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defaultarch: handle caller-set return addresses when inlining calls #8246

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defaultarch: handle caller-set return addresses when inlining calls #8246

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52 changes: 51 additions & 1 deletion defaultarch.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,37 @@ static bool GetNextFunctionAfterAddress(Ref<BinaryView> data, Ref<Platform> plat
return nextFunc != nullptr;
}

static bool IsZeroConstant(LowLevelILInstruction expr)
{
return ((expr.operation == LLIL_CONST) || (expr.operation == LLIL_CONST_PTR)) && (expr.GetConstant() == 0);
}


static bool IsConstantPointer(LowLevelILInstruction expr, uint64_t value)

@plafosse plafosse Jun 23, 2026

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this is a misnomer

@appleflyerv3 appleflyerv3 Jun 23, 2026 •
edited
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the function name?
what would be a more suitable name for this, then?

@plafosse plafosse Jun 23, 2026

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IsConstantValue perhaps

@zznop zznop Jun 24, 2026

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I changed the function name to ConstantCompare since it's not only checking that the expression is a constant, it's also checking if it is equal to value

10e6eb0

{
return ((expr.operation == LLIL_CONST) || (expr.operation == LLIL_CONST_PTR)) && ((uint64_t)expr.GetConstant() == value);
}


static bool IsReturnAddressRegisterExpr(LowLevelILInstruction expr, const set<uint32_t>& returnAddressRegisters)
{
switch (expr.operation)
{
case LLIL_REG:
return returnAddressRegisters.count(expr.GetSourceRegister<LLIL_REG>()) != 0;
case LLIL_ADD:
return (IsReturnAddressRegisterExpr(expr.GetLeftExpr<LLIL_ADD>(), returnAddressRegisters)
&& IsZeroConstant(expr.GetRightExpr<LLIL_ADD>()))
|| (IsZeroConstant(expr.GetLeftExpr<LLIL_ADD>())
&& IsReturnAddressRegisterExpr(expr.GetRightExpr<LLIL_ADD>(), returnAddressRegisters));
case LLIL_SUB:
return IsReturnAddressRegisterExpr(expr.GetLeftExpr<LLIL_SUB>(), returnAddressRegisters)
&& IsZeroConstant(expr.GetRightExpr<LLIL_SUB>());
default:
return false;
}
}


void Architecture::DefaultAnalyzeBasicBlocks(Function* function, BasicBlockAnalysisContext& context)
{
Expand Down Expand Up @@ -992,7 +1023,18 @@ void FunctionLifterContext::CheckForInlinedCall(BasicBlock* block, size_t instrC
m_function->MarkLabel(start);
m_function->ReplaceExpr(lastInstr.exprIndex, m_function->Goto(start, lastInstr));

if (lastInstr.operation == LLIL_CALL)
set<uint32_t> returnAddressRegisters;
for (size_t instrIndex = instrCountBefore; instrIndex < instrCountAfter - 1; instrIndex++)
{
LowLevelILInstruction instr = m_function->GetInstruction(instrIndex);
if (instr.operation != LLIL_SET_REG)
continue;

if (IsConstantPointer(instr.GetSourceExpr<LLIL_SET_REG>(), addr))
returnAddressRegisters.insert(instr.GetDestRegister<LLIL_SET_REG>());
}

if (lastInstr.operation == LLIL_CALL && returnAddressRegisters.empty())
{
// Set up return address according to the architecture
// TODO: Handle architectures that use a nonstandard way of calling functions
Expand Down Expand Up @@ -1024,6 +1066,7 @@ void FunctionLifterContext::CheckForInlinedCall(BasicBlock* block, size_t instrC
}

// Copy the inlined code from the target function
Ref<Architecture> callArch = block->GetArchitecture();
auto blocks = PrepareToCopyForeignFunction(targetIL);
auto unresolvedIndirectBranches = targetFunc->GetUnresolvedIndirectBranches();
auto sourceLocation = inlineDuringAnalysis == InlineUsingCallAddress ? ILSourceLocation(lastInstr) : ILSourceLocation();
Expand All @@ -1046,6 +1089,13 @@ void FunctionLifterContext::CheckForInlinedCall(BasicBlock* block, size_t instrC
m_function->AddInstruction(instr.GetDestExpr<LLIL_RET>().CopyTo(m_function, sourceLocation));
m_function->AddInstruction(m_function->Goto(end, sourceLocation));
}
else if (lastInstr.operation == LLIL_CALL && instr.operation == LLIL_JUMP
&& (block->GetArchitecture() == callArch)
&& (IsConstantPointer(instr.GetDestExpr<LLIL_JUMP>(), addr)
|| IsReturnAddressRegisterExpr(instr.GetDestExpr<LLIL_JUMP>(), returnAddressRegisters)))
{
m_function->AddInstruction(m_function->Goto(end, sourceLocation));
}
else if (lastInstr.operation == LLIL_CALL && instr.operation == LLIL_JUMP
&& block->GetOutgoingEdges().empty() && (unresolvedIndirectBranches.count(loc) == 0))
{
Expand Down