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Use llvm.memset.p0i8.* to initialize all same-bytes arrays

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This commit is contained in:
Oli Scherer 2025-01-08 16:29:32 +00:00
parent 65ea9f3eb4
commit 65b01cb182
2 changed files with 12 additions and 10 deletions
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14
compiler/rustc_codegen_ssa/src/mir/rvalue.rs
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@ -97,11 +97,15 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
let start = dest.val.llval;
let size = bx.const_usize(dest.layout.size.bytes());
// Use llvm.memset.p0i8.* to initialize all zero arrays
if bx.cx().const_to_opt_u128(v, false) == Some(0) {
let fill = bx.cx().const_u8(0);
bx.memset(start, fill, size, dest.val.align, MemFlags::empty());
return true;
// Use llvm.memset.p0i8.* to initialize all same byte arrays
if let Some(int) = bx.cx().const_to_opt_u128(v, false) {
let bytes = &int.to_le_bytes()[..cg_elem.layout.size.bytes_usize()];
let first = bytes[0];
if bytes[1..].iter().all(|&b| b == first) {
let fill = bx.cx().const_u8(first);
bx.memset(start, fill, size, dest.val.align, MemFlags::empty());
return true;
}
}
// Use llvm.memset.p0i8.* to initialize byte arrays