bx.switch_to_block(then);
+        bx.ret(bx.const_i32(0));
+
+        // Type indicator for the exception being thrown.
+        //
+        // The first value in this tuple is a pointer to the exception object
+        // being thrown. The second value is a "selector" indicating which of
+        // the landing pad clauses the exception's type had been matched to.
+        // rust_try ignores the selector.
+        bx.switch_to_block(catch);
+        let lpad_ty = bx.type_struct(&[bx.type_ptr(), bx.type_i32()], false);
+        let vals = bx.landing_pad(lpad_ty, bx.eh_personality(), 1);
+        let tydesc = bx.const_null(bx.type_ptr());
+        bx.add_clause(vals, tydesc);
+        let ptr = bx.extract_value(vals, 0);
+        let catch_ty = bx.type_func(&[bx.type_ptr(), bx.type_ptr()], bx.type_void());
+        bx.call(catch_ty, None, None, catch_func, &[data, ptr], None);
+        bx.ret(bx.const_i32(1));
+    });
+
+    // Note that no invoke is used here because by definition this function
+    // can't panic (that's what it's catching).
+    let ret = bx.call(llty, None, None, llfn, &[try_func, data, catch_func], None);
+    let i32_align = bx.tcx().data_layout.i32_align.abi;
+    bx.store(ret, dest, i32_align);
+}
+
+// Variant of codegen_gnu_try used for emscripten where Rust panics are
+// implemented using C++ exceptions. Here we use exceptions of a specific type
+// (`struct rust_panic`) to represent Rust panics.
+fn codegen_emcc_try<'ll>(
+    bx: &mut Builder<'_, 'll, '_>,
+    try_func: &'ll Value,
+    data: &'ll Value,
+    catch_func: &'ll Value,
+    dest: &'ll Value,
+) {
+    let (llty, llfn) = get_rust_try_fn(bx, &mut |mut bx| {
+        // Codegens the shims described above:
+        //
+        //   bx:
+        //      invoke %try_func(%data) normal %normal unwind %catch
+        //
+        //   normal:
+        //      ret 0
+        //
+        //   catch:
+        //      (%ptr, %selector) = landingpad
+        //      %rust_typeid = @llvm.eh.typeid.for(@_ZTI10rust_panic)
+        //      %is_rust_panic = %selector == %rust_typeid
+        //      %catch_data = alloca { i8*, i8 }
+        //      %catch_data[0] = %ptr
+        //      %catch_data[1] = %is_rust_panic
+        //      call %catch_func(%data, %catch_data)
+        //      ret 1
+        let then = bx.append_sibling_block("then");
+        let catch = bx.append_sibling_block("catch");
+
+        let try_func = llvm::get_param(bx.llfn(), 0);
+        let data = llvm::get_param(bx.llfn(), 1);
+        let catch_func = llvm::get_param(bx.llfn(), 2);
+        let try_func_ty = bx.type_func(&[bx.type_ptr()], bx.type_void());
+        bx.invoke(try_func_ty, None, None, try_func, &[data], then, catch, None);
+
+        bx.switch_to_block(then);
+        bx.ret(bx.const_i32(0));
+
+        // Type indicator for the exception being thrown.
+        //
+        // The first value in this tuple is a pointer to the exception object
+        // being thrown. The second value is a "selector" indicating which of
+        // the landing pad clauses the exception's type had been matched to.
+        bx.switch_to_block(catch);
+        let tydesc = bx.eh_catch_typeinfo();
+        let lpad_ty = bx.type_struct(&[bx.type_ptr(), bx.type_i32()], false);
+        let vals = bx.landing_pad(lpad_ty, bx.eh_personality(), 2);
+        bx.add_clause(vals, tydesc);
+        bx.add_clause(vals, bx.const_null(bx.type_ptr()));
+        let ptr = bx.extract_value(vals, 0);
+        let selector = bx.extract_value(vals, 1);
+
+        // Check if the typeid we got is the one for a Rust panic.
+        let rust_typeid = bx.call_intrinsic("llvm.eh.typeid.for", &[tydesc]);
+        let is_rust_panic = bx.icmp(IntPredicate::IntEQ, selector, rust_typeid);
+        let is_rust_panic = bx.zext(is_rust_panic, bx.type_bool());
+
+        // We need to pass two values to catch_func (ptr and is_rust_panic), so
+        // create an alloca and pass a pointer to that.
+        let ptr_align = bx.tcx().data_layout.pointer_align.abi;
+        let i8_align = bx.tcx().data_layout.i8_align.abi;
+        let catch_data_type = bx.type_struct(&[bx.type_ptr(), bx.type_bool()], false);
+        let catch_data = bx.alloca(catch_data_type, ptr_align);
+        let catch_data_0 =
+            bx.inbounds_gep(catch_data_type, catch_data, &[bx.const_usize(0), bx.const_usize(0)]);
+        bx.store(ptr, catch_data_0, ptr_align);
+        let catch_data_1 =
+            bx.inbounds_gep(catch_data_type, catch_data, &[bx.const_usize(0), bx.const_usize(1)]);
+        bx.store(is_rust_panic, catch_data_1, i8_align);
+
+        let catch_ty = bx.type_func(&[bx.type_ptr(), bx.type_ptr()], bx.type_void());
+        bx.call(catch_ty, None, None, catch_func, &[data, catch_data], None);
+        bx.ret(bx.const_i32(1));
+    });
+
+    // Note that no invoke is used here because by definition this function
+    // can't panic (that's what it's catching).
+    let ret = bx.call(llty, None, None, llfn, &[try_func, data, catch_func], None);
+    let i32_align = bx.tcx().data_layout.i32_align.abi;
+    bx.store(ret, dest, i32_align);
+}
+
+// Helper function to give a Block to a closure to codegen a shim function.
+// This is currently primarily used for the `try` intrinsic functions above.
+fn gen_fn<'ll, 'tcx>(
+    cx: &CodegenCx<'ll, 'tcx>,
+    name: &str,
+    rust_fn_sig: ty::PolyFnSig<'tcx>,
+    codegen: &mut dyn FnMut(Builder<'_, 'll, 'tcx>),
+) -> (&'ll Type, &'ll Value) {
+    let fn_abi = cx.fn_abi_of_fn_ptr(rust_fn_sig, ty::List::empty());
+    let llty = fn_abi.llvm_type(cx);
+    let llfn = cx.declare_fn(name, fn_abi, None);
+    cx.set_frame_pointer_type(llfn);
+    cx.apply_target_cpu_attr(llfn);
+    // FIXME(eddyb) find a nicer way to do this.
+    unsafe { llvm::LLVMRustSetLinkage(llfn, llvm::Linkage::InternalLinkage) };
+    let llbb = Builder::append_block(cx, llfn, "entry-block");
+    let bx = Builder::build(cx, llbb);
+    codegen(bx);
+    (llty, llfn)
+}
+
+// Helper function used to get a handle to the `__rust_try` function used to
+// catch exceptions.
+//
+// This function is only generated once and is then cached.
+fn get_rust_try_fn<'ll, 'tcx>(
+    cx: &CodegenCx<'ll, 'tcx>,
+    codegen: &mut dyn FnMut(Builder<'_, 'll, 'tcx>),
+) -> (&'ll Type, &'ll Value) {
+    if let Some(llfn) = cx.rust_try_fn.get() {
+        return llfn;
+    }
+
+    // Define the type up front for the signature of the rust_try function.
+    let tcx = cx.tcx;
+    let i8p = Ty::new_mut_ptr(tcx, tcx.types.i8);
+    // `unsafe fn(*mut i8) -> ()`
+    let try_fn_ty = Ty::new_fn_ptr(
+        tcx,
+        ty::Binder::dummy(tcx.mk_fn_sig(
+            [i8p],
+            Ty::new_unit(tcx),
+            false,
+            hir::Unsafety::Unsafe,
+            Abi::Rust,
+        )),
+    );
+    // `unsafe fn(*mut i8, *mut i8) -> ()`
+    let catch_fn_ty = Ty::new_fn_ptr(
+        tcx,
+        ty::Binder::dummy(tcx.mk_fn_sig(
+            [i8p, i8p],
+            Ty::new_unit(tcx),
+            false,
+            hir::Unsafety::Unsafe,
+            Abi::Rust,
+        )),
+    );
+    // `unsafe fn(unsafe fn(*mut i8) -> (), *mut i8, unsafe fn(*mut i8, *mut i8) -> ()) -> i32`
+    let rust_fn_sig = ty::Binder::dummy(cx.tcx.mk_fn_sig(
+        [try_fn_ty, i8p, catch_fn_ty],
+        tcx.types.i32,
+        false,
+        hir::Unsafety::Unsafe,
+        Abi::Rust,
+    ));
+    let rust_try = gen_fn(cx, "__rust_try", rust_fn_sig, codegen);
+    cx.rust_try_fn.set(Some(rust_try));
+    rust_try
+}
+
+fn generic_simd_intrinsic<'ll, 'tcx>(
+    bx: &mut Builder<'_, 'll, 'tcx>,
+    name: Symbol,
+    callee_ty: Ty<'tcx>,
+    fn_args: GenericArgsRef<'tcx>,
+    args: &[OperandRef<'tcx, &'ll Value>],
+    ret_ty: Ty<'tcx>,
+    llret_ty: &'ll Type,
+    span: Span,
+) -> Result<&'ll Value, ()> {
+    macro_rules! return_error {
+        ($diag: expr) => {{
+            bx.sess().dcx().emit_err($diag);
+            return Err(());
+        }};
+    }
+
+    macro_rules! require {
+        ($cond: expr, $diag: expr) => {
+            if !$cond {
+                return_error!($diag);
+            }
+        };
+    }
+
+    macro_rules! require_simd {
+        ($ty: expr, $variant:ident) => {{
+            require!($ty.is_simd(), InvalidMonomorphization::$variant { span, name, ty: $ty });
+            $ty.simd_size_and_type(bx.tcx())
+        }};
+    }
+
+    let tcx = bx.tcx();
+    let sig =
+        tcx.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), callee_ty.fn_sig(tcx));
+    let arg_tys = sig.inputs();
+
+    // Vectors must be immediates (non-power-of-2 #[repr(packed)] are not)
+    for (ty, arg) in arg_tys.iter().zip(args) {
+        if ty.is_simd() && !matches!(arg.val, OperandValue::Immediate(_)) {
+            return_error!(InvalidMonomorphization::SimdArgument { span, name, ty: *ty });
+        }
+    }
+
+    if name == sym::simd_select_bitmask {
+        let (len, _) = require_simd!(arg_tys[1], SimdArgument);
+
+        let expected_int_bits = (len.max(8) - 1).next_power_of_two();
+        let expected_bytes = len / 8 + ((len % 8 > 0) as u64);
+
+        let mask_ty = arg_tys[0];
+        let mask = match mask_ty.kind() {
+            ty::Int(i) if i.bit_width() == Some(expected_int_bits) => args[0].immediate(),
+            ty::Uint(i) if i.bit_width() == Some(expected_int_bits) => args[0].immediate(),
+            ty::Array(elem, len)
+                if matches!(elem.kind(), ty::Uint(ty::UintTy::U8))
+                    && len.try_eval_target_usize(bx.tcx, ty::ParamEnv::reveal_all())
+                        == Some(expected_bytes) =>
+            {
+                let place = PlaceRef::alloca(bx, args[0].layout);
+                args[0].val.store(bx, place);
+                let int_ty = bx.type_ix(expected_bytes * 8);
+                bx.load(int_ty, place.llval, Align::ONE)
+            }
+            _ => return_error!(InvalidMonomorphization::InvalidBitmask {
+                span,
+                name,
+                mask_ty,
+                expected_int_bits,
+                expected_bytes
+            }),
+        };
+
+        let i1 = bx.type_i1();
+        let im = bx.type_ix(len);
+        let i1xn = bx.type_vector(i1, len);
+        let m_im = bx.trunc(mask, im);
+        let m_i1s = bx.bitcast(m_im, i1xn);
+        return Ok(bx.select(m_i1s, args[1].immediate(), args[2].immediate()));
+    }
+
+    // every intrinsic below takes a SIMD vector as its first argument
+    let (in_len, in_elem) = require_simd!(arg_tys[0], SimdInput);
+    let in_ty = arg_tys[0];
+
+    let comparison = match name {
+        sym::simd_eq => Some(hir::BinOpKind::Eq),
+        sym::simd_ne => Some(hir::BinOpKind::Ne),
+        sym::simd_lt => Some(hir::BinOpKind::Lt),
+        sym::simd_le => Some(hir::BinOpKind::Le),
+        sym::simd_gt => Some(hir::BinOpKind::Gt),
+        sym::simd_ge => Some(hir::BinOpKind::Ge),
+        _ => None,
+    };
+
+    if let Some(cmp_op) = comparison {
+        let (out_len, out_ty) = require_simd!(ret_ty, SimdReturn);
+
+        require!(
+            in_len == out_len,
+            InvalidMonomorphization::ReturnLengthInputType {
+                span,
+                name,
+                in_len,
+                in_ty,
+                ret_ty,
+                out_len
+            }
+        );
+        require!(
+            bx.type_kind(bx.element_type(llret_ty)) == TypeKind::Integer,
+            InvalidMonomorphization::ReturnIntegerType { span, name, ret_ty, out_ty }
+        );
+
+        return Ok(compare_simd_types(
+            bx,
+            args[0].immediate(),
+            args[1].immediate(),
+            in_elem,
+            llret_ty,
+            cmp_op,
+        ));
+    }
+
+    if name == sym::simd_shuffle_generic {
+        let idx = fn_args[2]
+            .expect_const()
+            .eval(tcx, ty::ParamEnv::reveal_all(), Some(span))
+            .unwrap()
+            .unwrap_branch();
+        let n = idx.len() as u64;
+
+        let (out_len, out_ty) = require_simd!(ret_ty, SimdReturn);
+        require!(
+            out_len == n,
+            InvalidMonomorphization::ReturnLength { span, name, in_len: n, ret_ty, out_len }
+        );
+        require!(
+            in_elem == out_ty,
+            InvalidMonomorphization::ReturnElement { span, name, in_elem, in_ty, ret_ty, out_ty }
+        );
+
+        let total_len = in_len * 2;
+
+        let indices: Option<Vec<_>> = idx
+            .iter()
+            .enumerate()
+            .map(|(arg_idx, val)| {
+                let idx = val.unwrap_leaf().try_to_i32().unwrap();
+                if idx >= i32::try_from(total_len).unwrap() {
+                    bx.sess().dcx().emit_err(InvalidMonomorphization::ShuffleIndexOutOfBounds {
+                        span,
+                        name,
+                        arg_idx: arg_idx as u64,
+                        total_len: total_len.into(),
+                    });
+                    None
+                } else {
+                    Some(bx.const_i32(idx))
+                }
+            })
+            .collect();
+        let Some(indices) = indices else {
+            return Ok(bx.const_null(llret_ty));
+        };
+
+        return Ok(bx.shuffle_vector(
+            args[0].immediate(),
+            args[1].immediate(),
+            bx.const_vector(&indices),
+        ));
+    }
+
+    if name == sym::simd_shuffle {
+        // Make sure this is actually an array, since typeck only checks the length-suffixed
+        // version of this intrinsic.
+        let n: u64 = match args[2].layout.ty.kind() {
+            ty::Array(ty, len) if matches!(ty.kind(), ty::Uint(ty::UintTy::U32)) => {
+                len.try_eval_target_usize(bx.cx.tcx, ty::ParamEnv::reveal_all()).unwrap_or_else(
+                    || span_bug!(span, "could not evaluate shuffle index array length"),
+                )
+            }
+            _ => return_error!(InvalidMonomorphization::SimdShuffle {
+                span,
+                name,
+                ty: args[2].layout.ty
+            }),
+        };
+
+        let (out_len, out_ty) = require_simd!(ret_ty, SimdReturn);
+        require!(
+            out_len == n,
+            InvalidMonomorphization::ReturnLength { span, name, in_len: n, ret_ty, out_len }
+        );
+        require!(
+            in_elem == out_ty,
+            InvalidMonomorphization::ReturnElement { span, name, in_elem, in_ty, ret_ty, out_ty }
+        );
+
+        let total_len = u128::from(in_len) * 2;
+
+        let vector = args[2].immediate();
+
+        let indices: Option<Vec<_>> = (0..n)
+            .map(|i| {
+                let arg_idx = i;
+                let val = bx.const_get_elt(vector, i as u64);
+                match bx.const_to_opt_u128(val, true) {
+                    None => {
+                        bx.sess().dcx().emit_err(
+                            InvalidMonomorphization::ShuffleIndexNotConstant {
+                                span,
+                                name,
+                                arg_idx,
+                            },
+                        );
+                        None
+                    }
+                    Some(idx) if idx >= total_len => {
+                        bx.sess().dcx().emit_err(
+                            InvalidMonomorphization::ShuffleIndexOutOfBounds {
+                                span,
+                                name,
+                                arg_idx,
+                                total_len,
+                            },
+                        );
+                        None
+                    }
+                    Some(idx) => Some(bx.const_i32(idx as i32)),
+                }
+            })
+            .collect();
+        let Some(indices) = indices else {
+            return Ok(bx.const_null(llret_ty));
+        };
+
+        return Ok(bx.shuffle_vector(
+            args[0].immediate(),
+            args[1].immediate(),
+            bx.const_vector(&indices),
+        ));
+    }
+
+    if name == sym::simd_insert {
+        require!(
+            in_elem == arg_tys[2],
+            InvalidMonomorphization::InsertedType {
+                span,
+                name,
+                in_elem,
+                in_ty,
+                out_ty: arg_tys[2]
+            }
+        );
+        return Ok(bx.insert_element(
+            args[0].immediate(),
+            args[2].immediate(),
+            args[1].immediate(),
+        ));
+    }
+    if name == sym::simd_extract {
+        require!(
+            ret_ty == in_elem,
+            InvalidMonomorphization::ReturnType { span, name, in_elem, in_ty, ret_ty }
+        );
+        return Ok(bx.extract_element(args[0].immediate(), args[1].immediate()));
+    }
+
+    if name == sym::simd_select {
+        let m_elem_ty = in_elem;
+        let m_len = in_len;
+        let (v_len, _) = require_simd!(arg_tys[1], SimdArgument);
+        require!(
+            m_len == v_len,
+            InvalidMonomorphization::MismatchedLengths { span, name, m_len, v_len }
+        );
+        match m_elem_ty.kind() {
+            ty::Int(_) => {}
+            _ => return_error!(InvalidMonomorphization::MaskType { span, name, ty: m_elem_ty }),
+        }
+        // truncate the mask to a vector of i1s
+        let i1 = bx.type_i1();
+        let i1xn = bx.type_vector(i1, m_len as u64);
+        let m_i1s = bx.trunc(args[0].immediate(), i1xn);
+        return Ok(bx.select(m_i1s, args[1].immediate(), args[2].immediate()));
+    }
+
+    if name == sym::simd_bitmask {
+        // The `fn simd_bitmask(vector) -> unsigned integer` intrinsic takes a
+        // vector mask and returns the most significant bit (MSB) of each lane in the form
+        // of either:
+        // * an unsigned integer
+        // * an array of `u8`
+        // If the vector has less than 8 lanes, a u8 is returned with zeroed trailing bits.
+        //
+        // The bit order of the result depends on the byte endianness, LSB-first for little
+        // endian and MSB-first for big endian.
+        let expected_int_bits = in_len.max(8);
+        let expected_bytes = expected_int_bits / 8 + ((expected_int_bits % 8 > 0) as u64);
+
+        // Integer vector <i{in_bitwidth} x in_len>:
+        let (i_xn, in_elem_bitwidth) = match in_elem.kind() {
+            ty::Int(i) => (
+                args[0].immediate(),
+                i.bit_width().unwrap_or_else(|| bx.data_layout().pointer_size.bits()),
+            ),
+            ty::Uint(i) => (
+                args[0].immediate(),
+                i.bit_width().unwrap_or_else(|| bx.data_layout().pointer_size.bits()),
+            ),
+            _ => return_error!(InvalidMonomorphization::VectorArgument {
+                span,
+                name,
+                in_ty,
+                in_elem
+            }),
+        };
+
+        // Shift the MSB to the right by "in_elem_bitwidth - 1" into the first bit position.
+        let shift_indices =
+            vec![
+                bx.cx.const_int(bx.type_ix(in_elem_bitwidth), (in_elem_bitwidth - 1) as _);
+                in_len as _
+            ];
+        let i_xn_msb = bx.lshr(i_xn, bx.const_vector(shift_indices.as_slice()));
+        // Truncate vector to an <i1 x N>
+        let i1xn = bx.trunc(i_xn_msb, bx.type_vector(bx.type_i1(), in_len));
+        // Bitcast <i1 x N> to iN:
+        let i_ = bx.bitcast(i1xn, bx.type_ix(in_len));
+
+        match ret_ty.kind() {
+            ty::Uint(i) if i.bit_width() == Some(expected_int_bits) => {
+                // Zero-extend iN to the bitmask type:
+                return Ok(bx.zext(i_, bx.type_ix(expected_int_bits)));
+            }
+            ty::Array(elem, len)
+                if matches!(elem.kind(), ty::Uint(ty::UintTy::U8))
+                    && len.try_eval_target_usize(bx.tcx, ty::ParamEnv::reveal_all())
+                        == Some(expected_bytes) =>
+            {
+                // Zero-extend iN to the array length:
+                let ze = bx.zext(i_, bx.type_ix(expected_bytes * 8));
+
+                // Convert the integer to a byte array
+                let ptr = bx.alloca(bx.type_ix(expected_bytes * 8), Align::ONE);
+                bx.store(ze, ptr, Align::ONE);
+                let array_ty = bx.type_array(bx.type_i8(), expected_bytes);
+                return Ok(bx.load(array_ty, ptr, Align::ONE));
+            }
+            _ => return_error!(InvalidMonomorphization::CannotReturn {
+                span,
+                name,
+                ret_ty,
+                expected_int_bits,
+                expected_bytes
+            }),
+        }
+    }
+
+    fn simd_simple_float_intrinsic<'ll, 'tcx>(
+        name: Symbol,
+        in_elem: Ty<'_>,
+        in_ty: Ty<'_>,
+        in_len: u64,
+        bx: &mut Builder<'_, 'll, 'tcx>,
+        span: Span,
+        args: &[OperandRef<'tcx, &'ll Value>],
+    ) -> Result<&'ll Value, ()> {
+        macro_rules! return_error {
+            ($diag: expr) => {{
+                bx.sess().dcx().emit_err($diag);
+                return Err(());
+            }};
+        }
+
+        let (elem_ty_str, elem_ty) = if let ty::Float(f) = in_elem.kind() {
+            let elem_ty = bx.cx.type_float_from_ty(*f);
+            match f.bit_width() {
+                32 => ("f32", elem_ty),
+                64 => ("f64", elem_ty),
+                _ => return_error!(InvalidMonomorphization::FloatingPointVector {
+                    span,
+                    name,
+                    f_ty: *f,
+                    in_ty,
+                }),
+            }
+        } else {
+            return_error!(InvalidMonomorphization::FloatingPointType { span, name, in_ty });
+        };
+
+        let vec_ty = bx.type_vector(elem_ty, in_len);
+
+        let (intr_name, fn_ty) = match name {
+            sym::simd_ceil => ("ceil", bx.type_func(&[vec_ty], vec_ty)),
+            sym::simd_fabs => ("fabs", bx.type_func(&[vec_ty], vec_ty)),
+            sym::simd_fcos => ("cos", bx.type_func(&[vec_ty], vec_ty)),
+            sym::simd_fexp2 => ("exp2", bx.type_func(&[vec_ty], vec_ty)),
+            sym::simd_fexp => ("exp", bx.type_func(&[vec_ty], vec_ty)),
+            sym::simd_flog10 => ("log10", bx.type_func(&[vec_ty], vec_ty)),
+            sym::simd_flog2 => ("log2", bx.type_func(&[vec_ty], vec_ty)),
+            sym::simd_flog => ("log", bx.type_func(&[vec_ty], vec_ty)),
+            sym::simd_floor => ("floor", bx.type_func(&[vec_ty], vec_ty)),
+            sym::simd_fma => ("fma", bx.type_func(&[vec_ty, vec_ty, vec_ty], vec_ty)),
+            sym::simd_fpowi => ("powi", bx.type_func(&[vec_ty, bx.type_i32()], vec_ty)),
+            sym::simd_fpow => ("pow", bx.type_func(&[vec_ty, vec_ty], vec_ty)),
+            sym::simd_fsin => ("sin", bx.type_func(&[vec_ty], vec_ty)),
+            sym::simd_fsqrt => ("sqrt", bx.type_func(&[vec_ty], vec_ty)),
+            sym::simd_round => ("round", bx.type_func(&[vec_ty], vec_ty)),
+            sym::simd_trunc => ("trunc", bx.type_func(&[vec_ty], vec_ty)),
+            _ => return_error!(InvalidMonomorphization::UnrecognizedIntrinsic { span, name }),
+        };
+        let llvm_name = &format!("llvm.{intr_name}.v{in_len}{elem_ty_str}");
+        let f = bx.declare_cfn(llvm_name, llvm::UnnamedAddr::No, fn_ty);
+        let c = bx.call(
+            fn_ty,
+            None,
+            None,
+            f,
+            &args.iter().map(|arg| arg.immediate()).collect::<Vec<_>>(),
+            None,
+        );
+        Ok(c)
+    }
+
+    if std::matches!(
+        name,
+        sym::simd_ceil
+            | sym::simd_fabs
+            | sym::simd_fcos
+            | sym::simd_fexp2
+            | sym::simd_fexp
+            | sym::simd_flog10
+            | sym::simd_flog2
+            | sym::simd_flog
+            | sym::simd_floor
+            | sym::simd_fma
+            | sym::simd_fpow
+            | sym::simd_fpowi
+            | sym::simd_fsin
+            | sym::simd_fsqrt
+            | sym::simd_round
+            | sym::simd_trunc
+    ) {
+        return simd_simple_float_intrinsic(name, in_elem, in_ty, in_len, bx, span, args);
+    }
+
+    // FIXME: use:
+    //  https://github.com/llvm-mirror/llvm/blob/master/include/llvm/IR/Function.h#L182
+    //  https://github.com/llvm-mirror/llvm/blob/master/include/llvm/IR/Intrinsics.h#L81
+    fn llvm_vector_str(bx: &Builder<'_, '_, '_>, elem_ty: Ty<'_>, vec_len: u64) -> String {
+        match *elem_ty.kind() {
+            ty::Int(v) => format!(
+                "v{}i{}",
+                vec_len,
+                // Normalize to prevent crash if v: IntTy::Isize
+                v.normalize(bx.target_spec().pointer_width).bit_width().unwrap()
+            ),
+            ty::Uint(v) => format!(
+                "v{}i{}",
+                vec_len,
+                // Normalize to prevent crash if v: UIntTy::Usize
+                v.normalize(bx.target_spec().pointer_width).bit_width().unwrap()
+            ),
+            ty::Float(v) => format!("v{}f{}", vec_len, v.bit_width()),
+            ty::RawPtr(_) => format!("v{}p0", vec_len),
+            _ => unreachable!(),
+        }
+    }
+
+    fn llvm_vector_ty<'ll>(cx: &CodegenCx<'ll, '_>, elem_ty: Ty<'_>, vec_len: u64) -> &'ll Type {
+        let elem_ty = match *elem_ty.kind() {
+            ty::Int(v) => cx.type_int_from_ty(v),
+            ty::Uint(v) => cx.type_uint_from_ty(v),
+            ty::Float(v) => cx.type_float_from_ty(v),
+            ty::RawPtr(_) => cx.type_ptr(),
+            _ => unreachable!(),
+        };
+        cx.type_vector(elem_ty, vec_len)
+    }
+
+    if name == sym::simd_gather {
+        // simd_gather(values: <N x T>, pointers: <N x *_ T>,
+        //             mask: <N x i{M}>) -> <N x T>
+        // * N: number of elements in the input vectors
+        // * T: type of the element to load
+        // * M: any integer width is supported, will be truncated to i1
+
+        // All types must be simd vector types
+
+        // The second argument must be a simd vector with an element type that's a pointer
+        // to the element type of the first argument
+        let (_, element_ty0) = require_simd!(in_ty, SimdFirst);
+        let (out_len, element_ty1) = require_simd!(arg_tys[1], SimdSecond);
+        // The element type of the third argument must be a signed integer type of any width:
+        let (out_len2, element_ty2) = require_simd!(arg_tys[2], SimdThird);
+        require_simd!(ret_ty, SimdReturn);
+
+        // Of the same length:
+        require!(
+            in_len == out_len,
+            InvalidMonomorphization::SecondArgumentLength {
+                span,
+                name,
+                in_len,
+                in_ty,
+                arg_ty: arg_tys[1],
+                out_len
+            }
+        );
+        require!(
+            in_len == out_len2,
+            InvalidMonomorphization::ThirdArgumentLength {
+                span,
+                name,
+                in_len,
+                in_ty,
+                arg_ty: arg_tys[2],
+                out_len: out_len2
+            }
+        );
+
+        // The return type must match the first argument type
+        require!(
+            ret_ty == in_ty,
+            InvalidMonomorphization::ExpectedReturnType { span, name, in_ty, ret_ty }
+        );
+
+        require!(
+            matches!(
+                element_ty1.kind(),
+                ty::RawPtr(p) if p.ty == in_elem && p.ty.kind() == element_ty0.kind()
+            ),
+            InvalidMonomorphization::ExpectedElementType {
+                span,
+                name,
+                expected_element: element_ty1,
+                second_arg: arg_tys[1],
+                in_elem,
+                in_ty,
+                mutability: ExpectedPointerMutability::Not,
+            }
+        );
+
+        match element_ty2.kind() {
+            ty::Int(_) => (),
+            _ => {
+                return_error!(InvalidMonomorphization::ThirdArgElementType {
+                    span,
+                    name,
+                    expected_element: element_ty2,
+                    third_arg: arg_tys[2]
+                });
+            }
+        }
+
+        // Alignment of T, must be a constant integer value:
+        let alignment_ty = bx.type_i32();
+        let alignment = bx.const_i32(bx.align_of(in_elem).bytes() as i32);
+
+        // Truncate the mask vector to a vector of i1s:
+        let (mask, mask_ty) = {
+            let i1 = bx.type_i1();
+            let i1xn = bx.type_vector(i1, in_len);
+            (bx.trunc(args[2].immediate(), i1xn), i1xn)
+        };
+
+        // Type of the vector of pointers:
+        let llvm_pointer_vec_ty = llvm_vector_ty(bx, element_ty1, in_len);
+        let llvm_pointer_vec_str = llvm_vector_str(bx, element_ty1, in_len);
+
+        // Type of the vector of elements:
+        let llvm_elem_vec_ty = llvm_vector_ty(bx, element_ty0, in_len);
+        let llvm_elem_vec_str = llvm_vector_str(bx, element_ty0, in_len);
+
+        let llvm_intrinsic =
+            format!("llvm.masked.gather.{llvm_elem_vec_str}.{llvm_pointer_vec_str}");
+        let fn_ty = bx.type_func(
+            &[llvm_pointer_vec_ty, alignment_ty, mask_ty, llvm_elem_vec_ty],
+            llvm_elem_vec_ty,
+        );
+        let f = bx.declare_cfn(&llvm_intrinsic, llvm::UnnamedAddr::No, fn_ty);
+        let v = bx.call(
+            fn_ty,
+            None,
+            None,
+            f,
+            &[args[1].immediate(), alignment, mask, args[0].immediate()],
+            None,
+        );
+        return Ok(v);
+    }
+
+    if name == sym::simd_masked_load {
+        // simd_masked_load(mask: <N x i{M}>, pointer: *_ T, values: <N x T>) -> <N x T>
+        // * N: number of elements in the input vectors
+        // * T: type of the element to load
+        // * M: any integer width is supported, will be truncated to i1
+        // Loads contiguous elements from memory behind `pointer`, but only for
+        // those lanes whose `mask` bit is enabled.
+        // The memory addresses corresponding to the “off” lanes are not accessed.
+
+        // The element type of the "mask" argument must be a signed integer type of any width
+        let mask_ty = in_ty;
+        let (mask_len, mask_elem) = (in_len, in_elem);
+
+        // The second argument must be a pointer matching the element type
+        let pointer_ty = arg_tys[1];
+
+        // The last argument is a passthrough vector providing values for disabled lanes
+        let values_ty = arg_tys[2];
+        let (values_len, values_elem) = require_simd!(values_ty, SimdThird);
+
+        require_simd!(ret_ty, SimdReturn);
+
+        // Of the same length:
+        require!(
+            values_len == mask_len,
+            InvalidMonomorphization::ThirdArgumentLength {
+                span,
+                name,
+                in_len: mask_len,
+                in_ty: mask_ty,
+                arg_ty: values_ty,
+                out_len: values_len
+            }
+        );
+
+        // The return type must match the last argument type
+        require!(
+            ret_ty == values_ty,
+            InvalidMonomorphization::ExpectedReturnType { span, name, in_ty: values_ty, ret_ty }
+        );
+
+        require!(
+            matches!(
+                pointer_ty.kind(),
+                ty::RawPtr(p) if p.ty == values_elem && p.ty.kind() == values_elem.kind()
+            ),
+            InvalidMonomorphization::ExpectedElementType {
+                span,
+                name,
+                expected_element: values_elem,
+                second_arg: pointer_ty,
+                in_elem: values_elem,
+                in_ty: values_ty,
+                mutability: ExpectedPointerMutability::Not,
+            }
+        );
+
+        require!(
+            matches!(mask_elem.kind(), ty::Int(_)),
+            InvalidMonomorphization::ThirdArgElementType {
+                span,
+                name,
+                expected_element: values_elem,
+                third_arg: mask_ty,
+            }
+        );
+
+        // Alignment of T, must be a constant integer value:
+        let alignment_ty = bx.type_i32();
+        let alignment = bx.const_i32(bx.align_of(values_elem).bytes() as i32);
+
+        // Truncate the mask vector to a vector of i1s:
+        let (mask, mask_ty) = {
+            let i1 = bx.type_i1();
+            let i1xn = bx.type_vector(i1, mask_len);
+            (bx.trunc(args[0].immediate(), i1xn), i1xn)
+        };
+
+        let llvm_pointer = bx.type_ptr();
+
+        // Type of the vector of elements:
+        let llvm_elem_vec_ty = llvm_vector_ty(bx, values_elem, values_len);
+        let llvm_elem_vec_str = llvm_vector_str(bx, values_elem, values_len);
+
+        let llvm_intrinsic = format!("llvm.masked.load.{llvm_elem_vec_str}.p0");
+        let fn_ty = bx
+            .type_func(&[llvm_pointer, alignment_ty, mask_ty, llvm_elem_vec_ty], llvm_elem_vec_ty);
+        let f = bx.declare_cfn(&llvm_intrinsic, llvm::UnnamedAddr::No, fn_ty);
+        let v = bx.call(
+            fn_ty,
+            None,
+            None,
+            f,
+            &[args[1].immediate(), alignment, mask, args[2].immediate()],
+            None,
+        );
+        return Ok(v);
+    }
+
+    if name == sym::simd_masked_store {
+        // simd_masked_store(mask: <N x i{M}>, pointer: *mut T, values: <N x T>) -> ()
+        // * N: number of elements in the input vectors
+        // * T: type of the element to load
+        // * M: any integer width is supported, will be truncated to i1
+        // Stores contiguous elements to memory behind `pointer`, but only for
+        // those lanes whose `mask` bit is enabled.
+        // The memory addresses corresponding to the “off” lanes are not accessed.
+
+        // The element type of the "mask" argument must be a signed integer type of any width
+        let mask_ty = in_ty;
+        let (mask_len, mask_elem) = (in_len, in_elem);
+
+        // The second argument must be a pointer matching the element type
+        let pointer_ty = arg_tys[1];
+
+        // The last argument specifies the values to store to memory
+        let values_ty = arg_tys[2];
+        let (values_len, values_elem) = require_simd!(values_ty, SimdThird);
+
+        // Of the same length:
+        require!(
+            values_len == mask_len,
+            InvalidMonomorphization::ThirdArgumentLength {
+                span,
+                name,
+                in_len: mask_len,
+                in_ty: mask_ty,
+                arg_ty: values_ty,
+                out_len: values_len
+            }
+        );
+
+        // The second argument must be a mutable pointer type matching the element type
+        require!(
+            matches!(
+                pointer_ty.kind(),
+                ty::RawPtr(p) if p.ty == values_elem && p.ty.kind() == values_elem.kind() && p.mutbl.is_mut()
+            ),
+            InvalidMonomorphization::ExpectedElementType {
+                span,
+                name,
+                expected_element: values_elem,
+                second_arg: pointer_ty,
+                in_elem: values_elem,
+                in_ty: values_ty,
+                mutability: ExpectedPointerMutability::Mut,
+            }
+        );
+
+        require!(
+            matches!(mask_elem.kind(), ty::Int(_)),
+            InvalidMonomorphization::ThirdArgElementType {
+                span,
+                name,
+                expected_element: values_elem,
+                third_arg: mask_ty,
+            }
+        );
+
+        // Alignment of T, must be a constant integer value:
+        let alignment_ty = bx.type_i32();
+        let alignment = bx.const_i32(bx.align_of(values_elem).bytes() as i32);
+
+        // Truncate the mask vector to a vector of i1s:
+        let (mask, mask_ty) = {
+            let i1 = bx.type_i1();
+            let i1xn = bx.type_vector(i1, in_len);
+            (bx.trunc(args[0].immediate(), i1xn), i1xn)
+        };
+
+        let ret_t = bx.type_void();
+
+        let llvm_pointer = bx.type_ptr();
+
+        // Type of the vector of elements:
+        let llvm_elem_vec_ty = llvm_vector_ty(bx, values_elem, values_len);
+        let llvm_elem_vec_str = llvm_vector_str(bx, values_elem, values_len);
+
+        let llvm_intrinsic = format!("llvm.masked.store.{llvm_elem_vec_str}.p0");
+        let fn_ty = bx.type_func(&[llvm_elem_vec_ty, llvm_pointer, alignment_ty, mask_ty], ret_t);
+        let f = bx.declare_cfn(&llvm_intrinsic, llvm::UnnamedAddr::No, fn_ty);
+        let v = bx.call(
+            fn_ty,
+            None,
+            None,
+            f,
+            &[args[2].immediate(), args[1].immediate(), alignment, mask],
+            None,
+        );
+        return Ok(v);
+    }
+
+    if name == sym::simd_scatter {
+        // simd_scatter(values: <N x T>, pointers: <N x *mut T>,
+        //             mask: <N x i{M}>) -> ()
+        // * N: number of elements in the input vectors
+        // * T: type of the element to load
+        // * M: any integer width is supported, will be truncated to i1
+
+        // All types must be simd vector types
+        // The second argument must be a simd vector with an element type that's a pointer
+        // to the element type of the first argument
+        let (_, element_ty0) = require_simd!(in_ty, SimdFirst);
+        let (element_len1, element_ty1) = require_simd!(arg_tys[1], SimdSecond);
+        let (element_len2, element_ty2) = require_simd!(arg_tys[2], SimdThird);
+
+        // Of the same length:
+        require!(
+            in_len == element_len1,
+            InvalidMonomorphization::SecondArgumentLength {
+                span,
+                name,
+                in_len,
+                in_ty,
+                arg_ty: arg_tys[1],
+                out_len: element_len1
+            }
+        );
+        require!(
+            in_len == element_len2,
+            InvalidMonomorphization::ThirdArgumentLength {
+                span,
+                name,
+                in_len,
+                in_ty,
+                arg_ty: arg_tys[2],
+                out_len: element_len2
+            }
+        );
+
+        require!(
+            matches!(
+                element_ty1.kind(),
+                ty::RawPtr(p)
+                    if p.ty == in_elem && p.mutbl.is_mut() && p.ty.kind() == element_ty0.kind()
+            ),
+            InvalidMonomorphization::ExpectedElementType {
+                span,
+                name,
+                expected_element: element_ty1,
+                second_arg: arg_tys[1],
+                in_elem,
+                in_ty,
+                mutability: ExpectedPointerMutability::Mut,
+            }
+        );
+
+        // The element type of the third argument must be a signed integer type of any width:
+        match element_ty2.kind() {
+            ty::Int(_) => (),
+            _ => {
+                return_error!(InvalidMonomorphization::ThirdArgElementType {
+                    span,
+                    name,
+                    expected_element: element_ty2,
+                    third_arg: arg_tys[2]
+                });
+            }
+        }
+
+        // Alignment of T, must be a constant integer value:
+        let alignment_ty = bx.type_i32();
+        let alignment = bx.const_i32(bx.align_of(in_elem).bytes() as i32);
+
+        // Truncate the mask vector to a vector of i1s:
+        let (mask, mask_ty) = {
+            let i1 = bx.type_i1();
+            let i1xn = bx.type_vector(i1, in_len);
+            (bx.trunc(args[2].immediate(), i1xn), i1xn)
+        };
+
+        let ret_t = bx.type_void();
+
+        // Type of the vector of pointers:
+        let llvm_pointer_vec_ty = llvm_vector_ty(bx, element_ty1, in_len);
+        let llvm_pointer_vec_str = llvm_vector_str(bx, element_ty1, in_len);
+
+        // Type of the vector of elements:
+        let llvm_elem_vec_ty = llvm_vector_ty(bx, element_ty0, in_len);
+        let llvm_elem_vec_str = llvm_vector_str(bx, element_ty0, in_len);
+
+        let llvm_intrinsic =
+            format!("llvm.masked.scatter.{llvm_elem_vec_str}.{llvm_pointer_vec_str}");
+        let fn_ty =
+            bx.type_func(&[llvm_elem_vec_ty, llvm_pointer_vec_ty, alignment_ty, mask_ty], ret_t);
+        let f = bx.declare_cfn(&llvm_intrinsic, llvm::UnnamedAddr::No, fn_ty);
+        let v = bx.call(
+            fn_ty,
+            None,
+            None,
+            f,
+            &[args[0].immediate(), args[1].immediate(), alignment, mask],
+            None,
+        );
+        return Ok(v);
+    }
+
+    macro_rules! arith_red {
+        ($name:ident : $integer_reduce:ident, $float_reduce:ident, $ordered:expr, $op:ident,
+         $identity:expr) => {
+            if name == sym::$name {
+                require!(
+                    ret_ty == in_elem,
+                    InvalidMonomorphization::ReturnType { span, name, in_elem, in_ty, ret_ty }
+                );
+                return match in_elem.kind() {
+                    ty::Int(_) | ty::Uint(_) => {
+                        let r = bx.$integer_reduce(args[0].immediate());
+                        if $ordered {
+                            // if overflow occurs, the result is the
+                            // mathematical result modulo 2^n:
+                            Ok(bx.$op(args[1].immediate(), r))
+                        } else {
+                            Ok(bx.$integer_reduce(args[0].immediate()))
+                        }
+                    }
+                    ty::Float(f) => {
+                        let acc = if $ordered {
+                            // ordered arithmetic reductions take an accumulator
+                            args[1].immediate()
+                        } else {
+                            // unordered arithmetic reductions use the identity accumulator
+                            match f.bit_width() {
+                                32 => bx.const_real(bx.type_f32(), $identity),
+                                64 => bx.const_real(bx.type_f64(), $identity),
+                                v => return_error!(
+                                    InvalidMonomorphization::UnsupportedSymbolOfSize {
+                                        span,
+                                        name,
+                                        symbol: sym::$name,
+                                        in_ty,
+                                        in_elem,
+                                        size: v,
+                                        ret_ty
+                                    }
+                                ),
+                            }
+                        };
+                        Ok(bx.$float_reduce(acc, args[0].immediate()))
+                    }
+                    _ => return_error!(InvalidMonomorphization::UnsupportedSymbol {
+                        span,
+                        name,
+                        symbol: sym::$name,
+                        in_ty,
+                        in_elem,
+                        ret_ty
+                    }),
+                };
+            }
+        };
+    }
+
+    arith_red!(simd_reduce_add_ordered: vector_reduce_add, vector_reduce_fadd, true, add, 0.0);
+    arith_red!(simd_reduce_mul_ordered: vector_reduce_mul, vector_reduce_fmul, true, mul, 1.0);
+    arith_red!(
+        simd_reduce_add_unordered: vector_reduce_add,
+        vector_reduce_fadd_fast,
+        false,
+        add,
+        0.0
+    );
+    arith_red!(
+        simd_reduce_mul_unordered: vector_reduce_mul,
+        vector_reduce_fmul_fast,
+        false,
+        mul,
+        1.0
+    );
+
+    macro_rules! minmax_red {
+        ($name:ident: $int_red:ident, $float_red:ident) => {
+            if name == sym::$name {
+                require!(
+                    ret_ty == in_elem,
+                    InvalidMonomorphization::ReturnType { span, name, in_elem, in_ty, ret_ty }
+                );
+                return match in_elem.kind() {
+                    ty::Int(_i) => Ok(bx.$int_red(args[0].immediate(), true)),
+                    ty::Uint(_u) => Ok(bx.$int_red(args[0].immediate(), false)),
+                    ty::Float(_f) => Ok(bx.$float_red(args[0].immediate())),
+                    _ => return_error!(InvalidMonomorphization::UnsupportedSymbol {
+                        span,
+                        name,
+                        symbol: sym::$name,
+                        in_ty,
+                        in_elem,
+                        ret_ty
+                    }),
+                };
+            }
+        };
+    }
+
+    minmax_red!(simd_reduce_min: vector_reduce_min, vector_reduce_fmin);
+    minmax_red!(simd_reduce_max: vector_reduce_max, vector_reduce_fmax);
+
+    minmax_red!(simd_reduce_min_nanless: vector_reduce_min, vector_reduce_fmin_fast);
+    minmax_red!(simd_reduce_max_nanless: vector_reduce_max, vector_reduce_fmax_fast);
+
+    macro_rules! bitwise_red {
+        ($name:ident : $red:ident, $boolean:expr) => {
+            if name == sym::$name {
+                let input = if !$boolean {
+                    require!(
+                        ret_ty == in_elem,
+                        InvalidMonomorphization::ReturnType { span, name, in_elem, in_ty, ret_ty }
+                    );
+                    args[0].immediate()
+                } else {
+                    match in_elem.kind() {
+                        ty::Int(_) | ty::Uint(_) => {}
+                        _ => return_error!(InvalidMonomorphization::UnsupportedSymbol {
+                            span,
+                            name,
+                            symbol: sym::$name,
+                            in_ty,
+                            in_elem,
+                            ret_ty
+                        }),
+                    }
+
+                    // boolean reductions operate on vectors of i1s:
+                    let i1 = bx.type_i1();
+                    let i1xn = bx.type_vector(i1, in_len as u64);
+                    bx.trunc(args[0].immediate(), i1xn)
+                };
+                return match in_elem.kind() {
+                    ty::Int(_) | ty::Uint(_) => {
+                        let r = bx.$red(input);
+                        Ok(if !$boolean { r } else { bx.zext(r, bx.type_bool()) })
+                    }
+                    _ => return_error!(InvalidMonomorphization::UnsupportedSymbol {
+                        span,
+                        name,
+                        symbol: sym::$name,
+                        in_ty,
+                        in_elem,
+                        ret_ty
+                    }),
+                };
+            }
+        };
+    }
+
+    bitwise_red!(simd_reduce_and: vector_reduce_and, false);
+    bitwise_red!(simd_reduce_or: vector_reduce_or, false);
+    bitwise_red!(simd_reduce_xor: vector_reduce_xor, false);
+    bitwise_red!(simd_reduce_all: vector_reduce_and, true);
+    bitwise_red!(simd_reduce_any: vector_reduce_or, true);
+
+    if name == sym::simd_cast_ptr {
+        let (out_len, out_elem) = require_simd!(ret_ty, SimdReturn);
+        require!(
+            in_len == out_len,
+            InvalidMonomorphization::ReturnLengthInputType {
+                span,
+                name,
+                in_len,
+                in_ty,
+                ret_ty,
+                out_len
+            }
+        );
+
+        match in_elem.kind() {
+            ty::RawPtr(p) => {
+                let (metadata, check_sized) = p.ty.ptr_metadata_ty(bx.tcx, |ty| {
+                    bx.tcx.normalize_erasing_regions(ty::ParamEnv::reveal_all(), ty)
+                });
+                assert!(!check_sized); // we are in codegen, so we shouldn't see these types
+                require!(
+                    metadata.is_unit(),
+                    InvalidMonomorphization::CastFatPointer { span, name, ty: in_elem }
+                );
+            }
+            _ => {
+                return_error!(InvalidMonomorphization::ExpectedPointer { span, name, ty: in_elem })
+            }
+        }
+        match out_elem.kind() {
+            ty::RawPtr(p) => {
+                let (metadata, check_sized) = p.ty.ptr_metadata_ty(bx.tcx, |ty| {
+                    bx.tcx.normalize_erasing_regions(ty::ParamEnv::reveal_all(), ty)
+                });
+                assert!(!check_sized); // we are in codegen, so we shouldn't see these types
+                require!(
+                    metadata.is_unit(),
+                    InvalidMonomorphization::CastFatPointer { span, name, ty: out_elem }
+                );
+            }
+            _ => {
+                return_error!(InvalidMonomorphization::ExpectedPointer { span, name, ty: out_elem })
+            }
+        }
+
+        return Ok(args[0].immediate());
+    }
+
+    if name == sym::simd_expose_addr {
+        let (out_len, out_elem) = require_simd!(ret_ty, SimdReturn);
+        require!(
+            in_len == out_len,
+            InvalidMonomorphization::ReturnLengthInputType {
+                span,
+                name,
+                in_len,
+                in_ty,
+                ret_ty,
+                out_len
+            }
+        );
+
+        match in_elem.kind() {
+            ty::RawPtr(_) => {}
+            _ => {
+                return_error!(InvalidMonomorphization::ExpectedPointer { span, name, ty: in_elem })
+            }
+        }
+        match out_elem.kind() {
+            ty::Uint(ty::UintTy::Usize) => {}
+            _ => return_error!(InvalidMonomorphization::ExpectedUsize { span, name, ty: out_elem }),
+        }
+
+        return Ok(bx.ptrtoint(args[0].immediate(), llret_ty));
+    }
+
+    if name == sym::simd_from_exposed_addr {
+        let (out_len, out_elem) = require_simd!(ret_ty, SimdReturn);
+        require!(
+            in_len == out_len,
+            InvalidMonomorphization::ReturnLengthInputType {
+                span,
+                name,
+                in_len,
+                in_ty,
+                ret_ty,
+                out_len
+            }
+        );
+
+        match in_elem.kind() {
+            ty::Uint(ty::UintTy::Usize) => {}
+            _ => return_error!(InvalidMonomorphization::ExpectedUsize { span, name, ty: in_elem }),
+        }
+        match out_elem.kind() {
+            ty::RawPtr(_) => {}
+            _ => {
+                return_error!(InvalidMonomorphization::ExpectedPointer { span, name, ty: out_elem })
+            }
+        }
+
+        return Ok(bx.inttoptr(args[0].immediate(), llret_ty));
+    }
+
+    if name == sym::simd_cast || name == sym::simd_as {
+        let (out_len, out_elem) = require_simd!(ret_ty, SimdReturn);
+        require!(
+            in_len == out_len,
+            InvalidMonomorphization::ReturnLengthInputType {
+                span,
+                name,
+                in_len,
+                in_ty,
+                ret_ty,
+                out_len
+            }
+        );
+        // casting cares about nominal type, not just structural type
+        if in_elem == out_elem {
+            return Ok(args[0].immediate());
+        }
+
+        enum Style {
+            Float,
+            Int(/* is signed? */ bool),
+            Unsupported,
+        }
+
+        let (in_style, in_width) = match in_elem.kind() {
+            // vectors of pointer-sized integers should've been
+            // disallowed before here, so this unwrap is safe.
+            ty::Int(i) => (
+                Style::Int(true),
+                i.normalize(bx.tcx().sess.target.pointer_width).bit_width().unwrap(),
+            ),
+            ty::Uint(u) => (
+                Style::Int(false),
+                u.normalize(bx.tcx().sess.target.pointer_width).bit_width().unwrap(),
+            ),
+            ty::Float(f) => (Style::Float, f.bit_width()),
+            _ => (Style::Unsupported, 0),
+        };
+        let (out_style, out_width) = match out_elem.kind() {
+            ty::Int(i) => (
+                Style::Int(true),
+                i.normalize(bx.tcx().sess.target.pointer_width).bit_width().unwrap(),
+            ),
+            ty::Uint(u) => (
+                Style::Int(false),
+                u.normalize(bx.tcx().sess.target.pointer_width).bit_width().unwrap(),
+            ),
+            ty::Float(f) => (Style::Float, f.bit_width()),
+            _ => (Style::Unsupported, 0),
+        };
+
+        match (in_style, out_style) {
+            (Style::Int(in_is_signed), Style::Int(_)) => {
+                return Ok(match in_width.cmp(&out_width) {
+                    Ordering::Greater => bx.trunc(args[0].immediate(), llret_ty),
+                    Ordering::Equal => args[0].immediate(),
+                    Ordering::Less => {
+                        if in_is_signed {
+                            bx.sext(args[0].immediate(), llret_ty)
+                        } else {
+                            bx.zext(args[0].immediate(), llret_ty)
+                        }
+                    }
+                });
+            }
+            (Style::Int(in_is_signed), Style::Float) => {
+                return Ok(if in_is_signed {
+                    bx.sitofp(args[0].immediate(), llret_ty)
+                } else {
+                    bx.uitofp(args[0].immediate(), llret_ty)
+                });
+            }
+            (Style::Float, Style::Int(out_is_signed)) => {
+                return Ok(match (out_is_signed, name == sym::simd_as) {
+                    (false, false) => bx.fptoui(args[0].immediate(), llret_ty),
+                    (true, false) => bx.fptosi(args[0].immediate(), llret_ty),
+                    (_, true) => bx.cast_float_to_int(out_is_signed, args[0].immediate(), llret_ty),
+                });
+            }
+            (Style::Float, Style::Float) => {
+                return Ok(match in_width.cmp(&out_width) {
+                    Ordering::Greater => bx.fptrunc(args[0].immediate(), llret_ty),
+                    Ordering::Equal => args[0].immediate(),
+                    Ordering::Less => bx.fpext(args[0].immediate(), llret_ty),
+                });
+            }
+            _ => { /* Unsupported. Fallthrough. */ }
+        }
+        return_error!(InvalidMonomorphization::UnsupportedCast {
+            span,
+            name,
+            in_ty,
+            in_elem,
+            ret_ty,
+            out_elem
+        });
+    }
+    macro_rules! arith_binary {
+        ($($name: ident: $($($p: ident),* => $call: ident),*;)*) => {
+            $(if name == sym::$name {
+                match in_elem.kind() {
+                    $($(ty::$p(_))|* => {
+                        return Ok(bx.$call(args[0].immediate(), args[1].immediate()))
+                    })*
+                    _ => {},
+                }
+                return_error!(
+                    InvalidMonomorphization::UnsupportedOperation { span, name, in_ty, in_elem }
+                );
+            })*
+        }
+    }
+    arith_binary! {
+        simd_add: Uint, Int => add, Float => fadd;
+        simd_sub: Uint, Int => sub, Float => fsub;
+        simd_mul: Uint, Int => mul, Float => fmul;
+        simd_div: Uint => udiv, Int => sdiv, Float => fdiv;
+        simd_rem: Uint => urem, Int => srem, Float => frem;
+        simd_shl: Uint, Int => shl;
+        simd_shr: Uint => lshr, Int => ashr;
+        simd_and: Uint, Int => and;
+        simd_or: Uint, Int => or;
+        simd_xor: Uint, Int => xor;
+        simd_fmax: Float => maxnum;
+        simd_fmin: Float => minnum;
+
+    }
+    macro_rules! arith_unary {
+        ($($name: ident: $($($p: ident),* => $call: ident),*;)*) => {
+            $(if name == sym::$name {
+                match in_elem.kind() {
+                    $($(ty::$p(_))|* => {
+                        return Ok(bx.$call(args[0].immediate()))
+                    })*
+                    _ => {},
+                }
+                return_error!(
+                    InvalidMonomorphization::UnsupportedOperation { span, name, in_ty, in_elem }
+                );
+            })*
+        }
+    }
+    arith_unary! {
+        simd_neg: Int => neg, Float => fneg;
+    }
+
+    // Unary integer intrinsics
+    if matches!(name, sym::simd_bswap | sym::simd_bitreverse | sym::simd_ctlz | sym::simd_cttz) {
+        let vec_ty = bx.cx.type_vector(
+            match *in_elem.kind() {
+                ty::Int(i) => bx.cx.type_int_from_ty(i),
+                ty::Uint(i) => bx.cx.type_uint_from_ty(i),
+                _ => return_error!(InvalidMonomorphization::UnsupportedOperation {
+                    span,
+                    name,
+                    in_ty,
+                    in_elem
+                }),
+            },
+            in_len as u64,
+        );
+        let intrinsic_name = match name {
+            sym::simd_bswap => "bswap",
+            sym::simd_bitreverse => "bitreverse",
+            sym::simd_ctlz => "ctlz",
+            sym::simd_cttz => "cttz",
+            _ => unreachable!(),
+        };
+        let int_size = in_elem.int_size_and_signed(bx.tcx()).0.bits();
+        let llvm_intrinsic = &format!("llvm.{}.v{}i{}", intrinsic_name, in_len, int_size,);
+
+        return if name == sym::simd_bswap && int_size == 8 {
+            // byte swap is no-op for i8/u8
+            Ok(args[0].immediate())
+        } else if matches!(name, sym::simd_ctlz | sym::simd_cttz) {
+            let fn_ty = bx.type_func(&[vec_ty, bx.type_i1()], vec_ty);
+            let f = bx.declare_cfn(llvm_intrinsic, llvm::UnnamedAddr::No, fn_ty);
+            Ok(bx.call(
+                fn_ty,
+                None,
+                None,
+                f,
+                &[args[0].immediate(), bx.const_int(bx.type_i1(), 0)],
+                None,
+            ))
+        } else {
+            let fn_ty = bx.type_func(&[vec_ty], vec_ty);
+            let f = bx.declare_cfn(llvm_intrinsic, llvm::UnnamedAddr::No, fn_ty);
+            Ok(bx.call(fn_ty, None, None, f, &[args[0].immediate()], None))
+        };
+    }
+
+    if name == sym::simd_arith_offset {
+        // This also checks that the first operand is a ptr type.
+        let pointee = in_elem.builtin_deref(true).unwrap_or_else(|| {
+            span_bug!(span, "must be called with a vector of pointer types as first argument")
+        });
+        let layout = bx.layout_of(pointee.ty);
+        let ptrs = args[0].immediate();
+        // The second argument must be a ptr-sized integer.
+        // (We don't care about the signedness, this is wrapping anyway.)
+        let (_offsets_len, offsets_elem) = arg_tys[1].simd_size_and_type(bx.tcx());
+        if !matches!(offsets_elem.kind(), ty::Int(ty::IntTy::Isize) | ty::Uint(ty::UintTy::Usize)) {
+            span_bug!(
+                span,
+                "must be called with a vector of pointer-sized integers as second argument"
+            );
+        }
+        let offsets = args[1].immediate();
+
+        return Ok(bx.gep(bx.backend_type(layout), ptrs, &[offsets]));
+    }
+
+    if name == sym::simd_saturating_add || name == sym::simd_saturating_sub {
+        let lhs = args[0].immediate();
+        let rhs = args[1].immediate();
+        let is_add = name == sym::simd_saturating_add;
+        let ptr_bits = bx.tcx().data_layout.pointer_size.bits() as _;
+        let (signed, elem_width, elem_ty) = match *in_elem.kind() {
+            ty::Int(i) => (true, i.bit_width().unwrap_or(ptr_bits), bx.cx.type_int_from_ty(i)),
+            ty::Uint(i) => (false, i.bit_width().unwrap_or(ptr_bits), bx.cx.type_uint_from_ty(i)),
+            _ => {
+                return_error!(InvalidMonomorphization::ExpectedVectorElementType {
+                    span,
+                    name,
+                    expected_element: arg_tys[0].simd_size_and_type(bx.tcx()).1,
+                    vector_type: arg_tys[0]
+                });
+            }
+        };
+        let llvm_intrinsic = &format!(
+            "llvm.{}{}.sat.v{}i{}",
+            if signed { 's' } else { 'u' },
+            if is_add { "add" } else { "sub" },
+            in_len,
+            elem_width
+        );
+        let vec_ty = bx.cx.type_vector(elem_ty, in_len as u64);
+
+        let fn_ty = bx.type_func(&[vec_ty, vec_ty], vec_ty);
+        let f = bx.declare_cfn(llvm_intrinsic, llvm::UnnamedAddr::No, fn_ty);
+        let v = bx.call(fn_ty, None, None, f, &[lhs, rhs], None);
+        return Ok(v);
+    }
+
+    span_bug!(span, "unknown SIMD intrinsic");
+}
+
+// Returns the width of an int Ty, and if it's signed or not
+// Returns None if the type is not an integer
+// FIXME: there’s multiple of this functions, investigate using some of the already existing
+// stuffs.
+fn int_type_width_signed(ty: Ty<'_>, cx: &CodegenCx<'_, '_>) -> Option<(u64, bool)> {
+    match ty.kind() {
+        ty::Int(t) => {
+            Some((t.bit_width().unwrap_or(u64::from(cx.tcx.sess.target.pointer_width)), true))
+        }
+        ty::Uint(t) => {
+            Some((t.bit_width().unwrap_or(u64::from(cx.tcx.sess.target.pointer_width)), false))
+        }
+        _ => None,
+    }
+}