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[stackprotector] Refactored ssp prologue creation code into its own helper function. 

No functionality change.

rdar://13935163

llvm-svn: 186868
This commit is contained in:
Michael Gottesman 2013-07-22 20:44:11 +00:00
parent 14dd2a656e
commit a6188f9fcd
1 changed files with 41 additions and 35 deletions
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58
llvm/lib/CodeGen/StackProtector.cpp
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@ -265,32 +265,17 @@ bool StackProtector::RequiresStackProtector() {
return false; return false;
} }
/// InsertStackProtectors - Insert code into the prologue and epilogue of the /// Insert code into the entry block that stores the __stack_chk_guard
/// function. /// variable onto the stack:
/// ///
/// - The prologue code loads and stores the stack guard onto the stack. /// entry:
/// - The epilogue checks the value stored in the prologue against the original /// StackGuardSlot = alloca i8*
/// value. It calls __stack_chk_fail if they differ. /// StackGuard = load __stack_chk_guard
bool StackProtector::InsertStackProtectors() { /// call void @llvm.stackprotect.create(StackGuard, StackGuardSlot)
BasicBlock *FailBB = 0; // The basic block to jump to if check fails. ///
BasicBlock *FailBBDom = 0; // FailBB's dominator. static void CreatePrologue(Function *F, Module *M, ReturnInst *RI,
AllocaInst *AI = 0; // Place on stack that stores the stack guard. const TargetLoweringBase *TLI, const Triple &Trip,
Value *StackGuardVar = 0; // The stack guard variable. AllocaInst *&AI, Value *&StackGuardVar) {
for (Function::iterator I = F->begin(), E = F->end(); I != E; ) {
BasicBlock *BB = I++;
ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator());
if (!RI) continue;
if (!FailBB) {
// Insert code into the entry block that stores the __stack_chk_guard
// variable onto the stack:
//
// entry:
// StackGuardSlot = alloca i8*
// StackGuard = load __stack_chk_guard
// call void @llvm.stackprotect.create(StackGuard, StackGuardSlot)
//
PointerType *PtrTy = Type::getInt8PtrTy(RI->getContext()); PointerType *PtrTy = Type::getInt8PtrTy(RI->getContext());
unsigned AddressSpace, Offset; unsigned AddressSpace, Offset;
if (TLI->getStackCookieLocation(AddressSpace, Offset)) { if (TLI->getStackCookieLocation(AddressSpace, Offset)) {
@ -298,7 +283,8 @@ bool StackProtector::InsertStackProtectors() {
ConstantInt::get(Type::getInt32Ty(RI->getContext()), Offset); ConstantInt::get(Type::getInt32Ty(RI->getContext()), Offset);
StackGuardVar = ConstantExpr::getIntToPtr(OffsetVal, StackGuardVar = ConstantExpr::getIntToPtr(OffsetVal,
PointerType::get(PtrTy, AddressSpace)); PointerType::get(PtrTy,
AddressSpace));
} else if (Trip.getOS() == llvm::Triple::OpenBSD) { } else if (Trip.getOS() == llvm::Triple::OpenBSD) {
StackGuardVar = M->getOrInsertGlobal("__guard_local", PtrTy); StackGuardVar = M->getOrInsertGlobal("__guard_local", PtrTy);
cast<GlobalValue>(StackGuardVar) cast<GlobalValue>(StackGuardVar)
@ -317,7 +303,27 @@ bool StackProtector::InsertStackProtectors() {
CallInst:: CallInst::
Create(Intrinsic::getDeclaration(M, Intrinsic::stackprotector), Create(Intrinsic::getDeclaration(M, Intrinsic::stackprotector),
Args, "", InsPt); Args, "", InsPt);
}
/// InsertStackProtectors - Insert code into the prologue and epilogue of the
/// function.
///
/// - The prologue code loads and stores the stack guard onto the stack.
/// - The epilogue checks the value stored in the prologue against the original
/// value. It calls __stack_chk_fail if they differ.
bool StackProtector::InsertStackProtectors() {
BasicBlock *FailBB = 0; // The basic block to jump to if check fails.
BasicBlock *FailBBDom = 0; // FailBB's dominator.
AllocaInst *AI = 0; // Place on stack that stores the stack guard.
Value *StackGuardVar = 0; // The stack guard variable.
for (Function::iterator I = F->begin(), E = F->end(); I != E; ) {
BasicBlock *BB = I++;
ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator());
if (!RI) continue;
if (!FailBB) {
CreatePrologue(F, M, RI, TLI, Trip, AI, StackGuardVar);
// Create the basic block to jump to when the guard check fails. // Create the basic block to jump to when the guard check fails.
FailBB = CreateFailBB(); FailBB = CreateFailBB();
} }