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Rework the logic (and removing the bad check for an unreachable block) so that

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the FailBB dominator is correctly calculated. Believe it or not, there isn't a
functionality change here.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128455 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling 2011-03-29 07:28:52 +00:00
parent 9827b78b51
commit 3c288b9787
1 changed files with 5 additions and 8 deletions
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13
lib/CodeGen/StackProtector.cpp
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@ -150,12 +150,9 @@ bool StackProtector::InsertStackProtectors() {
BasicBlock *FailBBDom = 0; // FailBB's dominator.
AllocaInst *AI = 0; // Place on stack that stores the stack guard.
Value *StackGuardVar = 0; // The stack guard variable.
BasicBlock &Entry = F->getEntryBlock();
for (Function::iterator I = F->begin(), E = F->end(); I != E; ) {
BasicBlock *BB = I++;
if (BB->getNumUses() == 0 && BB != &Entry) continue;
ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator());
if (!RI) continue;
@ -180,6 +177,7 @@ bool StackProtector::InsertStackProtectors() {
StackGuardVar = M->getOrInsertGlobal("__stack_chk_guard", PtrTy);
}
BasicBlock &Entry = F->getEntryBlock();
Instruction *InsPt = &Entry.front();
AI = new AllocaInst(PtrTy, "StackGuardSlot", InsPt);
@ -192,8 +190,6 @@ bool StackProtector::InsertStackProtectors() {
// Create the basic block to jump to when the guard check fails.
FailBB = CreateFailBB();
if (DT)
FailBBDom = DT->isReachableFromEntry(BB) ? BB : 0;
}
// For each block with a return instruction, convert this:
@ -219,11 +215,12 @@ bool StackProtector::InsertStackProtectors() {
// unreachable
// Split the basic block before the return instruction.
bool BBIsReachable = (DT && DT->isReachableFromEntry(BB));
BasicBlock *NewBB = BB->splitBasicBlock(RI, "SP_return");
if (DT && DT->isReachableFromEntry(BB)) {
if (BBIsReachable) {
DT->addNewBlock(NewBB, BB);
if (FailBBDom)
FailBBDom = DT->findNearestCommonDominator(FailBBDom, BB);
FailBBDom = FailBBDom ? DT->findNearestCommonDominator(FailBBDom, BB) :BB;
}
// Remove default branch instruction to the new BB.