[llvm-commits] [llvm] r42299 - in /llvm/trunk: lib/Transforms/Scalar/LoopIndexSplit.cpp test/Transforms/LoopIndexSplit/2007-09-24-UpdateIterationSpace.ll
Devang Patel
dpatel at apple.com
Tue Sep 25 10:31:20 PDT 2007
Author: dpatel
Date: Tue Sep 25 12:31:19 2007
New Revision: 42299
URL: http://llvm.org/viewvc/llvm-project?rev=42299&view=rev
Log:
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();
Added:
llvm/trunk/test/Transforms/LoopIndexSplit/2007-09-24-UpdateIterationSpace.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp?rev=42299&r1=42298&r2=42299&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopIndexSplit.cpp Tue Sep 25 12:31:19 2007
@@ -728,6 +728,27 @@
else
NV = V1;
+ if (ExitCondition->getPredicate() == ICmpInst::ICMP_SGT
+ || ExitCondition->getPredicate() == ICmpInst::ICMP_UGT
+ || ExitCondition->getPredicate() == ICmpInst::ICMP_SGE
+ || ExitCondition->getPredicate() == ICmpInst::ICMP_UGE) {
+ ExitCondition->swapOperands();
+ if (ExitValueNum)
+ ExitValueNum = 0;
+ else
+ ExitValueNum = 1;
+ }
+
+ Value *NUB = NULL;
+ Value *NLB = NULL;
+ Value *UB = ExitCondition->getOperand(ExitValueNum);
+ const Type *Ty = NV->getType();
+ bool Sign = ExitCondition->isSignedPredicate();
+ BasicBlock *Preheader = L->getLoopPreheader();
+ Instruction *PHTerminator = Preheader->getTerminator();
+
+ assert (NV && "Unexpected value");
+
switch (CI->getPredicate()) {
case ICmpInst::ICMP_ULE:
case ICmpInst::ICMP_SLE:
@@ -740,9 +761,15 @@
// for (i = LB; i < NUB ; ++i)
// LOOP_BODY
//
-
-
-
+ if (ExitCondition->getPredicate() == ICmpInst::ICMP_SLT
+ || ExitCondition->getPredicate() == ICmpInst::ICMP_ULT) {
+ Value *A = BinaryOperator::createAdd(NV, ConstantInt::get(Ty, 1, Sign),
+ "lsplit.add", PHTerminator);
+ Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
+ A, UB,"lsplit,c", PHTerminator);
+ NUB = new SelectInst (C, A, UB, "lsplit.nub", PHTerminator);
+ }
+
// for (i = LB; i <= UB; ++i)
// if (i <= NV && ...)
// LOOP_BODY
@@ -752,6 +779,12 @@
// for (i = LB; i <= NUB ; ++i)
// LOOP_BODY
//
+ else if (ExitCondition->getPredicate() == ICmpInst::ICMP_SLE
+ || ExitCondition->getPredicate() == ICmpInst::ICMP_ULE) {
+ Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
+ NV, UB, "lsplit.c", PHTerminator);
+ NUB = new SelectInst (C, NV, UB, "lsplit.nub", PHTerminator);
+ }
break;
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_SLT:
@@ -764,8 +797,12 @@
// for (i = LB; i < NUB ; ++i)
// LOOP_BODY
//
-
-
+ if (ExitCondition->getPredicate() == ICmpInst::ICMP_SLT
+ || ExitCondition->getPredicate() == ICmpInst::ICMP_ULT) {
+ Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
+ NV, UB, "lsplit.c", PHTerminator);
+ NUB = new SelectInst (C, NV, UB, "lsplit.nub", PHTerminator);
+ }
// for (i = LB; i <= UB; ++i)
// if (i < NV && ...)
@@ -776,6 +813,14 @@
// for (i = LB; i <= NUB ; ++i)
// LOOP_BODY
//
+ else if (ExitCondition->getPredicate() == ICmpInst::ICMP_SLE
+ || ExitCondition->getPredicate() == ICmpInst::ICMP_ULE) {
+ Value *S = BinaryOperator::createSub(NV, ConstantInt::get(Ty, 1, Sign),
+ "lsplit.add", PHTerminator);
+ Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
+ S, UB, "lsplit.c", PHTerminator);
+ NUB = new SelectInst (C, S, UB, "lsplit.nub", PHTerminator);
+ }
break;
case ICmpInst::ICMP_UGE:
case ICmpInst::ICMP_SGE:
@@ -788,6 +833,11 @@
// for (i = NLB; i (< or <=) UB ; ++i)
// LOOP_BODY
//
+ {
+ Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
+ NV, StartValue, "lsplit.c", PHTerminator);
+ NLB = new SelectInst (C, StartValue, NV, "lsplit.nlb", PHTerminator);
+ }
break;
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_SGT:
@@ -800,10 +850,26 @@
// for (i = NLB; i (< or <=) UB ; ++i)
// LOOP_BODY
//
+ {
+ Value *A = BinaryOperator::createAdd(NV, ConstantInt::get(Ty, 1, Sign),
+ "lsplit.add", PHTerminator);
+ Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
+ A, StartValue, "lsplit.c", PHTerminator);
+ NLB = new SelectInst (C, StartValue, A, "lsplit.nlb", PHTerminator);
+ }
break;
default:
assert ( 0 && "Unexpected split condition predicate");
}
+
+ if (NLB) {
+ unsigned i = IndVar->getBasicBlockIndex(Preheader);
+ IndVar->setIncomingValue(i, NLB);
+ }
+
+ if (NUB) {
+ ExitCondition->setOperand(ExitValueNum, NUB);
+ }
}
/// updateLoopIterationSpace - Current loop body is covered by an AND
/// instruction whose operands compares induction variables with loop
@@ -811,6 +877,9 @@
/// updating appropriate start and end values for induction variable.
bool LoopIndexSplit::updateLoopIterationSpace(SplitInfo &SD) {
BasicBlock *Header = L->getHeader();
+ BasicBlock *ExitingBlock = ExitCondition->getParent();
+ BasicBlock *SplitCondBlock = SD.SplitCondition->getParent();
+
ICmpInst *Op0 = cast<ICmpInst>(SD.SplitCondition->getOperand(0));
ICmpInst *Op1 = cast<ICmpInst>(SD.SplitCondition->getOperand(1));
@@ -865,11 +934,83 @@
// loop may not be eliminated.
if (!safeExitingBlock(SD, ExitCondition->getParent()))
return false;
-
+
+ // Verify that loop exiting block has only two predecessor, where one predecessor
+ // is split condition block. The other predecessor will become exiting block's
+ // dominator after CFG is updated. TODO : Handle CFG's where exiting block has
+ // more then two predecessors. This requires extra work in updating dominator
+ // information.
+ BasicBlock *ExitingBBPred = NULL;
+ for (pred_iterator PI = pred_begin(ExitingBlock), PE = pred_end(ExitingBlock);
+ PI != PE; ++PI) {
+ BasicBlock *BB = *PI;
+ if (SplitCondBlock == BB)
+ continue;
+ if (ExitingBBPred)
+ return false;
+ else
+ ExitingBBPred = BB;
+ }
+
+ // Update loop bounds to absorb Op0 check.
updateLoopBounds(Op0);
+ // Update loop bounds to absorb Op1 check.
updateLoopBounds(Op1);
+
// Update CFG
- return false;
+
+ // Unconditionally connect split block to its remaining successor.
+ BranchInst *SplitTerminator =
+ cast<BranchInst>(SplitCondBlock->getTerminator());
+ BasicBlock *Succ0 = SplitTerminator->getSuccessor(0);
+ BasicBlock *Succ1 = SplitTerminator->getSuccessor(1);
+ if (Succ0 == ExitCondition->getParent())
+ SplitTerminator->setUnconditionalDest(Succ1);
+ else
+ SplitTerminator->setUnconditionalDest(Succ0);
+
+ // Remove split condition.
+ SD.SplitCondition->eraseFromParent();
+ if (Op0->use_begin() == Op0->use_end())
+ Op0->eraseFromParent();
+ if (Op1->use_begin() == Op1->use_end())
+ Op1->eraseFromParent();
+
+ BranchInst *ExitInsn =
+ dyn_cast<BranchInst>(ExitingBlock->getTerminator());
+ assert (ExitInsn && "Unable to find suitable loop exit branch");
+ BasicBlock *ExitBlock = ExitInsn->getSuccessor(1);
+ if (L->contains(ExitBlock))
+ ExitBlock = ExitInsn->getSuccessor(0);
+
+ // Update domiantor info. Now, ExitingBlock has only one predecessor,
+ // ExitingBBPred, and it is ExitingBlock's immediate domiantor.
+ DT->changeImmediateDominator(ExitingBlock, ExitingBBPred);
+
+ // If ExitingBlock is a member of loop BB's DF list then replace it with
+ // loop header and exit block.
+ for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
+ I != E; ++I) {
+ BasicBlock *BB = *I;
+ if (BB == Header || BB == ExitingBlock)
+ continue;
+ DominanceFrontier::iterator BBDF = DF->find(BB);
+ DominanceFrontier::DomSetType::iterator DomSetI = BBDF->second.begin();
+ DominanceFrontier::DomSetType::iterator DomSetE = BBDF->second.end();
+ while (DomSetI != DomSetE) {
+ DominanceFrontier::DomSetType::iterator CurrentItr = DomSetI;
+ ++DomSetI;
+ BasicBlock *DFBB = *CurrentItr;
+ if (DFBB == ExitingBlock) {
+ BBDF->second.erase(DFBB);
+ BBDF->second.insert(Header);
+ if (Header != ExitingBlock)
+ BBDF->second.insert(ExitBlock);
+ }
+ }
+ }
+
+ return return;
}
Added: llvm/trunk/test/Transforms/LoopIndexSplit/2007-09-24-UpdateIterationSpace.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopIndexSplit/2007-09-24-UpdateIterationSpace.ll?rev=42299&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopIndexSplit/2007-09-24-UpdateIterationSpace.ll (added)
+++ llvm/trunk/test/Transforms/LoopIndexSplit/2007-09-24-UpdateIterationSpace.ll Tue Sep 25 12:31:19 2007
@@ -0,0 +1,57 @@
+
+; Update loop iteraton space to eliminate condition inside loop.
+; RUN: llvm-as < %s | opt -loop-index-split | llvm-dis | not grep bothcond
+define void @test(float* %x, i32 %ndat, float** %y, float %xcen, i32 %xmin, i32 %xmax, float %sigmal, float %contribution) {
+entry:
+ %tmp519 = icmp sgt i32 %xmin, %xmax ; <i1> [#uses=1]
+ br i1 %tmp519, label %return, label %bb.preheader
+
+bb.preheader: ; preds = %entry
+ %tmp3031 = fpext float %contribution to double ; <double> [#uses=1]
+ %tmp32 = mul double %tmp3031, 5.000000e-01 ; <double> [#uses=1]
+ %tmp3839 = fpext float %sigmal to double ; <double> [#uses=1]
+ br label %bb
+
+bb: ; preds = %bb.preheader, %cond_next45
+ %i.01.0 = phi i32 [ %tmp47, %cond_next45 ], [ %xmin, %bb.preheader ] ; <i32> [#uses=6]
+ %tmp2 = icmp sgt i32 %i.01.0, -1 ; <i1> [#uses=1]
+ %tmp6 = icmp slt i32 %i.01.0, %ndat ; <i1> [#uses=1]
+ %bothcond = and i1 %tmp2, %tmp6 ; <i1> [#uses=1]
+ br i1 %bothcond, label %cond_true9, label %cond_next45
+
+cond_true9: ; preds = %bb
+ %tmp12 = getelementptr float* %x, i32 %i.01.0 ; <float*> [#uses=1]
+ %tmp13 = load float* %tmp12, align 4 ; <float> [#uses=1]
+ %tmp15 = sub float %xcen, %tmp13 ; <float> [#uses=1]
+ %tmp16 = tail call float @fabsf( float %tmp15 ) ; <float> [#uses=1]
+ %tmp18 = fdiv float %tmp16, %sigmal ; <float> [#uses=1]
+ %tmp21 = load float** %y, align 4 ; <float*> [#uses=2]
+ %tmp27 = getelementptr float* %tmp21, i32 %i.01.0 ; <float*> [#uses=1]
+ %tmp28 = load float* %tmp27, align 4 ; <float> [#uses=1]
+ %tmp2829 = fpext float %tmp28 to double ; <double> [#uses=1]
+ %tmp34 = sub float -0.000000e+00, %tmp18 ; <float> [#uses=1]
+ %tmp3435 = fpext float %tmp34 to double ; <double> [#uses=1]
+ %tmp36 = tail call double @exp( double %tmp3435 ) ; <double> [#uses=1]
+ %tmp37 = mul double %tmp32, %tmp36 ; <double> [#uses=1]
+ %tmp40 = fdiv double %tmp37, %tmp3839 ; <double> [#uses=1]
+ %tmp41 = add double %tmp2829, %tmp40 ; <double> [#uses=1]
+ %tmp4142 = fptrunc double %tmp41 to float ; <float> [#uses=1]
+ %tmp44 = getelementptr float* %tmp21, i32 %i.01.0 ; <float*> [#uses=1]
+ store float %tmp4142, float* %tmp44, align 4
+ br label %cond_next45
+
+cond_next45: ; preds = %bb, %cond_true9
+ %tmp47 = add i32 %i.01.0, 1 ; <i32> [#uses=2]
+ %tmp51 = icmp sgt i32 %tmp47, %xmax ; <i1> [#uses=1]
+ br i1 %tmp51, label %return.loopexit, label %bb
+
+return.loopexit: ; preds = %cond_next45
+ br label %return
+
+return: ; preds = %return.loopexit, %entry
+ ret void
+}
+
+declare float @fabsf(float)
+
+declare double @exp(double)
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