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compiler: add simd_ctpop intrinsic #125266

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merged 4 commits into from
May 21, 2024
Merged

compiler: add simd_ctpop intrinsic #125266

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1914c72
compiler: add simd_ctpop intrinsic
workingjubilee May 19, 2024
1185a64
miri: support simd_ctpop
workingjubilee May 20, 2024
9557b90
cg_clif: support simd_ctpop
workingjubilee May 20, 2024
213351a
clarify the second arg to llvm.ctlz and cttz
workingjubilee May 20, 2024
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6 changes: 3 additions & 3 deletions compiler/rustc_codegen_llvm/src/intrinsic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2368,16 +2368,16 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
// byte swap is no-op for i8/u8
sym::simd_bswap if int_size == 8 => Ok(args[0].immediate()),
sym::simd_ctlz | sym::simd_cttz => {
// this fun bonus i1 arg means "poison if the arg vector contains zero"
// for the (int, i1 immediate) pair, the second arg adds `(0, true) => poison`
let fn_ty = bx.type_func(&[vec_ty, bx.type_i1()], vec_ty);
let dont_poison_on_zero = bx.const_int(bx.type_i1(), 0);
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Shouldn't this be called poison_on_zero, which we are then setting to false?

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hmmm, plausible. I was going for a "nah nah" instead of a "yeah nah".

let f = bx.declare_cfn(llvm_intrinsic, llvm::UnnamedAddr::No, fn_ty);
Ok(bx.call(
fn_ty,
None,
None,
f,
// simd_ctlz and simd_cttz are exposed to safe code, so let's not poison anything
&[args[0].immediate(), bx.const_int(bx.type_i1(), 0)],
&[args[0].immediate(), dont_poison_on_zero],
None,
None,
))
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