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Add transformation to update loop interation space. Now,
for (i=A; i<N; i++) {
if (i < X && i > Y)
do_something();
}
is transformed into
U=min(N,X); L=max(A,Y);
for (i=L;i<U;i++)
do_somethihg();
llvm-svn: 42299
This commit is contained in:
Devang Patel
parent
ee2f3359f4
commit
de9d1c3654
@ -728,6 +728,27 @@ void LoopIndexSplit::updateLoopBounds(ICmpInst *CI) {
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else
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NV = V1;
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if (ExitCondition->getPredicate() == ICmpInst::ICMP_SGT
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|| ExitCondition->getPredicate() == ICmpInst::ICMP_UGT
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|| ExitCondition->getPredicate() == ICmpInst::ICMP_SGE
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|| ExitCondition->getPredicate() == ICmpInst::ICMP_UGE) {
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ExitCondition->swapOperands();
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if (ExitValueNum)
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ExitValueNum = 0;
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else
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ExitValueNum = 1;
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}
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Value *NUB = NULL;
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Value *NLB = NULL;
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Value *UB = ExitCondition->getOperand(ExitValueNum);
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const Type *Ty = NV->getType();
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bool Sign = ExitCondition->isSignedPredicate();
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BasicBlock *Preheader = L->getLoopPreheader();
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Instruction *PHTerminator = Preheader->getTerminator();
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assert (NV && "Unexpected value");
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switch (CI->getPredicate()) {
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case ICmpInst::ICMP_ULE:
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case ICmpInst::ICMP_SLE:
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@ -740,9 +761,15 @@ void LoopIndexSplit::updateLoopBounds(ICmpInst *CI) {
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// for (i = LB; i < NUB ; ++i)
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// LOOP_BODY
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//
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if (ExitCondition->getPredicate() == ICmpInst::ICMP_SLT
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|| ExitCondition->getPredicate() == ICmpInst::ICMP_ULT) {
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Value *A = BinaryOperator::createAdd(NV, ConstantInt::get(Ty, 1, Sign),
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"lsplit.add", PHTerminator);
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Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
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A, UB,"lsplit,c", PHTerminator);
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NUB = new SelectInst (C, A, UB, "lsplit.nub", PHTerminator);
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}
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// for (i = LB; i <= UB; ++i)
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// if (i <= NV && ...)
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// LOOP_BODY
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@ -752,6 +779,12 @@ void LoopIndexSplit::updateLoopBounds(ICmpInst *CI) {
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// for (i = LB; i <= NUB ; ++i)
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// LOOP_BODY
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//
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else if (ExitCondition->getPredicate() == ICmpInst::ICMP_SLE
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|| ExitCondition->getPredicate() == ICmpInst::ICMP_ULE) {
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Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
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NV, UB, "lsplit.c", PHTerminator);
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NUB = new SelectInst (C, NV, UB, "lsplit.nub", PHTerminator);
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}
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break;
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case ICmpInst::ICMP_ULT:
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case ICmpInst::ICMP_SLT:
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@ -764,8 +797,12 @@ void LoopIndexSplit::updateLoopBounds(ICmpInst *CI) {
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// for (i = LB; i < NUB ; ++i)
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// LOOP_BODY
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//
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if (ExitCondition->getPredicate() == ICmpInst::ICMP_SLT
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|| ExitCondition->getPredicate() == ICmpInst::ICMP_ULT) {
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Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
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NV, UB, "lsplit.c", PHTerminator);
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NUB = new SelectInst (C, NV, UB, "lsplit.nub", PHTerminator);
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}
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// for (i = LB; i <= UB; ++i)
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// if (i < NV && ...)
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@ -776,6 +813,14 @@ void LoopIndexSplit::updateLoopBounds(ICmpInst *CI) {
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// for (i = LB; i <= NUB ; ++i)
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// LOOP_BODY
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//
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else if (ExitCondition->getPredicate() == ICmpInst::ICMP_SLE
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|| ExitCondition->getPredicate() == ICmpInst::ICMP_ULE) {
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Value *S = BinaryOperator::createSub(NV, ConstantInt::get(Ty, 1, Sign),
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"lsplit.add", PHTerminator);
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Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
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S, UB, "lsplit.c", PHTerminator);
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NUB = new SelectInst (C, S, UB, "lsplit.nub", PHTerminator);
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}
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break;
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case ICmpInst::ICMP_UGE:
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case ICmpInst::ICMP_SGE:
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@ -788,6 +833,11 @@ void LoopIndexSplit::updateLoopBounds(ICmpInst *CI) {
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// for (i = NLB; i (< or <=) UB ; ++i)
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// LOOP_BODY
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//
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{
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Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
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NV, StartValue, "lsplit.c", PHTerminator);
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NLB = new SelectInst (C, StartValue, NV, "lsplit.nlb", PHTerminator);
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}
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break;
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case ICmpInst::ICMP_UGT:
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case ICmpInst::ICMP_SGT:
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@ -800,10 +850,26 @@ void LoopIndexSplit::updateLoopBounds(ICmpInst *CI) {
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// for (i = NLB; i (< or <=) UB ; ++i)
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// LOOP_BODY
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//
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{
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Value *A = BinaryOperator::createAdd(NV, ConstantInt::get(Ty, 1, Sign),
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"lsplit.add", PHTerminator);
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Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
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A, StartValue, "lsplit.c", PHTerminator);
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NLB = new SelectInst (C, StartValue, A, "lsplit.nlb", PHTerminator);
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}
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break;
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default:
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assert ( 0 && "Unexpected split condition predicate");
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}
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if (NLB) {
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unsigned i = IndVar->getBasicBlockIndex(Preheader);
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IndVar->setIncomingValue(i, NLB);
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}
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if (NUB) {
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ExitCondition->setOperand(ExitValueNum, NUB);
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}
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}
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/// updateLoopIterationSpace - Current loop body is covered by an AND
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/// instruction whose operands compares induction variables with loop
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@ -811,6 +877,9 @@ void LoopIndexSplit::updateLoopBounds(ICmpInst *CI) {
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/// updating appropriate start and end values for induction variable.
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bool LoopIndexSplit::updateLoopIterationSpace(SplitInfo &SD) {
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BasicBlock *Header = L->getHeader();
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BasicBlock *ExitingBlock = ExitCondition->getParent();
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BasicBlock *SplitCondBlock = SD.SplitCondition->getParent();
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ICmpInst *Op0 = cast<ICmpInst>(SD.SplitCondition->getOperand(0));
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ICmpInst *Op1 = cast<ICmpInst>(SD.SplitCondition->getOperand(1));
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@ -865,11 +934,83 @@ bool LoopIndexSplit::updateLoopIterationSpace(SplitInfo &SD) {
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// loop may not be eliminated.
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if (!safeExitingBlock(SD, ExitCondition->getParent()))
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return false;
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// Verify that loop exiting block has only two predecessor, where one predecessor
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// is split condition block. The other predecessor will become exiting block's
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// dominator after CFG is updated. TODO : Handle CFG's where exiting block has
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// more then two predecessors. This requires extra work in updating dominator
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// information.
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BasicBlock *ExitingBBPred = NULL;
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for (pred_iterator PI = pred_begin(ExitingBlock), PE = pred_end(ExitingBlock);
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PI != PE; ++PI) {
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BasicBlock *BB = *PI;
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if (SplitCondBlock == BB)
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continue;
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if (ExitingBBPred)
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return false;
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else
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ExitingBBPred = BB;
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}
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// Update loop bounds to absorb Op0 check.
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updateLoopBounds(Op0);
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// Update loop bounds to absorb Op1 check.
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updateLoopBounds(Op1);
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// Update CFG
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return false;
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// Unconditionally connect split block to its remaining successor.
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BranchInst *SplitTerminator =
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cast<BranchInst>(SplitCondBlock->getTerminator());
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BasicBlock *Succ0 = SplitTerminator->getSuccessor(0);
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BasicBlock *Succ1 = SplitTerminator->getSuccessor(1);
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if (Succ0 == ExitCondition->getParent())
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SplitTerminator->setUnconditionalDest(Succ1);
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else
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SplitTerminator->setUnconditionalDest(Succ0);
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// Remove split condition.
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SD.SplitCondition->eraseFromParent();
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if (Op0->use_begin() == Op0->use_end())
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Op0->eraseFromParent();
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if (Op1->use_begin() == Op1->use_end())
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Op1->eraseFromParent();
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BranchInst *ExitInsn =
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dyn_cast<BranchInst>(ExitingBlock->getTerminator());
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assert (ExitInsn && "Unable to find suitable loop exit branch");
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BasicBlock *ExitBlock = ExitInsn->getSuccessor(1);
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if (L->contains(ExitBlock))
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ExitBlock = ExitInsn->getSuccessor(0);
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// Update domiantor info. Now, ExitingBlock has only one predecessor,
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// ExitingBBPred, and it is ExitingBlock's immediate domiantor.
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DT->changeImmediateDominator(ExitingBlock, ExitingBBPred);
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// If ExitingBlock is a member of loop BB's DF list then replace it with
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// loop header and exit block.
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for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
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I != E; ++I) {
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BasicBlock *BB = *I;
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if (BB == Header || BB == ExitingBlock)
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continue;
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DominanceFrontier::iterator BBDF = DF->find(BB);
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DominanceFrontier::DomSetType::iterator DomSetI = BBDF->second.begin();
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DominanceFrontier::DomSetType::iterator DomSetE = BBDF->second.end();
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while (DomSetI != DomSetE) {
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DominanceFrontier::DomSetType::iterator CurrentItr = DomSetI;
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++DomSetI;
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BasicBlock *DFBB = *CurrentItr;
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if (DFBB == ExitingBlock) {
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BBDF->second.erase(DFBB);
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BBDF->second.insert(Header);
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if (Header != ExitingBlock)
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BBDF->second.insert(ExitBlock);
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}
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}
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}
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return return;
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}
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@ -0,0 +1,57 @@
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; Update loop iteraton space to eliminate condition inside loop.
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; RUN: llvm-as < %s | opt -loop-index-split | llvm-dis | not grep bothcond
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define void @test(float* %x, i32 %ndat, float** %y, float %xcen, i32 %xmin, i32 %xmax, float %sigmal, float %contribution) {
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entry:
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%tmp519 = icmp sgt i32 %xmin, %xmax ; <i1> [#uses=1]
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br i1 %tmp519, label %return, label %bb.preheader
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bb.preheader: ; preds = %entry
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%tmp3031 = fpext float %contribution to double ; <double> [#uses=1]
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%tmp32 = mul double %tmp3031, 5.000000e-01 ; <double> [#uses=1]
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%tmp3839 = fpext float %sigmal to double ; <double> [#uses=1]
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br label %bb
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bb: ; preds = %bb.preheader, %cond_next45
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%i.01.0 = phi i32 [ %tmp47, %cond_next45 ], [ %xmin, %bb.preheader ] ; <i32> [#uses=6]
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%tmp2 = icmp sgt i32 %i.01.0, -1 ; <i1> [#uses=1]
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%tmp6 = icmp slt i32 %i.01.0, %ndat ; <i1> [#uses=1]
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%bothcond = and i1 %tmp2, %tmp6 ; <i1> [#uses=1]
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br i1 %bothcond, label %cond_true9, label %cond_next45
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cond_true9: ; preds = %bb
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%tmp12 = getelementptr float* %x, i32 %i.01.0 ; <float*> [#uses=1]
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%tmp13 = load float* %tmp12, align 4 ; <float> [#uses=1]
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%tmp15 = sub float %xcen, %tmp13 ; <float> [#uses=1]
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%tmp16 = tail call float @fabsf( float %tmp15 ) ; <float> [#uses=1]
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%tmp18 = fdiv float %tmp16, %sigmal ; <float> [#uses=1]
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%tmp21 = load float** %y, align 4 ; <float*> [#uses=2]
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%tmp27 = getelementptr float* %tmp21, i32 %i.01.0 ; <float*> [#uses=1]
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%tmp28 = load float* %tmp27, align 4 ; <float> [#uses=1]
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%tmp2829 = fpext float %tmp28 to double ; <double> [#uses=1]
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%tmp34 = sub float -0.000000e+00, %tmp18 ; <float> [#uses=1]
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%tmp3435 = fpext float %tmp34 to double ; <double> [#uses=1]
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%tmp36 = tail call double @exp( double %tmp3435 ) ; <double> [#uses=1]
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%tmp37 = mul double %tmp32, %tmp36 ; <double> [#uses=1]
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%tmp40 = fdiv double %tmp37, %tmp3839 ; <double> [#uses=1]
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%tmp41 = add double %tmp2829, %tmp40 ; <double> [#uses=1]
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%tmp4142 = fptrunc double %tmp41 to float ; <float> [#uses=1]
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%tmp44 = getelementptr float* %tmp21, i32 %i.01.0 ; <float*> [#uses=1]
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store float %tmp4142, float* %tmp44, align 4
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br label %cond_next45
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cond_next45: ; preds = %bb, %cond_true9
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%tmp47 = add i32 %i.01.0, 1 ; <i32> [#uses=2]
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%tmp51 = icmp sgt i32 %tmp47, %xmax ; <i1> [#uses=1]
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br i1 %tmp51, label %return.loopexit, label %bb
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return.loopexit: ; preds = %cond_next45
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br label %return
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return: ; preds = %return.loopexit, %entry
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ret void
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}
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declare float @fabsf(float)
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declare double @exp(double)
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