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PowerPC: Negate m_dec values in frsqrte table

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This value is used in a multiplication. The result of this
multiplication is then subtracted from m_base. By negating m_dec, we are
free to use an addition instead.

On x64, this saves an instruction.
This commit is contained in:
Sintendo
2023-10-10 22:47:31 +02:00
parent 60e3b4c093
commit 3c3168706c
3 changed files with 14 additions and 15 deletions
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9
Source/Core/Core/PowerPC/Jit64Common/Jit64AsmCommon.cpp
View File

@ -150,14 +150,13 @@ void CommonAsmRoutines::GenFrsqrte()
AND(32, R(RSCRATCH), Imm32(0x7FF));
IMUL(32, RSCRATCH,
MComplex(RSCRATCH2, RSCRATCH_EXTRA, SCALE_8, offsetof(Common::BaseAndDec, m_dec)));
MOV(32, R(RSCRATCH_EXTRA),
ADD(32, R(RSCRATCH),
MComplex(RSCRATCH2, RSCRATCH_EXTRA, SCALE_8, offsetof(Common::BaseAndDec, m_base)));
SUB(32, R(RSCRATCH_EXTRA), R(RSCRATCH));
SHL(64, R(RSCRATCH_EXTRA), Imm8(26));
SHL(64, R(RSCRATCH), Imm8(26));
POP(RSCRATCH2);
OR(64, R(RSCRATCH2), R(RSCRATCH_EXTRA)); // vali |= (s64)(frsqrte_expected_base[index] -
// frsqrte_expected_dec[index] * (i % 2048)) << 26;
OR(64, R(RSCRATCH2), R(RSCRATCH)); // vali |= (s64)(frsqrte_expected_base[index] +
// frsqrte_expected_dec[index] * (i % 2048)) << 26;
MOVQ_xmm(XMM0, R(RSCRATCH2));
RET();

2
Source/Core/Core/PowerPC/JitArm64/JitAsm.cpp
View File

@ -347,7 +347,7 @@ void JitArm64::GenerateFrsqrte()
LDP(IndexType::Signed, ARM64Reg::W1, ARM64Reg::W2, ARM64Reg::X2, 0);
UBFX(ARM64Reg::X3, ARM64Reg::X3, 37, 11);
AND(ARM64Reg::X0, ARM64Reg::X0, LogicalImm(Common::DOUBLE_SIGN | Common::DOUBLE_EXP, 64));
MSUB(ARM64Reg::W3, ARM64Reg::W3, ARM64Reg::W2, ARM64Reg::W1);
MADD(ARM64Reg::W3, ARM64Reg::W3, ARM64Reg::W2, ARM64Reg::W1);
ORR(ARM64Reg::X0, ARM64Reg::X0, ARM64Reg::X3, ArithOption(ARM64Reg::X3, ShiftType::LSL, 26));
RET();