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Make more passes preserve dominators (or state that they preserve dominators if

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they all ready do). This removes two dominator recomputations prior to isel,
which is a 1% improvement in total llc time for 403.gcc.

The only potentially suspect thing is making GCStrategy recompute dominators if
it used a custom lowering strategy.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123064 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Cameron Zwarich
2011-01-08 17:01:52 +00:00
parent bea4626f93
commit 80f6a507d4
5 changed files with 49 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
lib/CodeGen/StackProtector.cpp
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@ -16,6 +16,7 @@
#define DEBUG_TYPE "stack-protector"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Attributes.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
@ -45,6 +46,8 @@ namespace {
Function *F;
Module *M;
DominatorTree* DT;
/// InsertStackProtectors - Insert code into the prologue and epilogue of
/// the function.
///
@ -70,6 +73,10 @@ namespace {
initializeStackProtectorPass(*PassRegistry::getPassRegistry());
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addPreserved<DominatorTree>();
}
virtual bool runOnFunction(Function &Fn);
};
} // end anonymous namespace
@ -85,6 +92,7 @@ FunctionPass *llvm::createStackProtectorPass(const TargetLowering *tli) {
bool StackProtector::runOnFunction(Function &Fn) {
F = &Fn;
M = F->getParent();
DT = getAnalysisIfAvailable<DominatorTree>();
if (!RequiresStackProtector()) return false;
@ -139,6 +147,7 @@ bool StackProtector::RequiresStackProtector() const {
/// value. It calls __stack_chk_fail if they differ.
bool StackProtector::InsertStackProtectors() {
BasicBlock *FailBB = 0; // The basic block to jump to if check fails.
BasicBlock *FailBBDom = 0; // FailBB's dominator.
AllocaInst *AI = 0; // Place on stack that stores the stack guard.
Value *StackGuardVar = 0; // The stack guard variable.
@ -182,6 +191,8 @@ 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:
@ -208,6 +219,10 @@ bool StackProtector::InsertStackProtectors() {
// Split the basic block before the return instruction.
BasicBlock *NewBB = BB->splitBasicBlock(RI, "SP_return");
if (DT) {
DT->addNewBlock(NewBB, DT->isReachableFromEntry(BB) ? BB : 0);
FailBBDom = DT->findNearestCommonDominator(FailBBDom, BB);
}
// Remove default branch instruction to the new BB.
BB->getTerminator()->eraseFromParent();
@ -227,6 +242,9 @@ bool StackProtector::InsertStackProtectors() {
// statements in the function.
if (!FailBB) return false;
if (DT)
DT->addNewBlock(FailBB, FailBBDom);
return true;
}