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[LV] Factor the creation of the loop induction variable out of createEmptyLoop()

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It makes things easier to understand if this is in a helper method. This is part of my ongoing spaghetti-removal operation on createEmptyLoop.

llvm-svn: 246632
This commit is contained in:
James Molloy 2015-09-02 10:15:09 +00:00
parent fe6bb5c6e4
commit e4648bcb86
1 changed files with 43 additions and 19 deletions
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62
lib/Transforms/Vectorize/LoopVectorize.cpp
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@ -316,6 +316,9 @@ protected:
/// Create an empty loop, based on the loop ranges of the old loop.
void createEmptyLoop();
/// Create a new induction variable inside L.
PHINode *createInductionVariable(Loop *L, Value *Start, Value *End,
Value *Step, Instruction *DL);
/// Copy and widen the instructions from the old loop.
virtual void vectorizeLoop();
@ -2560,6 +2563,38 @@ InnerLoopVectorizer::addStrideCheck(Instruction *Loc) {
return std::make_pair(FirstInst, TheCheck);
}
PHINode *InnerLoopVectorizer::createInductionVariable(Loop *L,
Value *Start,
Value *End,
Value *Step,
Instruction *DL) {
BasicBlock *Header = L->getHeader();
BasicBlock *Latch = L->getLoopLatch();
// As we're just creating this loop, it's possible no latch exists
// yet. If so, use the header as this will be a single block loop.
if (!Latch)
Latch = Header;
IRBuilder<> Builder(Header->getFirstInsertionPt());
setDebugLocFromInst(Builder, getDebugLocFromInstOrOperands(OldInduction));
auto *Induction = Builder.CreatePHI(Start->getType(), 2, "index");
Builder.SetInsertPoint(Latch->getTerminator());
// Create i+1 and fill the PHINode.
Value *Next = Builder.CreateAdd(Induction, Step, "index.next");
Induction->addIncoming(Start, L->getLoopPreheader());
Induction->addIncoming(Next, Latch);
// Create the compare.
Value *ICmp = Builder.CreateICmpEQ(Next, End);
Builder.CreateCondBr(ICmp, L->getExitBlock(), Header);
// Now we have two terminators. Remove the old one from the block.
Latch->getTerminator()->eraseFromParent();
return Induction;
}
void InnerLoopVectorizer::createEmptyLoop() {
/*
In this function we generate a new loop. The new loop will contain
@ -2657,7 +2692,6 @@ void InnerLoopVectorizer::createEmptyLoop() {
ConstantInt::get(ExitCountValue->getType(), VF * UF),
"min.iters.check", VectorPH->getTerminator());
Builder.SetInsertPoint(VectorPH->getTerminator());
Value *StartIdx = ConstantInt::get(IdxTy, 0);
LoopBypassBlocks.push_back(VectorPH);
@ -2689,13 +2723,6 @@ void InnerLoopVectorizer::createEmptyLoop() {
// inside the loop.
Builder.SetInsertPoint(VecBody->getFirstNonPHI());
// Generate the induction variable.
setDebugLocFromInst(Builder, getDebugLocFromInstOrOperands(OldInduction));
Induction = Builder.CreatePHI(IdxTy, 2, "index");
// The loop step is equal to the vectorization factor (num of SIMD elements)
// times the unroll factor (num of SIMD instructions).
Constant *Step = ConstantInt::get(IdxTy, VF * UF);
// Generate code to check that the loop's trip count is not less than the
// minimum loop iteration number threshold.
BasicBlock *NewVectorPH =
@ -2717,11 +2744,19 @@ void InnerLoopVectorizer::createEmptyLoop() {
// Now we need to generate the expression for N - (N % VF), which is
// the part that the vectorized body will execute.
// The loop step is equal to the vectorization factor (num of SIMD elements)
// times the unroll factor (num of SIMD instructions).
Constant *Step = ConstantInt::get(IdxTy, VF * UF);
Value *R = BypassBuilder.CreateURem(ExitCountValue, Step, "n.mod.vf");
Value *CountRoundDown = BypassBuilder.CreateSub(ExitCountValue, R, "n.vec");
Value *IdxEndRoundDown = BypassBuilder.CreateAdd(CountRoundDown, StartIdx,
"end.idx.rnd.down");
// Generate the induction variable.
Induction =
createInductionVariable(Lp, StartIdx, IdxEndRoundDown, Step,
getDebugLocFromInstOrOperands(OldInduction));
// Now, compare the new count to zero. If it is zero skip the vector loop and
// jump to the scalar loop.
Value *Cmp =
@ -2869,17 +2904,6 @@ void InnerLoopVectorizer::createEmptyLoop() {
ReplaceInstWithInst(MiddleBlock->getTerminator(),
BranchInst::Create(ExitBlock, ScalarPH, CmpN));
// Create i+1 and fill the PHINode.
Value *NextIdx = Builder.CreateAdd(Induction, Step, "index.next");
Induction->addIncoming(StartIdx, VectorPH);
Induction->addIncoming(NextIdx, VecBody);
// Create the compare.
Value *ICmp = Builder.CreateICmpEQ(NextIdx, IdxEndRoundDown);
Builder.CreateCondBr(ICmp, MiddleBlock, VecBody);
// Now we have two terminators. Remove the old one from the block.
VecBody->getTerminator()->eraseFromParent();
// Get ready to start creating new instructions into the vectorized body.
Builder.SetInsertPoint(VecBody->getFirstInsertionPt());