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emit_x64_vector: GNFI implementation of EmitVectorLogicalShiftLeft8

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Same principle as EmitVectorLogicalShiftRight8. An 8x8 galois identity
matrix is bit-shfited to allow for arbitrary 8-bit-lane shifts.
This commit is contained in:
Wunkolo 2020-10-28 06:41:57 -07:00 committed by merry
parent 5cc646ffed
commit 7df235aefb
1 changed files with 10 additions and 4 deletions
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6
src/backend/x64/emit_x64_vector.cpp
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@ -1460,12 +1460,18 @@ void EmitX64::EmitVectorLogicalShiftLeft8(EmitContext& ctx, IR::Inst* inst) {
if (shift_amount == 1) {
code.paddb(result, result);
} else if (shift_amount > 0) {
if (code.HasAVX512_Icelake()) {
// Galois 8x8 identity matrix, bit-shifted by the shift-amount
const u64 shift_matrix = 0x0102040810204080 >> (shift_amount * 8);
code.vgf2p8affineqb(result, result, code.MConst(xword_b, shift_matrix), 0);
} else {
const u64 replicand = (0xFFULL << shift_amount) & 0xFF;
const u64 mask = Common::Replicate(replicand, Common::BitSize<u8>());
code.psllw(result, shift_amount);
code.pand(result, code.MConst(xword, mask, mask));
}
}
ctx.reg_alloc.DefineValue(inst, result);
}