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Merge pull request #13836 from Sintendo/jitarm64-subfe

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JitArm64_Integer: Minor subfe optimizations
This commit is contained in:
JosJuice
2025-08-20 22:40:14 +02:00
committed by GitHub
parent 5aaf522a6f e9d28649dc
commit 09e68e707e
1 changed files with 25 additions and 12 deletions
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37
Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp
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@@ -6,18 +6,14 @@
#include <bit> #include <bit>
#include "Common/Arm64Emitter.h" #include "Common/Arm64Emitter.h"
#include "Common/Assert.h" #include "Common/ArmCommon.h"
#include "Common/BitUtils.h"
#include "Common/CommonTypes.h" #include "Common/CommonTypes.h"
#include "Common/MathUtil.h" #include "Common/MathUtil.h"
#include "Core/Core.h"
#include "Core/CoreTiming.h"
#include "Core/PowerPC/Interpreter/Interpreter.h" #include "Core/PowerPC/Interpreter/Interpreter.h"
#include "Core/PowerPC/JitArm64/JitArm64_RegCache.h" #include "Core/PowerPC/JitArm64/JitArm64_RegCache.h"
#include "Core/PowerPC/JitCommon/DivUtils.h" #include "Core/PowerPC/JitCommon/DivUtils.h"
#include "Core/PowerPC/PPCTables.h" #include "Core/PowerPC/PPCTables.h"
#include "Core/PowerPC/PowerPC.h"
using namespace Arm64Gen; using namespace Arm64Gen;
using namespace JitCommon; using namespace JitCommon;
@@ -1306,13 +1302,10 @@ void JitArm64::subfex(UGeckoInstruction inst)
JITDISABLE(bJITIntegerOff); JITDISABLE(bJITIntegerOff);
FALLBACK_IF(inst.OE); FALLBACK_IF(inst.OE);
bool mex = inst.SUBOP10 & 32; const bool mex = inst.SUBOP10 & 32;
int a = inst.RA, b = inst.RB, d = inst.RD; const int a = inst.RA, b = inst.RB, d = inst.RD;
if (gpr.IsImm(a) && (mex || gpr.IsImm(b))) const auto handle_imm = [&](const u32 i, const u32 j) {
{
const u32 i = gpr.GetImm(a);
const u32 j = mex ? -1 : gpr.GetImm(b);
const u32 imm = ~i + j; const u32 imm = ~i + j;
const bool is_zero = imm == 0; const bool is_zero = imm == 0;
const bool is_all_ones = imm == 0xFFFFFFFF; const bool is_all_ones = imm == 0xFFFFFFFF;
@@ -1339,7 +1332,12 @@ void JitArm64::subfex(UGeckoInstruction inst)
{ {
gpr.BindToRegister(d, false); gpr.BindToRegister(d, false);
ARM64Reg RD = gpr.R(d); ARM64Reg RD = gpr.R(d);
if (is_all_ones) if (is_zero)
{
// RD = 0 + carry
CSET(RD, CC_CS);
}
else if (is_all_ones)
{ {
// RD = -1 + carry = carry ? 0 : -1 // RD = -1 + carry = carry ? 0 : -1
// CSETM sets the destination to -1 if the condition is true, 0 // CSETM sets the destination to -1 if the condition is true, 0
@@ -1380,6 +1378,21 @@ void JitArm64::subfex(UGeckoInstruction inst)
{ {
ComputeCarry(false); ComputeCarry(false);
} }
};
if (!mex && a == b)
{
// Special case: subfe A, B, B is a common compiler idiom to copy the carry
// flag to a register.
// We handle this as-if we're dealing with two identical immediate values.
// The exact values used here don't matter. We use zeroes.
handle_imm(0, 0);
}
else if (gpr.IsImm(a) && (mex || gpr.IsImm(b)))
{
const u32 i = gpr.GetImm(a);
const u32 j = mex ? -1 : gpr.GetImm(b);
handle_imm(i, j);
} }
else else
{ {