[llvm-commits] [llvm] r123457 - /llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp
Chris Lattner
sabre at nondot.org
Fri Jan 14 11:50:47 PST 2011
Author: lattner
Date: Fri Jan 14 13:50:47 2011
New Revision: 123457
URL: http://llvm.org/viewvc/llvm-project?rev=123457&view=rev
Log:
switch SRoA to use LoadAndStorePromoter instead of its own copy of the code.
Modified:
llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp?rev=123457&r1=123456&r2=123457&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp Fri Jan 14 13:50:47 2011
@@ -840,144 +840,35 @@
return Changed;
}
-/// PromoteAlloca - Promote an alloca to registers, using SSAUpdater.
-static void PromoteAlloca(AllocaInst *AI, SSAUpdater &SSA) {
- SSA.Initialize(AI->getType()->getElementType(), AI->getName());
-
- // First step: bucket up uses of the alloca by the block they occur in.
- // This is important because we have to handle multiple defs/uses in a block
- // ourselves: SSAUpdater is purely for cross-block references.
- // FIXME: Want a TinyVector<Instruction*> since there is often 0/1 element.
- DenseMap<BasicBlock*, std::vector<Instruction*> > UsesByBlock;
+namespace {
+class AllocaPromoter : public LoadAndStorePromoter {
+ AllocaInst *AI;
+public:
+ AllocaPromoter() : AI(0) {}
- for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
- UI != E; ++UI) {
- Instruction *User = cast<Instruction>(*UI);
- UsesByBlock[User->getParent()].push_back(User);
- }
-
- // Okay, now we can iterate over all the blocks in the function with uses,
- // processing them. Keep track of which loads are loading a live-in value.
- // Walk the uses in the use-list order to be determinstic.
- SmallVector<LoadInst*, 32> LiveInLoads;
- DenseMap<Value*, Value*> ReplacedLoads;
-
- for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
- UI != E; ++UI) {
- Instruction *User = cast<Instruction>(*UI);
- BasicBlock *BB = User->getParent();
- std::vector<Instruction*> &BlockUses = UsesByBlock[BB];
-
- // If this block has already been processed, ignore this repeat use.
- if (BlockUses.empty()) continue;
-
- // Okay, this is the first use in the block. If this block just has a
- // single user in it, we can rewrite it trivially.
- if (BlockUses.size() == 1) {
- // If it is a store, it is a trivial def of the value in the block.
- if (StoreInst *SI = dyn_cast<StoreInst>(User))
- SSA.AddAvailableValue(BB, SI->getOperand(0));
- else
- // Otherwise it is a load, queue it to rewrite as a live-in load.
- LiveInLoads.push_back(cast<LoadInst>(User));
- BlockUses.clear();
- continue;
- }
-
- // Otherwise, check to see if this block is all loads.
- bool HasStore = false;
- for (unsigned i = 0, e = BlockUses.size(); i != e; ++i) {
- if (isa<StoreInst>(BlockUses[i])) {
- HasStore = true;
- break;
- }
- }
-
- // If so, we can queue them all as live in loads. We don't have an
- // efficient way to tell which on is first in the block and don't want to
- // scan large blocks, so just add all loads as live ins.
- if (!HasStore) {
- for (unsigned i = 0, e = BlockUses.size(); i != e; ++i)
- LiveInLoads.push_back(cast<LoadInst>(BlockUses[i]));
- BlockUses.clear();
- continue;
- }
+ void run(AllocaInst *AI, SSAUpdater &SSA) {
+ // Remember which alloca we're promoting (for isInstInList).
+ this->AI = AI;
+
+ // Build the list of instructions to promote.
+ SmallVector<Instruction*, 64> Insts;
+ for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
+ UI != E; ++UI)
+ Insts.push_back(cast<Instruction>(*UI));
- // Otherwise, we have mixed loads and stores (or just a bunch of stores).
- // Since SSAUpdater is purely for cross-block values, we need to determine
- // the order of these instructions in the block. If the first use in the
- // block is a load, then it uses the live in value. The last store defines
- // the live out value. We handle this by doing a linear scan of the block.
- Value *StoredValue = 0;
- for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) {
- if (LoadInst *L = dyn_cast<LoadInst>(II)) {
- // If this is a load from an unrelated pointer, ignore it.
- if (L->getOperand(0) != AI) continue;
-
- // If we haven't seen a store yet, this is a live in use, otherwise
- // use the stored value.
- if (StoredValue) {
- L->replaceAllUsesWith(StoredValue);
- ReplacedLoads[L] = StoredValue;
- } else {
- LiveInLoads.push_back(L);
- }
- continue;
- }
-
- if (StoreInst *S = dyn_cast<StoreInst>(II)) {
- // If this is a store to an unrelated pointer, ignore it.
- if (S->getPointerOperand() != AI) continue;
-
- // Remember that this is the active value in the block.
- StoredValue = S->getOperand(0);
- }
- }
+ LoadAndStorePromoter::run(AI->getName(), Insts, &SSA);
- // The last stored value that happened is the live-out for the block.
- assert(StoredValue && "Already checked that there is a store in block");
- SSA.AddAvailableValue(BB, StoredValue);
- BlockUses.clear();
+ AI->eraseFromParent();
}
- // Okay, now we rewrite all loads that use live-in values in the loop,
- // inserting PHI nodes as necessary.
- for (unsigned i = 0, e = LiveInLoads.size(); i != e; ++i) {
- LoadInst *ALoad = LiveInLoads[i];
- Value *NewVal = SSA.GetValueInMiddleOfBlock(ALoad->getParent());
- ALoad->replaceAllUsesWith(NewVal);
- ReplacedLoads[ALoad] = NewVal;
+ virtual bool isInstInList(Instruction *I,
+ const SmallVectorImpl<Instruction*> &Insts) const {
+ if (LoadInst *LI = dyn_cast<LoadInst>(I))
+ return LI->getOperand(0) == AI;
+ return cast<StoreInst>(I)->getPointerOperand() == AI;
}
-
- // Now that everything is rewritten, delete the old instructions from the
- // function. They should all be dead now.
- for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); UI != E; ) {
- Instruction *User = cast<Instruction>(*UI++);
-
- // If this is a load that still has uses, then the load must have been added
- // as a live value in the SSAUpdate data structure for a block (e.g. because
- // the loaded value was stored later). In this case, we need to recursively
- // propagate the updates until we get to the real value.
- if (!User->use_empty()) {
- Value *NewVal = ReplacedLoads[User];
- assert(NewVal && "not a replaced load?");
-
- // Propagate down to the ultimate replacee. The intermediately loads
- // could theoretically already have been deleted, so we don't want to
- // dereference the Value*'s.
- DenseMap<Value*, Value*>::iterator RLI = ReplacedLoads.find(NewVal);
- while (RLI != ReplacedLoads.end()) {
- NewVal = RLI->second;
- RLI = ReplacedLoads.find(NewVal);
- }
-
- User->replaceAllUsesWith(NewVal);
- }
-
- User->eraseFromParent();
- }
-}
-
+};
+} // end anon namespace
bool SROA::performPromotion(Function &F) {
std::vector<AllocaInst*> Allocas;
@@ -1008,10 +899,9 @@
PromoteMemToReg(Allocas, *DT, *DF);
else {
SSAUpdater SSA;
- for (unsigned i = 0, e = Allocas.size(); i != e; ++i) {
- PromoteAlloca(Allocas[i], SSA);
- Allocas[i]->eraseFromParent();
- }
+ AllocaPromoter Promoter;
+ for (unsigned i = 0, e = Allocas.size(); i != e; ++i)
+ Promoter.run(Allocas[i], SSA);
}
NumPromoted += Allocas.size();
Changed = true;
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