Merge from rustc

7 files changed, 83 insertions, 93 deletions

diff --git a/compiler/rustc_codegen_ssa/src/back/linker.rs b/compiler/rustc_codegen_ssa/src/back/linker.rs
index 1896f63bd2d..e0a3ad55be0 100644
--- a/compiler/rustc_codegen_ssa/src/back/linker.rs
+++ b/compiler/rustc_codegen_ssa/src/back/linker.rs
@@ -800,9 +800,7 @@ impl<'a> Linker for GccLinker<'a> {
             return;
         }
 
-        let is_windows = self.sess.target.is_like_windows;
-        let path = tmpdir.join(if is_windows { "list.def" } else { "list" });
-
+        let path = tmpdir.join(if self.sess.target.is_like_windows { "list.def" } else { "list" });
         debug!("EXPORTED SYMBOLS:");
 
         if self.sess.target.is_like_darwin {
@@ -817,7 +815,8 @@ impl<'a> Linker for GccLinker<'a> {
             if let Err(error) = res {
                 self.sess.dcx().emit_fatal(errors::LibDefWriteFailure { error });
             }
-        } else if is_windows {
+            self.link_arg("-exported_symbols_list").link_arg(path);
+        } else if self.sess.target.is_like_windows {
             let res: io::Result<()> = try {
                 let mut f = File::create_buffered(&path)?;
 
@@ -835,6 +834,21 @@ impl<'a> Linker for GccLinker<'a> {
             if let Err(error) = res {
                 self.sess.dcx().emit_fatal(errors::LibDefWriteFailure { error });
             }
+            self.link_arg(path);
+        } else if crate_type == CrateType::Executable && !self.sess.target.is_like_solaris {
+            let res: io::Result<()> = try {
+                let mut f = File::create_buffered(&path)?;
+                writeln!(f, "{{")?;
+                for (sym, _) in symbols {
+                    debug!(sym);
+                    writeln!(f, "  {sym};")?;
+                }
+                writeln!(f, "}};")?;
+            };
+            if let Err(error) = res {
+                self.sess.dcx().emit_fatal(errors::VersionScriptWriteFailure { error });
+            }
+            self.link_arg("--dynamic-list").link_arg(path);
         } else {
             // Write an LD version script
             let res: io::Result<()> = try {
@@ -852,18 +866,13 @@ impl<'a> Linker for GccLinker<'a> {
             if let Err(error) = res {
                 self.sess.dcx().emit_fatal(errors::VersionScriptWriteFailure { error });
             }
-        }
-
-        if self.sess.target.is_like_darwin {
-            self.link_arg("-exported_symbols_list").link_arg(path);
-        } else if self.sess.target.is_like_solaris {
-            self.link_arg("-M").link_arg(path);
-        } else if is_windows {
-            self.link_arg(path);
-        } else {
-            let mut arg = OsString::from("--version-script=");
-            arg.push(path);
-            self.link_arg(arg).link_arg("--no-undefined-version");
+            if self.sess.target.is_like_solaris {
+                self.link_arg("-M").link_arg(path);
+            } else {
+                let mut arg = OsString::from("--version-script=");
+                arg.push(path);
+                self.link_arg(arg).link_arg("--no-undefined-version");
+            }
         }
     }
 
diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs
index 10b44a1faf0..fa69820d5d2 100644
--- a/compiler/rustc_codegen_ssa/src/mir/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs
@@ -140,8 +140,13 @@ enum LocalRef<'tcx, V> {
     Place(PlaceRef<'tcx, V>),
     /// `UnsizedPlace(p)`: `p` itself is a thin pointer (indirect place).
     /// `*p` is the wide pointer that references the actual unsized place.
-    /// Every time it is initialized, we have to reallocate the place
-    /// and update the wide pointer. That's the reason why it is indirect.
+    ///
+    /// MIR only supports unsized args, not dynamically-sized locals, so
+    /// new unsized temps don't exist and we must reuse the referred-to place.
+    ///
+    /// FIXME: Since the removal of unsized locals in <https://github.com/rust-lang/rust/pull/142911>,
+    /// can we maybe use `Place` here? Or refactor it in another way? There are quite a few
+    /// `UnsizedPlace => bug` branches now.
     UnsizedPlace(PlaceRef<'tcx, V>),
     /// The backend [`OperandValue`] has already been generated.
     Operand(OperandRef<'tcx, V>),
@@ -498,7 +503,7 @@ fn arg_local_refs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
                         LocalRef::Place(PlaceRef::new_sized(llarg, arg.layout))
                     }
                 }
-                // Unsized indirect qrguments
+                // Unsized indirect arguments
                 PassMode::Indirect { attrs: _, meta_attrs: Some(_), on_stack: _ } => {
                     // As the storage for the indirect argument lives during
                     // the whole function call, we just copy the wide pointer.
diff --git a/compiler/rustc_codegen_ssa/src/mir/operand.rs b/compiler/rustc_codegen_ssa/src/mir/operand.rs
index bc83e41b278..b0d191528a8 100644
--- a/compiler/rustc_codegen_ssa/src/mir/operand.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/operand.rs
@@ -16,9 +16,9 @@ use tracing::{debug, instrument};
 use super::place::{PlaceRef, PlaceValue};
 use super::rvalue::transmute_scalar;
 use super::{FunctionCx, LocalRef};
+use crate::MemFlags;
 use crate::common::IntPredicate;
 use crate::traits::*;
-use crate::{MemFlags, size_of_val};
 
 /// The representation of a Rust value. The enum variant is in fact
 /// uniquely determined by the value's type, but is kept as a
@@ -861,44 +861,6 @@ impl<'a, 'tcx, V: CodegenObject> OperandValue<V> {
             }
         }
     }
-
-    pub fn store_unsized<Bx: BuilderMethods<'a, 'tcx, Value = V>>(
-        self,
-        bx: &mut Bx,
-        indirect_dest: PlaceRef<'tcx, V>,
-    ) {
-        debug!("OperandRef::store_unsized: operand={:?}, indirect_dest={:?}", self, indirect_dest);
-        // `indirect_dest` must have `*mut T` type. We extract `T` out of it.
-        let unsized_ty = indirect_dest
-            .layout
-            .ty
-            .builtin_deref(true)
-            .unwrap_or_else(|| bug!("indirect_dest has non-pointer type: {:?}", indirect_dest));
-
-        let OperandValue::Ref(PlaceValue { llval: llptr, llextra: Some(llextra), .. }) = self
-        else {
-            bug!("store_unsized called with a sized value (or with an extern type)")
-        };
-
-        // Allocate an appropriate region on the stack, and copy the value into it. Since alloca
-        // doesn't support dynamic alignment, we allocate an extra align - 1 bytes, and align the
-        // pointer manually.
-        let (size, align) = size_of_val::size_and_align_of_dst(bx, unsized_ty, Some(llextra));
-        let one = bx.const_usize(1);
-        let align_minus_1 = bx.sub(align, one);
-        let size_extra = bx.add(size, align_minus_1);
-        let min_align = Align::ONE;
-        let alloca = bx.dynamic_alloca(size_extra, min_align);
-        let address = bx.ptrtoint(alloca, bx.type_isize());
-        let neg_address = bx.neg(address);
-        let offset = bx.and(neg_address, align_minus_1);
-        let dst = bx.inbounds_ptradd(alloca, offset);
-        bx.memcpy(dst, min_align, llptr, min_align, size, MemFlags::empty());
-
-        // Store the allocated region and the extra to the indirect place.
-        let indirect_operand = OperandValue::Pair(dst, llextra);
-        indirect_operand.store(bx, indirect_dest);
-    }
 }
 
 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
diff --git a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
index cbbb0196890..e90463aacc8 100644
--- a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
@@ -207,9 +207,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         {
             // These cases are all UB to actually hit, so don't emit code for them.
             // (The size mismatches are reachable via `transmute_unchecked`.)
-            // We can't use unreachable because that's a terminator, and we
-            // need something that can be in the middle of a basic block.
-            bx.assume(bx.cx().const_bool(false))
+            bx.unreachable_nonterminator();
         } else {
             // Since in this path we have a place anyway, we can store or copy to it,
             // making sure we use the destination place's alignment even if the
@@ -236,14 +234,10 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             || operand.layout.is_uninhabited()
             || cast.is_uninhabited()
         {
-            if !operand.layout.is_uninhabited() {
-                // Since this is known statically and the input could have existed
-                // without already having hit UB, might as well trap for it.
-                bx.abort();
-            }
+            bx.unreachable_nonterminator();
 
-            // Because this transmute is UB, return something easy to generate,
-            // since it's fine that later uses of the value are probably UB.
+            // We still need to return a value of the appropriate type, but
+            // it's already UB so do the easiest thing available.
             return OperandValue::poison(bx, cast);
         }
 
@@ -327,27 +321,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         Some(imm)
     }
 
-    pub(crate) fn codegen_rvalue_unsized(
-        &mut self,
-        bx: &mut Bx,
-        indirect_dest: PlaceRef<'tcx, Bx::Value>,
-        rvalue: &mir::Rvalue<'tcx>,
-    ) {
-        debug!(
-            "codegen_rvalue_unsized(indirect_dest.llval={:?}, rvalue={:?})",
-            indirect_dest.val.llval, rvalue
-        );
-
-        match *rvalue {
-            mir::Rvalue::Use(ref operand) => {
-                let cg_operand = self.codegen_operand(bx, operand);
-                cg_operand.val.store_unsized(bx, indirect_dest);
-            }
-
-            _ => bug!("unsized assignment other than `Rvalue::Use`"),
-        }
-    }
-
     pub(crate) fn codegen_rvalue_operand(
         &mut self,
         bx: &mut Bx,
diff --git a/compiler/rustc_codegen_ssa/src/mir/statement.rs b/compiler/rustc_codegen_ssa/src/mir/statement.rs
index cd55a838a75..f164e0f9123 100644
--- a/compiler/rustc_codegen_ssa/src/mir/statement.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/statement.rs
@@ -15,7 +15,12 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     match self.locals[index] {
                         LocalRef::Place(cg_dest) => self.codegen_rvalue(bx, cg_dest, rvalue),
                         LocalRef::UnsizedPlace(cg_indirect_dest) => {
-                            self.codegen_rvalue_unsized(bx, cg_indirect_dest, rvalue)
+                            let ty = cg_indirect_dest.layout.ty;
+                            span_bug!(
+                                statement.source_info.span,
+                                "cannot reallocate from `UnsizedPlace({ty})` \
+                                into `{rvalue:?}`; dynamic alloca is not supported",
+                            );
                         }
                         LocalRef::PendingOperand => {
                             let operand = self.codegen_rvalue_operand(bx, rvalue);
diff --git a/compiler/rustc_codegen_ssa/src/traits/builder.rs b/compiler/rustc_codegen_ssa/src/traits/builder.rs
index 9d367748c2a..979456a6ba7 100644
--- a/compiler/rustc_codegen_ssa/src/traits/builder.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/builder.rs
@@ -136,6 +136,16 @@ pub trait BuilderMethods<'a, 'tcx>:
     ) -> Self::Value;
     fn unreachable(&mut self);
 
+    /// Like [`Self::unreachable`], but for use in the middle of a basic block.
+    fn unreachable_nonterminator(&mut self) {
+        // This is the preferred LLVM incantation for this per
+        // https://llvm.org/docs/Frontend/PerformanceTips.html#other-things-to-consider
+        // Other backends may override if they have a better way.
+        let const_true = self.cx().const_bool(true);
+        let poison_ptr = self.const_poison(self.cx().type_ptr());
+        self.store(const_true, poison_ptr, Align::ONE);
+    }
+
     fn add(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
     fn fadd(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
     fn fadd_fast(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
@@ -224,7 +234,6 @@ pub trait BuilderMethods<'a, 'tcx>:
     fn to_immediate_scalar(&mut self, val: Self::Value, scalar: Scalar) -> Self::Value;
 
     fn alloca(&mut self, size: Size, align: Align) -> Self::Value;
-    fn dynamic_alloca(&mut self, size: Self::Value, align: Align) -> Self::Value;
 
     fn load(&mut self, ty: Self::Type, ptr: Self::Value, align: Align) -> Self::Value;
     fn volatile_load(&mut self, ty: Self::Type, ptr: Self::Value) -> Self::Value;
@@ -555,12 +564,33 @@ pub trait BuilderMethods<'a, 'tcx>:
     /// Called for `StorageDead`
     fn lifetime_end(&mut self, ptr: Self::Value, size: Size);
 
+    /// "Finally codegen the call"
+    ///
+    /// ## Arguments
+    ///
+    /// The `fn_attrs`, `fn_abi`, and `instance` arguments are Options because they are advisory.
+    /// They relate to optional codegen enhancements like LLVM CFI, and do not affect ABI per se.
+    /// Any ABI-related transformations should be handled by different, earlier stages of codegen.
+    /// For instance, in the caller of `BuilderMethods::call`.
+    ///
+    /// This means that a codegen backend which disregards `fn_attrs`, `fn_abi`, and `instance`
+    /// should still do correct codegen, and code should not be miscompiled if they are omitted.
+    /// It is not a miscompilation in this sense if it fails to run under CFI, other sanitizers, or
+    /// in the context of other compiler-enhanced security features.
+    ///
+    /// The typical case that they are None is during the codegen of intrinsics and lang-items,
+    /// as those are "fake functions" with only a trivial ABI if any, et cetera.
+    ///
+    /// ## Return
+    ///
+    /// Must return the value the function will return so it can be written to the destination,
+    /// assuming the function does not explicitly pass the destination as a pointer in `args`.
     fn call(
         &mut self,
         llty: Self::Type,
         fn_attrs: Option<&CodegenFnAttrs>,
         fn_abi: Option<&FnAbi<'tcx, Ty<'tcx>>>,
-        llfn: Self::Value,
+        fn_val: Self::Value,
         args: &[Self::Value],
         funclet: Option<&Self::Funclet>,
         instance: Option<Instance<'tcx>>,
diff --git a/compiler/rustc_codegen_ssa/src/traits/intrinsic.rs b/compiler/rustc_codegen_ssa/src/traits/intrinsic.rs
index 7d0c6be4c65..c5ecf43046c 100644
--- a/compiler/rustc_codegen_ssa/src/traits/intrinsic.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/intrinsic.rs
@@ -6,16 +6,22 @@ use crate::mir::operand::OperandRef;
 use crate::mir::place::PlaceRef;
 
 pub trait IntrinsicCallBuilderMethods<'tcx>: BackendTypes {
+    /// Higher-level interface to emitting calls to intrinsics
+    ///
     /// Remember to add all intrinsics here, in `compiler/rustc_hir_analysis/src/check/mod.rs`,
     /// and in `library/core/src/intrinsics.rs`; if you need access to any LLVM intrinsics,
     /// add them to `compiler/rustc_codegen_llvm/src/context.rs`.
     /// Returns `Err` if another instance should be called instead. This is used to invoke
     /// intrinsic default bodies in case an intrinsic is not implemented by the backend.
+    ///
+    /// NOTE: allowed to call [`BuilderMethods::call`]
+    ///
+    /// [`BuilderMethods::call`]: super::builder::BuilderMethods::call
     fn codegen_intrinsic_call(
         &mut self,
         instance: ty::Instance<'tcx>,
         args: &[OperandRef<'tcx, Self::Value>],
-        result: PlaceRef<'tcx, Self::Value>,
+        result_dest: PlaceRef<'tcx, Self::Value>,
         span: Span,
     ) -> Result<(), ty::Instance<'tcx>>;