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- Modify the stack protector algorithm so that the stack slot is allocated in

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LLVM IR code and not in the selection DAG ISel. This is a cleaner solution.

- Fix the heuristic for determining if protectors are necessary. The previous
  one wasn't checking the proper type size.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58824 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling 2008-11-07 01:23:58 +00:00
parent 848693c254
commit b7c6ebcb47
3 changed files with 36 additions and 41 deletions
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7
include/llvm/Intrinsics.td
View File

@ -179,9 +179,10 @@ def int_readcyclecounter : Intrinsic<[llvm_i64_ty]>;
// Stack Protector Intrinsics - The stackprotector_create writes the stack guard
// to the correct place on the stack frame. The stackprotector_check reads back
// the stack guard that the stackprotector_create stored.
def int_stackprotector_create : Intrinsic<[llvm_void_ty, llvm_ptr_ty],
[IntrWriteMem]>;
def int_stackprotector_check : Intrinsic<[llvm_ptr_ty], [IntrReadMem]>;
def int_stackprotector_create : Intrinsic<[llvm_void_ty, llvm_ptr_ty,
llvm_ptrptr_ty], [IntrWriteMem]>;
def int_stackprotector_check : Intrinsic<[llvm_ptr_ty, llvm_ptrptr_ty],
[IntrReadMem]>;
//===------------------- Standard C Library Intrinsics --------------------===//
//

10
lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
View File

@ -3801,14 +3801,10 @@ SelectionDAGLowering::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
MachineFrameInfo *MFI = MF.getFrameInfo();
MVT PtrTy = TLI.getPointerTy();
// Retrieve the stack protector guard's value.
SDValue Src = getValue(I.getOperand(1));
SDValue Src = getValue(I.getOperand(1)); // The guard's value.
AllocaInst *Slot = cast<AllocaInst>(I.getOperand(2));
// Create a slot on the stack for the stack protector. It should go first
// before local variables are allocated.
unsigned Align =
TLI.getTargetData()->getPrefTypeAlignment(PtrTy.getTypeForMVT());
int FI = MFI->CreateStackObject(PtrTy.getSizeInBits() / 8, Align);
int FI = FuncInfo.StaticAllocaMap[Slot];
MFI->setStackProtectorIndex(FI);
SDValue FIN = DAG.getFrameIndex(FI, PtrTy);

60
lib/CodeGen/StackProtector.cpp
View File

@ -97,9 +97,6 @@ bool StackProtector::runOnFunction(Function &Fn) {
/// - The epilogue checks the value stored in the prologue against the original
/// value. It calls __stack_chk_fail if they differ.
bool StackProtector::InsertStackProtectors() {
Constant *StackGuardVar = 0; // The global variable for the stack guard.
BasicBlock *FailBB = 0; // The basic block to jump to if check fails.
// Loop through the basic blocks that have return instructions. Convert this:
//
// return:
@ -122,18 +119,34 @@ bool StackProtector::InsertStackProtectors() {
// call void @__stack_chk_fail()
// unreachable
//
BasicBlock *FailBB = 0; // The basic block to jump to if check fails.
AllocaInst *AI = 0; // Place on stack that stores the stack guard.
Constant *StackGuardVar = 0; // The stack guard variable.
for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
BasicBlock *BB = I;
if (isa<ReturnInst>(BB->getTerminator())) {
// Create the basic block to jump to when the guard check fails.
if (!FailBB)
if (!FailBB) {
// Create the basic block to jump to when the guard check fails.
FailBB = CreateFailBB();
if (!StackGuardVar)
StackGuardVar =
M->getOrInsertGlobal("__stack_chk_guard",
PointerType::getUnqual(Type::Int8Ty));
// Insert code into the entry block that stores the __stack_chk_guard
// variable onto the stack.
PointerType *PtrTy = PointerType::getUnqual(Type::Int8Ty);
StackGuardVar = M->getOrInsertGlobal("__stack_chk_guard", PtrTy);
BasicBlock &Entry = F->getEntryBlock();
Instruction *InsPt = &Entry.front();
AI = new AllocaInst(PtrTy, "StackGuardSlot", InsPt);
LoadInst *LI = new LoadInst(StackGuardVar, "StackGuard", false, InsPt);
Value *Args[] = { LI, AI };
CallInst::
Create(Intrinsic::getDeclaration(M, Intrinsic::stackprotector_create),
&Args[0], array_endof(Args), "", InsPt);
}
ReturnInst *RI = cast<ReturnInst>(BB->getTerminator());
Function::iterator InsPt = BB; ++InsPt; // Insertion point for new BB.
@ -151,7 +164,7 @@ bool StackProtector::InsertStackProtectors() {
LoadInst *LI1 = new LoadInst(StackGuardVar, "", false, BB);
CallInst *CI = CallInst::
Create(Intrinsic::getDeclaration(M, Intrinsic::stackprotector_check),
"", BB);
AI, "", BB);
ICmpInst *Cmp = new ICmpInst(CmpInst::ICMP_EQ, CI, LI1, "", BB);
BranchInst::Create(NewBB, FailBB, Cmp, BB);
}
@ -161,16 +174,6 @@ bool StackProtector::InsertStackProtectors() {
// statements in the function.
if (!FailBB) return false;
// Insert code into the entry block that stores the __stack_chk_guard variable
// onto the stack.
BasicBlock &Entry = F->getEntryBlock();
Instruction *InsertPt = &Entry.front();
LoadInst *LI = new LoadInst(StackGuardVar, "StackGuard", false, InsertPt);
CallInst::
Create(Intrinsic::getDeclaration(M, Intrinsic::stackprotector_create),
LI, "", InsertPt);
return true;
}
@ -202,21 +205,16 @@ bool StackProtector::RequiresStackProtector() const {
for (BasicBlock::iterator
II = BB->begin(), IE = BB->end(); II != IE; ++II)
if (AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
if (!AI->isArrayAllocation()) continue; // Only care about arrays.
if (ConstantInt *CI = dyn_cast<ConstantInt>(AI->getArraySize())) {
const Type *Ty = AI->getAllocatedType();
uint64_t TySize = TD->getABITypeSize(Ty);
if (AI->isArrayAllocation())
// This is a call to alloca with a variable size. Emit stack
// protectors.
return true;
if (const ArrayType *AT = dyn_cast<ArrayType>(AI->getAllocatedType()))
// If an array has more than 8 bytes of allocated space, then we
// emit stack protectors.
if (SSPBufferSize <= TySize * CI->getZExtValue())
if (SSPBufferSize <= TD->getABITypeSize(AT))
return true;
} else {
// This is a call to alloca with a variable size. Default to adding
// stack protectors.
return true;
}
}
}