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Introduce Unsafe_InaccurateNaN

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This commit is contained in:
MerryMage 2021-01-01 07:17:34 +00:00
parent 4a9a0d07f7
commit eeeafaf5fb
2 changed files with 19 additions and 0 deletions
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3
include/dynarmic/optimization_flags.h
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@ -39,6 +39,9 @@ enum class OptimizationFlag : std::uint32_t {
/// This is an UNSAFE optimization that reduces accuracy of certain floating-point instructions.
/// This allows results of FRECPE and FRSQRTE to have **less** error than spec allows.
Unsafe_ReducedErrorFP = 0x00020000,
/// This is an UNSAFE optimization that causes floating-point instructions to not produce correct NaNs.
/// This may also result in inaccurate results when instructions are given certain special values.
Unsafe_InaccurateNaN = 0x00040000,
};
constexpr OptimizationFlag no_optimizations = static_cast<OptimizationFlag>(0);

16
src/backend/x64/emit_x64_floating_point.cpp
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@ -810,6 +810,22 @@ static void EmitFPRecipStepFused(BlockOfCode& code, EmitContext& ctx, IR::Inst*
using FPT = mp::unsigned_integer_of_size<fsize>;
if constexpr (fsize != 16) {
if (code.HasFMA() && ctx.HasOptimization(OptimizationFlag::Unsafe_InaccurateNaN)) {
auto args = ctx.reg_alloc.GetArgumentInfo(inst);
Xbyak::Label end, fallback;
const Xbyak::Xmm operand1 = ctx.reg_alloc.UseXmm(args[0]);
const Xbyak::Xmm operand2 = ctx.reg_alloc.UseXmm(args[1]);
const Xbyak::Xmm result = ctx.reg_alloc.ScratchXmm();
code.movaps(result, code.MConst(xword, FP::FPValue<FPT, false, 0, 2>()));
FCODE(vfnmadd231s)(result, operand1, operand2);
ctx.reg_alloc.DefineValue(inst, result);
return;
}
if (code.HasFMA()) {
auto args = ctx.reg_alloc.GetArgumentInfo(inst);