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CPU/Recompiler: Trap constant signed arithmetic overflow

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Detect overflow in folded ADD, SUB and ADDI and use the interpreter exception path, including writes to zero and branch delay slots.
This commit is contained in:
Stenzek
2026-10-10 21:47:41 +10:00
parent bd29ee475f
commit 3a8b6fccfc
1 changed files with 21 additions and 9 deletions
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src/core/cpu_recompiler.cpp
+21 -9
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@@ -2117,10 +2117,14 @@ void CPU::Recompiler::Recompiler::Compile_divu_const(CompileFlags cf)
void CPU::Recompiler::Recompiler::Compile_add_const(CompileFlags cf)
{
// TODO: Overflow
DebugAssert(HasConstantReg(cf.MipsS()) && HasConstantReg(cf.MipsT()));
if (MipsD() != Reg::zero)
SetConstantReg(MipsD(), GetConstantRegU32(cf.MipsS()) + GetConstantRegU32(cf.MipsT()));
const u32 rs = GetConstantRegU32(cf.MipsS());
const u32 rt = GetConstantRegU32(cf.MipsT());
const u32 result = rs + rt;
if (g_settings.cpu_recompiler_memory_exceptions && ((result ^ rs) & (result ^ rt) & 0x80000000u) != 0)
Compile_Fallback();
else if (MipsD() != Reg::zero)
SetConstantReg(MipsD(), result);
}
void CPU::Recompiler::Recompiler::Compile_addu_const(CompileFlags cf)
@@ -2131,10 +2135,14 @@ void CPU::Recompiler::Recompiler::Compile_addu_const(CompileFlags cf)
void CPU::Recompiler::Recompiler::Compile_sub_const(CompileFlags cf)
{
// TODO: Overflow
DebugAssert(HasConstantReg(cf.MipsS()) && HasConstantReg(cf.MipsT()));
if (MipsD() != Reg::zero)
SetConstantReg(MipsD(), GetConstantRegU32(cf.MipsS()) - GetConstantRegU32(cf.MipsT()));
const u32 rs = GetConstantRegU32(cf.MipsS());
const u32 rt = GetConstantRegU32(cf.MipsT());
const u32 result = rs - rt;
if (g_settings.cpu_recompiler_memory_exceptions && ((result ^ rs) & (rs ^ rt) & 0x80000000u) != 0)
Compile_Fallback();
else if (MipsD() != Reg::zero)
SetConstantReg(MipsD(), result);
}
void CPU::Recompiler::Recompiler::Compile_subu_const(CompileFlags cf)
@@ -2145,10 +2153,14 @@ void CPU::Recompiler::Recompiler::Compile_subu_const(CompileFlags cf)
void CPU::Recompiler::Recompiler::Compile_addi_const(CompileFlags cf)
{
// TODO: Overflow
DebugAssert(HasConstantReg(cf.MipsS()));
if (cf.MipsT() != Reg::zero)
SetConstantReg(cf.MipsT(), GetConstantRegU32(cf.MipsS()) + inst->i.imm_sext32());
const u32 rs = GetConstantRegU32(cf.MipsS());
const u32 imm = inst->i.imm_sext32();
const u32 result = rs + imm;
if (g_settings.cpu_recompiler_memory_exceptions && ((result ^ rs) & (result ^ imm) & 0x80000000u) != 0)
Compile_Fallback();
else if (cf.MipsT() != Reg::zero)
SetConstantReg(cf.MipsT(), result);
}
void CPU::Recompiler::Recompiler::Compile_addiu_const(CompileFlags cf)