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split rewriting of single-store allocas into its own 

method.

llvm-svn: 40806
This commit is contained in:
Chris Lattner 2007-08-04 01:47:41 +00:00
parent 3cede09c67
commit 886a41a007
1 changed files with 57 additions and 39 deletions
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96
llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
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@ -78,6 +78,7 @@ bool llvm::isAllocaPromotable(const AllocaInst *AI) {
}
namespace {
struct AllocaInfo;
// Data package used by RenamePass()
class VISIBILITY_HIDDEN RenamePassData {
@ -165,6 +166,8 @@ namespace {
--AllocaIdx;
}
void RewriteSingleStoreAlloca(AllocaInst *AI, AllocaInfo &Info);
void MarkDominatingPHILive(BasicBlock *BB, unsigned AllocaNum,
SmallPtrSet<PHINode*, 16> &DeadPHINodes);
bool PromoteLocallyUsedAlloca(BasicBlock *BB, AllocaInst *AI);
@ -232,6 +235,7 @@ namespace {
} // end of anonymous namespace
void PromoteMem2Reg::run() {
Function &F = *DF.getRoot()->getParent();
@ -282,45 +286,7 @@ void PromoteMem2Reg::run() {
// If there is only a single store to this value, replace any loads of
// it that are directly dominated by the definition with the value stored.
if (Info.DefiningBlocks.size() == 1) {
// Be aware of loads before the store.
std::set<BasicBlock*> ProcessedBlocks;
for (unsigned i = 0, e = Info.UsingBlocks.size(); i != e; ++i)
// If the store dominates the block and if we haven't processed it yet,
// do so now.
if (dominates(Info.OnlyStore->getParent(), Info.UsingBlocks[i]))
if (ProcessedBlocks.insert(Info.UsingBlocks[i]).second) {
BasicBlock *UseBlock = Info.UsingBlocks[i];
// If the use and store are in the same block, do a quick scan to
// verify that there are no uses before the store.
if (UseBlock == Info.OnlyStore->getParent()) {
BasicBlock::iterator I = UseBlock->begin();
for (; &*I != Info.OnlyStore; ++I) { // scan block for store.
if (isa<LoadInst>(I) && I->getOperand(0) == AI)
break;
}
if (&*I != Info.OnlyStore) break; // Do not handle this case.
}
// Otherwise, if this is a different block or if all uses happen
// after the store, do a simple linear scan to replace loads with
// the stored value.
for (BasicBlock::iterator I = UseBlock->begin(),E = UseBlock->end();
I != E; ) {
if (LoadInst *LI = dyn_cast<LoadInst>(I++)) {
if (LI->getOperand(0) == AI) {
LI->replaceAllUsesWith(Info.OnlyStore->getOperand(0));
if (AST && isa<PointerType>(LI->getType()))
AST->deleteValue(LI);
LI->eraseFromParent();
}
}
}
// Finally, remove this block from the UsingBlock set.
Info.UsingBlocks[i] = Info.UsingBlocks.back();
--i; --e;
}
RewriteSingleStoreAlloca(AI, Info);
// Finally, after the scan, check to see if the store is all that is left.
if (Info.UsingBlocks.empty()) {
@ -559,6 +525,58 @@ void PromoteMem2Reg::run() {
NewPhiNodes.clear();
}
/// RewriteSingleStoreAlloca - If there is only a single store to this value,
/// replace any loads of it that are directly dominated by the definition with
/// the value stored.
void PromoteMem2Reg::RewriteSingleStoreAlloca(AllocaInst *AI,
AllocaInfo &Info) {
// Be aware of loads before the store.
std::set<BasicBlock*> ProcessedBlocks;
for (unsigned i = 0, e = Info.UsingBlocks.size(); i != e; ++i) {
// If the store dominates the block and if we haven't processed it yet,
// do so now.
if (!dominates(Info.OnlyStore->getParent(), Info.UsingBlocks[i]))
continue;
if (!ProcessedBlocks.insert(Info.UsingBlocks[i]).second)
continue;
BasicBlock *UseBlock = Info.UsingBlocks[i];
// If the use and store are in the same block, do a quick scan to
// verify that there are no uses before the store.
if (UseBlock == Info.OnlyStore->getParent()) {
BasicBlock::iterator I = UseBlock->begin();
for (; &*I != Info.OnlyStore; ++I) { // scan block for store.
if (isa<LoadInst>(I) && I->getOperand(0) == AI)
break;
}
if (&*I != Info.OnlyStore) break; // Do not handle this case.
}
// Otherwise, if this is a different block or if all uses happen
// after the store, do a simple linear scan to replace loads with
// the stored value.
for (BasicBlock::iterator I = UseBlock->begin(),E = UseBlock->end();
I != E; ) {
if (LoadInst *LI = dyn_cast<LoadInst>(I++)) {
if (LI->getOperand(0) == AI) {
LI->replaceAllUsesWith(Info.OnlyStore->getOperand(0));
if (AST && isa<PointerType>(LI->getType()))
AST->deleteValue(LI);
LI->eraseFromParent();
}
}
}
// Finally, remove this block from the UsingBlock set.
Info.UsingBlocks[i] = Info.UsingBlocks.back();
--i; --e;
}
}
// MarkDominatingPHILive - Mem2Reg wants to construct "pruned" SSA form, not
// "minimal" SSA form. To do this, it inserts all of the PHI nodes on the IDF
// as usual (inserting the PHI nodes in the DeadPHINodes set), then processes