Add 'compiler/rustc_codegen_cranelift/' from commit '793d26047f994e23415f8f6bb5686ff25d3dda92'

git-subtree-dir: compiler/rustc_codegen_cranelift
git-subtree-mainline: cf798c1ec65a5ec3491846777f9003fabb881b4a
git-subtree-split: 793d26047f994e23415f8f6bb5686ff25d3dda92

1 files changed, 476 insertions, 0 deletions

diff --git a/compiler/rustc_codegen_cranelift/src/constant.rs b/compiler/rustc_codegen_cranelift/src/constant.rs
new file mode 100644
index 00000000000..1b514958a48
--- /dev/null
+++ b/compiler/rustc_codegen_cranelift/src/constant.rs
@@ -0,0 +1,476 @@
+//! Handling of `static`s, `const`s and promoted allocations
+
+use rustc_span::DUMMY_SP;
+
+use rustc_data_structures::fx::FxHashSet;
+use rustc_errors::ErrorReported;
+use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
+use rustc_middle::mir::interpret::{
+    read_target_uint, AllocId, Allocation, ConstValue, ErrorHandled, GlobalAlloc, Pointer, Scalar,
+};
+use rustc_middle::ty::{Const, ConstKind};
+
+use cranelift_codegen::ir::GlobalValueData;
+use cranelift_module::*;
+
+use crate::prelude::*;
+
+#[derive(Default)]
+pub(crate) struct ConstantCx {
+    todo: Vec<TodoItem>,
+    done: FxHashSet<DataId>,
+}
+
+#[derive(Copy, Clone, Debug)]
+enum TodoItem {
+    Alloc(AllocId),
+    Static(DefId),
+}
+
+impl ConstantCx {
+    pub(crate) fn finalize(mut self, tcx: TyCtxt<'_>, module: &mut impl Module) {
+        //println!("todo {:?}", self.todo);
+        define_all_allocs(tcx, module, &mut self);
+        //println!("done {:?}", self.done);
+        self.done.clear();
+    }
+}
+
+pub(crate) fn check_constants(fx: &mut FunctionCx<'_, '_, impl Module>) {
+    for constant in &fx.mir.required_consts {
+        let const_ = fx.monomorphize(&constant.literal);
+        match const_.val {
+            ConstKind::Value(_) => {}
+            ConstKind::Unevaluated(def, ref substs, promoted) => {
+                if let Err(err) =
+                    fx.tcx
+                        .const_eval_resolve(ParamEnv::reveal_all(), def, substs, promoted, None)
+                {
+                    match err {
+                        ErrorHandled::Reported(ErrorReported) | ErrorHandled::Linted => {
+                            fx.tcx
+                                .sess
+                                .span_err(constant.span, "erroneous constant encountered");
+                        }
+                        ErrorHandled::TooGeneric => {
+                            span_bug!(
+                                constant.span,
+                                "codgen encountered polymorphic constant: {:?}",
+                                err
+                            );
+                        }
+                    }
+                }
+            }
+            ConstKind::Param(_)
+            | ConstKind::Infer(_)
+            | ConstKind::Bound(_, _)
+            | ConstKind::Placeholder(_)
+            | ConstKind::Error(_) => unreachable!("{:?}", const_),
+        }
+    }
+}
+
+pub(crate) fn codegen_static(constants_cx: &mut ConstantCx, def_id: DefId) {
+    constants_cx.todo.push(TodoItem::Static(def_id));
+}
+
+pub(crate) fn codegen_tls_ref<'tcx>(
+    fx: &mut FunctionCx<'_, 'tcx, impl Module>,
+    def_id: DefId,
+    layout: TyAndLayout<'tcx>,
+) -> CValue<'tcx> {
+    let data_id = data_id_for_static(fx.tcx, &mut fx.cx.module, def_id, false);
+    let local_data_id = fx.cx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
+    #[cfg(debug_assertions)]
+    fx.add_comment(local_data_id, format!("tls {:?}", def_id));
+    let tls_ptr = fx.bcx.ins().tls_value(fx.pointer_type, local_data_id);
+    CValue::by_val(tls_ptr, layout)
+}
+
+fn codegen_static_ref<'tcx>(
+    fx: &mut FunctionCx<'_, 'tcx, impl Module>,
+    def_id: DefId,
+    layout: TyAndLayout<'tcx>,
+) -> CPlace<'tcx> {
+    let data_id = data_id_for_static(fx.tcx, &mut fx.cx.module, def_id, false);
+    let local_data_id = fx.cx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
+    #[cfg(debug_assertions)]
+    fx.add_comment(local_data_id, format!("{:?}", def_id));
+    let global_ptr = fx.bcx.ins().global_value(fx.pointer_type, local_data_id);
+    assert!(!layout.is_unsized(), "unsized statics aren't supported");
+    assert!(
+        matches!(fx.bcx.func.global_values[local_data_id], GlobalValueData::Symbol { tls: false, ..}),
+        "tls static referenced without Rvalue::ThreadLocalRef"
+    );
+    CPlace::for_ptr(crate::pointer::Pointer::new(global_ptr), layout)
+}
+
+pub(crate) fn trans_constant<'tcx>(
+    fx: &mut FunctionCx<'_, 'tcx, impl Module>,
+    constant: &Constant<'tcx>,
+) -> CValue<'tcx> {
+    let const_ = fx.monomorphize(&constant.literal);
+    let const_val = match const_.val {
+        ConstKind::Value(const_val) => const_val,
+        ConstKind::Unevaluated(def, ref substs, promoted) if fx.tcx.is_static(def.did) => {
+            assert!(substs.is_empty());
+            assert!(promoted.is_none());
+
+            return codegen_static_ref(
+                fx,
+                def.did,
+                fx.layout_of(fx.monomorphize(&constant.literal.ty)),
+            )
+            .to_cvalue(fx);
+        }
+        ConstKind::Unevaluated(def, ref substs, promoted) => {
+            match fx
+                .tcx
+                .const_eval_resolve(ParamEnv::reveal_all(), def, substs, promoted, None)
+            {
+                Ok(const_val) => const_val,
+                Err(_) => {
+                    if promoted.is_none() {
+                        fx.tcx
+                            .sess
+                            .span_err(constant.span, "erroneous constant encountered");
+                    }
+                    return crate::trap::trap_unreachable_ret_value(
+                        fx,
+                        fx.layout_of(const_.ty),
+                        "erroneous constant encountered",
+                    );
+                }
+            }
+        }
+        ConstKind::Param(_)
+        | ConstKind::Infer(_)
+        | ConstKind::Bound(_, _)
+        | ConstKind::Placeholder(_)
+        | ConstKind::Error(_) => unreachable!("{:?}", const_),
+    };
+
+    trans_const_value(fx, const_val, const_.ty)
+}
+
+pub(crate) fn trans_const_value<'tcx>(
+    fx: &mut FunctionCx<'_, 'tcx, impl Module>,
+    const_val: ConstValue<'tcx>,
+    ty: Ty<'tcx>,
+) -> CValue<'tcx> {
+    let layout = fx.layout_of(ty);
+    assert!(!layout.is_unsized(), "sized const value");
+
+    if layout.is_zst() {
+        return CValue::by_ref(
+            crate::Pointer::const_addr(fx, i64::try_from(layout.align.pref.bytes()).unwrap()),
+            layout,
+        );
+    }
+
+    match const_val {
+        ConstValue::Scalar(x) => {
+            if fx.clif_type(layout.ty).is_none() {
+                let (size, align) = (layout.size, layout.align.pref);
+                let mut alloc = Allocation::from_bytes(
+                    std::iter::repeat(0)
+                        .take(size.bytes_usize())
+                        .collect::<Vec<u8>>(),
+                    align,
+                );
+                let ptr = Pointer::new(AllocId(!0), Size::ZERO); // The alloc id is never used
+                alloc.write_scalar(fx, ptr, x.into(), size).unwrap();
+                let alloc = fx.tcx.intern_const_alloc(alloc);
+                return CValue::by_ref(pointer_for_allocation(fx, alloc), layout);
+            }
+
+            match x {
+                Scalar::Raw { data, size } => {
+                    assert_eq!(u64::from(size), layout.size.bytes());
+                    return CValue::const_val(fx, layout, data);
+                }
+                Scalar::Ptr(ptr) => {
+                    let alloc_kind = fx.tcx.get_global_alloc(ptr.alloc_id);
+                    let base_addr = match alloc_kind {
+                        Some(GlobalAlloc::Memory(alloc)) => {
+                            fx.cx.constants_cx.todo.push(TodoItem::Alloc(ptr.alloc_id));
+                            let data_id = data_id_for_alloc_id(
+                                &mut fx.cx.module,
+                                ptr.alloc_id,
+                                alloc.mutability,
+                            );
+                            let local_data_id =
+                                fx.cx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
+                            #[cfg(debug_assertions)]
+                            fx.add_comment(local_data_id, format!("{:?}", ptr.alloc_id));
+                            fx.bcx.ins().global_value(fx.pointer_type, local_data_id)
+                        }
+                        Some(GlobalAlloc::Function(instance)) => {
+                            let func_id =
+                                crate::abi::import_function(fx.tcx, &mut fx.cx.module, instance);
+                            let local_func_id =
+                                fx.cx.module.declare_func_in_func(func_id, &mut fx.bcx.func);
+                            fx.bcx.ins().func_addr(fx.pointer_type, local_func_id)
+                        }
+                        Some(GlobalAlloc::Static(def_id)) => {
+                            assert!(fx.tcx.is_static(def_id));
+                            let data_id =
+                                data_id_for_static(fx.tcx, &mut fx.cx.module, def_id, false);
+                            let local_data_id =
+                                fx.cx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
+                            #[cfg(debug_assertions)]
+                            fx.add_comment(local_data_id, format!("{:?}", def_id));
+                            fx.bcx.ins().global_value(fx.pointer_type, local_data_id)
+                        }
+                        None => bug!("missing allocation {:?}", ptr.alloc_id),
+                    };
+                    let val = if ptr.offset.bytes() != 0 {
+                        fx.bcx
+                            .ins()
+                            .iadd_imm(base_addr, i64::try_from(ptr.offset.bytes()).unwrap())
+                    } else {
+                        base_addr
+                    };
+                    return CValue::by_val(val, layout);
+                }
+            }
+        }
+        ConstValue::ByRef { alloc, offset } => CValue::by_ref(
+            pointer_for_allocation(fx, alloc)
+                .offset_i64(fx, i64::try_from(offset.bytes()).unwrap()),
+            layout,
+        ),
+        ConstValue::Slice { data, start, end } => {
+            let ptr = pointer_for_allocation(fx, data)
+                .offset_i64(fx, i64::try_from(start).unwrap())
+                .get_addr(fx);
+            let len = fx.bcx.ins().iconst(
+                fx.pointer_type,
+                i64::try_from(end.checked_sub(start).unwrap()).unwrap(),
+            );
+            CValue::by_val_pair(ptr, len, layout)
+        }
+    }
+}
+
+fn pointer_for_allocation<'tcx>(
+    fx: &mut FunctionCx<'_, 'tcx, impl Module>,
+    alloc: &'tcx Allocation,
+) -> crate::pointer::Pointer {
+    let alloc_id = fx.tcx.create_memory_alloc(alloc);
+    fx.cx.constants_cx.todo.push(TodoItem::Alloc(alloc_id));
+    let data_id = data_id_for_alloc_id(&mut fx.cx.module, alloc_id, alloc.mutability);
+
+    let local_data_id = fx.cx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
+    #[cfg(debug_assertions)]
+    fx.add_comment(local_data_id, format!("{:?}", alloc_id));
+    let global_ptr = fx.bcx.ins().global_value(fx.pointer_type, local_data_id);
+    crate::pointer::Pointer::new(global_ptr)
+}
+
+fn data_id_for_alloc_id(
+    module: &mut impl Module,
+    alloc_id: AllocId,
+    mutability: rustc_hir::Mutability,
+) -> DataId {
+    module
+        .declare_data(
+            &format!("__alloc_{:x}", alloc_id.0),
+            Linkage::Local,
+            mutability == rustc_hir::Mutability::Mut,
+            false,
+        )
+        .unwrap()
+}
+
+fn data_id_for_static(
+    tcx: TyCtxt<'_>,
+    module: &mut impl Module,
+    def_id: DefId,
+    definition: bool,
+) -> DataId {
+    let rlinkage = tcx.codegen_fn_attrs(def_id).linkage;
+    let linkage = if definition {
+        crate::linkage::get_static_linkage(tcx, def_id)
+    } else {
+        if rlinkage == Some(rustc_middle::mir::mono::Linkage::ExternalWeak)
+            || rlinkage == Some(rustc_middle::mir::mono::Linkage::WeakAny)
+        {
+            Linkage::Preemptible
+        } else {
+            Linkage::Import
+        }
+    };
+
+    let instance = Instance::mono(tcx, def_id).polymorphize(tcx);
+    let symbol_name = tcx.symbol_name(instance).name;
+    let ty = instance.ty(tcx, ParamEnv::reveal_all());
+    let is_mutable = if tcx.is_mutable_static(def_id) {
+        true
+    } else {
+        !ty.is_freeze(tcx.at(DUMMY_SP), ParamEnv::reveal_all())
+    };
+    let align = tcx
+        .layout_of(ParamEnv::reveal_all().and(ty))
+        .unwrap()
+        .align
+        .pref
+        .bytes();
+
+    let attrs = tcx.codegen_fn_attrs(def_id);
+
+    let data_id = module
+        .declare_data(
+            &*symbol_name,
+            linkage,
+            is_mutable,
+            attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL),
+        )
+        .unwrap();
+
+    if rlinkage.is_some() {
+        // Comment copied from https://github.com/rust-lang/rust/blob/45060c2a66dfd667f88bd8b94261b28a58d85bd5/src/librustc_codegen_llvm/consts.rs#L141
+        // Declare an internal global `extern_with_linkage_foo` which
+        // is initialized with the address of `foo`.  If `foo` is
+        // discarded during linking (for example, if `foo` has weak
+        // linkage and there are no definitions), then
+        // `extern_with_linkage_foo` will instead be initialized to
+        // zero.
+
+        let ref_name = format!("_rust_extern_with_linkage_{}", symbol_name);
+        let ref_data_id = module
+            .declare_data(&ref_name, Linkage::Local, false, false)
+            .unwrap();
+        let mut data_ctx = DataContext::new();
+        data_ctx.set_align(align);
+        let data = module.declare_data_in_data(data_id, &mut data_ctx);
+        data_ctx.define(
+            std::iter::repeat(0)
+                .take(pointer_ty(tcx).bytes() as usize)
+                .collect(),
+        );
+        data_ctx.write_data_addr(0, data, 0);
+        match module.define_data(ref_data_id, &data_ctx) {
+            // Every time the static is referenced there will be another definition of this global,
+            // so duplicate definitions are expected and allowed.
+            Err(ModuleError::DuplicateDefinition(_)) => {}
+            res => res.unwrap(),
+        }
+        ref_data_id
+    } else {
+        data_id
+    }
+}
+
+fn define_all_allocs(tcx: TyCtxt<'_>, module: &mut impl Module, cx: &mut ConstantCx) {
+    while let Some(todo_item) = cx.todo.pop() {
+        let (data_id, alloc, section_name) = match todo_item {
+            TodoItem::Alloc(alloc_id) => {
+                //println!("alloc_id {}", alloc_id);
+                let alloc = match tcx.get_global_alloc(alloc_id).unwrap() {
+                    GlobalAlloc::Memory(alloc) => alloc,
+                    GlobalAlloc::Function(_) | GlobalAlloc::Static(_) => unreachable!(),
+                };
+                let data_id = data_id_for_alloc_id(module, alloc_id, alloc.mutability);
+                (data_id, alloc, None)
+            }
+            TodoItem::Static(def_id) => {
+                //println!("static {:?}", def_id);
+
+                let section_name = tcx
+                    .codegen_fn_attrs(def_id)
+                    .link_section
+                    .map(|s| s.as_str());
+
+                let alloc = tcx.eval_static_initializer(def_id).unwrap();
+
+                let data_id = data_id_for_static(tcx, module, def_id, true);
+                (data_id, alloc, section_name)
+            }
+        };
+
+        //("data_id {}", data_id);
+        if cx.done.contains(&data_id) {
+            continue;
+        }
+
+        let mut data_ctx = DataContext::new();
+        data_ctx.set_align(alloc.align.bytes());
+
+        if let Some(section_name) = section_name {
+            // FIXME set correct segment for Mach-O files
+            data_ctx.set_segment_section("", &*section_name);
+        }
+
+        let bytes = alloc
+            .inspect_with_uninit_and_ptr_outside_interpreter(0..alloc.len())
+            .to_vec();
+        data_ctx.define(bytes.into_boxed_slice());
+
+        for &(offset, (_tag, reloc)) in alloc.relocations().iter() {
+            let addend = {
+                let endianness = tcx.data_layout.endian;
+                let offset = offset.bytes() as usize;
+                let ptr_size = tcx.data_layout.pointer_size;
+                let bytes = &alloc.inspect_with_uninit_and_ptr_outside_interpreter(
+                    offset..offset + ptr_size.bytes() as usize,
+                );
+                read_target_uint(endianness, bytes).unwrap()
+            };
+
+            let reloc_target_alloc = tcx.get_global_alloc(reloc).unwrap();
+            let data_id = match reloc_target_alloc {
+                GlobalAlloc::Function(instance) => {
+                    assert_eq!(addend, 0);
+                    let func_id = crate::abi::import_function(tcx, module, instance);
+                    let local_func_id = module.declare_func_in_data(func_id, &mut data_ctx);
+                    data_ctx.write_function_addr(offset.bytes() as u32, local_func_id);
+                    continue;
+                }
+                GlobalAlloc::Memory(target_alloc) => {
+                    cx.todo.push(TodoItem::Alloc(reloc));
+                    data_id_for_alloc_id(module, reloc, target_alloc.mutability)
+                }
+                GlobalAlloc::Static(def_id) => {
+                    if tcx
+                        .codegen_fn_attrs(def_id)
+                        .flags
+                        .contains(CodegenFnAttrFlags::THREAD_LOCAL)
+                    {
+                        tcx.sess.fatal(&format!(
+                            "Allocation {:?} contains reference to TLS value {:?}",
+                            alloc, def_id
+                        ));
+                    }
+
+                    // Don't push a `TodoItem::Static` here, as it will cause statics used by
+                    // multiple crates to be duplicated between them. It isn't necessary anyway,
+                    // as it will get pushed by `codegen_static` when necessary.
+                    data_id_for_static(tcx, module, def_id, false)
+                }
+            };
+
+            let global_value = module.declare_data_in_data(data_id, &mut data_ctx);
+            data_ctx.write_data_addr(offset.bytes() as u32, global_value, addend as i64);
+        }
+
+        module.define_data(data_id, &data_ctx).unwrap();
+        cx.done.insert(data_id);
+    }
+
+    assert!(cx.todo.is_empty(), "{:?}", cx.todo);
+}
+
+pub(crate) fn mir_operand_get_const_val<'tcx>(
+    fx: &FunctionCx<'_, 'tcx, impl Module>,
+    operand: &Operand<'tcx>,
+) -> Option<&'tcx Const<'tcx>> {
+    match operand {
+        Operand::Copy(_) | Operand::Move(_) => None,
+        Operand::Constant(const_) => Some(
+            fx.monomorphize(&const_.literal)
+                .eval(fx.tcx, ParamEnv::reveal_all()),
+        ),
+    }
+}