Re-submitting changes in D51550 because it failed to patch.
Reviewers: javed.absar, trentxintong, courbet
Reviewed By: trentxintong
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D52433
llvm-svn: 342919
diff --git a/llvm/lib/Transforms/Scalar/MergeICmps.cpp b/llvm/lib/Transforms/Scalar/MergeICmps.cpp
index 7b3c3f9..1e4bbd4 100644
--- a/llvm/lib/Transforms/Scalar/MergeICmps.cpp
+++ b/llvm/lib/Transforms/Scalar/MergeICmps.cpp
@@ -41,6 +41,15 @@
#define DEBUG_TYPE "mergeicmps"
+// Returns true if the instruction is a simple load or a simple store
+static bool isSimpleLoadOrStore(const Instruction *I) {
+ if (const LoadInst *LI = dyn_cast<LoadInst>(I))
+ return LI->isSimple();
+ if (const StoreInst *SI = dyn_cast<StoreInst>(I))
+ return SI->isSimple();
+ return false;
+}
+
// A BCE atom.
struct BCEAtom {
BCEAtom() : GEP(nullptr), LoadI(nullptr), Offset() {}
@@ -151,18 +160,19 @@
// Returns true if the non-BCE-cmp instructions can be separated from BCE-cmp
// instructions in the block.
- bool canSplit() const;
+ bool canSplit(AliasAnalysis *AA) const;
// Return true if this all the relevant instructions in the BCE-cmp-block can
// be sunk below this instruction. By doing this, we know we can separate the
// BCE-cmp-block instructions from the non-BCE-cmp-block instructions in the
// block.
- bool canSinkBCECmpInst(const Instruction *, DenseSet<Instruction *> &) const;
+ bool canSinkBCECmpInst(const Instruction *, DenseSet<Instruction *> &,
+ AliasAnalysis *AA) const;
// We can separate the BCE-cmp-block instructions and the non-BCE-cmp-block
// instructions. Split the old block and move all non-BCE-cmp-insts into the
// new parent block.
- void split(BasicBlock *NewParent) const;
+ void split(BasicBlock *NewParent, AliasAnalysis *AA) const;
// The basic block where this comparison happens.
BasicBlock *BB = nullptr;
@@ -180,12 +190,21 @@
};
bool BCECmpBlock::canSinkBCECmpInst(const Instruction *Inst,
- DenseSet<Instruction *> &BlockInsts) const {
+ DenseSet<Instruction *> &BlockInsts,
+ AliasAnalysis *AA) const {
// If this instruction has side effects and its in middle of the BCE cmp block
// instructions, then bail for now.
- // TODO: use alias analysis to tell whether there is real interference.
- if (Inst->mayHaveSideEffects())
- return false;
+ if (Inst->mayHaveSideEffects()) {
+ // Bail if this is not a simple load or store
+ if (!isSimpleLoadOrStore(Inst))
+ return false;
+ // Disallow stores that might alias the BCE operands
+ MemoryLocation LLoc = MemoryLocation::get(Lhs_.LoadI);
+ MemoryLocation RLoc = MemoryLocation::get(Rhs_.LoadI);
+ if (isModSet(AA->getModRefInfo(Inst, LLoc)) ||
+ isModSet(AA->getModRefInfo(Inst, RLoc)))
+ return false;
+ }
// Make sure this instruction does not use any of the BCE cmp block
// instructions as operand.
for (auto BI : BlockInsts) {
@@ -195,14 +214,15 @@
return true;
}
-void BCECmpBlock::split(BasicBlock *NewParent) const {
+void BCECmpBlock::split(BasicBlock *NewParent, AliasAnalysis *AA) const {
DenseSet<Instruction *> BlockInsts(
{Lhs_.GEP, Rhs_.GEP, Lhs_.LoadI, Rhs_.LoadI, CmpI, BranchI});
llvm::SmallVector<Instruction *, 4> OtherInsts;
for (Instruction &Inst : *BB) {
if (BlockInsts.count(&Inst))
continue;
- assert(canSinkBCECmpInst(&Inst, BlockInsts) && "Split unsplittable block");
+ assert(canSinkBCECmpInst(&Inst, BlockInsts, AA) &&
+ "Split unsplittable block");
// This is a non-BCE-cmp-block instruction. And it can be separated
// from the BCE-cmp-block instruction.
OtherInsts.push_back(&Inst);
@@ -214,12 +234,12 @@
}
}
-bool BCECmpBlock::canSplit() const {
+bool BCECmpBlock::canSplit(AliasAnalysis *AA) const {
DenseSet<Instruction *> BlockInsts(
{Lhs_.GEP, Rhs_.GEP, Lhs_.LoadI, Rhs_.LoadI, CmpI, BranchI});
for (Instruction &Inst : *BB) {
if (!BlockInsts.count(&Inst)) {
- if (!canSinkBCECmpInst(&Inst, BlockInsts))
+ if (!canSinkBCECmpInst(&Inst, BlockInsts, AA))
return false;
}
}
@@ -325,7 +345,8 @@
// A chain of comparisons.
class BCECmpChain {
public:
- BCECmpChain(const std::vector<BasicBlock *> &Blocks, PHINode &Phi);
+ BCECmpChain(const std::vector<BasicBlock *> &Blocks, PHINode &Phi,
+ AliasAnalysis *AA);
int size() const { return Comparisons_.size(); }
@@ -333,7 +354,7 @@
void dump() const;
#endif // MERGEICMPS_DOT_ON
- bool simplify(const TargetLibraryInfo *const TLI);
+ bool simplify(const TargetLibraryInfo *const TLI, AliasAnalysis *AA);
private:
static bool IsContiguous(const BCECmpBlock &First,
@@ -349,7 +370,7 @@
// null, the merged block will link to the phi block.
void mergeComparisons(ArrayRef<BCECmpBlock> Comparisons,
BasicBlock *const NextBBInChain, PHINode &Phi,
- const TargetLibraryInfo *const TLI);
+ const TargetLibraryInfo *const TLI, AliasAnalysis *AA);
PHINode &Phi_;
std::vector<BCECmpBlock> Comparisons_;
@@ -357,7 +378,8 @@
BasicBlock *EntryBlock_;
};
-BCECmpChain::BCECmpChain(const std::vector<BasicBlock *> &Blocks, PHINode &Phi)
+BCECmpChain::BCECmpChain(const std::vector<BasicBlock *> &Blocks, PHINode &Phi,
+ AliasAnalysis *AA)
: Phi_(Phi) {
assert(!Blocks.empty() && "a chain should have at least one block");
// Now look inside blocks to check for BCE comparisons.
@@ -389,7 +411,7 @@
// and start anew.
//
// NOTE: we only handle block with single predecessor for now.
- if (Comparison.canSplit()) {
+ if (Comparison.canSplit(AA)) {
LLVM_DEBUG(dbgs()
<< "Split initial block '" << Comparison.BB->getName()
<< "' that does extra work besides compare\n");
@@ -476,7 +498,8 @@
}
#endif // MERGEICMPS_DOT_ON
-bool BCECmpChain::simplify(const TargetLibraryInfo *const TLI) {
+bool BCECmpChain::simplify(const TargetLibraryInfo *const TLI,
+ AliasAnalysis *AA) {
// First pass to check if there is at least one merge. If not, we don't do
// anything and we keep analysis passes intact.
{
@@ -524,13 +547,13 @@
// Merge all previous comparisons and start a new merge block.
mergeComparisons(
makeArrayRef(Comparisons_).slice(I - NumMerged, NumMerged),
- Comparisons_[I].BB, Phi_, TLI);
+ Comparisons_[I].BB, Phi_, TLI, AA);
NumMerged = 1;
}
}
mergeComparisons(makeArrayRef(Comparisons_)
.slice(Comparisons_.size() - NumMerged, NumMerged),
- nullptr, Phi_, TLI);
+ nullptr, Phi_, TLI, AA);
return true;
}
@@ -538,7 +561,8 @@
void BCECmpChain::mergeComparisons(ArrayRef<BCECmpBlock> Comparisons,
BasicBlock *const NextBBInChain,
PHINode &Phi,
- const TargetLibraryInfo *const TLI) {
+ const TargetLibraryInfo *const TLI,
+ AliasAnalysis *AA) {
assert(!Comparisons.empty());
const auto &FirstComparison = *Comparisons.begin();
BasicBlock *const BB = FirstComparison.BB;
@@ -551,7 +575,7 @@
auto C = std::find_if(Comparisons.begin(), Comparisons.end(),
[](const BCECmpBlock &B) { return B.RequireSplit; });
if (C != Comparisons.end())
- C->split(EntryBlock_);
+ C->split(EntryBlock_, AA);
LLVM_DEBUG(dbgs() << "Merging " << Comparisons.size() << " comparisons\n");
const auto TotalSize =
@@ -667,7 +691,8 @@
return Blocks;
}
-bool processPhi(PHINode &Phi, const TargetLibraryInfo *const TLI) {
+bool processPhi(PHINode &Phi, const TargetLibraryInfo *const TLI,
+ AliasAnalysis *AA) {
LLVM_DEBUG(dbgs() << "processPhi()\n");
if (Phi.getNumIncomingValues() <= 1) {
LLVM_DEBUG(dbgs() << "skip: only one incoming value in phi\n");
@@ -725,14 +750,14 @@
const auto Blocks =
getOrderedBlocks(Phi, LastBlock, Phi.getNumIncomingValues());
if (Blocks.empty()) return false;
- BCECmpChain CmpChain(Blocks, Phi);
+ BCECmpChain CmpChain(Blocks, Phi, AA);
if (CmpChain.size() < 2) {
LLVM_DEBUG(dbgs() << "skip: only one compare block\n");
return false;
}
- return CmpChain.simplify(TLI);
+ return CmpChain.simplify(TLI, AA);
}
class MergeICmps : public FunctionPass {
@@ -747,7 +772,8 @@
if (skipFunction(F)) return false;
const auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
const auto &TTI = getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
- auto PA = runImpl(F, &TLI, &TTI);
+ AliasAnalysis *AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
+ auto PA = runImpl(F, &TLI, &TTI, AA);
return !PA.areAllPreserved();
}
@@ -755,14 +781,16 @@
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<TargetLibraryInfoWrapperPass>();
AU.addRequired<TargetTransformInfoWrapperPass>();
+ AU.addRequired<AAResultsWrapperPass>();
}
PreservedAnalyses runImpl(Function &F, const TargetLibraryInfo *TLI,
- const TargetTransformInfo *TTI);
+ const TargetTransformInfo *TTI, AliasAnalysis *AA);
};
PreservedAnalyses MergeICmps::runImpl(Function &F, const TargetLibraryInfo *TLI,
- const TargetTransformInfo *TTI) {
+ const TargetTransformInfo *TTI,
+ AliasAnalysis *AA) {
LLVM_DEBUG(dbgs() << "MergeICmpsPass: " << F.getName() << "\n");
// We only try merging comparisons if the target wants to expand memcmp later.
@@ -778,7 +806,7 @@
for (auto BBIt = ++F.begin(); BBIt != F.end(); ++BBIt) {
// A Phi operation is always first in a basic block.
if (auto *const Phi = dyn_cast<PHINode>(&*BBIt->begin()))
- MadeChange |= processPhi(*Phi, TLI);
+ MadeChange |= processPhi(*Phi, TLI, AA);
}
if (MadeChange) return PreservedAnalyses::none();
@@ -792,6 +820,7 @@
"Merge contiguous icmps into a memcmp", false, false)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
INITIALIZE_PASS_END(MergeICmps, "mergeicmps",
"Merge contiguous icmps into a memcmp", false, false)