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Enhance loopsimplify to preserve alias analysis instead of clobbering it.

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This prevents crashes on some programs when using -ds-aa -licm.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@20831 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-03-25 06:37:22 +00:00
parent 2958eeabcf
commit cec5b8831d
1 changed files with 15 additions and 2 deletions
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17
lib/Transforms/Utils/LoopSimplify.cpp
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@ -37,6 +37,7 @@
#include "llvm/Instructions.h"
#include "llvm/Function.h"
#include "llvm/Type.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Support/CFG.h"
@ -54,6 +55,10 @@ namespace {
NumNested("loopsimplify", "Number of nested loops split out");
struct LoopSimplify : public FunctionPass {
// AA - If we have an alias analysis object to update, this is it, otherwise
// this is null.
AliasAnalysis *AA;
virtual bool runOnFunction(Function &F);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
@ -96,6 +101,7 @@ FunctionPass *llvm::createLoopSimplifyPass() { return new LoopSimplify(); }
bool LoopSimplify::runOnFunction(Function &F) {
bool Changed = false;
LoopInfo &LI = getAnalysis<LoopInfo>();
AA = getAnalysisToUpdate<AliasAnalysis>();
for (LoopInfo::iterator I = LI.begin(), E = LI.end(); I != E; ++I)
Changed |= ProcessLoop(*I);
@ -130,6 +136,7 @@ bool LoopSimplify::ProcessLoop(Loop *L) {
(*SI)->removePredecessor(DeadBlock); // Remove PHI node entries
// Delete the dead terminator.
if (AA) AA->deleteValue(&DeadBlock->back());
DeadBlock->getInstList().pop_back();
Value *RetVal = 0;
@ -230,6 +237,7 @@ BasicBlock *LoopSimplify::SplitBlockPredecessors(BasicBlock *BB,
if (InVal == 0) {
// Create the new PHI node, insert it into NewBB at the end of the block
PHINode *NewPHI = new PHINode(PN->getType(), PN->getName()+".ph", BI);
if (AA) AA->copyValue(PN, NewPHI);
// Move all of the edges from blocks outside the loop to the new PHI
for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
@ -253,6 +261,7 @@ BasicBlock *LoopSimplify::SplitBlockPredecessors(BasicBlock *BB,
if (!isa<Instruction>(V) ||
getAnalysis<DominatorSet>().dominates(cast<Instruction>(V), PN)) {
PN->replaceAllUsesWith(V);
if (AA) AA->deleteValue(PN);
BB->getInstList().erase(PN);
}
}
@ -429,7 +438,8 @@ static void AddBlockAndPredsToSet(BasicBlock *BB, BasicBlock *StopBlock,
/// FindPHIToPartitionLoops - The first part of loop-nestification is to find a
/// PHI node that tells us how to partition the loops.
static PHINode *FindPHIToPartitionLoops(Loop *L, DominatorSet &DS) {
static PHINode *FindPHIToPartitionLoops(Loop *L, DominatorSet &DS,
AliasAnalysis *AA) {
for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ) {
PHINode *PN = cast<PHINode>(I);
++I;
@ -437,6 +447,7 @@ static PHINode *FindPHIToPartitionLoops(Loop *L, DominatorSet &DS) {
if (!isa<Instruction>(V) || DS.dominates(cast<Instruction>(V), PN)) {
// This is a degenerate PHI already, don't modify it!
PN->replaceAllUsesWith(V);
if (AA) AA->deleteValue(PN);
PN->eraseFromParent();
continue;
}
@ -469,7 +480,7 @@ static PHINode *FindPHIToPartitionLoops(Loop *L, DominatorSet &DS) {
/// created.
///
Loop *LoopSimplify::SeparateNestedLoop(Loop *L) {
PHINode *PN = FindPHIToPartitionLoops(L, getAnalysis<DominatorSet>());
PHINode *PN = FindPHIToPartitionLoops(L, getAnalysis<DominatorSet>(), AA);
if (PN == 0) return 0; // No known way to partition.
// Pull out all predecessors that have varying values in the loop. This
@ -576,6 +587,7 @@ void LoopSimplify::InsertUniqueBackedgeBlock(Loop *L) {
PHINode *NewPN = new PHINode(PN->getType(), PN->getName()+".be",
BETerminator);
NewPN->reserveOperandSpace(BackedgeBlocks.size());
if (AA) AA->copyValue(PN, NewPN);
// Loop over the PHI node, moving all entries except the one for the
// preheader over to the new PHI node.
@ -616,6 +628,7 @@ void LoopSimplify::InsertUniqueBackedgeBlock(Loop *L) {
// eliminate the PHI Node.
if (HasUniqueIncomingValue) {
NewPN->replaceAllUsesWith(UniqueValue);
if (AA) AA->deleteValue(NewPN);
BEBlock->getInstList().erase(NewPN);
}
}