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emit_x64_vector: Bugfix for ArithmeticShiftRightByte: shift_amount can be >= 8

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This commit is contained in:
Merry 2021-03-27 21:31:22 +00:00
parent ad9b33164e
commit dc37fe6e28
1 changed files with 4 additions and 4 deletions
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8
src/backend/x64/emit_x64_vector.cpp
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@ -440,13 +440,13 @@ void EmitX64::EmitVectorAnd(EmitContext& ctx, IR::Inst* inst) {
static void ArithmeticShiftRightByte(EmitContext& ctx, BlockOfCode& code, const Xbyak::Xmm& result, u8 shift_amount) {
if (code.HasAVX512_Icelake()) {
// Do a logical shift right upon the 8x8 bit-matrix, but shift in
// `0x80` bytes into the matrix to repeat the most significant bit.
const u64 zero_extend = ~(0xFFFFFFFFFFFFFFFF << (shift_amount * 8)) & 0x8080808080808080;
const u64 shift_matrix = (0x0102040810204080 >> (shift_amount * 8)) | zero_extend;
const u64 shift_matrix = shift_amount < 8
? (0x0102040810204080 << (shift_amount * 8)) | (0x8080808080808080 >> (64 - shift_amount * 8))
: 0x8080808080808080;
code.vgf2p8affineqb(result, result, code.MConst(xword_b, shift_matrix), 0);
return;
}
const Xbyak::Xmm tmp = ctx.reg_alloc.ScratchXmm();
code.punpckhbw(tmp, result);