forked from OSchip/llvm-project
[MergeICmps] Preserve the dominator tree.
Summary: In preparation for D60318 . Reviewers: gchatelet, efriedma Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D62068 llvm-svn: 361239
This commit is contained in:
Clement Courbet
parent
823458f9b8
commit
a95d95d392
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@ -41,9 +41,12 @@
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/DomTreeUpdater.h"
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#include "llvm/Analysis/GlobalsModRef.h"
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#include "llvm/Analysis/Loads.h"
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#include "llvm/Analysis/TargetLibraryInfo.h"
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#include "llvm/Analysis/TargetTransformInfo.h"
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#include "llvm/IR/Dominators.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/Pass.h"
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@ -396,9 +399,10 @@ class BCECmpChain {
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void dump() const;
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#endif // MERGEICMPS_DOT_ON
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bool simplify(const TargetLibraryInfo *const TLI, AliasAnalysis *AA);
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bool simplify(const TargetLibraryInfo *const TLI, AliasAnalysis *AA,
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DomTreeUpdater &DTU);
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private:
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private:
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static bool IsContiguous(const BCECmpBlock &First,
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const BCECmpBlock &Second) {
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return First.Lhs().BaseId == Second.Lhs().BaseId &&
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@ -583,10 +587,11 @@ private:
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// Merges the given contiguous comparison blocks into one memcmp block.
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static BasicBlock *mergeComparisons(ArrayRef<BCECmpBlock> Comparisons,
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BasicBlock *const InsertBefore,
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BasicBlock *const NextCmpBlock,
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PHINode &Phi,
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const TargetLibraryInfo *const TLI,
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AliasAnalysis *AA) {
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AliasAnalysis *AA, DomTreeUpdater &DTU) {
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assert(!Comparisons.empty() && "merging zero comparisons");
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LLVMContext &Context = NextCmpBlock->getContext();
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const BCECmpBlock &FirstCmp = Comparisons[0];
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@ -594,13 +599,15 @@ static BasicBlock *mergeComparisons(ArrayRef<BCECmpBlock> Comparisons,
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// Create a new cmp block before next cmp block.
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BasicBlock *const BB =
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BasicBlock::Create(Context, MergedBlockName(Comparisons).Name,
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NextCmpBlock->getParent(), NextCmpBlock);
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NextCmpBlock->getParent(), InsertBefore);
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IRBuilder<> Builder(BB);
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// Add the GEPs from the first BCECmpBlock.
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Value *const Lhs = Builder.Insert(FirstCmp.Lhs().GEP->clone());
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Value *const Rhs = Builder.Insert(FirstCmp.Rhs().GEP->clone());
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Value *IsEqual = nullptr;
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LLVM_DEBUG(dbgs() << "Merging " << Comparisons.size() << " comparisons -> "
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<< BB->getName() << "\n");
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if (Comparisons.size() == 1) {
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LLVM_DEBUG(dbgs() << "Only one comparison, updating branches\n");
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Value *const LhsLoad =
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@ -610,8 +617,6 @@ static BasicBlock *mergeComparisons(ArrayRef<BCECmpBlock> Comparisons,
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// There are no blocks to merge, just do the comparison.
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IsEqual = Builder.CreateICmpEQ(LhsLoad, RhsLoad);
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} else {
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LLVM_DEBUG(dbgs() << "Merging " << Comparisons.size() << " comparisons\n");
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// If there is one block that requires splitting, we do it now, i.e.
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// just before we know we will collapse the chain. The instructions
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// can be executed before any of the instructions in the chain.
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@ -641,18 +646,21 @@ static BasicBlock *mergeComparisons(ArrayRef<BCECmpBlock> Comparisons,
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// Add a branch to the next basic block in the chain.
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if (NextCmpBlock == PhiBB) {
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// Continue to phi, passing it the comparison result.
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Builder.CreateBr(Phi.getParent());
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Builder.CreateBr(PhiBB);
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Phi.addIncoming(IsEqual, BB);
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DTU.applyUpdates({{DominatorTree::Insert, BB, PhiBB}});
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} else {
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// Continue to next block if equal, exit to phi else.
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Builder.CreateCondBr(IsEqual, NextCmpBlock, PhiBB);
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Phi.addIncoming(ConstantInt::getFalse(Context), BB);
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DTU.applyUpdates({{DominatorTree::Insert, BB, NextCmpBlock},
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{DominatorTree::Insert, BB, PhiBB}});
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}
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return BB;
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}
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bool BCECmpChain::simplify(const TargetLibraryInfo *const TLI,
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AliasAnalysis *AA) {
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AliasAnalysis *AA, DomTreeUpdater &DTU) {
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assert(Comparisons_.size() >= 2 && "simplifying trivial BCECmpChain");
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// First pass to check if there is at least one merge. If not, we don't do
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// anything and we keep analysis passes intact.
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@ -671,9 +679,11 @@ bool BCECmpChain::simplify(const TargetLibraryInfo *const TLI,
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// Effectively merge blocks. We go in the reverse direction from the phi block
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// so that the next block is always available to branch to.
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const auto mergeRange = [this, TLI, AA](int I, int Num, BasicBlock *Next) {
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return mergeComparisons(makeArrayRef(Comparisons_).slice(I, Num), Next,
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Phi_, TLI, AA);
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const auto mergeRange = [this, TLI, AA, &DTU](int I, int Num,
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BasicBlock *InsertBefore,
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BasicBlock *Next) {
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return mergeComparisons(makeArrayRef(Comparisons_).slice(I, Num),
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InsertBefore, Next, Phi_, TLI, AA, DTU);
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};
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int NumMerged = 1;
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BasicBlock *NextCmpBlock = Phi_.getParent();
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@ -684,11 +694,14 @@ bool BCECmpChain::simplify(const TargetLibraryInfo *const TLI,
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<< "\n");
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++NumMerged;
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} else {
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NextCmpBlock = mergeRange(I + 1, NumMerged, NextCmpBlock);
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NextCmpBlock = mergeRange(I + 1, NumMerged, NextCmpBlock, NextCmpBlock);
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NumMerged = 1;
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}
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}
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NextCmpBlock = mergeRange(0, NumMerged, NextCmpBlock);
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// Insert the entry block for the new chain before the old entry block.
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// If the old entry block was the function entry, this ensures that the new
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// entry can become the function entry.
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NextCmpBlock = mergeRange(0, NumMerged, EntryBlock_, NextCmpBlock);
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// Replace the original cmp chain with the new cmp chain by pointing all
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// predecessors of EntryBlock_ to NextCmpBlock instead. This makes all cmp
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@ -698,6 +711,20 @@ bool BCECmpChain::simplify(const TargetLibraryInfo *const TLI,
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LLVM_DEBUG(dbgs() << "Updating jump into old chain from " << Pred->getName()
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<< "\n");
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Pred->getTerminator()->replaceUsesOfWith(EntryBlock_, NextCmpBlock);
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DTU.applyUpdates({{DominatorTree::Delete, Pred, EntryBlock_},
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{DominatorTree::Insert, Pred, NextCmpBlock}});
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}
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// If the old cmp chain was the function entry, we need to update the function
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// entry.
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const bool ChainEntryIsFnEntry =
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(EntryBlock_ == &EntryBlock_->getParent()->getEntryBlock());
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if (ChainEntryIsFnEntry && DTU.hasDomTree()) {
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LLVM_DEBUG(dbgs() << "Changing function entry from "
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<< EntryBlock_->getName() << " to "
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<< NextCmpBlock->getName() << "\n");
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DTU.getDomTree().setNewRoot(NextCmpBlock);
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DTU.applyUpdates({{DominatorTree::Delete, NextCmpBlock, EntryBlock_}});
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}
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EntryBlock_ = nullptr;
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@ -707,7 +734,7 @@ bool BCECmpChain::simplify(const TargetLibraryInfo *const TLI,
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LLVM_DEBUG(dbgs() << "Deleting merged block " << Cmp.BB->getName() << "\n");
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DeadBlocks.push_back(Cmp.BB);
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}
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DeleteDeadBlocks(DeadBlocks);
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DeleteDeadBlocks(DeadBlocks, &DTU);
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Comparisons_.clear();
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return true;
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@ -749,7 +776,7 @@ std::vector<BasicBlock *> getOrderedBlocks(PHINode &Phi,
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}
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bool processPhi(PHINode &Phi, const TargetLibraryInfo *const TLI,
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AliasAnalysis *AA) {
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AliasAnalysis *AA, DomTreeUpdater &DTU) {
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LLVM_DEBUG(dbgs() << "processPhi()\n");
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if (Phi.getNumIncomingValues() <= 1) {
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LLVM_DEBUG(dbgs() << "skip: only one incoming value in phi\n");
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@ -814,7 +841,7 @@ bool processPhi(PHINode &Phi, const TargetLibraryInfo *const TLI,
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return false;
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}
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return CmpChain.simplify(TLI, AA);
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return CmpChain.simplify(TLI, AA, DTU);
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}
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class MergeICmps : public FunctionPass {
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@ -829,8 +856,14 @@ class MergeICmps : public FunctionPass {
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if (skipFunction(F)) return false;
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const auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
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const auto &TTI = getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
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// MergeICmps does not need the DominatorTree, but we update it if it's
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// already available.
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auto *DTWP = getAnalysisIfAvailable<DominatorTreeWrapperPass>();
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DomTreeUpdater DTU(DTWP ? &DTWP->getDomTree() : nullptr,
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/*PostDominatorTree*/ nullptr,
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DomTreeUpdater::UpdateStrategy::Eager);
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AliasAnalysis *AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
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auto PA = runImpl(F, &TLI, &TTI, AA);
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auto PA = runImpl(F, &TLI, &TTI, AA, DTU);
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return !PA.areAllPreserved();
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}
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@ -839,15 +872,18 @@ class MergeICmps : public FunctionPass {
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AU.addRequired<TargetLibraryInfoWrapperPass>();
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AU.addRequired<TargetTransformInfoWrapperPass>();
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AU.addRequired<AAResultsWrapperPass>();
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AU.addPreserved<GlobalsAAWrapperPass>();
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AU.addPreserved<DominatorTreeWrapperPass>();
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}
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PreservedAnalyses runImpl(Function &F, const TargetLibraryInfo *TLI,
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const TargetTransformInfo *TTI, AliasAnalysis *AA);
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const TargetTransformInfo *TTI, AliasAnalysis *AA,
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DomTreeUpdater &DTU);
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};
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PreservedAnalyses MergeICmps::runImpl(Function &F, const TargetLibraryInfo *TLI,
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const TargetTransformInfo *TTI,
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AliasAnalysis *AA) {
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AliasAnalysis *AA, DomTreeUpdater &DTU) {
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LLVM_DEBUG(dbgs() << "MergeICmpsPass: " << F.getName() << "\n");
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// We only try merging comparisons if the target wants to expand memcmp later.
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@ -863,11 +899,15 @@ PreservedAnalyses MergeICmps::runImpl(Function &F, const TargetLibraryInfo *TLI,
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for (auto BBIt = ++F.begin(); BBIt != F.end(); ++BBIt) {
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// A Phi operation is always first in a basic block.
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if (auto *const Phi = dyn_cast<PHINode>(&*BBIt->begin()))
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MadeChange |= processPhi(*Phi, TLI, AA);
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MadeChange |= processPhi(*Phi, TLI, AA, DTU);
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}
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if (MadeChange) return PreservedAnalyses::none();
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return PreservedAnalyses::all();
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if (!MadeChange)
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return PreservedAnalyses::all();
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PreservedAnalyses PA;
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PA.preserve<GlobalsAA>();
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PA.preserve<DominatorTreeAnalysis>();
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return PA;
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}
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} // namespace
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@ -1,5 +1,5 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -mtriple=x86_64-unknown-unknown -mergeicmps -S | FileCheck %s --check-prefix=X86
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; RUN: opt < %s -mtriple=x86_64-unknown-unknown -mergeicmps -verify-dom-info -S | FileCheck %s --check-prefix=X86
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%S = type { i32, i32, i32, i32 }
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@ -1,5 +1,5 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -mergeicmps -mtriple=x86_64-unknown-unknown -S | FileCheck %s
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; RUN: opt < %s -mergeicmps -verify-dom-info -mtriple=x86_64-unknown-unknown -S | FileCheck %s
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%S = type { i32, i32 }
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@ -1,5 +1,5 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -mergeicmps -mtriple=x86_64-unknown-unknown -S | FileCheck %s
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; RUN: opt < %s -mergeicmps -verify-dom-info -mtriple=x86_64-unknown-unknown -S | FileCheck %s
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%S = type { i32, i32, i32, i32 }
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@ -1,5 +1,5 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -mergeicmps -mtriple=x86_64-unknown-unknown -S | FileCheck %s
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; RUN: opt < %s -mergeicmps -verify-dom-info -mtriple=x86_64-unknown-unknown -S | FileCheck %s
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%S = type { i32, i32 }
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@ -1,5 +1,5 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -mtriple=x86_64-unknown-unknown -mergeicmps -S | FileCheck %s --check-prefix=X86
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; RUN: opt < %s -mtriple=x86_64-unknown-unknown -mergeicmps -verify-dom-info -S | FileCheck %s --check-prefix=X86
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; 8-byte int and 8-byte pointer should merge into a 16-byte memcmp.
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; X86: memcmp(i8* {{.*}}, i8* {{.*}}, i64 16)
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@ -1,5 +1,5 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -mergeicmps -mtriple=x86_64-unknown-unknown -S | FileCheck %s
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; RUN: opt < %s -mergeicmps -verify-dom-info -mtriple=x86_64-unknown-unknown -S | FileCheck %s
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%S = type { i32, i32, i32 }
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@ -1,5 +1,5 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -mergeicmps -mtriple=x86_64-unknown-unknown -S | FileCheck %s --check-prefix=X86
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; RUN: opt < %s -mergeicmps -verify-dom-info -mtriple=x86_64-unknown-unknown -S | FileCheck %s --check-prefix=X86
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%S = type { i32, i32, i32, i32 }
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@ -1,6 +1,6 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -mergeicmps -mtriple=x86_64-unknown-unknown -S | FileCheck %s --check-prefix=X86
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; RUN: opt < %s -mergeicmps -mtriple=x86_64-unknown-unknown -S -disable-simplify-libcalls | FileCheck %s --check-prefix=X86-NOBUILTIN
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; RUN: opt < %s -mergeicmps -verify-dom-info -mtriple=x86_64-unknown-unknown -S | FileCheck %s --check-prefix=X86
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; RUN: opt < %s -mergeicmps -verify-dom-info -mtriple=x86_64-unknown-unknown -S -disable-simplify-libcalls | FileCheck %s --check-prefix=X86-NOBUILTIN
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%S = type { i32, i32 }
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@ -1,5 +1,5 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -mergeicmps -mtriple=x86_64-unknown-unknown -S | FileCheck %s --check-prefix=X86
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; RUN: opt < %s -mergeicmps -verify-dom-info -mtriple=x86_64-unknown-unknown -S | FileCheck %s --check-prefix=X86
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source_filename = "qabstractitemmodeltester.cpp"
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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@ -1,5 +1,5 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -mergeicmps -S | FileCheck %s
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; RUN: opt < %s -mergeicmps -verify-dom-info -S | FileCheck %s
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target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
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target triple = "i386-pc-windows-msvc19.11.0"
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@ -1,5 +1,5 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -mergeicmps -mtriple=x86_64-unknown-unknown -S | FileCheck %s --check-prefix=X86
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; RUN: opt < %s -mergeicmps -verify-dom-info -mtriple=x86_64-unknown-unknown -S | FileCheck %s --check-prefix=X86
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%S = type { i32, i32, i32, i32 }
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@ -1,6 +1,6 @@
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; XFAIL: *
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -mergeicmps -mtriple=x86_64-unknown-unknown -S | FileCheck %s
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; RUN: opt < %s -mergeicmps -verify-dom-info -mtriple=x86_64-unknown-unknown -S | FileCheck %s
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; This is a more involved test: clang generates this weird pattern for
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; tuple<uint8_t, uint8_t, uint8_t, uint8_t>. Right now we skip the entry block
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@ -1,5 +1,5 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -mergeicmps -mtriple=x86_64-unknown-unknown -S | FileCheck %s --check-prefix=X86
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; RUN: opt < %s -mergeicmps -verify-dom-info -mtriple=x86_64-unknown-unknown -S | FileCheck %s --check-prefix=X86
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%S = type { i32, i32 }
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@ -1,5 +1,5 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -mergeicmps -mtriple=x86_64-unknown-unknown -S | FileCheck %s
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; RUN: opt < %s -mergeicmps -verify-dom-info -mtriple=x86_64-unknown-unknown -S | FileCheck %s
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%S = type { i32, i32 }
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