[llvm-commits] [llvm] r80926 - in /llvm/trunk: include/llvm/Analysis/LoopInfo.h include/llvm/Transforms/Utils/BasicBlockUtils.h lib/Analysis/LoopInfo.cpp lib/Transforms/Scalar/LICM.cpp lib/Transforms/Scalar/LoopStrengthReduce.cpp lib/Transforms/Scalar/LoopUnswitch.cpp lib/Transforms/Utils/BasicBlockUtils.cpp lib/Transforms/Utils/BreakCriticalEdges.cpp lib/Transforms/Utils/LCSSA.cpp lib/Transforms/Utils/LoopSimplify.cpp
Dan Gohman
gohman at apple.com
Thu Sep 3 09:31:42 PDT 2009
Author: djg
Date: Thu Sep 3 11:31:42 2009
New Revision: 80926
URL: http://llvm.org/viewvc/llvm-project?rev=80926&view=rev
Log:
Add a verifyAnalysis to LoopInfo, LoopSimplify, and LCSSA form that verify
that these passes are properly preserved.
Fix several transformation passes that claimed to preserve LoopSimplify
form but weren't.
Modified:
llvm/trunk/include/llvm/Analysis/LoopInfo.h
llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
llvm/trunk/lib/Analysis/LoopInfo.cpp
llvm/trunk/lib/Transforms/Scalar/LICM.cpp
llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp
llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
llvm/trunk/lib/Transforms/Utils/BreakCriticalEdges.cpp
llvm/trunk/lib/Transforms/Utils/LCSSA.cpp
llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp
Modified: llvm/trunk/include/llvm/Analysis/LoopInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/LoopInfo.h?rev=80926&r1=80925&r2=80926&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/LoopInfo.h (original)
+++ llvm/trunk/include/llvm/Analysis/LoopInfo.h Thu Sep 3 11:31:42 2009
@@ -376,11 +376,73 @@
/// verifyLoop - Verify loop structure
void verifyLoop() const {
#ifndef NDEBUG
- assert (getHeader() && "Loop header is missing");
- assert (getLoopPreheader() && "Loop preheader is missing");
- assert (getLoopLatch() && "Loop latch is missing");
- for (iterator I = SubLoops.begin(), E = SubLoops.end(); I != E; ++I)
+ assert(!Blocks.empty() && "Loop header is missing");
+ assert(getHeader() && "Loop header is missing");
+
+ // Verify the individual blocks.
+ for (block_iterator I = block_begin(), E = block_end(); I != E; ++I) {
+ BlockT *BB = *I;
+ bool HasInsideLoopSuccs = false;
+ bool HasInsideLoopPreds = false;
+ SmallVector<BlockT *, 2> OutsideLoopPreds;
+
+ typedef GraphTraits<BlockT*> BlockTraits;
+ for (typename BlockTraits::ChildIteratorType SI =
+ BlockTraits::child_begin(BB), SE = BlockTraits::child_end(BB);
+ SI != SE; ++SI)
+ if (contains(*SI))
+ HasInsideLoopSuccs = true;
+ typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
+ for (typename InvBlockTraits::ChildIteratorType PI =
+ InvBlockTraits::child_begin(BB), PE = InvBlockTraits::child_end(BB);
+ PI != PE; ++PI) {
+ if (contains(*PI))
+ HasInsideLoopPreds = true;
+ else
+ OutsideLoopPreds.push_back(*PI);
+ }
+
+ if (BB == getHeader()) {
+ assert(!OutsideLoopPreds.empty() && "Loop is unreachable!");
+ } else if (!OutsideLoopPreds.empty()) {
+ // A non-header loop shouldn't be reachable from outside the loop,
+ // though it is permitted if the predecessor is not itself actually
+ // reachable.
+ BlockT *EntryBB = BB->getParent()->begin();
+ for (df_iterator<BlockT *> NI = df_begin(EntryBB),
+ NE = df_end(EntryBB); NI != NE; ++NI)
+ for (unsigned i = 0, e = OutsideLoopPreds.size(); i != e; ++i)
+ assert(*NI != OutsideLoopPreds[i] &&
+ "Loop has multiple entry points!");
+ }
+ assert(HasInsideLoopPreds && "Loop block has no in-loop predecessors!");
+ assert(HasInsideLoopSuccs && "Loop block has no in-loop successors!");
+ assert(BB != getHeader()->getParent()->begin() &&
+ "Loop contains function entry block!");
+ }
+
+ // Verify the subloops.
+ for (iterator I = begin(), E = end(); I != E; ++I) {
+ // Each block in each subloop should be contained within this loop.
+ for (block_iterator BI = (*I)->block_begin(), BE = (*I)->block_end();
+ BI != BE; ++BI) {
+ assert(contains(*BI) &&
+ "Loop does not contain all the blocks of a subloop!");
+ }
+ // Recursively check the subloop.
(*I)->verifyLoop();
+ }
+
+ // Verify the parent loop.
+ if (ParentLoop) {
+ bool FoundSelf = false;
+ for (iterator I = ParentLoop->begin(), E = ParentLoop->end(); I != E; ++I)
+ if (*I == this) {
+ FoundSelf = true;
+ break;
+ }
+ assert(FoundSelf && "Loop is not a subloop of its parent!");
+ }
#endif
}
@@ -873,6 +935,8 @@
///
virtual bool runOnFunction(Function &F);
+ virtual void verifyAnalysis() const;
+
virtual void releaseMemory() { LI.releaseMemory(); }
virtual void print(raw_ostream &O, const Module* M = 0) const;
Modified: llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h?rev=80926&r1=80925&r2=80926&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h (original)
+++ llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h Thu Sep 3 11:31:42 2009
@@ -126,10 +126,10 @@
/// dest go to one block instead of each going to a different block, but isn't
/// the standard definition of a "critical edge".
///
-bool SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, Pass *P = 0,
- bool MergeIdenticalEdges = false);
+BasicBlock *SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum,
+ Pass *P = 0, bool MergeIdenticalEdges = false);
-inline bool SplitCriticalEdge(BasicBlock *BB, succ_iterator SI, Pass *P = 0) {
+inline BasicBlock *SplitCriticalEdge(BasicBlock *BB, succ_iterator SI, Pass *P = 0) {
return SplitCriticalEdge(BB->getTerminator(), SI.getSuccessorIndex(), P);
}
@@ -143,7 +143,7 @@
TerminatorInst *TI = (*PI)->getTerminator();
for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
if (TI->getSuccessor(i) == Succ)
- MadeChange |= SplitCriticalEdge(TI, i, P);
+ MadeChange |= !!SplitCriticalEdge(TI, i, P);
return MadeChange;
}
@@ -151,8 +151,9 @@
/// and return true, otherwise return false. This method requires that there be
/// an edge between the two blocks. If P is specified, it updates the analyses
/// described above.
-inline bool SplitCriticalEdge(BasicBlock *Src, BasicBlock *Dst, Pass *P = 0,
- bool MergeIdenticalEdges = false) {
+inline BasicBlock *SplitCriticalEdge(BasicBlock *Src, BasicBlock *Dst,
+ Pass *P = 0,
+ bool MergeIdenticalEdges = false) {
TerminatorInst *TI = Src->getTerminator();
unsigned i = 0;
while (1) {
@@ -180,8 +181,12 @@
/// Preds array, which has NumPreds elements in it. The new block is given a
/// suffix of 'Suffix'. This function returns the new block.
///
-/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree and
-/// DominanceFrontier, but no other analyses.
+/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree,
+/// DominanceFrontier, LoopInfo, and LCCSA but no other analyses.
+/// In particular, it does not preserve LoopSimplify (because it's
+/// complicated to handle the case where one of the edges being split
+/// is an exit of a loop with other exits).
+///
BasicBlock *SplitBlockPredecessors(BasicBlock *BB, BasicBlock *const *Preds,
unsigned NumPreds, const char *Suffix,
Pass *P = 0);
Modified: llvm/trunk/lib/Analysis/LoopInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/LoopInfo.cpp?rev=80926&r1=80925&r2=80926&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/LoopInfo.cpp (original)
+++ llvm/trunk/lib/Analysis/LoopInfo.cpp Thu Sep 3 11:31:42 2009
@@ -300,6 +300,9 @@
///
void
Loop::getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const {
+ assert(isLoopSimplifyForm() &&
+ "getUniqueExitBlocks assumes the loop is in canonical form!");
+
// Sort the blocks vector so that we can use binary search to do quick
// lookups.
SmallVector<BasicBlock *, 128> LoopBBs(block_begin(), block_end());
@@ -371,6 +374,13 @@
return false;
}
+void LoopInfo::verifyAnalysis() const {
+ for (iterator I = begin(), E = end(); I != E; ++I) {
+ assert(!(*I)->getParentLoop() && "Top-level loop has a parent!");
+ (*I)->verifyLoop();
+ }
+}
+
void LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<DominatorTree>();
Modified: llvm/trunk/lib/Transforms/Scalar/LICM.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LICM.cpp?rev=80926&r1=80925&r2=80926&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LICM.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LICM.cpp Thu Sep 3 11:31:42 2009
@@ -91,6 +91,7 @@
AU.addRequired<AliasAnalysis>();
AU.addPreserved<ScalarEvolution>();
AU.addPreserved<DominanceFrontier>();
+ AU.addPreservedID(LoopSimplifyID);
}
bool doFinalization() {
Modified: llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp?rev=80926&r1=80925&r2=80926&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp Thu Sep 3 11:31:42 2009
@@ -484,36 +484,37 @@
// loop because multiple copies sometimes do useful sinking of code in
// that case(?).
Instruction *OldLoc = dyn_cast<Instruction>(OperandValToReplace);
+ BasicBlock *PHIPred = PN->getIncomingBlock(i);
if (L->contains(OldLoc->getParent())) {
// If this is a critical edge, split the edge so that we do not insert
// the code on all predecessor/successor paths. We do this unless this
// is the canonical backedge for this loop, as this can make some
// inserted code be in an illegal position.
- BasicBlock *PHIPred = PN->getIncomingBlock(i);
if (e != 1 && PHIPred->getTerminator()->getNumSuccessors() > 1 &&
(PN->getParent() != L->getHeader() || !L->contains(PHIPred))) {
// First step, split the critical edge.
- SplitCriticalEdge(PHIPred, PN->getParent(), P, false);
+ BasicBlock *NewBB = SplitCriticalEdge(PHIPred, PN->getParent(),
+ P, false);
// Next step: move the basic block. In particular, if the PHI node
// is outside of the loop, and PredTI is in the loop, we want to
// move the block to be immediately before the PHI block, not
// immediately after PredTI.
- if (L->contains(PHIPred) && !L->contains(PN->getParent())) {
- BasicBlock *NewBB = PN->getIncomingBlock(i);
+ if (L->contains(PHIPred) && !L->contains(PN->getParent()))
NewBB->moveBefore(PN->getParent());
- }
// Splitting the edge can reduce the number of PHI entries we have.
e = PN->getNumIncomingValues();
+ PHIPred = NewBB;
+ i = PN->getBasicBlockIndex(PHIPred);
}
}
- Value *&Code = InsertedCode[PN->getIncomingBlock(i)];
+ Value *&Code = InsertedCode[PHIPred];
if (!Code) {
// Insert the code into the end of the predecessor block.
Instruction *InsertPt = (L->contains(OldLoc->getParent())) ?
- PN->getIncomingBlock(i)->getTerminator() :
+ PHIPred->getTerminator() :
OldLoc->getParent()->getTerminator();
Code = InsertCodeForBaseAtPosition(NewBase, PN->getType(),
Rewriter, InsertPt, L, LI);
Modified: llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp?rev=80926&r1=80925&r2=80926&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopUnswitch.cpp Thu Sep 3 11:31:42 2009
@@ -518,7 +518,12 @@
std::swap(TrueDest, FalseDest);
// Insert the new branch.
- BranchInst::Create(TrueDest, FalseDest, BranchVal, InsertPt);
+ BranchInst *BI = BranchInst::Create(TrueDest, FalseDest, BranchVal, InsertPt);
+
+ // If either edge is critical, split it. This helps preserve LoopSimplify
+ // form for enclosing loops.
+ SplitCriticalEdge(BI, 0, this);
+ SplitCriticalEdge(BI, 1, this);
}
/// UnswitchTrivialCondition - Given a loop that has a trivial unswitchable
@@ -575,47 +580,11 @@
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
BasicBlock *ExitBlock = ExitBlocks[i];
- std::vector<BasicBlock*> Preds(pred_begin(ExitBlock), pred_end(ExitBlock));
-
- for (unsigned j = 0, e = Preds.size(); j != e; ++j) {
- BasicBlock* NewExitBlock = SplitEdge(Preds[j], ExitBlock, this);
- BasicBlock* StartBlock = Preds[j];
- BasicBlock* EndBlock;
- if (NewExitBlock->getSinglePredecessor() == ExitBlock) {
- EndBlock = NewExitBlock;
- NewExitBlock = EndBlock->getSinglePredecessor();
- } else {
- EndBlock = ExitBlock;
- }
-
- std::set<PHINode*> InsertedPHIs;
- PHINode* OldLCSSA = 0;
- for (BasicBlock::iterator I = EndBlock->begin();
- (OldLCSSA = dyn_cast<PHINode>(I)); ++I) {
- Value* OldValue = OldLCSSA->getIncomingValueForBlock(NewExitBlock);
- PHINode* NewLCSSA = PHINode::Create(OldLCSSA->getType(),
- OldLCSSA->getName() + ".us-lcssa",
- NewExitBlock->getTerminator());
- NewLCSSA->addIncoming(OldValue, StartBlock);
- OldLCSSA->setIncomingValue(OldLCSSA->getBasicBlockIndex(NewExitBlock),
- NewLCSSA);
- InsertedPHIs.insert(NewLCSSA);
- }
-
- BasicBlock::iterator InsertPt = EndBlock->getFirstNonPHI();
- for (BasicBlock::iterator I = NewExitBlock->begin();
- (OldLCSSA = dyn_cast<PHINode>(I)) && InsertedPHIs.count(OldLCSSA) == 0;
- ++I) {
- PHINode *NewLCSSA = PHINode::Create(OldLCSSA->getType(),
- OldLCSSA->getName() + ".us-lcssa",
- InsertPt);
- OldLCSSA->replaceAllUsesWith(NewLCSSA);
- NewLCSSA->addIncoming(OldLCSSA, NewExitBlock);
- }
-
- }
+ SmallVector<BasicBlock *, 4> Preds(pred_begin(ExitBlock),
+ pred_end(ExitBlock));
+ SplitBlockPredecessors(ExitBlock, Preds.data(), Preds.size(),
+ ".us-lcssa", this);
}
-
}
/// UnswitchNontrivialCondition - We determined that the loop is profitable
@@ -945,27 +914,29 @@
// FIXME: This is a hack. We need to keep the successor around
// and hooked up so as to preserve the loop structure, because
// trying to update it is complicated. So instead we preserve the
- // loop structure and put the block on an dead code path.
-
- BasicBlock *SISucc = SI->getSuccessor(i);
- BasicBlock* Old = SI->getParent();
- BasicBlock* Split = SplitBlock(Old, SI, this);
-
- Instruction* OldTerm = Old->getTerminator();
- BranchInst::Create(Split, SISucc,
- ConstantInt::getTrue(Context), OldTerm);
-
- LPM->deleteSimpleAnalysisValue(Old->getTerminator(), L);
- Old->getTerminator()->eraseFromParent();
-
- PHINode *PN;
- for (BasicBlock::iterator II = SISucc->begin();
- (PN = dyn_cast<PHINode>(II)); ++II) {
- Value *InVal = PN->removeIncomingValue(Split, false);
- PN->addIncoming(InVal, Old);
- }
-
- SI->removeCase(i);
+ // loop structure and put the block on a dead code path.
+ BasicBlock *Switch = SI->getParent();
+ SplitEdge(Switch, SI->getSuccessor(i), this);
+ // Compute the successors instead of relying on the return value
+ // of SplitEdge, since it may have split the switch successor
+ // after PHI nodes.
+ BasicBlock *NewSISucc = SI->getSuccessor(i);
+ BasicBlock *OldSISucc = *succ_begin(NewSISucc);
+ // Create an "unreachable" destination.
+ BasicBlock *Abort = BasicBlock::Create(Context, "us-unreachable",
+ Switch->getParent(),
+ OldSISucc);
+ new UnreachableInst(Context, Abort);
+ // Force the new case destination to branch to the "unreachable"
+ // block while maintaining a (dead) CFG edge to the old block.
+ NewSISucc->getTerminator()->eraseFromParent();
+ BranchInst::Create(Abort, OldSISucc,
+ ConstantInt::getTrue(Context), NewSISucc);
+ // Release the PHI operands for this edge.
+ for (BasicBlock::iterator II = NewSISucc->begin();
+ PHINode *PN = dyn_cast<PHINode>(II); ++II)
+ PN->setIncomingValue(PN->getBasicBlockIndex(Switch),
+ UndefValue::get(PN->getType()));
break;
}
}
Modified: llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp?rev=80926&r1=80925&r2=80926&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp Thu Sep 3 11:31:42 2009
@@ -24,6 +24,7 @@
#include "llvm/Analysis/Dominators.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Scalar.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ValueHandle.h"
#include <algorithm>
@@ -319,7 +320,8 @@
++SplitIt;
BasicBlock *New = Old->splitBasicBlock(SplitIt, Old->getName()+".split");
- // The new block lives in whichever loop the old one did.
+ // The new block lives in whichever loop the old one did. This preserves
+ // LCSSA as well, because we force the split point to be after any PHI nodes.
if (LoopInfo* LI = P->getAnalysisIfAvailable<LoopInfo>())
if (Loop *L = LI->getLoopFor(Old))
L->addBasicBlockToLoop(New, LI->getBase());
@@ -353,8 +355,12 @@
/// Preds array, which has NumPreds elements in it. The new block is given a
/// suffix of 'Suffix'.
///
-/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree and
-/// DominanceFrontier, but no other analyses.
+/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree,
+/// DominanceFrontier, LoopInfo, and LCCSA but no other analyses.
+/// In particular, it does not preserve LoopSimplify (because it's
+/// complicated to handle the case where one of the edges being split
+/// is an exit of a loop with other exits).
+///
BasicBlock *llvm::SplitBlockPredecessors(BasicBlock *BB,
BasicBlock *const *Preds,
unsigned NumPreds, const char *Suffix,
@@ -366,19 +372,44 @@
// The new block unconditionally branches to the old block.
BranchInst *BI = BranchInst::Create(BB, NewBB);
+ LoopInfo *LI = P ? P->getAnalysisIfAvailable<LoopInfo>() : 0;
+ Loop *L = LI ? LI->getLoopFor(BB) : 0;
+ bool PreserveLCSSA = P->mustPreserveAnalysisID(LCSSAID);
+
// Move the edges from Preds to point to NewBB instead of BB.
- for (unsigned i = 0; i != NumPreds; ++i)
+ // While here, if we need to preserve loop analyses, collect
+ // some information about how this split will affect loops.
+ bool HasLoopExit = false;
+ bool IsLoopEntry = !!L;
+ bool SplitMakesNewLoopHeader = false;
+ for (unsigned i = 0; i != NumPreds; ++i) {
Preds[i]->getTerminator()->replaceUsesOfWith(BB, NewBB);
-
+
+ if (LI) {
+ // If we need to preserve LCSSA, determine if any of
+ // the preds is a loop exit.
+ if (PreserveLCSSA)
+ if (Loop *PL = LI->getLoopFor(Preds[i]))
+ if (!PL->contains(BB))
+ HasLoopExit = true;
+ // If we need to preserve LoopInfo, note whether any of the
+ // preds crosses an interesting loop boundary.
+ if (L) {
+ if (L->contains(Preds[i]))
+ IsLoopEntry = false;
+ else
+ SplitMakesNewLoopHeader = true;
+ }
+ }
+ }
+
// Update dominator tree and dominator frontier if available.
DominatorTree *DT = P ? P->getAnalysisIfAvailable<DominatorTree>() : 0;
if (DT)
DT->splitBlock(NewBB);
if (DominanceFrontier *DF = P ? P->getAnalysisIfAvailable<DominanceFrontier>():0)
DF->splitBlock(NewBB);
- AliasAnalysis *AA = P ? P->getAnalysisIfAvailable<AliasAnalysis>() : 0;
-
-
+
// Insert a new PHI node into NewBB for every PHI node in BB and that new PHI
// node becomes an incoming value for BB's phi node. However, if the Preds
// list is empty, we need to insert dummy entries into the PHI nodes in BB to
@@ -389,20 +420,42 @@
cast<PHINode>(I)->addIncoming(UndefValue::get(I->getType()), NewBB);
return NewBB;
}
+
+ AliasAnalysis *AA = P ? P->getAnalysisIfAvailable<AliasAnalysis>() : 0;
+
+ if (L) {
+ if (IsLoopEntry) {
+ if (Loop *PredLoop = LI->getLoopFor(Preds[0])) {
+ // Add the new block to the nearest enclosing loop (and not an
+ // adjacent loop).
+ while (PredLoop && !PredLoop->contains(BB))
+ PredLoop = PredLoop->getParentLoop();
+ if (PredLoop)
+ PredLoop->addBasicBlockToLoop(NewBB, LI->getBase());
+ }
+ } else {
+ L->addBasicBlockToLoop(NewBB, LI->getBase());
+ if (SplitMakesNewLoopHeader)
+ L->moveToHeader(NewBB);
+ }
+ }
// Otherwise, create a new PHI node in NewBB for each PHI node in BB.
for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ) {
PHINode *PN = cast<PHINode>(I++);
// Check to see if all of the values coming in are the same. If so, we
- // don't need to create a new PHI node.
- Value *InVal = PN->getIncomingValueForBlock(Preds[0]);
- for (unsigned i = 1; i != NumPreds; ++i)
- if (InVal != PN->getIncomingValueForBlock(Preds[i])) {
- InVal = 0;
- break;
- }
-
+ // don't need to create a new PHI node, unless it's needed for LCSSA.
+ Value *InVal = 0;
+ if (!HasLoopExit) {
+ InVal = PN->getIncomingValueForBlock(Preds[0]);
+ for (unsigned i = 1; i != NumPreds; ++i)
+ if (InVal != PN->getIncomingValueForBlock(Preds[i])) {
+ InVal = 0;
+ break;
+ }
+ }
+
if (InVal) {
// If all incoming values for the new PHI would be the same, just don't
// make a new PHI. Instead, just remove the incoming values from the old
@@ -427,13 +480,6 @@
// Add an incoming value to the PHI node in the loop for the preheader
// edge.
PN->addIncoming(InVal, NewBB);
-
- // Check to see if we can eliminate this phi node.
- if (Value *V = PN->hasConstantValue(DT)) {
- PN->replaceAllUsesWith(V);
- if (AA) AA->deleteValue(PN);
- PN->eraseFromParent();
- }
}
return NewBB;
Modified: llvm/trunk/lib/Transforms/Utils/BreakCriticalEdges.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/BreakCriticalEdges.cpp?rev=80926&r1=80925&r2=80926&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/BreakCriticalEdges.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/BreakCriticalEdges.cpp Thu Sep 3 11:31:42 2009
@@ -122,9 +122,9 @@
/// false otherwise. This ensures that all edges to that dest go to one block
/// instead of each going to a different block.
//
-bool llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, Pass *P,
- bool MergeIdenticalEdges) {
- if (!isCriticalEdge(TI, SuccNum, MergeIdenticalEdges)) return false;
+BasicBlock *llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum,
+ Pass *P, bool MergeIdenticalEdges) {
+ if (!isCriticalEdge(TI, SuccNum, MergeIdenticalEdges)) return 0;
BasicBlock *TIBB = TI->getParent();
BasicBlock *DestBB = TI->getSuccessor(SuccNum);
@@ -172,7 +172,7 @@
// If we don't have a pass object, we can't update anything...
- if (P == 0) return true;
+ if (P == 0) return NewBB;
// Now update analysis information. Since the only predecessor of NewBB is
// the TIBB, TIBB clearly dominates NewBB. TIBB usually doesn't dominate
@@ -254,9 +254,9 @@
// Update LoopInfo if it is around.
if (LoopInfo *LI = P->getAnalysisIfAvailable<LoopInfo>()) {
- // If one or the other blocks were not in a loop, the new block is not
- // either, and thus LI doesn't need to be updated.
- if (Loop *TIL = LI->getLoopFor(TIBB))
+ if (Loop *TIL = LI->getLoopFor(TIBB)) {
+ // If one or the other blocks were not in a loop, the new block is not
+ // either, and thus LI doesn't need to be updated.
if (Loop *DestLoop = LI->getLoopFor(DestBB)) {
if (TIL == DestLoop) {
// Both in the same loop, the NewBB joins loop.
@@ -278,6 +278,55 @@
P->addBasicBlockToLoop(NewBB, LI->getBase());
}
}
+ // If TIBB is in a loop and DestBB is outside of that loop, split the
+ // other exit blocks of the loop that also have predecessors outside
+ // the loop, to maintain a LoopSimplify guarantee.
+ if (!TIL->contains(DestBB) &&
+ P->mustPreserveAnalysisID(LoopSimplifyID)) {
+ // For each unique exit block...
+ SmallVector<BasicBlock *, 4> ExitBlocks;
+ TIL->getExitBlocks(ExitBlocks);
+ for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
+ // Collect all the preds that are inside the loop, and note
+ // whether there are any preds outside the loop.
+ SmallVector<BasicBlock *, 4> Preds;
+ bool AllPredsInLoop = false;
+ BasicBlock *Exit = ExitBlocks[i];
+ for (pred_iterator I = pred_begin(Exit), E = pred_end(Exit);
+ I != E; ++I)
+ if (TIL->contains(*I))
+ Preds.push_back(*I);
+ else
+ AllPredsInLoop = true;
+ // If there are any preds not in the loop, we'll need to split
+ // the edges. The Preds.empty() check is needed because a block
+ // may appear multiple times in the list. We can't use
+ // getUniqueExitBlocks above because that depends on LoopSimplify
+ // form, which we're in the process of restoring!
+ if (Preds.empty() || !AllPredsInLoop) continue;
+ BasicBlock *NewBB = SplitBlockPredecessors(Exit,
+ Preds.data(), Preds.size(),
+ "split", P);
+ // Update LCSSA form. This is fairly simple in LoopSimplify form:
+ // just move the existing LCSSA-mandated PHI nodes from the old exit
+ // block to the new one.
+ if (P->mustPreserveAnalysisID(LCSSAID))
+ for (BasicBlock::iterator I = Exit->begin();
+ PHINode *PN = dyn_cast<PHINode>(I); ++I)
+ PN->moveBefore(NewBB->getTerminator());
+ }
+ }
+ // LCSSA form was updated above for the case where LoopSimplify is
+ // available, which means that all predecessors of loop exit blocks
+ // are within the loop. Without LoopSimplify form, it would be
+ // necessary to insert a new phi.
+ assert((!P->mustPreserveAnalysisID(LCSSAID) ||
+ P->mustPreserveAnalysisID(LoopSimplifyID)) &&
+ "SplitCriticalEdge doesn't know how to update LCCSA form "
+ "without LoopSimplify!");
+ }
+
}
- return true;
+
+ return NewBB;
}
Modified: llvm/trunk/lib/Transforms/Utils/LCSSA.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LCSSA.cpp?rev=80926&r1=80925&r2=80926&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LCSSA.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LCSSA.cpp Thu Sep 3 11:31:42 2009
@@ -58,6 +58,7 @@
DominatorTree *DT;
std::vector<BasicBlock*> LoopBlocks;
PredIteratorCache PredCache;
+ Loop *L;
virtual bool runOnLoop(Loop *L, LPPassManager &LPM);
@@ -72,9 +73,9 @@
AU.setPreservesCFG();
AU.addRequiredID(LoopSimplifyID);
AU.addPreservedID(LoopSimplifyID);
- AU.addRequired<LoopInfo>();
+ AU.addRequiredTransitive<LoopInfo>();
AU.addPreserved<LoopInfo>();
- AU.addRequired<DominatorTree>();
+ AU.addRequiredTransitive<DominatorTree>();
AU.addPreserved<ScalarEvolution>();
AU.addPreserved<DominatorTree>();
@@ -86,6 +87,17 @@
AU.addPreserved<DominanceFrontier>();
}
private:
+
+ /// verifyAnalysis() - Verify loop nest.
+ virtual void verifyAnalysis() const {
+#ifndef NDEBUG
+ // Sanity check: Check basic loop invariants.
+ L->verifyLoop();
+ // Check the special guarantees that LCSSA makes.
+ assert(L->isLCSSAForm());
+#endif
+ }
+
void getLoopValuesUsedOutsideLoop(Loop *L,
SetVector<Instruction*> &AffectedValues,
const SmallVector<BasicBlock*, 8>& exitBlocks);
@@ -107,7 +119,8 @@
const PassInfo *const llvm::LCSSAID = &X;
/// runOnFunction - Process all loops in the function, inner-most out.
-bool LCSSA::runOnLoop(Loop *L, LPPassManager &LPM) {
+bool LCSSA::runOnLoop(Loop *l, LPPassManager &LPM) {
+ L = l;
PredCache.clear();
LI = &LPM.getAnalysis<LoopInfo>();
Modified: llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp?rev=80926&r1=80925&r2=80926&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp Thu Sep 3 11:31:42 2009
@@ -69,8 +69,8 @@
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
// We need loop information to identify the loops...
- AU.addRequired<LoopInfo>();
- AU.addRequired<DominatorTree>();
+ AU.addRequiredTransitive<LoopInfo>();
+ AU.addRequiredTransitive<DominatorTree>();
AU.addPreserved<LoopInfo>();
AU.addPreserved<DominatorTree>();
@@ -83,9 +83,13 @@
void verifyAnalysis() const {
#ifndef NDEBUG
LoopInfo *NLI = &getAnalysis<LoopInfo>();
- for (LoopInfo::iterator I = NLI->begin(), E = NLI->end(); I != E; ++I)
+ for (LoopInfo::iterator I = NLI->begin(), E = NLI->end(); I != E; ++I) {
+ // Sanity check: Check basic loop invariants.
(*I)->verifyLoop();
-#endif
+ // Check the special guarantees that LoopSimplify makes.
+ assert((*I)->isLoopSimplifyForm());
+ }
+#endif
}
private:
@@ -346,15 +350,6 @@
BasicBlock *NewBB =
SplitBlockPredecessors(Header, &OutsideBlocks[0], OutsideBlocks.size(),
".preheader", this);
-
-
- //===--------------------------------------------------------------------===//
- // Update analysis results now that we have performed the transformation
- //
-
- // We know that we have loop information to update... update it now.
- if (Loop *Parent = L->getParentLoop())
- Parent->addBasicBlockToLoop(NewBB, LI->getBase());
// Make sure that NewBB is put someplace intelligent, which doesn't mess up
// code layout too horribly.
@@ -377,17 +372,6 @@
LoopBlocks.size(), ".loopexit",
this);
- // Update Loop Information - we know that the new block will be in whichever
- // loop the Exit block is in. Note that it may not be in that immediate loop,
- // if the successor is some other loop header. In that case, we continue
- // walking up the loop tree to find a loop that contains both the successor
- // block and the predecessor block.
- Loop *SuccLoop = LI->getLoopFor(Exit);
- while (SuccLoop && !SuccLoop->contains(L->getHeader()))
- SuccLoop = SuccLoop->getParentLoop();
- if (SuccLoop)
- SuccLoop->addBasicBlockToLoop(NewBB, LI->getBase());
-
return NewBB;
}
@@ -521,10 +505,6 @@
else
LI->changeTopLevelLoop(L, NewOuter);
- // This block is going to be our new header block: add it to this loop and all
- // parent loops.
- NewOuter->addBasicBlockToLoop(NewBB, LI->getBase());
-
// L is now a subloop of our outer loop.
NewOuter->addChildLoop(L);
@@ -532,6 +512,10 @@
I != E; ++I)
NewOuter->addBlockEntry(*I);
+ // Now reset the header in L, which had been moved by
+ // SplitBlockPredecessors for the outer loop.
+ L->moveToHeader(Header);
+
// Determine which blocks should stay in L and which should be moved out to
// the Outer loop now.
std::set<BasicBlock*> BlocksInL;
More information about the llvm-commits
mailing list