bjoernager/rust
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Add transmute optimization tests and some extra comments

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This commit is contained in:
Scott McMurray 2023-04-19 23:14:28 -07:00
parent 1bcb0ec28c
commit baf98e7515
2 changed files with 118 additions and 0 deletions
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9
compiler/rustc_codegen_ssa/src/mir/rvalue.rs
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@ -290,7 +290,13 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
use abi::Primitive::*;
imm = bx.from_immediate(imm);
// When scalars are passed by value, there's no metadata recording their
// valid ranges. For example, `char`s are passed as just `i32`, with no
// way for LLVM to know that they're 0x10FFFF at most. Thus we assume
// the range of the input value too, not just the output range.
self.assume_scalar_range(bx, imm, from_scalar, from_backend_ty);
imm = match (from_scalar.primitive(), to_scalar.primitive()) {
(Int(..) | F32 | F64, Int(..) | F32 | F64) => bx.bitcast(imm, to_backend_ty),
(Pointer(..), Pointer(..)) => bx.pointercast(imm, to_backend_ty),
@ -318,6 +324,9 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
backend_ty: Bx::Type,
) {
if matches!(self.cx.sess().opts.optimize, OptLevel::No | OptLevel::Less)
// For now, the critical niches are all over `Int`eger values.
// Should floating-point values or pointers ever get more complex
// niches, then this code will probably want to handle them too.
|| !matches!(scalar.primitive(), abi::Primitive::Int(..))
|| scalar.is_always_valid(self.cx)
{