[llvm] r230178 - [LICM] Refactor to expose functionality as utility functions
Hal Finkel
hfinkel at anl.gov
Sun Feb 22 10:35:32 PST 2015
Author: hfinkel
Date: Sun Feb 22 12:35:32 2015
New Revision: 230178
URL: http://llvm.org/viewvc/llvm-project?rev=230178&view=rev
Log:
[LICM] Refactor to expose functionality as utility functions
This refactors the core functionality of LICM: HoistRegion, SinkRegion and
PromoteAliasSet (renamed to promoteLoopAccessesToScalars) as utility functions
in LoopUtils. This will enable other transformations to make use of them
directly.
Patch by Ashutosh Nema.
Modified:
llvm/trunk/include/llvm/Transforms/Utils/LoopUtils.h
llvm/trunk/lib/Transforms/Scalar/LICM.cpp
Modified: llvm/trunk/include/llvm/Transforms/Utils/LoopUtils.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/LoopUtils.h?rev=230178&r1=230177&r2=230178&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/LoopUtils.h (original)
+++ llvm/trunk/include/llvm/Transforms/Utils/LoopUtils.h Sun Feb 22 12:35:32 2015
@@ -24,6 +24,19 @@ class Loop;
class LoopInfo;
class Pass;
class ScalarEvolution;
+class AliasSetTracker;
+class AliasSet;
+class PredIteratorCache;
+
+/// \brief Captures loop safety information.
+/// It keep information for loop & its header may throw exception.
+struct LICMSafetyInfo {
+ bool MayThrow; // The current loop contains an instruction which
+ // may throw.
+ bool HeaderMayThrow; // Same as previous, but specific to loop header
+ LICMSafetyInfo() : MayThrow(false), HeaderMayThrow(false)
+ {}
+};
BasicBlock *InsertPreheaderForLoop(Loop *L, Pass *P);
@@ -63,6 +76,49 @@ bool formLCSSA(Loop &L, DominatorTree &D
/// Returns true if any modifications are made to the loop.
bool formLCSSARecursively(Loop &L, DominatorTree &DT, LoopInfo *LI,
ScalarEvolution *SE = nullptr);
+
+/// \brief Walk the specified region of the CFG (defined by all blocks
+/// dominated by the specified block, and that are in the current loop) in
+/// reverse depth first order w.r.t the DominatorTree. This allows us to visit
+/// uses before definitions, allowing us to sink a loop body in one pass without
+/// iteration. Takes DomTreeNode, AliasAnalysis, LoopInfo, DominatorTree,
+/// DataLayout, TargetLibraryInfo, Loop, AliasSet information for all
+/// instructions of the loop and loop safety information as arguments.
+/// It returns changed status.
+bool sinkRegion(DomTreeNode *, AliasAnalysis *, LoopInfo *, DominatorTree *,
+ const DataLayout *, TargetLibraryInfo *, Loop *,
+ AliasSetTracker *, LICMSafetyInfo *);
+
+/// \brief Walk the specified region of the CFG (defined by all blocks
+/// dominated by the specified block, and that are in the current loop) in depth
+/// first order w.r.t the DominatorTree. This allows us to visit definitions
+/// before uses, allowing us to hoist a loop body in one pass without iteration.
+/// Takes DomTreeNode, AliasAnalysis, LoopInfo, DominatorTree, DataLayout,
+/// TargetLibraryInfo, Loop, AliasSet information for all instructions of the
+/// loop and loop safety information as arguments. It returns changed status.
+bool hoistRegion(DomTreeNode *, AliasAnalysis *, LoopInfo *, DominatorTree *,
+ const DataLayout *, TargetLibraryInfo *, Loop *,
+ AliasSetTracker *, LICMSafetyInfo *);
+
+/// \brief 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 which are
+/// loop invariant. It takes AliasSet, Loop exit blocks vector, loop exit blocks
+/// insertion point vector, PredIteratorCache, LoopInfo, DominatorTree, Loop,
+/// AliasSet information for all instructions of the loop and loop safety
+/// information as arguments. It returns changed status.
+bool promoteLoopAccessesToScalars(AliasSet &, SmallVectorImpl<BasicBlock*> &,
+ SmallVectorImpl<Instruction*> &,
+ PredIteratorCache &, LoopInfo *,
+ DominatorTree *, Loop *, AliasSetTracker *,
+ LICMSafetyInfo *);
+
+/// \brief Computes safety information for a loop
+/// checks loop body & header for the possiblity of may throw
+/// exception, it takes LICMSafetyInfo and loop as argument.
+/// Updates safety information in LICMSafetyInfo argument.
+void computeLICMSafetyInfo(LICMSafetyInfo *, Loop *);
+
}
#endif
Modified: llvm/trunk/lib/Transforms/Scalar/LICM.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LICM.cpp?rev=230178&r1=230177&r2=230178&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LICM.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LICM.cpp Sun Feb 22 12:35:32 2015
@@ -71,6 +71,27 @@ static cl::opt<bool>
DisablePromotion("disable-licm-promotion", cl::Hidden,
cl::desc("Disable memory promotion in LICM pass"));
+static bool inSubLoop(BasicBlock *BB, Loop *CurLoop, LoopInfo *LI);
+static bool isNotUsedInLoop(Instruction &I, Loop *CurLoop);
+static bool hoist(Instruction &I, BasicBlock *Preheader);
+static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
+ Loop *CurLoop, AliasSetTracker *CurAST );
+static bool isGuaranteedToExecute(Instruction &Inst, DominatorTree *DT,
+ Loop *CurLoop, LICMSafetyInfo * SafetyInfo);
+static bool isSafeToExecuteUnconditionally(Instruction &Inst,DominatorTree *DT,
+ const DataLayout *DL, Loop *CurLoop,
+ LICMSafetyInfo * SafetyInfo);
+static bool pointerInvalidatedByLoop(Value *V, uint64_t Size,
+ const AAMDNodes &AAInfo,
+ AliasSetTracker *CurAST);
+static Instruction *CloneInstructionInExitBlock(Instruction &I,
+ BasicBlock &ExitBlock,
+ PHINode &PN, LoopInfo *LI);
+static bool canSinkOrHoistInst(Instruction &I, AliasAnalysis *AA,
+ DominatorTree *DT, const DataLayout *DL,
+ Loop *CurLoop, AliasSetTracker *CurAST,
+ LICMSafetyInfo * SafetyInfo);
+
namespace {
struct LICM : public LoopPass {
static char ID; // Pass identification, replacement for typeid
@@ -117,10 +138,6 @@ namespace {
BasicBlock *Preheader; // The preheader block of the current loop...
Loop *CurLoop; // The current loop we are working on...
AliasSetTracker *CurAST; // AliasSet information for the current loop...
- bool MayThrow; // The current loop contains an instruction which
- // may throw, thus preventing code motion of
- // instructions with side effects.
- bool HeaderMayThrow; // Same as previous, but specific to loop header
DenseMap<Loop*, AliasSetTracker*> LoopToAliasSetMap;
/// cloneBasicBlockAnalysis - Simple Analysis hook. Clone alias set info.
@@ -133,77 +150,6 @@ namespace {
/// Simple Analysis hook. Delete loop L from alias set map.
void deleteAnalysisLoop(Loop *L) override;
-
- /// SinkRegion - Walk the specified region of the CFG (defined by all blocks
- /// dominated by the specified block, and that are in the current loop) in
- /// reverse depth first order w.r.t the DominatorTree. This allows us to
- /// visit uses before definitions, allowing us to sink a loop body in one
- /// pass without iteration.
- ///
- void SinkRegion(DomTreeNode *N);
-
- /// HoistRegion - Walk the specified region of the CFG (defined by all
- /// blocks dominated by the specified block, and that are in the current
- /// loop) in depth first order w.r.t the DominatorTree. This allows us to
- /// visit definitions before uses, allowing us to hoist a loop body in one
- /// pass without iteration.
- ///
- void HoistRegion(DomTreeNode *N);
-
- /// inSubLoop - Little predicate that returns true if the specified basic
- /// block is in a subloop of the current one, not the current one itself.
- ///
- bool inSubLoop(BasicBlock *BB) {
- assert(CurLoop->contains(BB) && "Only valid if BB is IN the loop");
- return LI->getLoopFor(BB) != CurLoop;
- }
-
- /// sink - When an instruction is found to only be used outside of the loop,
- /// this function moves it to the exit blocks and patches up SSA form as
- /// needed.
- ///
- void sink(Instruction &I);
-
- /// hoist - When an instruction is found to only use loop invariant operands
- /// that is safe to hoist, this instruction is called to do the dirty work.
- ///
- void hoist(Instruction &I);
-
- /// isSafeToExecuteUnconditionally - Only sink or hoist an instruction if it
- /// is not a trapping instruction or if it is a trapping instruction and is
- /// guaranteed to execute.
- ///
- bool isSafeToExecuteUnconditionally(Instruction &I);
-
- /// isGuaranteedToExecute - Check that the instruction is guaranteed to
- /// execute.
- ///
- bool isGuaranteedToExecute(Instruction &I);
-
- /// pointerInvalidatedByLoop - Return true if the body of this loop may
- /// store into the memory location pointed to by V.
- ///
- bool pointerInvalidatedByLoop(Value *V, uint64_t Size,
- const AAMDNodes &AAInfo) {
- // Check to see if any of the basic blocks in CurLoop invalidate *V.
- return CurAST->getAliasSetForPointer(V, Size, AAInfo).isMod();
- }
-
- bool canSinkOrHoistInst(Instruction &I);
- bool isNotUsedInLoop(Instruction &I);
-
- void PromoteAliasSet(AliasSet &AS,
- SmallVectorImpl<BasicBlock*> &ExitBlocks,
- SmallVectorImpl<Instruction*> &InsertPts,
- PredIteratorCache &PIC);
-
- /// \brief Create a copy of the instruction in the exit block and patch up
- /// SSA.
- /// PN is a user of I in ExitBlock that can be used to get the number and
- /// list of predecessors fast.
- Instruction *CloneInstructionInExitBlock(Instruction &I,
- BasicBlock &ExitBlock,
- PHINode &PN);
};
}
@@ -274,19 +220,9 @@ bool LICM::runOnLoop(Loop *L, LPPassMana
CurAST->add(*BB); // Incorporate the specified basic block
}
- HeaderMayThrow = false;
- BasicBlock *Header = L->getHeader();
- for (BasicBlock::iterator I = Header->begin(), E = Header->end();
- (I != E) && !HeaderMayThrow; ++I)
- HeaderMayThrow |= I->mayThrow();
- MayThrow = HeaderMayThrow;
- // TODO: We've already searched for instructions which may throw in subloops.
- // We may want to reuse this information.
- for (Loop::block_iterator BB = L->block_begin(), BBE = L->block_end();
- (BB != BBE) && !MayThrow ; ++BB)
- for (BasicBlock::iterator I = (*BB)->begin(), E = (*BB)->end();
- (I != E) && !MayThrow; ++I)
- MayThrow |= I->mayThrow();
+ // Compute loop safety information.
+ LICMSafetyInfo SafetyInfo;
+ computeLICMSafetyInfo(&SafetyInfo, CurLoop);
// We want to visit all of the instructions in this loop... that are not parts
// of our subloops (they have already had their invariants hoisted out of
@@ -299,9 +235,11 @@ bool LICM::runOnLoop(Loop *L, LPPassMana
// instructions, we perform another pass to hoist them out of the loop.
//
if (L->hasDedicatedExits())
- SinkRegion(DT->getNode(L->getHeader()));
+ Changed |= sinkRegion(DT->getNode(L->getHeader()), AA, LI, DT, DL, TLI,
+ CurLoop, CurAST, &SafetyInfo);
if (Preheader)
- HoistRegion(DT->getNode(L->getHeader()));
+ Changed |= hoistRegion(DT->getNode(L->getHeader()), AA, LI, DT, DL, TLI,
+ CurLoop, CurAST, &SafetyInfo);
// Now that all loop invariants have been removed from the loop, promote any
// memory references to scalars that we can.
@@ -313,7 +251,9 @@ bool LICM::runOnLoop(Loop *L, LPPassMana
// Loop over all of the alias sets in the tracker object.
for (AliasSetTracker::iterator I = CurAST->begin(), E = CurAST->end();
I != E; ++I)
- PromoteAliasSet(*I, ExitBlocks, InsertPts, PIC);
+ Changed |= promoteLoopAccessesToScalars(*I, ExitBlocks, InsertPts,
+ PIC, LI, DT, CurLoop,
+ CurAST, &SafetyInfo);
// Once we have promoted values across the loop body we have to recursively
// reform LCSSA as any nested loop may now have values defined within the
@@ -346,27 +286,36 @@ bool LICM::runOnLoop(Loop *L, LPPassMana
return Changed;
}
-/// SinkRegion - Walk the specified region of the CFG (defined by all blocks
-/// dominated by the specified block, and that are in the current loop) in
-/// reverse depth first order w.r.t the DominatorTree. This allows us to visit
-/// uses before definitions, allowing us to sink a loop body in one pass without
-/// iteration.
+/// Walk the specified region of the CFG (defined by all blocks dominated by
+/// the specified block, and that are in the current loop) in reverse depth
+/// first order w.r.t the DominatorTree. This allows us to visit uses before
+/// definitions, allowing us to sink a loop body in one pass without iteration.
///
-void LICM::SinkRegion(DomTreeNode *N) {
- assert(N != nullptr && "Null dominator tree node?");
+bool llvm::sinkRegion(DomTreeNode *N, AliasAnalysis *AA, LoopInfo *LI,
+ DominatorTree *DT, const DataLayout *DL,
+ TargetLibraryInfo *TLI, Loop *CurLoop,
+ AliasSetTracker *CurAST, LICMSafetyInfo * SafetyInfo) {
+
+ // Verify inputs.
+ assert(N != nullptr && AA != nullptr && LI != nullptr &&
+ DT != nullptr && CurLoop != nullptr && CurAST != nullptr &&
+ SafetyInfo != nullptr && "Unexpected input to sinkRegion");
+
+ // Set changed as false.
+ bool Changed = false;
+ // Get basic block
BasicBlock *BB = N->getBlock();
-
// If this subregion is not in the top level loop at all, exit.
- if (!CurLoop->contains(BB)) return;
+ if (!CurLoop->contains(BB)) return Changed;
// We are processing blocks in reverse dfo, so process children first.
const std::vector<DomTreeNode*> &Children = N->getChildren();
for (unsigned i = 0, e = Children.size(); i != e; ++i)
- SinkRegion(Children[i]);
-
+ Changed |= sinkRegion(Children[i], AA, LI, DT, DL, TLI, CurLoop,
+ CurAST, SafetyInfo);
// Only need to process the contents of this block if it is not part of a
// subloop (which would already have been processed).
- if (inSubLoop(BB)) return;
+ if (inSubLoop(BB,CurLoop,LI)) return Changed;
for (BasicBlock::iterator II = BB->end(); II != BB->begin(); ) {
Instruction &I = *--II;
@@ -387,31 +336,39 @@ void LICM::SinkRegion(DomTreeNode *N) {
// outside of the loop. In this case, it doesn't even matter if the
// operands of the instruction are loop invariant.
//
- if (isNotUsedInLoop(I) && canSinkOrHoistInst(I)) {
+ if (isNotUsedInLoop(I, CurLoop) &&
+ canSinkOrHoistInst(I, AA, DT, DL, CurLoop, CurAST, SafetyInfo)) {
++II;
- sink(I);
+ Changed |= sink(I, LI, DT, CurLoop, CurAST);
}
}
+ return Changed;
}
-/// HoistRegion - Walk the specified region of the CFG (defined by all blocks
-/// dominated by the specified block, and that are in the current loop) in depth
-/// first order w.r.t the DominatorTree. This allows us to visit definitions
-/// before uses, allowing us to hoist a loop body in one pass without iteration.
+/// Walk the specified region of the CFG (defined by all blocks dominated by
+/// the specified block, and that are in the current loop) in depth first
+/// order w.r.t the DominatorTree. This allows us to visit definitions before
+/// uses, allowing us to hoist a loop body in one pass without iteration.
///
-void LICM::HoistRegion(DomTreeNode *N) {
- assert(N != nullptr && "Null dominator tree node?");
+bool llvm::hoistRegion(DomTreeNode *N, AliasAnalysis *AA, LoopInfo *LI,
+ DominatorTree *DT, const DataLayout *DL,
+ TargetLibraryInfo *TLI, Loop *CurLoop,
+ AliasSetTracker *CurAST, LICMSafetyInfo *SafetyInfo) {
+ // Verify inputs.
+ assert(N != nullptr && AA != nullptr && LI != nullptr &&
+ DT != nullptr && CurLoop != nullptr && CurAST != nullptr &&
+ SafetyInfo != nullptr && "Unexpected input to hoistRegion");
+ // Set changed as false.
+ bool Changed = false;
+ // Get basic block
BasicBlock *BB = N->getBlock();
-
// If this subregion is not in the top level loop at all, exit.
- if (!CurLoop->contains(BB)) return;
-
+ if (!CurLoop->contains(BB)) return Changed;
// Only need to process the contents of this block if it is not part of a
// subloop (which would already have been processed).
- if (!inSubLoop(BB))
+ if (!inSubLoop(BB, CurLoop, LI))
for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ) {
Instruction &I = *II++;
-
// Try constant folding this instruction. If all the operands are
// constants, it is technically hoistable, but it would be better to just
// fold it.
@@ -428,20 +385,49 @@ void LICM::HoistRegion(DomTreeNode *N) {
// if all of the operands of the instruction are loop invariant and if it
// is safe to hoist the instruction.
//
- if (CurLoop->hasLoopInvariantOperands(&I) && canSinkOrHoistInst(I) &&
- isSafeToExecuteUnconditionally(I))
- hoist(I);
+ if (CurLoop->hasLoopInvariantOperands(&I) &&
+ canSinkOrHoistInst(I, AA, DT, DL, CurLoop, CurAST, SafetyInfo) &&
+ isSafeToExecuteUnconditionally(I, DT, DL, CurLoop, SafetyInfo))
+ Changed |= hoist(I, CurLoop->getLoopPreheader());
}
const std::vector<DomTreeNode*> &Children = N->getChildren();
for (unsigned i = 0, e = Children.size(); i != e; ++i)
- HoistRegion(Children[i]);
+ Changed |= hoistRegion(Children[i], AA, LI, DT, DL, TLI, CurLoop,
+ CurAST, SafetyInfo);
+ return Changed;
+}
+
+/// Computes loop safety information, checks loop body & header
+/// for the possiblity of may throw exception.
+///
+void llvm::computeLICMSafetyInfo(LICMSafetyInfo * SafetyInfo, Loop * CurLoop) {
+ assert(CurLoop != nullptr && "CurLoop cant be null");
+ BasicBlock *Header = CurLoop->getHeader();
+ // Setting default safety values.
+ SafetyInfo->MayThrow = false;
+ SafetyInfo->HeaderMayThrow = false;
+ // Iterate over header and compute dafety info.
+ for (BasicBlock::iterator I = Header->begin(), E = Header->end();
+ (I != E) && !SafetyInfo->HeaderMayThrow; ++I)
+ SafetyInfo->HeaderMayThrow |= I->mayThrow();
+
+ SafetyInfo->MayThrow = SafetyInfo->HeaderMayThrow;
+ // Iterate over loop instructions and compute safety info.
+ for (Loop::block_iterator BB = CurLoop->block_begin(),
+ BBE = CurLoop->block_end(); (BB != BBE) && !SafetyInfo->MayThrow ; ++BB)
+ for (BasicBlock::iterator I = (*BB)->begin(), E = (*BB)->end();
+ (I != E) && !SafetyInfo->MayThrow; ++I)
+ SafetyInfo->MayThrow |= I->mayThrow();
}
/// canSinkOrHoistInst - Return true if the hoister and sinker can handle this
/// instruction.
///
-bool LICM::canSinkOrHoistInst(Instruction &I) {
+bool canSinkOrHoistInst(Instruction &I, AliasAnalysis *AA,
+ DominatorTree *DT, const DataLayout *DL,
+ Loop *CurLoop, AliasSetTracker *CurAST,
+ LICMSafetyInfo * SafetyInfo) {
// Loads have extra constraints we have to verify before we can hoist them.
if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
if (!LI->isUnordered())
@@ -462,7 +448,7 @@ bool LICM::canSinkOrHoistInst(Instructio
AAMDNodes AAInfo;
LI->getAAMetadata(AAInfo);
- return !pointerInvalidatedByLoop(LI->getOperand(0), Size, AAInfo);
+ return !pointerInvalidatedByLoop(LI->getOperand(0), Size, AAInfo, CurAST);
} else if (CallInst *CI = dyn_cast<CallInst>(&I)) {
// Don't sink or hoist dbg info; it's legal, but not useful.
if (isa<DbgInfoIntrinsic>(I))
@@ -501,14 +487,14 @@ bool LICM::canSinkOrHoistInst(Instructio
!isa<InsertValueInst>(I))
return false;
- return isSafeToExecuteUnconditionally(I);
+ return isSafeToExecuteUnconditionally(I, DT, DL, CurLoop, SafetyInfo);
}
-/// \brief Returns true if a PHINode is a trivially replaceable with an
+/// Returns true if a PHINode is a trivially replaceable with an
/// Instruction.
+/// This is true when all incoming values are that instruction.
+/// This pattern occurs most often with LCSSA PHI nodes.
///
-/// This is true when all incoming values are that instruction. This pattern
-/// occurs most often with LCSSA PHI nodes.
static bool isTriviallyReplacablePHI(PHINode &PN, Instruction &I) {
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
if (PN.getIncomingValue(i) != &I)
@@ -517,11 +503,11 @@ static bool isTriviallyReplacablePHI(PHI
return true;
}
-/// isNotUsedInLoop - Return true if the only users of this instruction are
-/// outside of the loop. If this is true, we can sink the instruction to the
-/// exit blocks of the loop.
+/// Return true if the only users of this instruction are outside of
+/// the loop. If this is true, we can sink the instruction to the exit
+/// blocks of the loop.
///
-bool LICM::isNotUsedInLoop(Instruction &I) {
+static bool isNotUsedInLoop(Instruction &I, Loop *CurLoop) {
for (User *U : I.users()) {
Instruction *UI = cast<Instruction>(U);
if (PHINode *PN = dyn_cast<PHINode>(UI)) {
@@ -552,9 +538,9 @@ bool LICM::isNotUsedInLoop(Instruction &
return true;
}
-Instruction *LICM::CloneInstructionInExitBlock(Instruction &I,
- BasicBlock &ExitBlock,
- PHINode &PN) {
+static Instruction *CloneInstructionInExitBlock(Instruction &I,
+ BasicBlock &ExitBlock,
+ PHINode &PN, LoopInfo *LI) {
Instruction *New = I.clone();
ExitBlock.getInstList().insert(ExitBlock.getFirstInsertionPt(), New);
if (!I.getName().empty()) New->setName(I.getName() + ".le");
@@ -581,14 +567,15 @@ Instruction *LICM::CloneInstructionInExi
return New;
}
-/// sink - When an instruction is found to only be used outside of the loop,
-/// this function moves it to the exit blocks and patches up SSA form as needed.
+/// When an instruction is found to only be used outside of the loop, this
+/// function moves it to the exit blocks and patches up SSA form as needed.
/// This method is guaranteed to remove the original instruction from its
/// position, and may either delete it or move it to outside of the loop.
///
-void LICM::sink(Instruction &I) {
+static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
+ Loop *CurLoop, AliasSetTracker *CurAST ) {
DEBUG(dbgs() << "LICM sinking instruction: " << I << "\n");
-
+ bool Changed = false;
if (isa<LoadInst>(I)) ++NumMovedLoads;
else if (isa<CallInst>(I)) ++NumMovedCalls;
++NumSunk;
@@ -597,7 +584,8 @@ void LICM::sink(Instruction &I) {
#ifndef NDEBUG
SmallVector<BasicBlock *, 32> ExitBlocks;
CurLoop->getUniqueExitBlocks(ExitBlocks);
- SmallPtrSet<BasicBlock *, 32> ExitBlockSet(ExitBlocks.begin(), ExitBlocks.end());
+ SmallPtrSet<BasicBlock *, 32> ExitBlockSet(ExitBlocks.begin(),
+ ExitBlocks.end());
#endif
// Clones of this instruction. Don't create more than one per exit block!
@@ -625,7 +613,7 @@ void LICM::sink(Instruction &I) {
New = It->second;
else
New = SunkCopies[ExitBlock] =
- CloneInstructionInExitBlock(I, *ExitBlock, *PN);
+ CloneInstructionInExitBlock(I, *ExitBlock, *PN, LI);
PN->replaceAllUsesWith(New);
PN->eraseFromParent();
@@ -633,37 +621,39 @@ void LICM::sink(Instruction &I) {
CurAST->deleteValue(&I);
I.eraseFromParent();
+ return Changed;
}
-/// hoist - When an instruction is found to only use loop invariant operands
-/// that is safe to hoist, this instruction is called to do the dirty work.
+/// When an instruction is found to only use loop invariant operands that
+/// is safe to hoist, this instruction is called to do the dirty work.
///
-void LICM::hoist(Instruction &I) {
+static bool hoist(Instruction &I, BasicBlock *Preheader) {
DEBUG(dbgs() << "LICM hoisting to " << Preheader->getName() << ": "
<< I << "\n");
-
// Move the new node to the Preheader, before its terminator.
I.moveBefore(Preheader->getTerminator());
if (isa<LoadInst>(I)) ++NumMovedLoads;
else if (isa<CallInst>(I)) ++NumMovedCalls;
++NumHoisted;
- Changed = true;
+ return true;
}
-/// isSafeToExecuteUnconditionally - Only sink or hoist an instruction if it is
-/// not a trapping instruction or if it is a trapping instruction and is
-/// guaranteed to execute.
+/// Only sink or hoist an instruction if it is not a trapping instruction
+/// or if it is a trapping instruction and is guaranteed to execute.
///
-bool LICM::isSafeToExecuteUnconditionally(Instruction &Inst) {
+static bool isSafeToExecuteUnconditionally(Instruction &Inst, DominatorTree *DT,
+ const DataLayout *DL, Loop *CurLoop,
+ LICMSafetyInfo * SafetyInfo) {
// If it is not a trapping instruction, it is always safe to hoist.
if (isSafeToSpeculativelyExecute(&Inst, DL))
return true;
- return isGuaranteedToExecute(Inst);
+ return isGuaranteedToExecute(Inst, DT, CurLoop, SafetyInfo);
}
-bool LICM::isGuaranteedToExecute(Instruction &Inst) {
+static bool isGuaranteedToExecute(Instruction &Inst, DominatorTree *DT,
+ Loop *CurLoop, LICMSafetyInfo * SafetyInfo) {
// We have to check to make sure that the instruction dominates all
// of the exit blocks. If it doesn't, then there is a path out of the loop
@@ -675,11 +665,11 @@ bool LICM::isGuaranteedToExecute(Instruc
if (Inst.getParent() == CurLoop->getHeader())
// If there's a throw in the header block, we can't guarantee we'll reach
// Inst.
- return !HeaderMayThrow;
+ return !SafetyInfo->HeaderMayThrow;
// Somewhere in this loop there is an instruction which may throw and make us
// exit the loop.
- if (MayThrow)
+ if (SafetyInfo->MayThrow)
return false;
// Get the exit blocks for the current loop.
@@ -777,25 +767,37 @@ namespace {
};
} // 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
-/// which are loop invariant.
-///
-void LICM::PromoteAliasSet(AliasSet &AS,
- SmallVectorImpl<BasicBlock*> &ExitBlocks,
- SmallVectorImpl<Instruction*> &InsertPts,
- PredIteratorCache &PIC) {
+/// 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 which are
+/// loop invariant.
+///
+bool llvm::promoteLoopAccessesToScalars(AliasSet &AS,
+ SmallVectorImpl<BasicBlock*>&ExitBlocks,
+ SmallVectorImpl<Instruction*>&InsertPts,
+ PredIteratorCache &PIC, LoopInfo *LI,
+ DominatorTree *DT, Loop *CurLoop,
+ AliasSetTracker *CurAST,
+ LICMSafetyInfo * SafetyInfo) {
+ // Verify inputs.
+ assert(LI != nullptr && DT != nullptr &&
+ CurLoop != nullptr && CurAST != nullptr &&
+ SafetyInfo != nullptr &&
+ "Unexpected Input to promoteLoopAccessesToScalars");
+ // Initially set Changed status to false.
+ bool Changed = false;
// We can promote this alias set if it has a store, if it is a "Must" alias
// set, if the pointer is loop invariant, and if we are not eliminating any
// volatile loads or stores.
if (AS.isForwardingAliasSet() || !AS.isMod() || !AS.isMustAlias() ||
AS.isVolatile() || !CurLoop->isLoopInvariant(AS.begin()->getValue()))
- return;
+ return Changed;
assert(!AS.empty() &&
"Must alias set should have at least one pointer element in it!");
+
Value *SomePtr = AS.begin()->getValue();
+ BasicBlock * Preheader = CurLoop->getLoopPreheader();
// It isn't safe to promote a load/store from the loop if the load/store is
// conditional. For example, turning:
@@ -832,7 +834,7 @@ void LICM::PromoteAliasSet(AliasSet &AS,
// cannot (yet) promote a memory location that is loaded and stored in
// different sizes.
if (SomePtr->getType() != ASIV->getType())
- return;
+ return Changed;
for (User *U : ASIV->users()) {
// Ignore instructions that are outside the loop.
@@ -845,7 +847,7 @@ void LICM::PromoteAliasSet(AliasSet &AS,
if (LoadInst *load = dyn_cast<LoadInst>(UI)) {
assert(!load->isVolatile() && "AST broken");
if (!load->isSimple())
- return;
+ return Changed;
} else if (StoreInst *store = dyn_cast<StoreInst>(UI)) {
// Stores *of* the pointer are not interesting, only stores *to* the
// pointer.
@@ -853,14 +855,14 @@ void LICM::PromoteAliasSet(AliasSet &AS,
continue;
assert(!store->isVolatile() && "AST broken");
if (!store->isSimple())
- return;
+ return Changed;
// Don't sink stores from loops without dedicated block exits. Exits
// containing indirect branches are not transformed by loop simplify,
// make sure we catch that. An additional load may be generated in the
// preheader for SSA updater, so also avoid sinking when no preheader
// is available.
if (!HasDedicatedExits || !Preheader)
- return;
+ return Changed;
// Note that we only check GuaranteedToExecute inside the store case
// so that we do not introduce stores where they did not exist before
@@ -872,16 +874,17 @@ void LICM::PromoteAliasSet(AliasSet &AS,
// Larger is better, with the exception of 0 being the best alignment.
unsigned InstAlignment = store->getAlignment();
if ((InstAlignment > Alignment || InstAlignment == 0) && Alignment != 0)
- if (isGuaranteedToExecute(*UI)) {
+ if (isGuaranteedToExecute(*UI, DT, CurLoop, SafetyInfo)) {
GuaranteedToExecute = true;
Alignment = InstAlignment;
}
if (!GuaranteedToExecute)
- GuaranteedToExecute = isGuaranteedToExecute(*UI);
+ GuaranteedToExecute = isGuaranteedToExecute(*UI, DT,
+ CurLoop, SafetyInfo);
} else
- return; // Not a load or store.
+ return Changed; // Not a load or store.
// Merge the AA tags.
if (LoopUses.empty()) {
@@ -897,7 +900,7 @@ void LICM::PromoteAliasSet(AliasSet &AS,
// If there isn't a guaranteed-to-execute instruction, we can't promote.
if (!GuaranteedToExecute)
- return;
+ return Changed;
// Otherwise, this is safe to promote, lets do it!
DEBUG(dbgs() << "LICM: Promoting value stored to in loop: " <<*SomePtr<<'\n');
@@ -942,10 +945,12 @@ void LICM::PromoteAliasSet(AliasSet &AS,
// If the SSAUpdater didn't use the load in the preheader, just zap it now.
if (PreheaderLoad->use_empty())
PreheaderLoad->eraseFromParent();
-}
+ return Changed;
+}
-/// cloneBasicBlockAnalysis - Simple Analysis hook. Clone alias set info.
+/// Simple Analysis hook. Clone alias set info.
+///
void LICM::cloneBasicBlockAnalysis(BasicBlock *From, BasicBlock *To, Loop *L) {
AliasSetTracker *AST = LoopToAliasSetMap.lookup(L);
if (!AST)
@@ -954,8 +959,8 @@ void LICM::cloneBasicBlockAnalysis(Basic
AST->copyValue(From, To);
}
-/// deleteAnalysisValue - Simple Analysis hook. Delete value V from alias
-/// set.
+/// Simple Analysis hook. Delete value V from alias set
+///
void LICM::deleteAnalysisValue(Value *V, Loop *L) {
AliasSetTracker *AST = LoopToAliasSetMap.lookup(L);
if (!AST)
@@ -965,6 +970,7 @@ void LICM::deleteAnalysisValue(Value *V,
}
/// Simple Analysis hook. Delete value L from alias set map.
+///
void LICM::deleteAnalysisLoop(Loop *L) {
AliasSetTracker *AST = LoopToAliasSetMap.lookup(L);
if (!AST)
@@ -973,3 +979,23 @@ void LICM::deleteAnalysisLoop(Loop *L) {
delete AST;
LoopToAliasSetMap.erase(L);
}
+
+
+/// Return true if the body of this loop may store into the memory
+/// location pointed to by V.
+///
+static bool pointerInvalidatedByLoop(Value *V, uint64_t Size,
+ const AAMDNodes &AAInfo,
+ AliasSetTracker *CurAST) {
+ // Check to see if any of the basic blocks in CurLoop invalidate *V.
+ return CurAST->getAliasSetForPointer(V, Size, AAInfo).isMod();
+}
+
+/// Little predicate that returns true if the specified basic block is in
+/// a subloop of the current one, not the current one itself.
+///
+static bool inSubLoop(BasicBlock *BB, Loop *CurLoop, LoopInfo *LI) {
+ assert(CurLoop->contains(BB) && "Only valid if BB is IN the loop");
+ return LI->getLoopFor(BB) != CurLoop;
+}
+
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