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Don't build a vector of returns. Just modify the Function in the loop.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58822 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling
2008-11-06 23:55:49 +00:00
parent e0b436ac41
commit 1fb615f820
1 changed files with 46 additions and 43 deletions
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89
lib/CodeGen/StackProtector.cpp
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@@ -98,31 +98,8 @@ 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() {
std::vector<BasicBlock*> ReturnBBs;
for (Function::iterator I = F->begin(); I != F->end(); ++I)
if (isa<ReturnInst>(I->getTerminator()))
ReturnBBs.push_back(I);
// If this function doesn't return, don't bother with stack protectors.
if (ReturnBBs.empty()) 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();
const PointerType *GuardTy = PointerType::getUnqual(Type::Int8Ty);
// The global variable for the stack guard.
Constant *StackGuardVar = M->getOrInsertGlobal("__stack_chk_guard", GuardTy);
LoadInst *LI = new LoadInst(StackGuardVar, "StackGuard", false, InsertPt);
CallInst::
Create(Intrinsic::getDeclaration(M, Intrinsic::stackprotector_create),
LI, "", InsertPt);
// Create the basic block to jump to when the guard check fails.
BasicBlock *FailBB = CreateFailBB();
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:
//
@@ -146,29 +123,55 @@ bool StackProtector::InsertStackProtectors() {
// call void @__stack_chk_fail()
// unreachable
//
for (std::vector<BasicBlock*>::iterator
I = ReturnBBs.begin(), E = ReturnBBs.end(); I != E; ++I) {
BasicBlock *BB = *I;
ReturnInst *RI = cast<ReturnInst>(BB->getTerminator());
Function::iterator InsPt = BB; ++InsPt; // Insertion point for new BB.
for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
BasicBlock *BB = I;
// Split the basic block before the return instruction.
BasicBlock *NewBB = BB->splitBasicBlock(RI, "SP_return");
if (isa<ReturnInst>(BB->getTerminator())) {
// Create the basic block to jump to when the guard check fails.
if (!FailBB)
FailBB = CreateFailBB();
// Move the newly created basic block to the point right after the old basic
// block so that it's in the "fall through" position.
NewBB->removeFromParent();
F->getBasicBlockList().insert(InsPt, NewBB);
if (!StackGuardVar)
StackGuardVar =
M->getOrInsertGlobal("__stack_chk_guard",
PointerType::getUnqual(Type::Int8Ty));
// Generate the stack protector instructions in the old basic block.
LoadInst *LI1 = new LoadInst(StackGuardVar, "", false, BB);
CallInst *CI = CallInst::
Create(Intrinsic::getDeclaration(M, Intrinsic::stackprotector_check),
"", BB);
ICmpInst *Cmp = new ICmpInst(CmpInst::ICMP_EQ, CI, LI1, "", BB);
BranchInst::Create(NewBB, FailBB, Cmp, BB);
ReturnInst *RI = cast<ReturnInst>(BB->getTerminator());
Function::iterator InsPt = BB; ++InsPt; // Insertion point for new BB.
++I;
// Split the basic block before the return instruction.
BasicBlock *NewBB = BB->splitBasicBlock(RI, "SP_return");
// Move the newly created basic block to the point right after the old basic
// block so that it's in the "fall through" position.
NewBB->removeFromParent();
F->getBasicBlockList().insert(InsPt, NewBB);
// Generate the stack protector instructions in the old basic block.
LoadInst *LI1 = new LoadInst(StackGuardVar, "", false, BB);
CallInst *CI = CallInst::
Create(Intrinsic::getDeclaration(M, Intrinsic::stackprotector_check),
"", BB);
ICmpInst *Cmp = new ICmpInst(CmpInst::ICMP_EQ, CI, LI1, "", BB);
BranchInst::Create(NewBB, FailBB, Cmp, BB);
}
}
// Return if we didn't modify any basic blocks. I.e., there are no return
// 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;
}