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ARM optimization in ADDI2R: Dual adds instead of MOVI2R, ADD when possible

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This commit is contained in:
Henrik Rydgard 2013-11-08 12:28:27 +01:00
parent 381b6d0f05
commit 1bf83efe9e
1 changed files with 14 additions and 2 deletions
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16
Common/ArmEmitter.cpp
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@ -156,8 +156,20 @@ void ARMXEmitter::ADDI2R(ARMReg rd, ARMReg rs, u32 val, ARMReg scratch)
else
SUB(rd, rs, op2);
} else {
MOVI2R(scratch, val);
ADD(rd, rs, scratch);
// Try 16-bit additions and subtractions - easy to test for.
// Should also try other rotations...
if ((val & 0xFFFF0000) == 0) {
// Decompose into two additions.
ADD(rd, rs, Operand2((u8)(val >> 8), 12)); // rotation right by 12*2 == rotation left by 8
ADD(rd, rd, Operand2((u8)(val), 0));
} else if (((-(u32)(s32)val) & 0xFFFF0000) == 0) {
val = -(u32)(s32)val;
SUB(rd, rs, Operand2((u8)(val >> 8), 12));
SUB(rd, rd, Operand2((u8)(val), 0));
} else {
MOVI2R(scratch, val);
ADD(rd, rs, scratch);
}
}
}