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Rollup merge of #77504 - Amanieu:select_simd_bitmask, r=ecstatic-morse

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Support vectors with fewer than 8 elements for simd_select_bitmask

Resolves the issue raised here: https://github.com/rust-lang/stdarch/issues/310#issuecomment-693730094
This commit is contained in:
Jonas Schievink 2020-10-04 15:45:43 +02:00 • committed by GitHub
commit 5bd9ce5cd4
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4 changed files with 37 additions and 8 deletions
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10
compiler/rustc_codegen_llvm/src/intrinsic.rs
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@ -793,14 +793,18 @@ fn generic_simd_intrinsic(
require_simd!(arg_tys[1], "argument");
let v_len = arg_tys[1].simd_size(tcx);
require!(
m_len == v_len,
// Allow masks for vectors with fewer than 8 elements to be
// represented with a u8 or i8.
m_len == v_len || (m_len == 8 && v_len < 8),
"mismatched lengths: mask length `{}` != other vector length `{}`",
m_len,
v_len
);
let i1 = bx.type_i1();
let i1xn = bx.type_vector(i1, m_len);
let m_i1s = bx.bitcast(args[0].immediate(), i1xn);
let im = bx.type_ix(v_len);
let i1xn = bx.type_vector(i1, v_len);
let m_im = bx.trunc(args[0].immediate(), im);
let m_i1s = bx.bitcast(m_im, i1xn);
return Ok(bx.select(m_i1s, args[1].immediate(), args[2].immediate()));
}