emit_x64_floating_point: EmitFPToFixed: No need to round if rounding_mode == TowardsZero
cvttsd2si truncates during operation
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1 changed files with 11 additions and 3 deletions
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@ -1470,7 +1470,10 @@ static void EmitFPToFixed(BlockOfCode& code, EmitContext& ctx, IR::Inst* inst) {
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if constexpr (fsize != 16) {
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const auto round_imm = ConvertRoundingModeToX64Immediate(rounding_mode);
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if (code.HasHostFeature(HostFeature::SSE41) && round_imm) {
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// cvttsd2si truncates during operation so rounding (and thus SSE4.1) not required
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const bool truncating = rounding_mode == FP::RoundingMode::TowardsZero;
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if (round_imm && (truncating || code.HasHostFeature(HostFeature::SSE41))) {
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const Xbyak::Xmm src = ctx.reg_alloc.UseScratchXmm(args[0]);
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const Xbyak::Reg64 result = ctx.reg_alloc.ScratchGpr().cvt64();
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@ -1480,14 +1483,19 @@ static void EmitFPToFixed(BlockOfCode& code, EmitContext& ctx, IR::Inst* inst) {
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code.mulsd(src, code.MConst(xword, scale_factor));
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}
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if (!truncating) {
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code.roundsd(src, src, *round_imm);
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}
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} else {
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if (fbits != 0) {
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const u32 scale_factor = static_cast<u32>((fbits + 127) << 23);
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code.mulss(src, code.MConst(xword, scale_factor));
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}
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if (!truncating) {
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code.roundss(src, src, *round_imm);
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}
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code.cvtss2sd(src, src);
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}
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