SMPFunction.cpp

//  into the statement:
//    mov eax,[esp+3Ch+var_30]
//  Here, 3Ch == 60 decimal is the distance between ESP and EBP, and
//  var_30 is defined to have the value -30h == -48 decimal. So, the
//  "frame size" in IDA Pro is 60 bytes, and a certain local can be
//  addressed in ESP-relative manner as shown, or as [ebp+var_30] for
//  EBP-relative addressing. The interactive IDA user can then edit
//  the name var_30 to something mnemonic, such as "virus_size", and IDA
//  will replace all occurrences with the new name, so that code references
//  automatically become [ebp+virus_size]. As the user proceeds
//  interactively, he eventually produces very understandable code.
// This all makes sense for producing readable assembly text. However,
//  our analyses have a compiler perspective as well as a memory access
//  defense perspective. SMP distinguishes between callee saved regs,
//  which should not be overwritten in the function body, and local
//  variables, which can be written. We view the stack frame in logical
//  pieces: here are the saved regs, here are the locals, here is the
//  return address, etc. We don't care which direction from EBP the
//  callee-saved registers lie; we don't want to lump them in with the
//  local variables. We also don't like the fact that IDA Pro will take
//  the function prologue code shown above and declare frregs=4 and
//  frsize=60, because frsize no longer matches the stack allocation
//  statement sub esp,34h == sub esp,52. We prefer frsize=52 and frregs=12.
// So, the task of this function is to fix these stack sizes in our
//  private data members for the function, while leaving the IDA database
//  alone because IDA needs to maintain its own definitions of these
//  variables.
// Fixing means we will update the data members LocalVarsSize and
//  CalleeSavedRegsSize.
// NOTE: This function is both machine dependent and platform dependent.
//  The prologue and epilogue code generated by gcc-linux is as discussed
//  above, while on Visual Studio and other Windows x86 compilers, the
//  saving of registers other than EBP happens AFTER local stack allocation.
//  A Windows version of the function would expect to see the pushing
//  of ESI and EDI AFTER the sub esp,34h statement.
bool SMPFunction::MDFixFrameInfo(void) {
	int SavedRegsSize = 0;
	int OtherPushesSize = 0;  // besides callee-saved regs
	int NewLocalsSize = 0;
	int OldFrameTotal = this->CalleeSavedRegsSize + this->LocalVarsSize;
	bool Changed = false;
	bool DebugFlag = (0 == strcmp("__libc_csu_init", this->GetFuncName()));

	// Iterate through the first basic block in the function. If we find
	//  a frame allocating Instr in it, then we have local vars. If not,
	//  we don't, and LocalVarsSize should have been zero. Count the callee
	//  register saves leading up to the local allocation. Set data members
	//  according to what we found if the values of the data members would
	//  change.
	SMPBasicBlock *CurrBlock = this->Blocks.front();
	list<SMPInstr *>::iterator CurrIter = CurrBlock->GetFirstInstr();
#if SMP_USE_SSA_FNOP_MARKER
	++CurrIter;  // skip marker instruction
#endif
	for ( ; CurrIter != CurrBlock->GetLastInstr(); ++CurrIter) {
		SMPInstr *CurrInstr = (*CurrIter);
		if (CurrInstr->MDIsPushInstr()) {
			// We will make the gcc-linux assumption that a PUSH in
			//  the first basic block, prior to the stack allocating
			//  instruction, is a callee register save. To make this
			//  more robust, we ensure that the register is from
			//  the callee saved group of registers, and that it has
			//  not been defined thus far in the function (else it might
			//  be a push of an outgoing argument to a call that happens
			//  in the first block when there are no locals). **!!!!**
			if (CurrInstr->MDUsesCalleeSavedReg()
				&& !CurrInstr->HasSourceMemoryOperand()) {
				SavedRegsSize += 4; // **!!** should check the size
				if (DebugFlag) SMP_msg("libc_csu_init SavedRegsSize: %d  %s\n", SavedRegsSize,
					CurrInstr->GetDisasm());
			}
			else {
				// Pushes of outgoing args can be scheduled so that
				//  they are mixed with the pushes of callee saved regs.
				OtherPushesSize += 4;
				if (DebugFlag) SMP_msg("libc_csu_init OtherPushesSize: %d  %s\n", OtherPushesSize,
					CurrInstr->GetDisasm());
			}
		}
		else if (CurrInstr->MDIsFrameAllocInstr()) {
			if (DebugFlag) SMP_msg("libc_csu_init allocinstr: %s\n", CurrInstr->GetDisasm());
			SavedRegsSize += OtherPushesSize;
			// Get the size being allocated.
			set<DefOrUse, LessDefUse>::iterator CurrUse;
			for (CurrUse = CurrInstr->GetFirstUse(); CurrUse != CurrInstr->GetLastUse(); ++CurrUse) {
				// Find the immediate operand.
				if (o_imm == CurrUse->GetOp().type) {
					// Get its value into LocalVarsSize.
					long AllocValue = (signed long) CurrUse->GetOp().value;
					// One compiler might have sub esp,24 and another
					//  might have add esp,-24. Take the absolute value.
					if (0 > AllocValue)
						AllocValue = -AllocValue;
					if (AllocValue != (long) this->LocalVarsSize) {
						Changed = true;
#if SMP_DEBUG_FRAMEFIXUP
						if (AllocValue + SavedRegsSize != OldFrameTotal)
							SMP_msg("Total frame size changed: %s\n", this->GetFuncName());
#endif
						this->LocalVarsSize = (asize_t) AllocValue;
						this->CalleeSavedRegsSize = (ushort) SavedRegsSize;
						NewLocalsSize = this->LocalVarsSize;
					}
					else { // Old value was correct; no change.
						NewLocalsSize = this->LocalVarsSize;
						if (SavedRegsSize != this->CalleeSavedRegsSize) {
							this->CalleeSavedRegsSize = (ushort) SavedRegsSize;
							Changed = true;
#if SMP_DEBUG_FRAMEFIXUP
							SMP_msg("Only callee regs size changed: %s\n", this->GetFuncName());
#endif
						}
					}
				} // end if (o_imm == ...)
			} // end for all uses
			break; // After frame allocation instr, we are done
		} // end if (push) .. elsif frame allocating instr
	} // end for all instructions in the first basic block

	// If we did not find an allocating instruction, see if it would keep
	//  the total size the same to set LocalVarsSize to 0 and to set
	//  CalleeSavedRegsSize to SavedRegsSize. If so, do it. If not, we
	//  might be better off to leave the numbers alone.
	if (!Changed && (NewLocalsSize == 0)) {
		if (DebugFlag) SMP_msg("libc_csu_init OldFrameTotal: %d \n", OldFrameTotal);
		if (OldFrameTotal == SavedRegsSize) {
			this->CalleeSavedRegsSize = (ushort) SavedRegsSize;
			this->LocalVarsSize = 0;
			Changed = true;
		}
#if SMP_DEBUG_FRAMEFIXUP
		else {
			SMP_msg("Could not update frame sizes: %s\n", this->GetFuncName());
		}
#endif
	}

#if SMP_DEBUG_FRAMEFIXUP
	if ((0 < OtherPushesSize) && (0 < NewLocalsSize))
		SMP_msg("Extra pushes found of size %d in %s\n", OtherPushesSize,
			this->GetFuncName());
#endif

#if SMP_DEBUG_FRAMEFIXUP
	if (Changed) {
		SMP_msg("Fixed stack frame size info: %s\n", this->GetFuncName());
		SMPBasicBlock *CurrBlock = this->Blocks.front();
		SMP_msg("First basic block:\n");
		for (list<SMPInstr *>::iterator CurrInstr = CurrBlock->GetFirstInstr();
			CurrInstr != CurrBlock->GetLastInstr();
			++CurrInstr) {
			SMP_msg("%s\n", (*CurrInstr)->GetDisasm());
		}
	}
#endif

	return Changed;
} // end of SMPFunction::MDFixFrameInfo()

// Some functions have difficult to find stack allocations. For example, in some
//  version of glibc, strpbrk() zeroes out register ECX and then pushes it more than
//  100 times in order to allocate zero-ed out local vars space for a character translation
//  table. We will use the stack pointer analysis of IDA to find out if there is a point
//  in the first basic block at which the stack pointer reaches the allocation total
//  that IDA is expecting for the local vars region.
// If so, we return the address of the instruction at which ESP reaches its value, else
//  we return BADADDR.
ea_t SMPFunction::FindAllocPoint(asize_t OriginalLocSize) {
	sval_t TargetSize = - ((sval_t) OriginalLocSize);  // negate; stack grows down 

#if SMP_DEBUG_FRAMEFIXUP
	bool DebugFlag = (0 == strcmp("_dl_runtime_resolve", this->GetFuncName()));
	if (DebugFlag)
		SMP_msg("%s OriginalLocSize: %d\n", this->GetFuncName(), OriginalLocSize);
#endif

	if (this->AnalyzedSP) {
		// Limit our analysis to the first basic block in the function.
		list<SMPInstr *>::iterator InstIter = this->Instrs.begin();
#if SMP_USE_SSA_FNOP_MARKER
		++InstIter;  // skip marker instruction
#endif
		for ( ; InstIter != this->Instrs.end(); ++InstIter) {
			SMPInstr *CurrInst = (*InstIter);
			ea_t addr = CurrInst->GetAddr();
			// get_spd() returns a cumulative delta of ESP
			sval_t sp_delta = get_spd(this->GetFuncInfo(), addr);
#if SMP_DEBUG_FRAMEFIXUP
			if (DebugFlag)
				SMP_msg("%s delta: %d at %x\n", this->GetFuncName(), sp_delta, addr);
#endif
			if (sp_delta == TargetSize) { // <= instead of == here?  **!!**
				// Previous instruction hit the frame size.
				if (InstIter == this->Instrs.begin()) {
					return BADADDR;  // cannot back up from first instruction
				}
				else {
					ea_t PrevAddr = (*(--InstIter))->GetAddr();
#if SMP_USE_SSA_FNOP_MARKER
					if ((*(this->Instrs.begin()))->GetAddr() == PrevAddr)
						return BADADDR;  // don't return marker instruction
					else
						return PrevAddr;
#else
					return PrevAddr;
#endif
				}
			}
			if (CurrInst->IsLastInBlock()) {
				// It could be that the current instruction will cause the stack pointer
				//  delta to reach the TargetSize. sp_delta is not updated until after the
				//  current instruction, so we need to look ahead one instruction if the
				//  current block falls through. On the other hand, if the current block
				//  ends with a jump or return, we cannot hit TargetSize.
				if (CurrInst->IsBasicBlockTerminator())
					return BADADDR;
				list<SMPInstr *>::iterator NextInstIter = InstIter;
				++NextInstIter;
				if (NextInstIter == this->Instrs.end())
					return BADADDR;
				sp_delta = get_spd(this->GetFuncInfo(), (*NextInstIter)->GetAddr());
				if (sp_delta == TargetSize) {
					// CurrInst will cause stack pointer delta to hit TargetSize.
					return addr;
				}
				else {
					return BADADDR;
				}
			} // end if LastInBlock
		} // end for all instructions
	} // end if (this->AnalyzedSP)
#if SMP_DEBUG_FRAMEFIXUP
	else {
		SMP_msg("AnalyzedSP is false for %s\n", this->GetFuncName());
	}
#endif
	return BADADDR;
} // end of SMPFunction::FindAllocPoint()

// IDA Pro is sometimes confused by a function that uses the frame pointer
//  register for other purposes. For the x86, a function that uses EBP
//  as a frame pointer would begin with: push ebp; mov ebp,esp to save
//  the old value of EBP and give it a new value as a frame pointer. The
//  allocation of local variable space would have to come AFTER the move
//  instruction. A function that begins: push ebp; push esi; sub esp,24
//  is obviously not using EBP as a frame pointer. IDA is apparently
//  confused by the push ebp instruction being the first instruction
//  in the function. We will reset UseFP to false in this case.
// The inverse problem happens with a function that begins with instructions
//  other than push ebp; mov ebp,esp; ... etc. but eventually has those
//  instructions in the first basic block. For example, a C compiler generates
//  for the first block of main():
//    lea ecx,[esp+arg0]
//    and esp, 0xfffffff0
//    push dword ptr [ecx-4]
//    push ebp
//    mov ebp,esp
//    push ecx
//    sub esp,<framesize>
//
//  This function is obviously using EBP as a frame pointer, but IDA Pro marks
//  the function as not using a frame pointer. We will reset UseFP to true in
//  this case.
// NOTE: This logic should work for both Linux and Windows x86 prologues.
bool SMPFunction::MDFixUseFP(void) {
	list<SMPInstr *>::iterator InstIter = this->Instrs.begin();
	ea_t addr = (*InstIter)->GetAddr();

#if SMP_USE_SSA_FNOP_MARKER
	++InstIter;  // skip marker instruction
#endif
	SMPInstr *CurrInst = (*InstIter);

	if (!(this->UseFP)) {
		// See if we can detect the instruction "push ebp" followed by the instruction
		//  "mov ebp,esp" in the first basic block. The instructions do not have to be
		//  consecutive. If we find them, we will reset UseFP to true.
		bool FirstBlockProcessed = false;
		bool EBPSaved = false;
		bool ESPintoEBP = false;
		do {
			FirstBlockProcessed = CurrInst->IsLastInBlock();
			if (!EBPSaved) { // still looking for "push ebp"
				if (CurrInst->MDIsPushInstr() && CurrInst->GetCmd().Operands[0].is_reg(R_bp)) {
					EBPSaved = true;
				}
			}
			else if (!ESPintoEBP) { // found "push ebp", looking for "mov ebp,esp"
				insn_t CurrCmd = CurrInst->GetCmd();
				if ((CurrCmd.itype == NN_mov) 
					&& (CurrInst->GetFirstDef()->GetOp().is_reg(R_bp))
					&& (CurrInst->GetFirstUse()->GetOp().is_reg(R_sp))) {
					ESPintoEBP = true;
					FirstBlockProcessed = true; // exit loop
				}
			}
			++InstIter;
			CurrInst = (*InstIter);
			addr = CurrInst->GetAddr();
			// We must get EBP set to its frame pointer value before we reach the
			//  local frame allocation instruction (i.e. the subtraction of locals space
			//   from the stack pointer).
			FirstBlockProcessed |= (addr >= this->LocalVarsAllocInstr);
		} while (!FirstBlockProcessed);
		// If we found ESPintoEBP, we also found EBPSaved first, and we need to change
		//  this->UseFP to true and return true. Otherwise, return false.
		this->UseFP = ESPintoEBP;
		if (ESPintoEBP)
			SMP_msg("INFO: MDFixUseFP reset UseFP to true for %s\n", this->GetFuncName());
		return ESPintoEBP;
	} // end if (!(this->UseFP))

	// At this point, this->UseFP must have been true on entry to this method and we will
	//  check whether it should be reset to false.
	while (addr < this->LocalVarsAllocInstr) {
		set<DefOrUse, LessDefUse>::iterator CurrDef = CurrInst->GetFirstDef();
		while (CurrDef != CurrInst->GetLastDef()) {
			if (CurrDef->GetOp().is_reg(R_bp))
				return false; // EBP got set before locals were allocated
			++CurrDef;
		}
		++InstIter;
		CurrInst = (*InstIter);
		addr = CurrInst->GetAddr();
	}
	// If we found no defs of the frame pointer before the local vars
	//  allocation, then the frame pointer register is not being used
	//  as a frame pointer, just as a general callee-saved register.
	this->UseFP = false;
	SMP_msg("INFO: MDFixUseFP reset UseFP to false for %s\n", this->GetFuncName());
	return true;
} // end of SMPFunction::MDFixUseFP()

// Find the callee-saved reg offsets (negative offset from return address)
//  for all registers pushed onto the stack before the stack frame allocation
//  instruction.
void SMPFunction::MDFindSavedRegs(void) {
	list<SMPInstr *>::iterator InstIter;
	int RegIndex;
	func_t *CurrFunc = SMP_get_func(this->GetStartAddr());
	assert(NULL != CurrFunc);

	for (InstIter = this->Instrs.begin(); InstIter != this->Instrs.end(); ++InstIter) {
		SMPInstr *CurrInst = (*InstIter);
		if (CurrInst->GetAddr() > this->LocalVarsAllocInstr)
			break;
		if (!(CurrInst->MDIsPushInstr()))
			continue;

		sval_t CurrOffset = get_spd(CurrFunc, CurrInst->GetAddr());
		if (CurrInst->GetCmd().itype == NN_push) {
			op_t PushedReg = CurrInst->GetPushedOpnd();
			if (o_reg == PushedReg.type) {
				RegIndex = (int) PushedReg.reg;
				if (RegIndex > R_di) {
					SMP_msg("WARNING: Skipping save of register %d\n", RegIndex);
					continue;
				}
				if (this->SavedRegLoc.at((size_t) RegIndex) == 0) {
					this->SavedRegLoc[(size_t) RegIndex] = CurrOffset - 4;
				}
				else {
					SMP_msg("WARNING: Multiple saves of register %d\n", RegIndex);
				}
			} // end if register push operand
		} // end if PUSH instruction
		else if (NN_pusha == CurrInst->GetCmd().itype) {
			// **!!** Handle pushes of all regs.
			this->SavedRegLoc[(size_t) R_ax] = CurrOffset - 4;
			this->SavedRegLoc[(size_t) R_cx] = CurrOffset - 8;
			this->SavedRegLoc[(size_t) R_dx] = CurrOffset - 12;
			this->SavedRegLoc[(size_t) R_bx] = CurrOffset - 16;
			this->SavedRegLoc[(size_t) R_sp] = CurrOffset - 20;
			this->SavedRegLoc[(size_t) R_bp] = CurrOffset - 24;
			this->SavedRegLoc[(size_t) R_si] = CurrOffset - 28;
			this->SavedRegLoc[(size_t) R_di] = CurrOffset - 32;
			break; // all regs accounted for
		}
		else if (CurrInst->MDIsEnterInstr()) {
			this->SavedRegLoc[(size_t) R_bp] = CurrOffset - 4;
		}
	} // end for all instructions

	return;
} // end of SMPFunction::MDFindSavedRegs()

// Compute the ReturnRegTypes[] as the meet over all register types
//  at all return instructions.
void SMPFunction::MDFindReturnTypes(void) {
	list<SMPBasicBlock *>::iterator BlockIter;
	SMPBasicBlock *CurrBlock;
	list<SMPInstr *>::iterator InstIter;
	vector<SMPOperandType> RegTypes;
	SMPInstr *CurrInst;

	for (BlockIter = this->Blocks.begin(); BlockIter != this->Blocks.end(); ++BlockIter) {
		CurrBlock = (*BlockIter);
		if (CurrBlock->HasReturn()) {
			// Get the types of all registers at the RETURN point.
			//  Calculate the meet function over them.
			InstIter = CurrBlock->GetLastInstr();
			--InstIter;
			CurrInst = (*InstIter);
			assert(RETURN == CurrInst->GetDataFlowType());
			set<DefOrUse, LessDefUse>::iterator CurrUse;
			for (CurrUse = CurrInst->GetFirstUse();
				CurrUse != CurrInst->GetLastUse();
				++CurrUse) {

				op_t UseOp = CurrUse->GetOp();
				if ((o_reg != UseOp.type) || (R_di < UseOp.reg))
					continue;
				this->ReturnRegTypes[UseOp.reg]
					= SMPTypeMeet(this->ReturnRegTypes.at(UseOp.reg),
						CurrUse->GetType());
			} // for all USEs in the RETURN instruction
		} // end if current block has a RETURN
	} // end for all blocks
	return;
} // end of SMPFunction::MDFindReturnTypes()

// Determine local variable boundaries in the stack frame.
void SMPFunction::BuildLocalVarTable(void) {
	// Currently we just use the info that IDA Pro has inferred from the direct
	//  addressing of stack locations.
	this->SemiNaiveLocalVarID();
	return;
} // end of SMPFunction::BuildLocalVarTable()

// Limit damage from garbage stack offset values produced by IDA Pro.
#define IDAPRO_KLUDGE_STACK_FRAME_SIZE_LIMIT 5000000

// Use the local variable offset list from IDA's stack frame structure to compute
//  the table of local variable boundaries.
void SMPFunction::SemiNaiveLocalVarID(void) {
	// NOTE: We use IDA Pro's offsets from this->FuncInfo (e.g. frsize) and NOT
	//  our own corrected values in our private data members. The offsets we
	//  read from the stack frame structure returned by get_frame() are consistent
	//  with other IDA Pro values, not with our corrected values.
	list<SMPInstr *>::iterator InstIter;
	bool DebugFlag = false;
	this->LocalVarOffsetLimit = -20000;
#if SMP_DEBUG_STACK_GRANULARITY
	DebugFlag |= (0 == strcmp("qSort3", this->GetFuncName()));
#endif
	func_t *FuncPtr = SMP_get_func(this->FuncInfo.startEA);
	if (NULL == FuncPtr) {
		SMP_msg("ERROR in SMPFunction::SemiNaiveLocalVarID; no func ptr\n");
	}
	assert(NULL != FuncPtr);
	struc_t *StackFrame = get_frame(FuncPtr);

	if (NULL == StackFrame) {
		SMP_msg("WARNING: No stack frame info from get_frame for %s\n", this->GetFuncName());
		return;
	}

	member_t *Member = StackFrame->members;
	for (size_t i = 0; i < StackFrame->memqty; ++i, ++Member) {
		long offset;
		char MemberName[MAXSMPVARSTR] = {'\0'};
		if (NULL == Member) {
			SMP_msg("NULL stack frame member pointer in %s\n", this->GetFuncName());
			break;
		}
		get_member_name(Member->id, MemberName, MAXSMPVARSTR - 1);
		if (MemberName == NULL) {
#if SMP_DEBUG_STACK_GRANULARITY
			SMP_msg("NULL stack frame member in %s\n", this->GetFuncName());
#endif
			continue;
		}
		if (Member->unimem()) {
			// Not a separate variable; name for member of a union.
			// The union itself should have a separate entry, so we skip this.
			SMP_msg("STACK INFO: Skipping union member %s frame member %zu in stack frame for %s\n",
				MemberName, i, this->GetFuncName());
			continue;
		}
		offset = (long) Member->get_soff(); // Would be 0 for union member, so we skipped them above.
		if (DebugFlag) {
			SMP_msg("%s local var %s at offset %ld\n", this->GetFuncName(), MemberName, offset);
		}
		if (offset > IDAPRO_KLUDGE_STACK_FRAME_SIZE_LIMIT) {
			SMP_msg("ERROR: Rejected enormous stack offset %ld for var %s in func %s\n", offset, MemberName, this->GetFuncName());
			continue;
		}
		struct LocalVar TempLocal;
		TempLocal.offset = offset;
		TempLocal.size = Member->eoff - Member->soff; // audit later
		SMP_strncpy(TempLocal.VarName, MemberName, sizeof(TempLocal.VarName) - 1);
		this->LocalVarTable.push_back(TempLocal);
		if ((offset + (long) TempLocal.size) >= this->LocalVarOffsetLimit) {
			this->LocalVarOffsetLimit = (long) (TempLocal.offset + TempLocal.size);
		}
	} // end for all stack frame members

	// If AnalyzedSP is false, that is all we can do.
	if (!this->AnalyzedSP) {
		// No allocations; sometimes happens in library functions.
		this->OutgoingArgsSize = 0;
		this->MinStackDelta = 0;
		this->AllocPointDelta = 0;
		return;
	}

	// Calculate min and max stack point deltas.
	this->MinStackDelta = 20000; // Final value should be negative or zero
	this->MaxStackDelta = -1000; // Final value should be zero.
	InstIter = this->Instrs.begin();
#if SMP_USE_SSA_FNOP_MARKER
	if ((*InstIter)->IsFloatNop())
		++InstIter;  // skip marker instruction
#endif
	for ( ; InstIter != this->Instrs.end(); ++InstIter) {
		SMPInstr *CurrInst = (*InstIter);
		ea_t addr = CurrInst->GetAddr();
		sval_t sp_delta = get_spd(this->GetFuncInfo(), addr);
		if (sp_delta < this->MinStackDelta)
			this->MinStackDelta = sp_delta;
		if (sp_delta > this->MaxStackDelta)
			this->MaxStackDelta = sp_delta;
		if (addr == this->LocalVarsAllocInstr) {
			// Total stack pointer delta is sp_delta for the next instruction,
			//  because IDA updates the sp delta AFTER each instruction.
			list<SMPInstr *>::iterator NextInstIter = InstIter;
			++NextInstIter;
			sp_delta = get_spd(this->GetFuncInfo(), (*NextInstIter)->GetAddr());
			this->AllocPointDelta = sp_delta;
		}
	}

	// IDA Pro sometimes fails to add stack frame members for all incoming args, etc.
	//  Find and correct these omissions by examining stack accesses in instructions
	//  and extend the LocalVarTable to cover whatever is out of range.
	if (!this->AuditLocalVarTable()) {
		// Catastrophic error must have occurred, probably due to errors in IDA's
		//  stack pointer analysis, despite AnalyzedSP being true.
		return;
	}

	if (!(this->LocalVarTable.empty())) {
		this->GoodLocalVarTable = true;

		// Sort the LocalVarTable so that we do not depend on IDA Pro
		//  presenting the stack frame members in order.
		std::sort(this->LocalVarTable.begin(), this->LocalVarTable.end(), LocalVarCompare);
	}

#if SMP_DEBUG_STACK_GRANULARITY
	SMP_msg("Computing %d local var sizes\n", this->LocalVarTable.size());
#endif
	// Now we want to audit the size field for each local
	if (this->GoodLocalVarTable) {
		size_t VarLimit = this->LocalVarTable.size() - 1;
		assert(this->LocalVarTable.size() > 0);
		for (size_t VarIndex = 0; VarIndex < VarLimit; ++VarIndex) {
			struct LocalVar TempLocEntry = this->LocalVarTable[VarIndex];
			bool AboveLocalsRegion = (TempLocEntry.offset >= this->LocalVarsSize);
			size_t TempSize = this->LocalVarTable[VarIndex + 1].offset
				- TempLocEntry.offset;
			int DiffSize = ((int) TempSize) - ((int) TempLocEntry.size);
			// We don't have IDA Pro stack frame members for callee saved registers. This
			//  omission can make it seem that there is a gap between the uppermost local
			//  variable and the return address or saved frame pointer. Avoid expanding the
			//  last local variable into the callee saved registers region.
			if (DiffSize > 0) { // We are expanding the size.
				if (!AboveLocalsRegion && ((TempLocEntry.offset + TempLocEntry.size + DiffSize) > this->LocalVarsSize)) {
					// Current local does not start above the locals region, but its new size will
					//  carry it into the locals region.
					if ((TempLocEntry.offset + TempLocEntry.size) > this->LocalVarsSize) {
						// Weird. It already overlapped the callee saved regs region.
						SMP_msg("WARNING: Local var at offset %ld size %zu in %s extends above local vars region.\n",
							TempLocEntry.offset, TempLocEntry.size, this->GetFuncName());
					}
					// Limit DiffSize to avoid overlapping callee saved regs.
					DiffSize = this->LocalVarsSize - (TempLocEntry.offset + TempLocEntry.size);
					if (DiffSize < 0)
						DiffSize = 0; // started out positive, cap it at zero.
				}
			}
			if (DiffSize < 0)
				DiffSize = 0; // should not happen with sorted LocalVarTable unless duplicate entries.
			if (DiffSize != 0) {
#if SMP_DEBUG_STACK_GRANULARITY
				SMP_msg("STACK INFO: Adjusted size for stack frame member at %ld in %s\n",
					TempLocEntry.offset, this->GetFuncName());
#endif
				this->LocalVarTable[VarIndex].size += DiffSize;
			}
		}
#if 0 // Using Member->eoff seems to be working for all members, including the last one.
#if SMP_DEBUG_STACK_GRANULARITY
		SMP_msg("Computing last local var size for frsize %d\n", this->FuncInfo.frsize);
#endif
		// Size of last local is total frsize minus savedregs in frame minus offset of last local
		size_t SavedRegsSpace = 0; // portion of frsize that is saved regs, not locals.
		if (this->CalleeSavedRegsSize > this->FuncInfo.frregs) {
			// IDA Pro counts the save of EBP in frregs, but then EBP gets its new
			//  value and callee saved regs other than the old EBP push get counted
			//  in frsize rather than frregs. CalleeSavedRegsSize includes all saved
			//  regs on the stack, both above and below the current EBP offset.
			// NOTE: For windows, this has to be done differently, as callee saved regs
			//  happen at the bottom of the local frame, not the top.
#if 0
			SavedRegsSpace = this->CalleeSavedRegsSize - this->FuncInfo.frregs;
#else
			SavedRegsSpace = this->FuncInfo.frsize - this->LocalVarsSize;
#endif
		}

		this->LocalVarTable.back().size = this->FuncInfo.frsize
			- SavedRegsSpace - this->LocalVarTable.back().offset;
		this->LocalVarOffsetLimit = this->LocalVarTable.back().offset 
			+ (adiff_t) this->LocalVarTable.back().size;
#endif
	}

#if 0 // AboveLocalsSize is not a reliable number.
	// IDA Pro can have difficulty with some irregular functions such as are found
	//  in the C startup code. The frsize value might be bogus. Just punt on the
	//  local variable ID if that is the case.
	if ((this->LocalVarOffsetLimit - AboveLocalsSize) > (adiff_t) this->FuncInfo.frsize) {
		this->LocalVarTable.clear();
		this->GoodLocalVarTable = false;
		SMP_msg("WARNING: Bad frsize %d for %s OffsetLimit: %d AboveLocalsSize: %d LocalVarsSize: %d ; abandoning SemiNaiveLocalVarID.\n",
			this->FuncInfo.frsize, this->GetFuncName(), this->LocalVarOffsetLimit, AboveLocalsSize, this->LocalVarsSize);
		return;
	}
	assert((this->LocalVarOffsetLimit - AboveLocalsSize) <= (adiff_t) this->FuncInfo.frsize);
#endif

	// Find out how many of the locals are really outgoing args.
	if (this->AnalyzedSP && !this->CallsAlloca && (BADADDR != this->LocalVarsAllocInstr)) {
		this->FindOutgoingArgsSize();
	}
	else {
		SMP_msg("FindOutgoingArgsSize not called for %s ", this->GetFuncName());
		SMP_msg("AnalyzedSP: %d CallsAlloca: %d LocalVarsAllocInstr: %x \n",
			this->AnalyzedSP, this->CallsAlloca, this->LocalVarsAllocInstr);
	}
	return;
} // end of SMPFunction::SemiNaiveLocalVarID()

// Check and correct the LocalVarTable derived from IDA Pro stack frame members.
//  Examine each instruction and see if any stack accesses are beyond the LocalVarTable
//  and create new entries in the LocalVarTable if so.
bool SMPFunction::AuditLocalVarTable(void) {
	list<SMPInstr *>::iterator InstIter;
	int SignedOffset;

	// We cannot depend on IDA Pro making Member
	//  entries for everything that is accessed on the stack.
	//  When an incoming arg is accessed but no Member is
	//  created, then LocalVarOffsetLimit will be too small
	//  and we will get ERROR messages. Just loop through the
	//  instructions, find offsets higher than the LocalVarTable
	//  currently holds, and add new entries to LocalVarTable to
	//  handle them.
	// Iterate through all instructions and record stack frame accesses in the StackFrameMap.
	InstIter = this->Instrs.begin();
#if SMP_USE_SSA_FNOP_MARKER
	if ((*InstIter)->IsFloatNop())
		++InstIter;  // skip marker instruction
#endif
	for ( ; InstIter != this->Instrs.end(); ++InstIter) {
		SMPInstr *CurrInst = (*InstIter);
		ea_t InstAddr = CurrInst->GetAddr();
		sval_t sp_delta = get_spd(this->GetFuncInfo(), InstAddr);
		if (0 < sp_delta) {
			// Stack underflow; about to assert
			SMP_msg("Stack underflow at %x %s sp_delta: %d\n", CurrInst->GetAddr(),
				CurrInst->GetDisasm(), sp_delta);
			return false;
		}
		assert(0 >= sp_delta);
		ea_t offset;
		size_t DataSize;
		bool UsedFramePointer;
		bool IndexedAccess;
		bool SignedMove;
		bool UnsignedMove;
		if (CurrInst->HasDestMemoryOperand()) {
			// NOTE: We need to catch stack pushes here also (callee-saved regs). !!!!!*******!!!!!!!!
			set<DefOrUse, LessDefUse>::iterator CurrDef;
			for (CurrDef = CurrInst->GetFirstDef(); CurrDef != CurrInst->GetLastDef(); ++CurrDef) {
				op_t TempOp = CurrDef->GetOp();
				if (TempOp.type != o_phrase && TempOp.type != o_displ)
					continue;
				if (this->MDGetStackOffsetAndSize(CurrInst, TempOp, sp_delta, offset, DataSize, UsedFramePointer,
					IndexedAccess, SignedMove, UnsignedMove)) {
					SignedOffset = (int) offset;
					if (IndexedAccess && ((0 > SignedOffset) || ((offset + DataSize) > this->StackFrameMap.size()))) {
						continue; // Indexed expressions can be within frame but offset is outside frame
					}
#if 0 // ls_O3.exe has IDA trouble on chunked function get_funky_string().
					assert(0 <= SignedOffset);
#else
					if (0 > SignedOffset) { // negative offset but not Indexed; very bad
						SMP_msg("ERROR: Negative stack offset at %x in %s. Abandoning LocalVar ID.\n", CurrInst->GetAddr(), this->GetFuncName());
						return false;
					}
#endif
					if ((SignedOffset + (long) DataSize) > this->LocalVarOffsetLimit) {
						// Going out of range. Extend LocalVarTable.
						struct LocalVar TempLocal;
						char TempStr[20];
						TempLocal.offset = (long) SignedOffset;
						TempLocal.size = DataSize;
						SMP_strncpy(TempLocal.VarName, "SMP_InArg", sizeof(TempLocal.VarName) - 1);
						(void) SMP_snprintf(TempStr, 18, "%d", offset);
						SMP_strncat(TempLocal.VarName, TempStr, sizeof(TempLocal.VarName) - 1);
						this->LocalVarTable.push_back(TempLocal);
						this->LocalVarOffsetLimit = (long) (SignedOffset + (long) DataSize);
					}
				}
			}
		}
		if (CurrInst->HasSourceMemoryOperand()) {
			set<DefOrUse, LessDefUse>::iterator CurrUse;
			for (CurrUse = CurrInst->GetFirstUse(); CurrUse != CurrInst->GetLastUse(); ++CurrUse) {
				op_t TempOp = CurrUse->GetOp();
				if ((TempOp.type != o_phrase) && (TempOp.type != o_displ))
					continue;
				if (this->MDGetStackOffsetAndSize(CurrInst, TempOp, sp_delta, offset, DataSize, UsedFramePointer,
					IndexedAccess, SignedMove, UnsignedMove)) {
					SignedOffset = (int) offset;
					if (IndexedAccess && ((0 > SignedOffset) || ((offset + DataSize) > this->StackFrameMap.size()))) {
						continue; // Indexed expressions can be within frame but offset is outside frame
					}
					assert(0 <= SignedOffset);
					if ((SignedOffset + (long) DataSize) > this->LocalVarOffsetLimit) {
						// Going out of range. Extend LocalVarTable.
						struct LocalVar TempLocal;
						char TempStr[20];
						TempLocal.offset = (long) SignedOffset;
						TempLocal.size = DataSize;
						SMP_strncpy(TempLocal.VarName, "SMP_InArg", sizeof(TempLocal.VarName) - 1);
						(void) SMP_snprintf(TempStr, 18, "%d", offset);
						SMP_strncat(TempLocal.VarName, TempStr, sizeof(TempLocal.VarName) - 1);
						this->LocalVarTable.push_back(TempLocal);
						this->LocalVarOffsetLimit = (long) (SignedOffset + (long) DataSize);
					}
				}
			}
		}
	} // end for all instructions

	// Fill in the gaps with new variables as well. SHOULD WE? WHY?

	return true;
} // end of SMPFunction::AuditLocalVarTable()


// Determine how many bytes at the bottom of the stack frame (i.e. at bottom of
//  this->LocalVarsSize) are used for outgoing args. This is the case when the cdecl
//  calling convention is used, e.g. gcc/linux allocates local var space + out args space
//  in a single allocation and then writes outarg values directly to ESP+0, ESP+4, etc.
void SMPFunction::FindOutgoingArgsSize(void) {
	// Compute the lowest value reached by the stack pointer.
	list<SMPInstr *>::iterator InstIter;
	unsigned short BitWidthMask;
	bool DebugFlag = false;
	int SignedOffset;
#if SMP_DEBUG_STACK_GRANULARITY
	DebugFlag = (0 == strcmp("BZ2_blockSort", this->GetFuncName()));
#endif

	this->OutgoingArgsComputed = true;

	if (DebugFlag) {
		SMP_msg("DEBUG: Entered FindOutgoingArgsSize for %s\n", this->GetFuncName());
#if SMP_IDAPRO52_WORKAROUND
		this->OutgoingArgsSize = 16;
		return;
#endif
	}

#if SMP_DEBUG_STACK_GRANULARITY
	SMP_msg("AllocPointDelta: %d MinStackDelta: %d\n", this->AllocPointDelta, this->MinStackDelta);
#endif
	if ((0 <= this->MinStackDelta) || (0 <= this->AllocPointDelta)) {
		// No allocations; sometimes happens in library functions.
		this->OutgoingArgsSize = 0;
		this->MinStackDelta = 0;
		this->AllocPointDelta = 0;
		return;
	}
	assert(0 > this->MinStackDelta);

	// Allocate a vector of stack frame entries, one for each byte of the stack frame.
	//  This will be our memory map for analyzing stack usage.
	int limit = 0;
#if 1
	if (this->LocalVarOffsetLimit > 0) {
		if (limit < (this->LocalVarOffsetLimit + this->MinStackDelta)) {
			// Make room for incoming args, other stuff above local vars.
			limit = this->LocalVarOffsetLimit + this->MinStackDelta;
			if (this->MinStackDelta < this->AllocPointDelta) {
				// Also have stuff below alloc point to make room for.
				limit += (this->AllocPointDelta - this->MinStackDelta);
			}
		}
	}
#endif
	for (int i = this->MinStackDelta; i < limit; ++i) {
		struct StackFrameEntry TempEntry;
		TempEntry.VarPtr = NULL;
		TempEntry.offset = (long) i;
		TempEntry.Read = false;
		TempEntry.Written = false;
		TempEntry.AddressTaken = false;
		TempEntry.ESPRelativeAccess = false;
		TempEntry.EBPRelativeAccess = false;
		TempEntry.IndexedAccess = false;
		this->StackFrameMap.push_back(TempEntry);
		struct FineGrainedInfo TempFineGrained;
		TempFineGrained.SignMiscInfo = 0;
		TempFineGrained.SizeInfo = 0;
		this->FineGrainedStackTable.push_back(TempFineGrained);
	}
#if 0
	for (int i = 0; i < this->LocalVarOffsetLimit; ++i) {
		struct FineGrainedInfo TempFineGrained;
		TempFineGrained.SignMiscInfo = 0;
		TempFineGrained.SizeInfo = 0;
		this->FineGrainedStackTable.push_back(TempFineGrained);
	}
#endif

	// Fill in the VarPtr fields for each StackFrameMap entry.
	if (0 <= this->AllocPointDelta) {
		SMP_msg("FATAL ERROR: AllocPointDelta = %d in %s\n", this->AllocPointDelta, this->GetFuncName());
	}
	assert(0 > this->AllocPointDelta);
	for (size_t i = 0; i < this->LocalVarTable.size(); ++i) {
		assert(this->LocalVarTable.at(i).offset >= 0);
		// Picture that AllocPointDelta is -200, MinStackDelta is -210, and
		//  the LocalVarTable[i].offset is +8 (i.e. 8 bytes above alloc point).
		//  Then base = 8 + (-200 - -210) = 8 + 10 = 18, the proper offset into
		//  the StackFrameMap.
		size_t base = (size_t) (this->LocalVarTable.at(i).offset
			+ (this->AllocPointDelta - this->MinStackDelta));
		size_t limit = base + this->LocalVarTable.at(i).size;
		if (limit > this->StackFrameMap.size()) {
			SMP_msg("ERROR: FindOutArgsSize: base = %zu limit = %zu StackFrameMap size = %zu in %s\n",
				base, limit, this->StackFrameMap.size(), this->GetFuncName());
			this->OutgoingArgsComputed = false;
			this->OutgoingArgsSize = 0;
			return;
		}
		assert(limit <= this->StackFrameMap.size());
		for (size_t MapIndex = base; MapIndex < limit; ++MapIndex) {
			this->StackFrameMap[MapIndex].VarPtr = &(this->LocalVarTable.at(i));
		}
	}

	// Iterate through all instructions and record stack frame accesses in the StackFrameMap.
	InstIter = this->Instrs.begin();
#if SMP_USE_SSA_FNOP_MARKER
	if ((*InstIter)->IsFloatNop())
		++InstIter;  // skip marker instruction
#endif
	for ( ; InstIter != this->Instrs.end(); ++InstIter) {
		SMPInstr *CurrInst = (*InstIter);
		ea_t InstAddr = CurrInst->GetAddr();
		sval_t sp_delta = get_spd(this->GetFuncInfo(), InstAddr);
		if (0 < sp_delta) {
			// Stack underflow; about to assert
			SMP_msg("FATAL ERROR: Stack underflow at %x %s sp_delta: %d\n", CurrInst->GetAddr(),
				CurrInst->GetDisasm(), sp_delta);
		}
		assert(0 >= sp_delta);
		ea_t offset;
		size_t DataSize;
		bool UsedFramePointer;
		bool IndexedAccess;
		bool SignedMove;
		bool UnsignedMove;
		if (CurrInst->HasDestMemoryOperand()) {
			set<DefOrUse, LessDefUse>::iterator CurrDef;
			for (CurrDef = CurrInst->GetFirstDef(); CurrDef != CurrInst->GetLastDef(); ++CurrDef) {
				op_t TempOp = CurrDef->GetOp();
				if (TempOp.type != o_phrase && TempOp.type != o_displ)
					continue;
				if (this->MDGetStackOffsetAndSize(CurrInst, TempOp, sp_delta, offset, DataSize, UsedFramePointer,
					IndexedAccess, SignedMove, UnsignedMove)) {
					SignedOffset = (int) offset;
					if (IndexedAccess && ((0 > SignedOffset) || ((offset + DataSize) > this->StackFrameMap.size()))) {
						continue; // Indexed expressions can be within frame even when offset is outside frame
					}
					assert(0 <= SignedOffset);
#if 0
					if (offset >= this->FuncInfo.frsize)
						continue;  // limit processing to outgoing args and locals
#endif
					if ((offset + DataSize) > this->StackFrameMap.size()) {
						SMP_msg("ERROR: offset = %u DataSize = %zu FrameMapSize = %zu\n",
							offset, DataSize, this->StackFrameMap.size());
						continue;
					}
					assert((offset + DataSize) <= this->StackFrameMap.size());
					for (int j = 0; j < (int) DataSize; ++j) {
						this->StackFrameMap[offset + j].Written = true;
						this->StackFrameMap[offset + j].IndexedAccess = IndexedAccess;
						if (!UsedFramePointer) {
							this->StackFrameMap[offset + j].ESPRelativeAccess = true;
						}
						else {
							this->StackFrameMap[offset + j].EBPRelativeAccess = true;
						}
					}
					BitWidthMask = ComputeOperandBitWidthMask(TempOp, DataSize);
					this->FineGrainedStackTable.at(offset).SizeInfo |= BitWidthMask;
					this->FineGrainedStackTable.at(offset).SignMiscInfo |= FG_MASK_WRITTEN;
					if (IndexedAccess) {
						this->FineGrainedStackTable.at(offset).SignMiscInfo |= FG_MASK_INDEXED_ACCESS;
					}
					if (!UsedFramePointer) {
						this->FineGrainedStackTable.at(offset).SignMiscInfo |= FG_MASK_SP_RELATIVE;
					}
					else {
						this->FineGrainedStackTable.at(offset).SignMiscInfo |= FG_MASK_FP_RELATIVE;
					}
					// We will process the signedness of stores later, so that loads can take precedence
					//  over stores in determining signedness.
				} // end if MDGetStackOffsetAndSize()
			} // end for all DEFs
		} // end if DestMemoryOperand

		if (CurrInst->HasSourceMemoryOperand()) {
			set<DefOrUse, LessDefUse>::iterator CurrUse;
			for (CurrUse = CurrInst->GetFirstUse(); CurrUse != CurrInst->GetLastUse(); ++CurrUse) {
				op_t TempOp = CurrUse->GetOp();
				if (TempOp.type != o_phrase && TempOp.type != o_displ)
					continue;
				if (this->MDGetStackOffsetAndSize(CurrInst, TempOp, sp_delta, offset, DataSize, UsedFramePointer,
					IndexedAccess, SignedMove, UnsignedMove)) {
					SignedOffset = (int) offset;
					if (IndexedAccess && ((0 > SignedOffset) || ((SignedOffset + DataSize) > this->StackFrameMap.size()))) {
						continue; // Indexed expressions can be within frame but offset is outside frame
					}
					assert(0 <= SignedOffset);
#if 0
					if (offset >= this->FuncInfo.frsize)
						continue;  // limit processing to outgoing args and locals
#endif
					if ((SignedOffset + DataSize) > this->StackFrameMap.size()) {
						SMP_msg("ERROR: offset = %u DataSize = %zu FrameMapSize = %zu\n",
							offset, DataSize, this->StackFrameMap.size());
						continue;
					}
					assert((SignedOffset + DataSize) <= this->StackFrameMap.size());
					for (int j = 0; j < (int) DataSize; ++j) {
						this->StackFrameMap[offset + j].Read = true;
						this->StackFrameMap[offset + j].IndexedAccess |= IndexedAccess;
						if (!UsedFramePointer)
							this->StackFrameMap[offset + j].ESPRelativeAccess = true;
						else
							this->StackFrameMap[offset + j].EBPRelativeAccess = true;
					}
					BitWidthMask = ComputeOperandBitWidthMask(TempOp, DataSize);
					this->FineGrainedStackTable.at(offset).SizeInfo |= BitWidthMask;
					this->FineGrainedStackTable.at(offset).SignMiscInfo |= FG_MASK_READ;
					if (IndexedAccess) {
						this->FineGrainedStackTable.at(offset).SignMiscInfo |= FG_MASK_INDEXED_ACCESS;
					}
					if (!UsedFramePointer) {
						this->FineGrainedStackTable.at(offset).SignMiscInfo |= FG_MASK_SP_RELATIVE;
					}
					else {
						this->FineGrainedStackTable.at(offset).SignMiscInfo |= FG_MASK_FP_RELATIVE;
					}
					if (SignedMove) {
						this->FineGrainedStackTable.at(offset).SignMiscInfo |= FG_MASK_SIGNED;
					}
					else if (UnsignedMove) {
						this->FineGrainedStackTable.at(offset).SignMiscInfo |= FG_MASK_UNSIGNED;
					}
				} // end if MDGetStackOffsetAndSize()
			} // end for all USEs
		} // end if SourceMemoryOperand
		// NOTE: Detect taking the address of stack locations. **!!**
	} // end for all instructions

	// If function is a leaf function, set OutgoingArgsSize to zero and return.
	if (this->IsLeaf() && !(this->IsDirectlyRecursive())) {
		this->OutgoingArgsSize = 0;
		return;
	}

	// For non-leaf functions, set the OutgoingArgsSize to the write-only, ESP-relative
	//  region of the bottom of the StackFrameMap.
	bool OutgoingArgsRegionFinished = false;
	bool IndexedOutgoingArgs = false; // Any indexed accesses to outgoing args?
	size_t FramePadSize = 0;
	for (size_t MapIndex = 0; MapIndex < this->StackFrameMap.size(); ++MapIndex) {
		// Some of the bottom of the stack frame might be below the local frame allocation.
		//  These are pushes that happened after allocation, etc. We skip over these
		//  locations and define the outgoing args region to start strictly at the bottom