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Cosmetic change
"True Loop" and "False Loop" naming terminology to refer two loops after loop cloning is confusing. Instead just use A_Loop and B_Loop. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41287 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel
parent
b753a9bb62
commit
a8644e306d
@ -757,60 +757,73 @@ bool LoopIndexSplit::splitLoop(SplitInfo &SD) {
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if (!safeSplitCondition(SD))
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return false;
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// True loop is original loop. False loop is cloned loop.
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BasicBlock *TL_SplitCondBlock = SD.SplitCondition->getParent();
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BasicBlock *TL_Preheader = L->getLoopPreheader();
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// After loop is cloned there are two loops.
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//
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// First loop, referred as ALoop, executes first part of loop's iteration
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// space split. Second loop, referred as BLoop, executes remaining
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// part of loop's iteration space.
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//
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// ALoop's exit edge enters BLoop's header through a forwarding block which
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// acts as a BLoop's preheader.
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bool SignedPredicate = ExitCondition->isSignedPredicate();
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//[*] Calculate True loop's new Exit Value in loop preheader.
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// TL_ExitValue = min(SplitValue, ExitValue)
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//[*] Calculate False loop's new Start Value in loop preheader.
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// FL_StartValue = max(SplitValue, TrueLoop.StartValue)
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Value *TL_ExitValue = NULL;
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Value *FL_StartValue = NULL;
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//[*] Calculate ALoop induction variable's new exiting value and
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// BLoop induction variable's new starting value. Calculuate these
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// values in original loop's preheader.
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// A_ExitValue = min(SplitValue, OrignalLoopExitValue)
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// B_StartValue = max(SplitValue, OriginalLoopStartValue)
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Value *A_ExitValue = NULL;
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Value *B_StartValue = NULL;
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if (isa<ConstantInt>(SD.SplitValue)) {
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TL_ExitValue = SD.SplitValue;
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FL_StartValue = SD.SplitValue;
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A_ExitValue = SD.SplitValue;
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B_StartValue = SD.SplitValue;
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}
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else {
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Instruction *TL_PHTerminator = TL_Preheader->getTerminator();
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BasicBlock *Preheader = L->getLoopPreheader();
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Instruction *PHTerminator = Preheader->getTerminator();
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bool SignedPredicate = ExitCondition->isSignedPredicate();
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Value *C1 = new ICmpInst(SignedPredicate ?
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ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
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SD.SplitValue,
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ExitCondition->getOperand(ExitValueNum),
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"lsplit.ev", TL_PHTerminator);
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TL_ExitValue = new SelectInst(C1, SD.SplitValue,
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"lsplit.ev", PHTerminator);
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A_ExitValue = new SelectInst(C1, SD.SplitValue,
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ExitCondition->getOperand(ExitValueNum),
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"lsplit.ev", TL_PHTerminator);
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"lsplit.ev", PHTerminator);
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Value *C2 = new ICmpInst(SignedPredicate ?
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ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
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SD.SplitValue, StartValue, "lsplit.sv",
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TL_PHTerminator);
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FL_StartValue = new SelectInst(C2, StartValue, SD.SplitValue,
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"lsplit.sv", TL_PHTerminator);
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PHTerminator);
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B_StartValue = new SelectInst(C2, StartValue, SD.SplitValue,
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"lsplit.sv", PHTerminator);
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}
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//[*] Clone loop. Avoid true destination of split condition and
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// the blocks dominated by true destination.
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//[*] Clone loop.
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DenseMap<const Value *, Value *> ValueMap;
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Loop *FalseLoop = CloneLoop(L, LPM, LI, ValueMap, this);
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BasicBlock *FL_Header = FalseLoop->getHeader();
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Loop *BLoop = CloneLoop(L, LPM, LI, ValueMap, this);
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BasicBlock *B_Header = BLoop->getHeader();
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//[*] True loop's exit edge enters False loop.
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PHINode *FL_IndVar = cast<PHINode>(ValueMap[IndVar]);
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BasicBlock *TL_ExitingBlock = ExitCondition->getParent();
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BranchInst *TL_ExitInsn =
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dyn_cast<BranchInst>(TL_ExitingBlock->getTerminator());
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assert (TL_ExitInsn && "Unable to find suitable loop exit branch");
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BasicBlock *TL_ExitDest = TL_ExitInsn->getSuccessor(1);
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if (L->contains(TL_ExitDest)) {
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TL_ExitDest = TL_ExitInsn->getSuccessor(0);
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TL_ExitInsn->setSuccessor(0, FL_Header);
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//[*] ALoop's exiting edge BLoop's header.
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// ALoop's original exit block becomes BLoop's exit block.
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PHINode *B_IndVar = cast<PHINode>(ValueMap[IndVar]);
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BasicBlock *A_ExitingBlock = ExitCondition->getParent();
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BranchInst *A_ExitInsn =
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dyn_cast<BranchInst>(A_ExitingBlock->getTerminator());
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assert (A_ExitInsn && "Unable to find suitable loop exit branch");
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BasicBlock *B_ExitBlock = A_ExitInsn->getSuccessor(1);
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if (L->contains(B_ExitBlock)) {
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B_ExitBlock = A_ExitInsn->getSuccessor(0);
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A_ExitInsn->setSuccessor(0, B_Header);
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} else
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TL_ExitInsn->setSuccessor(1, FL_Header);
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A_ExitInsn->setSuccessor(1, B_Header);
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//[*] Update ALoop's exit value using new exit value.
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ExitCondition->setOperand(ExitValueNum, A_ExitValue);
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// [*] Update BLoop's header phi nodes. Remove incoming PHINode's from
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// original loop's preheader. Add incoming PHINode values from
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// ALoop's exiting block. Update BLoop header's domiantor info.
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// Collect inverse map of Header PHINodes.
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DenseMap<Value *, Value *> InverseMap;
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for (BasicBlock::iterator BI = L->getHeader()->begin(),
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@ -821,76 +834,81 @@ bool LoopIndexSplit::splitLoop(SplitInfo &SD) {
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} else
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break;
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}
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// Update False loop's header
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for (BasicBlock::iterator BI = FL_Header->begin(), BE = FL_Header->end();
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BasicBlock *Preheader = L->getLoopPreheader();
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for (BasicBlock::iterator BI = B_Header->begin(), BE = B_Header->end();
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BI != BE; ++BI) {
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if (PHINode *PN = dyn_cast<PHINode>(BI)) {
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PN->removeIncomingValue(TL_Preheader);
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if (PN == FL_IndVar)
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PN->addIncoming(FL_StartValue, TL_ExitingBlock);
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// Remove incoming value from original preheader.
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PN->removeIncomingValue(Preheader);
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// Add incoming value from A_ExitingBlock.
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if (PN == B_IndVar)
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PN->addIncoming(B_StartValue, A_ExitingBlock);
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else {
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PHINode *OrigPN = cast<PHINode>(InverseMap[PN]);
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Value *V2 = OrigPN->getIncomingValueForBlock(TL_ExitingBlock);
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PN->addIncoming(V2, TL_ExitingBlock);
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Value *V2 = OrigPN->getIncomingValueForBlock(A_ExitingBlock);
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PN->addIncoming(V2, A_ExitingBlock);
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}
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} else
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break;
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}
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DT->changeImmediateDominator(B_Header, A_ExitingBlock);
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DF->changeImmediateDominator(B_Header, A_ExitingBlock, DT);
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// Update TL_ExitDest. Now it's predecessor is False loop's exit block.
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BasicBlock *FL_ExitingBlock = cast<BasicBlock>(ValueMap[TL_ExitingBlock]);
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for (BasicBlock::iterator BI = TL_ExitDest->begin(), BE = TL_ExitDest->end();
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// [*] Update BLoop's exit block. Its new predecessor is BLoop's exit
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// block. Remove incoming PHINode values from ALoop's exiting block.
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// Add new incoming values from BLoop's incoming exiting value.
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// Update BLoop exit block's dominator info..
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BasicBlock *B_ExitingBlock = cast<BasicBlock>(ValueMap[A_ExitingBlock]);
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for (BasicBlock::iterator BI = B_ExitBlock->begin(), BE = B_ExitBlock->end();
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BI != BE; ++BI) {
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if (PHINode *PN = dyn_cast<PHINode>(BI)) {
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PN->addIncoming(ValueMap[PN->getIncomingValueForBlock(TL_ExitingBlock)],
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FL_ExitingBlock);
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PN->removeIncomingValue(TL_ExitingBlock);
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PN->addIncoming(ValueMap[PN->getIncomingValueForBlock(A_ExitingBlock)],
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B_ExitingBlock);
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PN->removeIncomingValue(A_ExitingBlock);
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} else
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break;
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}
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if (DT) {
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DT->changeImmediateDominator(FL_Header, TL_ExitingBlock);
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DT->changeImmediateDominator(TL_ExitDest,
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cast<BasicBlock>(ValueMap[TL_ExitingBlock]));
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}
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DT->changeImmediateDominator(B_ExitBlock, B_ExitingBlock);
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DF->changeImmediateDominator(B_ExitBlock, B_ExitingBlock, DT);
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assert (!L->contains(TL_ExitDest) && " Unable to find exit edge destination");
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//[*] Split ALoop's exit edge. This creates a new block which
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// serves two purposes. First one is to hold PHINode defnitions
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// to ensure that ALoop's LCSSA form. Second use it to act
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// as a preheader for BLoop.
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BasicBlock *A_ExitBlock = SplitEdge(A_ExitingBlock, B_Header, this);
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//[*] Split Exit Edge.
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BasicBlock *TL_ExitBlock = SplitEdge(TL_ExitingBlock, FL_Header, this);
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//[*] Eliminate split condition's false branch from True loop.
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BranchInst *TL_BR = cast<BranchInst>(TL_SplitCondBlock->getTerminator());
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BasicBlock *TL_FalseBlock = TL_BR->getSuccessor(1);
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TL_BR->setUnconditionalDest(TL_BR->getSuccessor(0));
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removeBlocks(TL_FalseBlock, L, TL_BR->getSuccessor(0));
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//[*] Update True loop's exit value using new exit value.
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ExitCondition->setOperand(ExitValueNum, TL_ExitValue);
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//[*] Eliminate split condition's true branch in False loop CFG.
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BasicBlock *FL_SplitCondBlock = cast<BasicBlock>(ValueMap[TL_SplitCondBlock]);
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BranchInst *FL_BR = cast<BranchInst>(FL_SplitCondBlock->getTerminator());
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BasicBlock *FL_TrueBlock = FL_BR->getSuccessor(0);
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FL_BR->setUnconditionalDest(FL_BR->getSuccessor(1));
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removeBlocks(FL_TrueBlock, FalseLoop,
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cast<BasicBlock>(FL_BR->getSuccessor(0)));
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//[*] Preserve LCSSA
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for(BasicBlock::iterator BI = FL_Header->begin(), BE = FL_Header->end();
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//[*] Preserve ALoop's LCSSA form. Create new forwarding PHINodes
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// in A_ExitBlock to redefine outgoing PHI definitions from ALoop.
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for(BasicBlock::iterator BI = B_Header->begin(), BE = B_Header->end();
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BI != BE; ++BI) {
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if (PHINode *PN = dyn_cast<PHINode>(BI)) {
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Value *V1 = PN->getIncomingValueForBlock(TL_ExitBlock);
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Value *V1 = PN->getIncomingValueForBlock(A_ExitBlock);
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PHINode *newPHI = new PHINode(PN->getType(), PN->getName());
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newPHI->addIncoming(V1, TL_ExitingBlock);
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TL_ExitBlock->getInstList().push_front(newPHI);
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PN->removeIncomingValue(TL_ExitBlock);
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PN->addIncoming(newPHI, TL_ExitBlock);
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newPHI->addIncoming(V1, A_ExitingBlock);
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A_ExitBlock->getInstList().push_front(newPHI);
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PN->removeIncomingValue(A_ExitBlock);
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PN->addIncoming(newPHI, A_ExitBlock);
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} else
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break;
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}
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//[*] Eliminate split condition's inactive branch from ALoop.
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BasicBlock *A_SplitCondBlock = SD.SplitCondition->getParent();
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BranchInst *A_BR = cast<BranchInst>(A_SplitCondBlock->getTerminator());
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BasicBlock *A_InactiveBranch = A_BR->getSuccessor(1);
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BasicBlock *A_ActiveBranch = A_BR->getSuccessor(1);
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A_BR->setUnconditionalDest(A_BR->getSuccessor(0));
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removeBlocks(A_InactiveBranch, L, A_ActiveBranch);
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//[*] Eliminate split condition's inactive branch in from BLoop.
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BasicBlock *B_SplitCondBlock = cast<BasicBlock>(ValueMap[A_SplitCondBlock]);
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BranchInst *B_BR = cast<BranchInst>(B_SplitCondBlock->getTerminator());
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BasicBlock *B_InactiveBranch = B_BR->getSuccessor(0);
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BasicBlock *B_ActiveBranch = B_BR->getSuccessor(1);
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B_BR->setUnconditionalDest(B_BR->getSuccessor(1));
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removeBlocks(B_InactiveBranch, BLoop, B_ActiveBranch);
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return true;
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}
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