- Modify the stack protector algorithm so that the stack slot is allocated in
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
diff --git a/lib/CodeGen/StackProtector.cpp b/lib/CodeGen/StackProtector.cpp
index 3f5e980..19fd45c 100644
--- a/lib/CodeGen/StackProtector.cpp
+++ b/lib/CodeGen/StackProtector.cpp
@@ -97,9 +97,6 @@
/// - 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 @@
// 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 @@
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 @@
// 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 @@
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 (AI->isArrayAllocation())
+ // This is a call to alloca with a variable size. Emit stack
+ // protectors.
+ return true;
- if (ConstantInt *CI = dyn_cast<ConstantInt>(AI->getArraySize())) {
- const Type *Ty = AI->getAllocatedType();
- uint64_t TySize = TD->getABITypeSize(Ty);
-
+ 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;
- }
}
}