diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_codegen_ssa/src/mir/block.rs | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs index e59832a8eed..ce56f163549 100644 --- a/compiler/rustc_codegen_ssa/src/mir/block.rs +++ b/compiler/rustc_codegen_ssa/src/mir/block.rs @@ -1395,6 +1395,25 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { dst: PlaceRef<'tcx, Bx::Value>, ) { let src = self.codegen_operand(bx, src); + + // Special-case transmutes between scalars as simple bitcasts. + match (&src.layout.abi, &dst.layout.abi) { + (abi::Abi::Scalar(src_scalar), abi::Abi::Scalar(dst_scalar)) => { + // HACK(eddyb) LLVM doesn't like `bitcast`s between pointers and non-pointers. + if (src_scalar.value == abi::Pointer) == (dst_scalar.value == abi::Pointer) { + assert_eq!(src.layout.size, dst.layout.size); + + // NOTE(eddyb) the `from_immediate` and `to_immediate_scalar` + // conversions allow handling `bool`s the same as `u8`s. + let src = bx.from_immediate(src.immediate()); + let src_as_dst = bx.bitcast(src, bx.backend_type(dst.layout)); + Immediate(bx.to_immediate_scalar(src_as_dst, dst_scalar)).store(bx, dst); + return; + } + } + _ => {} + } + let llty = bx.backend_type(src.layout); let cast_ptr = bx.pointercast(dst.llval, bx.type_ptr_to(llty)); let align = src.layout.align.abi.min(dst.align); |