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- Add a "getOrInsertGlobal" method to the Module class. This acts similarly to

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"getOrInsertFunction" in that it either adds a new declaration of the global
  and returns it, or returns the current one -- optionally casting it to the
  correct type.
- Use the new getOrInsertGlobal in the stack protector code.
- Use "splitBasicBlock" in the stack protector code.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58727 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling
2008-11-04 22:51:24 +00:00
parent f1f75b1bd1
commit b7c2c1246f
3 changed files with 42 additions and 14 deletions
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25
lib/CodeGen/StackProtector.cpp
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@ -52,7 +52,7 @@ namespace {
AllocaInst *StackProtFrameSlot;
/// StackGuardVar - The global variable for the stack guard.
GlobalVariable *StackGuardVar;
Constant *StackGuardVar;
Function *F;
Module *M;
@ -115,14 +115,8 @@ void StackProtector::InsertStackProtectorPrologue() {
BasicBlock &Entry = F->getEntryBlock();
Instruction &InsertPt = Entry.front();
const char *StackGuardStr = "__stack_chk_guard";
StackGuardVar = M->getNamedGlobal(StackGuardStr);
if (!StackGuardVar)
StackGuardVar = new GlobalVariable(PointerType::getUnqual(Type::Int8Ty),
false, GlobalValue::ExternalLinkage,
0, StackGuardStr, M);
StackGuardVar = M->getOrInsertGlobal("__stack_chk_guard",
PointerType::getUnqual(Type::Int8Ty));
StackProtFrameSlot = new AllocaInst(PointerType::getUnqual(Type::Int8Ty),
"StackProt_Frame", &InsertPt);
LoadInst *LI = new LoadInst(StackGuardVar, "StackGuard", false, &InsertPt);
@ -161,7 +155,7 @@ void StackProtector::InsertStackProtectorEpilogue() {
// %3 = cmp i1 %1, %2
// br i1 %3, label %SPRet, label %CallStackCheckFailBlk
//
// SPRet:
// SP_return:
// ret ...
//
// CallStackCheckFailBlk:
@ -174,12 +168,15 @@ void StackProtector::InsertStackProtectorEpilogue() {
ReturnInst *RI = cast<ReturnInst>(BB->getTerminator());
Function::iterator InsPt = BB; ++InsPt; // Insertion point for new BB.
BasicBlock *NewBB = BasicBlock::Create("SPRet", F, InsPt);
// Split the basic block before the return instruction.
BasicBlock *NewBB = BB->splitBasicBlock(RI, "SP_return");
// Move the return instruction into the new basic block.
RI->removeFromParent();
NewBB->getInstList().insert(NewBB->begin(), RI);
// Move the newly created basic block to the point right after the old basic
// block.
NewBB->removeFromParent();
F->getBasicBlockList().insert(InsPt, NewBB);
// Generate the stack protector instructions in the old basic block.
LoadInst *LI2 = new LoadInst(StackGuardVar, "", false, BB);
LoadInst *LI1 = new LoadInst(StackProtFrameSlot, "", true, BB);
ICmpInst *Cmp = new ICmpInst(CmpInst::ICMP_EQ, LI1, LI2, "", BB);