[llvm-commits] [llvm] r123501 - in /llvm/trunk: include/llvm/Transforms/Utils/SSAUpdater.h lib/Transforms/Scalar/LICM.cpp lib/Transforms/Scalar/ScalarReplAggregates.cpp lib/Transforms/Utils/SSAUpdater.cpp
Chris Lattner
sabre at nondot.org
Fri Jan 14 16:12:35 PST 2011
Author: lattner
Date: Fri Jan 14 18:12:35 2011
New Revision: 123501
URL: http://llvm.org/viewvc/llvm-project?rev=123501&view=rev
Log:
Generalize LoadAndStorePromoter a bit and switch LICM
to use it.
Modified:
llvm/trunk/include/llvm/Transforms/Utils/SSAUpdater.h
llvm/trunk/lib/Transforms/Scalar/LICM.cpp
llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp
llvm/trunk/lib/Transforms/Utils/SSAUpdater.cpp
Modified: llvm/trunk/include/llvm/Transforms/Utils/SSAUpdater.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/SSAUpdater.h?rev=123501&r1=123500&r2=123501&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/SSAUpdater.h (original)
+++ llvm/trunk/include/llvm/Transforms/Utils/SSAUpdater.h Fri Jan 14 18:12:35 2011
@@ -118,15 +118,17 @@
/// virtual methods.
///
class LoadAndStorePromoter {
+protected:
+ SSAUpdater &SSA;
public:
- LoadAndStorePromoter() {}
+ LoadAndStorePromoter(const SmallVectorImpl<Instruction*> &Insts,
+ SSAUpdater &S, StringRef Name = StringRef());
virtual ~LoadAndStorePromoter() {}
/// run - This does the promotion. Insts is a list of loads and stores to
/// promote, and Name is the basename for the PHIs to insert. After this is
/// complete, the loads and stores are removed from the code.
- void run(StringRef Name, const SmallVectorImpl<Instruction*> &Insts,
- SSAUpdater *SSA = 0);
+ void run(const SmallVectorImpl<Instruction*> &Insts) const;
/// Return true if the specified instruction is in the Inst list (which was
@@ -139,6 +141,21 @@
return true;
return false;
}
+
+ /// doExtraRewritesBeforeFinalDeletion - This hook is invoked after all the
+ /// stores are found and inserted as available values, but
+ virtual void doExtraRewritesBeforeFinalDeletion() const {
+ }
+
+ /// replaceLoadWithValue - Clients can choose to implement this to get
+ /// notified right before a load is RAUW'd another value.
+ virtual void replaceLoadWithValue(LoadInst *LI, Value *V) const {
+ }
+
+ /// This is called before each instruction is deleted.
+ virtual void instructionDeleted(Instruction *I) const {
+ }
+
};
} // End llvm namespace
Modified: llvm/trunk/lib/Transforms/Scalar/LICM.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LICM.cpp?rev=123501&r1=123500&r2=123501&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LICM.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LICM.cpp Fri Jan 14 18:12:35 2011
@@ -595,6 +595,53 @@
return true;
}
+namespace {
+ class LoopPromoter : public LoadAndStorePromoter {
+ Value *SomePtr; // Designated pointer to store to.
+ SmallPtrSet<Value*, 4> &PointerMustAliases;
+ SmallVectorImpl<BasicBlock*> &LoopExitBlocks;
+ AliasSetTracker &AST;
+ public:
+ LoopPromoter(Value *SP,
+ const SmallVectorImpl<Instruction*> &Insts, SSAUpdater &S,
+ SmallPtrSet<Value*, 4> &PMA,
+ SmallVectorImpl<BasicBlock*> &LEB, AliasSetTracker &ast)
+ : LoadAndStorePromoter(Insts, S), SomePtr(SP), PointerMustAliases(PMA),
+ LoopExitBlocks(LEB), AST(ast) {}
+
+ virtual bool isInstInList(Instruction *I,
+ const SmallVectorImpl<Instruction*> &) const {
+ Value *Ptr;
+ if (LoadInst *LI = dyn_cast<LoadInst>(I))
+ Ptr = LI->getOperand(0);
+ else
+ Ptr = cast<StoreInst>(I)->getPointerOperand();
+ return PointerMustAliases.count(Ptr);
+ }
+
+ virtual void doExtraRewritesBeforeFinalDeletion() const {
+ // Insert stores after in the loop exit blocks. Each exit block gets a
+ // store of the live-out values that feed them. Since we've already told
+ // the SSA updater about the defs in the loop and the preheader
+ // definition, it is all set and we can start using it.
+ for (unsigned i = 0, e = LoopExitBlocks.size(); i != e; ++i) {
+ BasicBlock *ExitBlock = LoopExitBlocks[i];
+ Value *LiveInValue = SSA.GetValueInMiddleOfBlock(ExitBlock);
+ Instruction *InsertPos = ExitBlock->getFirstNonPHI();
+ new StoreInst(LiveInValue, SomePtr, InsertPos);
+ }
+ }
+
+ virtual void replaceLoadWithValue(LoadInst *LI, Value *V) const {
+ // Update alias analysis.
+ AST.copyValue(LI, V);
+ }
+ virtual void instructionDeleted(Instruction *I) const {
+ AST.deleteValue(I);
+ }
+ };
+} // end anon namespace
+
/// PromoteAliasSet - Try to promote memory values to scalars by sinking
/// stores out of the loop and moving loads to before the loop. We do this by
/// looping over the stores in the loop, looking for stores to Must pointers
@@ -679,179 +726,43 @@
Changed = true;
++NumPromoted;
+ SmallVector<BasicBlock*, 8> ExitBlocks;
+ CurLoop->getUniqueExitBlocks(ExitBlocks);
+
// We use the SSAUpdater interface to insert phi nodes as required.
SmallVector<PHINode*, 16> NewPHIs;
SSAUpdater SSA(&NewPHIs);
+ LoopPromoter Promoter(SomePtr, LoopUses, SSA, PointerMustAliases, ExitBlocks,
+ *CurAST);
- // It wants to know some value of the same type as what we'll be inserting.
- Value *SomeValue;
- if (isa<LoadInst>(LoopUses[0]))
- SomeValue = LoopUses[0];
- else
- SomeValue = cast<StoreInst>(LoopUses[0])->getOperand(0);
- SSA.Initialize(SomeValue->getType(), SomeValue->getName());
-
- // First step: bucket up uses of the pointers 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 usually 0/1 element.
- DenseMap<BasicBlock*, std::vector<Instruction*> > UsesByBlock;
- for (unsigned i = 0, e = LoopUses.size(); i != e; ++i) {
- Instruction *User = LoopUses[i];
- UsesByBlock[User->getParent()].push_back(User);
- }
-
- // Okay, now we can iterate over all the blocks in the loop with uses,
- // processing them. Keep track of which loads are loading a live-in value.
- SmallVector<LoadInst*, 32> LiveInLoads;
- DenseMap<Value*, Value*> ReplacedLoads;
-
- for (unsigned LoopUse = 0, e = LoopUses.size(); LoopUse != e; ++LoopUse) {
- Instruction *User = LoopUses[LoopUse];
- std::vector<Instruction*> &BlockUses = UsesByBlock[User->getParent()];
-
- // 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 (isa<StoreInst>(User)) {
- SSA.AddAvailableValue(User->getParent(),
- cast<StoreInst>(User)->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. If so, we can queue
- // them all as live in loads.
- bool HasStore = false;
- for (unsigned i = 0, e = BlockUses.size(); i != e; ++i) {
- if (isa<StoreInst>(BlockUses[i])) {
- HasStore = true;
- break;
- }
- }
-
- if (!HasStore) {
- for (unsigned i = 0, e = BlockUses.size(); i != e; ++i)
- LiveInLoads.push_back(cast<LoadInst>(BlockUses[i]));
- BlockUses.clear();
- continue;
- }
-
- // 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.
- BasicBlock *BB = User->getParent();
- 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 (!PointerMustAliases.count(L->getOperand(0))) 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 (!PointerMustAliases.count(S->getOperand(1))) continue;
-
- // Remember that this is the active value in the block.
- StoredValue = S->getOperand(0);
- }
- }
-
- // 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();
- }
-
- // Now that all the intra-loop values are classified, set up the preheader.
- // It gets a load of the pointer we're promoting, and it is the live-out value
- // from the preheader.
- LoadInst *PreheaderLoad = new LoadInst(SomePtr,SomePtr->getName()+".promoted",
- Preheader->getTerminator());
+ // Set up the preheader to have a definition of the value. It is the live-out
+ // value from the preheader that uses in the loop will use.
+ LoadInst *PreheaderLoad =
+ new LoadInst(SomePtr, SomePtr->getName()+".promoted",
+ Preheader->getTerminator());
SSA.AddAvailableValue(Preheader, PreheaderLoad);
- // Now that the preheader is good to go, set up the exit blocks. Each exit
- // block gets a store of the live-out values that feed them. Since we've
- // already told the SSA updater about the defs in the loop and the preheader
- // definition, it is all set and we can start using it.
- SmallVector<BasicBlock*, 8> ExitBlocks;
- CurLoop->getUniqueExitBlocks(ExitBlocks);
- for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
- BasicBlock *ExitBlock = ExitBlocks[i];
- Value *LiveInValue = SSA.GetValueInMiddleOfBlock(ExitBlock);
- Instruction *InsertPos = ExitBlock->getFirstNonPHI();
- new StoreInst(LiveInValue, SomePtr, InsertPos);
+ // Copy any value stored to or loaded from a must-alias of the pointer.
+ if (PreheaderLoad->getType()->isPointerTy()) {
+ Value *SomeValue;
+ if (LoadInst *LI = dyn_cast<LoadInst>(LoopUses[0]))
+ SomeValue = LI;
+ else
+ SomeValue = cast<StoreInst>(LoopUses[0])->getValueOperand();
+
+ CurAST->copyValue(SomeValue, PreheaderLoad);
}
- // 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);
- CurAST->copyValue(ALoad, NewVal);
- ReplacedLoads[ALoad] = NewVal;
- }
+ // Rewrite all the loads in the loop and remember all the definitions from
+ // stores in the loop.
+ Promoter.run(LoopUses);
// If the preheader load is itself a pointer, we need to tell alias analysis
// about the new pointer we created in the preheader block and about any PHI
// nodes that just got inserted.
if (PreheaderLoad->getType()->isPointerTy()) {
- // Copy any value stored to or loaded from a must-alias of the pointer.
- CurAST->copyValue(SomeValue, PreheaderLoad);
-
for (unsigned i = 0, e = NewPHIs.size(); i != e; ++i)
- CurAST->copyValue(SomeValue, NewPHIs[i]);
- }
-
- // Now that everything is rewritten, delete the old instructions from the body
- // of the loop. They should all be dead now.
- for (unsigned i = 0, e = LoopUses.size(); i != e; ++i) {
- Instruction *User = LoopUses[i];
-
- // 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);
- CurAST->copyValue(User, NewVal);
- }
-
- CurAST->deleteValue(User);
- User->eraseFromParent();
+ CurAST->copyValue(PreheaderLoad, NewPHIs[i]);
}
// fwew, we're done!
Modified: llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp?rev=123501&r1=123500&r2=123501&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp Fri Jan 14 18:12:35 2011
@@ -844,20 +844,13 @@
class AllocaPromoter : public LoadAndStorePromoter {
AllocaInst *AI;
public:
- AllocaPromoter() : AI(0) {}
+ AllocaPromoter(const SmallVectorImpl<Instruction*> &Insts, SSAUpdater &S)
+ : LoadAndStorePromoter(Insts, S), AI(0) {}
- void run(AllocaInst *AI, SSAUpdater &SSA) {
+ void run(AllocaInst *AI, const SmallVectorImpl<Instruction*> &Insts) {
// 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));
-
- LoadAndStorePromoter::run(AI->getName(), Insts, &SSA);
-
+ LoadAndStorePromoter::run(Insts);
AI->eraseFromParent();
}
@@ -882,7 +875,7 @@
BasicBlock &BB = F.getEntryBlock(); // Get the entry node for the function
bool Changed = false;
-
+ SmallVector<Instruction*, 64> Insts;
while (1) {
Allocas.clear();
@@ -899,9 +892,17 @@
PromoteMemToReg(Allocas, *DT, *DF);
else {
SSAUpdater SSA;
- AllocaPromoter Promoter;
- for (unsigned i = 0, e = Allocas.size(); i != e; ++i)
- Promoter.run(Allocas[i], SSA);
+ for (unsigned i = 0, e = Allocas.size(); i != e; ++i) {
+ AllocaInst *AI = Allocas[i];
+
+ // Build list of instructions to promote.
+ for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
+ UI != E; ++UI)
+ Insts.push_back(cast<Instruction>(*UI));
+
+ AllocaPromoter(Insts, SSA).run(AI, Insts);
+ Insts.clear();
+ }
}
NumPromoted += Allocas.size();
Changed = true;
Modified: llvm/trunk/lib/Transforms/Utils/SSAUpdater.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SSAUpdater.cpp?rev=123501&r1=123500&r2=123501&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SSAUpdater.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SSAUpdater.cpp Fri Jan 14 18:12:35 2011
@@ -348,23 +348,25 @@
// LoadAndStorePromoter Implementation
//===----------------------------------------------------------------------===//
-void LoadAndStorePromoter::run(StringRef BaseName,
- const SmallVectorImpl<Instruction*> &Insts,
- SSAUpdater *SSA) {
+LoadAndStorePromoter::
+LoadAndStorePromoter(const SmallVectorImpl<Instruction*> &Insts,
+ SSAUpdater &S, StringRef BaseName) : SSA(S) {
if (Insts.empty()) return;
- // If no SSAUpdater was provided, use a default one. This allows the client
- // to capture inserted PHI nodes etc if they want.
- SSAUpdater DefaultSSA;
- if (SSA == 0) SSA = &DefaultSSA;
-
- const Type *ValTy;
+ Value *SomeVal;
if (LoadInst *LI = dyn_cast<LoadInst>(Insts[0]))
- ValTy = LI->getType();
+ SomeVal = LI;
else
- ValTy = cast<StoreInst>(Insts[0])->getOperand(0)->getType();
-
- SSA->Initialize(ValTy, BaseName);
+ SomeVal = cast<StoreInst>(Insts[0])->getOperand(0);
+
+ if (BaseName.empty())
+ BaseName = SomeVal->getName();
+ SSA.Initialize(SomeVal->getType(), BaseName);
+}
+
+
+void LoadAndStorePromoter::
+run(const SmallVectorImpl<Instruction*> &Insts) const {
// 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
@@ -396,7 +398,7 @@
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));
+ 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));
@@ -437,6 +439,7 @@
// If we haven't seen a store yet, this is a live in use, otherwise
// use the stored value.
if (StoredValue) {
+ replaceLoadWithValue(L, StoredValue);
L->replaceAllUsesWith(StoredValue);
ReplacedLoads[L] = StoredValue;
} else {
@@ -456,7 +459,7 @@
// 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);
+ SSA.AddAvailableValue(BB, StoredValue);
BlockUses.clear();
}
@@ -464,11 +467,15 @@
// 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());
+ Value *NewVal = SSA.GetValueInMiddleOfBlock(ALoad->getParent());
+ replaceLoadWithValue(ALoad, NewVal);
ALoad->replaceAllUsesWith(NewVal);
ReplacedLoads[ALoad] = NewVal;
}
+ // Allow the client to do stuff before we start nuking things.
+ doExtraRewritesBeforeFinalDeletion();
+
// Now that everything is rewritten, delete the old instructions from the
// function. They should all be dead now.
for (unsigned i = 0, e = Insts.size(); i != e; ++i) {
@@ -491,9 +498,11 @@
RLI = ReplacedLoads.find(NewVal);
}
+ replaceLoadWithValue(cast<LoadInst>(User), NewVal);
User->replaceAllUsesWith(NewVal);
}
+ instructionDeleted(User);
User->eraseFromParent();
}
}
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