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Jit64: rlwnmx - Optimize rotate by constant 

Only removes the scratch register and a MOV, but hey.

Before:
B9 02 00 00 00       mov         ecx,2
41 8B F5             mov         esi,r13d
D3 C6                rol         esi,cl
83 E6 01             and         esi,1

After:
41 8B F5             mov         esi,r13d
C1 C6 02             rol         esi,2
83 E6 01             and         esi,1
This commit is contained in:
Sintendo 2020-11-19 21:25:11 +01:00
parent cb70d5ee4f
commit 1a52fdf7e3
1 changed files with 19 additions and 0 deletions
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19
Source/Core/Core/PowerPC/Jit64/Jit_Integer.cpp
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@ -1729,6 +1729,25 @@ void Jit64::rlwnmx(UGeckoInstruction inst)
{
gpr.SetImmediate32(a, Common::RotateLeft(gpr.Imm32(s), gpr.Imm32(b) & 0x1F) & mask);
}
else if (gpr.IsImm(b))
{
u32 amount = gpr.Imm32(b) & 0x1f;
RCX64Reg Ra = gpr.Bind(a, RCMode::Write);
RCOpArg Rs = gpr.Use(s, RCMode::Read);
RegCache::Realize(Ra, Rs);
if (a != s)
MOV(32, Ra, Rs);
if (amount)
ROL(32, Ra, Imm8(amount));
// we need flags if we're merging the branch
if (inst.Rc && CheckMergedBranch(0))
AND(32, Ra, Imm32(mask));
else
AndWithMask(Ra, mask);
}
else
{
RCX64Reg ecx = gpr.Scratch(ECX); // no register choice