bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Auto merge of #135258 - oli-obk:push-ktzskvxuwnlt, r=saethlin

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

Similar to #43488

debug builds can now handle `0x0101_u16` and other multi-byte scalars that have all the same bytes (instead of special casing just `0`)
This commit is contained in:
bors 2025-01-11 03:40:38 +00:00
commit a2d7c8144f
2 changed files with 47 additions and 7 deletions
Download patch file Download diff file Expand all files Collapse all files

28
compiler/rustc_codegen_ssa/src/mir/rvalue.rs
View file

@ -93,23 +93,37 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
return;
}
if let OperandValue::Immediate(v) = cg_elem.val {
let try_init_all_same = |bx: &mut Bx, v| {
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;
// 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
let v = bx.from_immediate(v);
if bx.cx().val_ty(v) == bx.cx().type_i8() {
bx.memset(start, v, size, dest.val.align, MemFlags::empty());
return;
return true;
}
false
};
match cg_elem.val {
OperandValue::Immediate(v) => {
if try_init_all_same(bx, v) {
return;
}
}
_ => (),
}
let count = self