Make more passes preserve dominators (or state that they preserve dominators if
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
diff --git a/lib/CodeGen/StackProtector.cpp b/lib/CodeGen/StackProtector.cpp
index 61dd7b1..fcaee42 100644
--- a/lib/CodeGen/StackProtector.cpp
+++ b/lib/CodeGen/StackProtector.cpp
@@ -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 @@
Function *F;
Module *M;
+ DominatorTree* DT;
+
/// InsertStackProtectors - Insert code into the prologue and epilogue of
/// the function.
///
@@ -70,6 +73,10 @@
initializeStackProtectorPass(*PassRegistry::getPassRegistry());
}
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addPreserved<DominatorTree>();
+ }
+
virtual bool runOnFunction(Function &Fn);
};
} // end anonymous namespace
@@ -85,6 +92,7 @@
bool StackProtector::runOnFunction(Function &Fn) {
F = &Fn;
M = F->getParent();
+ DT = getAnalysisIfAvailable<DominatorTree>();
if (!RequiresStackProtector()) return false;
@@ -139,6 +147,7 @@
/// 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 @@
// 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 @@
// 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 @@
// statements in the function.
if (!FailBB) return false;
+ if (DT)
+ DT->addNewBlock(FailBB, FailBBDom);
+
return true;
}