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JitArm64_Integer: Optimize subfic for zero

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When the immediate value is zero, we can do a negation. On ARM64 the NEG
/NEGS instructions are just an alias for SUB/SUBS with a hardcoded WZR.

Before:
```
ldr    w22, [x29, #0x28]
mov    w21, #0x0                 ; =0
subs   w22, w21, w22
```

After:
```
ldr    w22, [x29, #0x28]
negs   w22, w22
```
This commit is contained in:
Sintendo 2024-06-26 00:07:20 +02:00
parent f49659fbfc
commit d877cfa4e2
1 changed files with 10 additions and 4 deletions
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12
Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp
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@ -1392,13 +1392,19 @@ void JitArm64::subfic(UGeckoInstruction inst)
}
else
{
const bool allocate_reg = d == a;
gpr.BindToRegister(d, allocate_reg);
const bool will_read = d == a;
const bool is_zero = imm == 0;
const bool allocate_reg = will_read && !is_zero;
gpr.BindToRegister(d, will_read);
// d = imm - a
ARM64Reg RD = gpr.R(d);
ARM64Reg WA = allocate_reg ? gpr.GetReg() : RD;
ARM64Reg WA = ARM64Reg::WZR;
if (!is_zero)
{
WA = will_read ? gpr.GetReg() : RD;
MOVI2R(WA, imm);
}
CARRY_IF_NEEDED(SUB, SUBS, RD, WA, gpr.R(a));
if (allocate_reg)