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[CPU] Improve vrefp accuracy

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This commit is contained in:
Joel Linn
2022-02-16 00:17:28 +01:00
committed by Rick Gibbed
parent 294c76f7c4
commit d64848245d
3 changed files with 26 additions and 8 deletions
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28
src/xenia/cpu/backend/x64/x64_sequences.cc
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@@ -2,7 +2,7 @@
******************************************************************************
* Xenia : Xbox 360 Emulator Research Project *
******************************************************************************
* Copyright 2020 Ben Vanik. All rights reserved. *
* Copyright 2022 Ben Vanik. All rights reserved. *
* Released under the BSD license - see LICENSE in the root for more details. *
******************************************************************************
*/
@@ -2376,21 +2376,37 @@ EMITTER_OPCODE_TABLE(OPCODE_RSQRT, RSQRT_F32, RSQRT_F64, RSQRT_V128);
// ============================================================================
// OPCODE_RECIP
// ============================================================================
// Altivec guarantees an error of < 1/4096 for vrefp while AVX only gives
// < 1.5*2^-12 ≈ 1/2730 for rcpps. This breaks camp, horse and random event
// spawning, breaks cactus collision as well as flickering grass in 5454082B
struct RECIP_F32 : Sequence<RECIP_F32, I<OPCODE_RECIP, F32Op, F32Op>> {
static void Emit(X64Emitter& e, const EmitArgType& i) {
e.vrcpss(i.dest, i.src1);
if (e.IsFeatureEnabled(kX64EmitAVX512Ortho)) {
e.vrcp14ss(i.dest, i.src1, i.src1);
} else {
e.vmovaps(e.xmm0, e.GetXmmConstPtr(XMMOne));
e.vdivss(i.dest, e.xmm0, i.src1);
}
}
};
struct RECIP_F64 : Sequence<RECIP_F64, I<OPCODE_RECIP, F64Op, F64Op>> {
static void Emit(X64Emitter& e, const EmitArgType& i) {
e.vcvtsd2ss(i.dest, i.src1);
e.vrcpss(i.dest, i.dest);
e.vcvtss2sd(i.dest, i.dest);
if (e.IsFeatureEnabled(kX64EmitAVX512Ortho)) {
e.vrcp14sd(i.dest, i.src1, i.src1);
} else {
e.vmovapd(e.xmm0, e.GetXmmConstPtr(XMMOnePD));
e.vdivsd(i.dest, e.xmm0, i.src1);
}
}
};
struct RECIP_V128 : Sequence<RECIP_V128, I<OPCODE_RECIP, V128Op, V128Op>> {
static void Emit(X64Emitter& e, const EmitArgType& i) {
e.vrcpps(i.dest, i.src1);
if (e.IsFeatureEnabled(kX64EmitAVX512Ortho)) {
e.vrcp14ps(i.dest, i.src1);
} else {
e.vmovaps(e.xmm0, e.GetXmmConstPtr(XMMOne));
e.vdivps(i.dest, e.xmm0, i.src1);
}
}
};
EMITTER_OPCODE_TABLE(OPCODE_RECIP, RECIP_F32, RECIP_F64, RECIP_V128);