Auto merge of #145126 - tgross35:rollup-6w87usd, r=tgross35

Rollup of 8 pull requests

Successful merges:

 - rust-lang/rust#139451 (Add `target_env = "macabi"` and `target_env = "sim"`)
 - rust-lang/rust#144039 (Use `tcx.short_string()` in more diagnostics)
 - rust-lang/rust#144192 (atomicrmw on pointers: move integer-pointer cast hacks into backend)
 - rust-lang/rust#144545 (In rustc_pattern_analysis, put `true` witnesses before `false` witnesses)
 - rust-lang/rust#144579 (Implement declarative (`macro_rules!`) attribute macros (RFC 3697))
 - rust-lang/rust#144649 (Account for bare tuples and `Pin` methods in field searching logic)
 - rust-lang/rust#144775 (more strongly dissuade use of `skip_binder`)
 - rust-lang/rust#144987 (Enable f16 and f128 on targets that were fixed in LLVM21)

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 6 insertions, 8 deletions

diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs
index bd175e560c7..32cdef075e7 100644
--- a/compiler/rustc_codegen_llvm/src/builder.rs
+++ b/compiler/rustc_codegen_llvm/src/builder.rs
@@ -1327,15 +1327,13 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         &mut self,
         op: rustc_codegen_ssa::common::AtomicRmwBinOp,
         dst: &'ll Value,
-        mut src: &'ll Value,
+        src: &'ll Value,
         order: rustc_middle::ty::AtomicOrdering,
+        ret_ptr: bool,
     ) -> &'ll Value {
-        // The only RMW operation that LLVM supports on pointers is compare-exchange.
-        let requires_cast_to_int = self.val_ty(src) == self.type_ptr()
-            && op != rustc_codegen_ssa::common::AtomicRmwBinOp::AtomicXchg;
-        if requires_cast_to_int {
-            src = self.ptrtoint(src, self.type_isize());
-        }
+        // FIXME: If `ret_ptr` is true and `src` is not a pointer, we *should* tell LLVM that the
+        // LHS is a pointer and the operation should be provenance-preserving, but LLVM does not
+        // currently support that (https://github.com/llvm/llvm-project/issues/120837).
         let mut res = unsafe {
             llvm::LLVMBuildAtomicRMW(
                 self.llbuilder,
@@ -1346,7 +1344,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
                 llvm::False, // SingleThreaded
             )
         };
-        if requires_cast_to_int {
+        if ret_ptr && self.val_ty(res) != self.type_ptr() {
             res = self.inttoptr(res, self.type_ptr());
         }
         res