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Jit64: divwx - Eliminate MOV for division by 2

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When destination and input registers match, a redundant MOV instruction
can be eliminated.

Before:
8B C7                mov         eax,edi
8B F8                mov         edi,eax
C1 EF 1F             shr         edi,1Fh
03 F8                add         edi,eax
D1 FF                sar         edi,1

After:
8B C7                mov         eax,edi
C1 EF 1F             shr         edi,1Fh
03 F8                add         edi,eax
D1 FF                sar         edi,1
This commit is contained in:
Sintendo 2021-03-24 22:40:35 +01:00
parent 4d37dad20d
commit 246adf0d6d
1 changed files with 13 additions and 4 deletions
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17
Source/Core/Core/PowerPC/Jit64/Jit_Integer.cpp
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@ -1464,12 +1464,21 @@ void Jit64::divwx(UGeckoInstruction inst)
else if (divisor == 2 || divisor == -2) else if (divisor == 2 || divisor == -2)
{ {
X64Reg tmp = RSCRATCH; X64Reg tmp = RSCRATCH;
if (Ra.IsSimpleReg() && Ra.GetSimpleReg() != Rd) if (!Ra.IsSimpleReg())
tmp = Ra.GetSimpleReg(); {
else
MOV(32, R(tmp), Ra); MOV(32, R(tmp), Ra);
MOV(32, Rd, R(tmp)); MOV(32, Rd, R(tmp));
}
else if (d == a)
{
MOV(32, R(tmp), Ra);
}
else
{
MOV(32, Rd, Ra);
tmp = Ra.GetSimpleReg();
}
SHR(32, Rd, Imm8(31)); SHR(32, Rd, Imm8(31));
ADD(32, Rd, R(tmp)); ADD(32, Rd, R(tmp));
SAR(32, Rd, Imm8(1)); SAR(32, Rd, Imm8(1));