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Merge pull request #12231 from JosJuice/jitarm64-frsqrte-optimization
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JitArm64: Optimize frsqrte routine
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@lioncash
lioncash committed Nov 28, 2023
2 parents 731013c + 9cc1df6 commit 7e9c19f
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Showing 3 changed files with 27 additions and 30 deletions.
4 changes: 2 additions & 2 deletions Source/Core/Core/PowerPC/JitArm64/JitArm64_FloatingPoint.cpp
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Expand Up @@ -686,7 +686,7 @@ void JitArm64::frsqrtex(UGeckoInstruction inst)
const ARM64Reg VB = fpr.R(b, RegType::LowerPair);
const ARM64Reg VD = fpr.RW(d, RegType::LowerPair);

gpr.Lock(ARM64Reg::W0, ARM64Reg::W1, ARM64Reg::W2, ARM64Reg::W3, ARM64Reg::W4, ARM64Reg::W30);
gpr.Lock(ARM64Reg::W0, ARM64Reg::W1, ARM64Reg::W2, ARM64Reg::W3, ARM64Reg::W30);

m_float_emit.FMOV(ARM64Reg::X1, EncodeRegToDouble(VB));
m_float_emit.FRSQRTE(ARM64Reg::D0, EncodeRegToDouble(VB));
Expand All @@ -697,7 +697,7 @@ void JitArm64::frsqrtex(UGeckoInstruction inst)

SetFPRFIfNeeded(false, ARM64Reg::X0);

gpr.Unlock(ARM64Reg::W0, ARM64Reg::W1, ARM64Reg::W2, ARM64Reg::W3, ARM64Reg::W4, ARM64Reg::W30);
gpr.Unlock(ARM64Reg::W0, ARM64Reg::W1, ARM64Reg::W2, ARM64Reg::W3, ARM64Reg::W30);
fpr.Unlock(ARM64Reg::Q0);
}

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4 changes: 2 additions & 2 deletions Source/Core/Core/PowerPC/JitArm64/JitArm64_Paired.cpp
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Expand Up @@ -514,7 +514,7 @@ void JitArm64::ps_rsqrte(UGeckoInstruction inst)
const u32 b = inst.FB;
const u32 d = inst.FD;

gpr.Lock(ARM64Reg::W0, ARM64Reg::W1, ARM64Reg::W2, ARM64Reg::W3, ARM64Reg::W4, ARM64Reg::W30);
gpr.Lock(ARM64Reg::W0, ARM64Reg::W1, ARM64Reg::W2, ARM64Reg::W3, ARM64Reg::W30);
fpr.Lock(ARM64Reg::Q0);

const ARM64Reg VB = fpr.R(b, RegType::Register);
Expand All @@ -529,7 +529,7 @@ void JitArm64::ps_rsqrte(UGeckoInstruction inst)
BL(GetAsmRoutines()->frsqrte);
m_float_emit.INS(64, EncodeRegToQuad(VD), 1, ARM64Reg::X0);

gpr.Unlock(ARM64Reg::W0, ARM64Reg::W1, ARM64Reg::W2, ARM64Reg::W3, ARM64Reg::W4, ARM64Reg::W30);
gpr.Unlock(ARM64Reg::W0, ARM64Reg::W1, ARM64Reg::W2, ARM64Reg::W3, ARM64Reg::W30);
fpr.Unlock(ARM64Reg::Q0);

fpr.FixSinglePrecision(d);
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49 changes: 23 additions & 26 deletions Source/Core/Core/PowerPC/JitArm64/JitAsm.cpp
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Expand Up @@ -307,7 +307,7 @@ void JitArm64::GenerateFres()
}

// Input: X1 contains input, and D0 contains result of running the input through AArch64 FRSQRTE.
// Output in X0 and memory (PPCState). Clobbers X0-X4 and flags.
// Output in X0 and memory (PPCState). Clobbers X0-X3 and flags.
void JitArm64::GenerateFrsqrte()
{
// The idea behind this implementation: AArch64's frsqrte instruction calculates the exponent and
Expand All @@ -323,35 +323,32 @@ void JitArm64::GenerateFrsqrte()
CMP(ARM64Reg::X2, ARM64Reg::X3);
FixupBranch nan_or_inf = B(CCFlags::CC_EQ);
FixupBranch negative = TBNZ(ARM64Reg::X1, 63);
AND(ARM64Reg::X3, ARM64Reg::X1, LogicalImm(Common::DOUBLE_FRAC, 64));
FixupBranch normal = CBNZ(ARM64Reg::X2);

// "Normalize" denormal values
CLZ(ARM64Reg::X3, ARM64Reg::X3);
SUB(ARM64Reg::X4, ARM64Reg::X3, 11);
MOVI2R(ARM64Reg::X2, 0x00C0'0000'0000'0000);
LSLV(ARM64Reg::X4, ARM64Reg::X1, ARM64Reg::X4);
SUB(ARM64Reg::X2, ARM64Reg::X2, ARM64Reg::X3, ArithOption(ARM64Reg::X3, ShiftType::LSL, 52));
AND(ARM64Reg::X3, ARM64Reg::X4, LogicalImm(Common::DOUBLE_FRAC - 1, 64));
// "Normalize" denormal values.
// The simplified calculation used here results in the upper 11 bits being incorrect,
// but that's fine, because the code below never reads those bits.
CLZ(ARM64Reg::X3, ARM64Reg::X1);
LSLV(ARM64Reg::X1, ARM64Reg::X1, ARM64Reg::X3);
LSR(ARM64Reg::X1, ARM64Reg::X1, 11);
BFI(ARM64Reg::X1, ARM64Reg::X3, 52, 12);

SetJumpTarget(normal);
LSR(ARM64Reg::X2, ARM64Reg::X2, 48);
AND(ARM64Reg::X2, ARM64Reg::X2, LogicalImm(0x10, 64));
MOVP2R(ARM64Reg::X1, &Common::frsqrte_expected);
ORR(ARM64Reg::X2, ARM64Reg::X2, ARM64Reg::X3, ArithOption(ARM64Reg::X3, ShiftType::LSR, 48));
ADD(ARM64Reg::X2, ARM64Reg::X1, ARM64Reg::X2, ArithOption(ARM64Reg::X2, ShiftType::LSL, 3));
LDP(IndexType::Signed, ARM64Reg::W1, ARM64Reg::W2, ARM64Reg::X2, 0);
UBFX(ARM64Reg::X3, ARM64Reg::X3, 37, 11);
UBFX(ARM64Reg::X2, ARM64Reg::X1, 48, 5);
MOVP2R(ARM64Reg::X3, &Common::frsqrte_expected);
ADD(ARM64Reg::X2, ARM64Reg::X3, ARM64Reg::X2, ArithOption(ARM64Reg::X2, ShiftType::LSL, 3));
LDP(IndexType::Signed, ARM64Reg::W3, ARM64Reg::W2, ARM64Reg::X2, 0);
UBFX(ARM64Reg::X1, ARM64Reg::X1, 37, 11);
AND(ARM64Reg::X0, ARM64Reg::X0, LogicalImm(Common::DOUBLE_SIGN | Common::DOUBLE_EXP, 64));
MADD(ARM64Reg::W3, ARM64Reg::W3, ARM64Reg::W2, ARM64Reg::W1);
ORR(ARM64Reg::X0, ARM64Reg::X0, ARM64Reg::X3, ArithOption(ARM64Reg::X3, ShiftType::LSL, 26));
MADD(ARM64Reg::W1, ARM64Reg::W1, ARM64Reg::W2, ARM64Reg::W3);
ORR(ARM64Reg::X0, ARM64Reg::X0, ARM64Reg::X1, ArithOption(ARM64Reg::X1, ShiftType::LSL, 26));
RET();

SetJumpTarget(zero);
LDR(IndexType::Unsigned, ARM64Reg::W4, PPC_REG, PPCSTATE_OFF(fpscr));
FixupBranch skip_set_zx = TBNZ(ARM64Reg::W4, 26);
ORRI2R(ARM64Reg::W4, ARM64Reg::W4, FPSCR_FX | FPSCR_ZX, ARM64Reg::W2);
STR(IndexType::Unsigned, ARM64Reg::W4, PPC_REG, PPCSTATE_OFF(fpscr));
LDR(IndexType::Unsigned, ARM64Reg::W3, PPC_REG, PPCSTATE_OFF(fpscr));
FixupBranch skip_set_zx = TBNZ(ARM64Reg::W3, 26);
ORRI2R(ARM64Reg::W3, ARM64Reg::W3, FPSCR_FX | FPSCR_ZX, ARM64Reg::W2);
STR(IndexType::Unsigned, ARM64Reg::W3, PPC_REG, PPCSTATE_OFF(fpscr));
SetJumpTarget(skip_set_zx);
RET();

Expand All @@ -361,10 +358,10 @@ void JitArm64::GenerateFrsqrte()
FixupBranch nan_or_positive_inf = B(CCFlags::CC_NEQ);

SetJumpTarget(negative);
LDR(IndexType::Unsigned, ARM64Reg::W4, PPC_REG, PPCSTATE_OFF(fpscr));
FixupBranch skip_set_vxsqrt = TBNZ(ARM64Reg::W4, 9);
ORRI2R(ARM64Reg::W4, ARM64Reg::W4, FPSCR_FX | FPSCR_VXSQRT, ARM64Reg::W2);
STR(IndexType::Unsigned, ARM64Reg::W4, PPC_REG, PPCSTATE_OFF(fpscr));
LDR(IndexType::Unsigned, ARM64Reg::W3, PPC_REG, PPCSTATE_OFF(fpscr));
FixupBranch skip_set_vxsqrt = TBNZ(ARM64Reg::W3, 9);
ORRI2R(ARM64Reg::W3, ARM64Reg::W3, FPSCR_FX | FPSCR_VXSQRT, ARM64Reg::W2);
STR(IndexType::Unsigned, ARM64Reg::W3, PPC_REG, PPCSTATE_OFF(fpscr));
SetJumpTarget(skip_set_vxsqrt);
SetJumpTarget(nan_or_positive_inf);
RET();
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