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[CPU] Improve vrsqrtefp accuracy

This commit is contained in:
Joel Linn 2022-02-16 00:51:24 +01:00 committed by Rick Gibbed
parent d64848245d
commit 00e7de9297
1 changed files with 24 additions and 6 deletions
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30
src/xenia/cpu/backend/x64/x64_sequences.cc
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@ -1,4 +1,4 @@
/**
/**
******************************************************************************
* Xenia : Xbox 360 Emulator Research Project *
******************************************************************************
@ -2354,21 +2354,39 @@ EMITTER_OPCODE_TABLE(OPCODE_SQRT, SQRT_F32, SQRT_F64, SQRT_V128);
// ============================================================================
// OPCODE_RSQRT
// ============================================================================
// Altivec guarantees an error of < 1/4096 for vrsqrtefp while AVX only gives
// < 1.5*2^-12 ≈ 1/2730 for vrsqrtps.
struct RSQRT_F32 : Sequence<RSQRT_F32, I<OPCODE_RSQRT, F32Op, F32Op>> {
static void Emit(X64Emitter& e, const EmitArgType& i) {
e.vrsqrtss(i.dest, i.src1);
if (e.IsFeatureEnabled(kX64EmitAVX512Ortho)) {
e.vrsqrt14ss(i.dest, i.src1, i.src1);
} else {
e.vmovaps(e.xmm0, e.GetXmmConstPtr(XMMOne));
e.vsqrtss(e.xmm1, i.src1, i.src1);
e.vdivss(i.dest, e.xmm0, e.xmm1);
}
}
};
struct RSQRT_F64 : Sequence<RSQRT_F64, I<OPCODE_RSQRT, F64Op, F64Op>> {
static void Emit(X64Emitter& e, const EmitArgType& i) {
e.vcvtsd2ss(i.dest, i.src1);
e.vrsqrtss(i.dest, i.dest);
e.vcvtss2sd(i.dest, i.dest);
if (e.IsFeatureEnabled(kX64EmitAVX512Ortho)) {
e.vrsqrt14sd(i.dest, i.src1, i.src1);
} else {
e.vmovapd(e.xmm0, e.GetXmmConstPtr(XMMOnePD));
e.vsqrtsd(e.xmm1, i.src1, i.src1);
e.vdivsd(i.dest, e.xmm0, e.xmm1);
}
}
};
struct RSQRT_V128 : Sequence<RSQRT_V128, I<OPCODE_RSQRT, V128Op, V128Op>> {
static void Emit(X64Emitter& e, const EmitArgType& i) {
e.vrsqrtps(i.dest, i.src1);
if (e.IsFeatureEnabled(kX64EmitAVX512Ortho)) {
e.vrsqrt14ps(i.dest, i.src1);
} else {
e.vmovaps(e.xmm0, e.GetXmmConstPtr(XMMOne));
e.vsqrtps(e.xmm1, i.src1);
e.vdivps(i.dest, e.xmm0, e.xmm1);
}
}
};
EMITTER_OPCODE_TABLE(OPCODE_RSQRT, RSQRT_F32, RSQRT_F64, RSQRT_V128);