2007-08-07 00:25:56 +00:00
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//===- LoopIndexSplit.cpp - Loop Index Splitting Pass ---------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by Devang Patel and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements Loop Index Splitting Pass.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "loop-index-split"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Analysis/LoopPass.h"
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#include "llvm/Analysis/ScalarEvolutionExpander.h"
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2007-08-08 21:39:47 +00:00
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#include "llvm/Analysis/Dominators.h"
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2007-08-10 18:07:13 +00:00
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/Cloning.h"
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2007-08-07 00:25:56 +00:00
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#include "llvm/Support/Compiler.h"
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2007-08-15 03:31:47 +00:00
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#include "llvm/ADT/DepthFirstIterator.h"
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2007-08-07 00:25:56 +00:00
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#include "llvm/ADT/Statistic.h"
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using namespace llvm;
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STATISTIC(NumIndexSplit, "Number of loops index split");
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namespace {
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class VISIBILITY_HIDDEN LoopIndexSplit : public LoopPass {
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public:
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static char ID; // Pass ID, replacement for typeid
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LoopIndexSplit() : LoopPass((intptr_t)&ID) {}
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// Index split Loop L. Return true if loop is split.
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bool runOnLoop(Loop *L, LPPassManager &LPM);
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void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequired<ScalarEvolution>();
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AU.addPreserved<ScalarEvolution>();
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AU.addRequiredID(LCSSAID);
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AU.addPreservedID(LCSSAID);
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2007-08-10 18:07:13 +00:00
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AU.addRequired<LoopInfo>();
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2007-08-07 00:25:56 +00:00
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AU.addPreserved<LoopInfo>();
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AU.addRequiredID(LoopSimplifyID);
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AU.addPreservedID(LoopSimplifyID);
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2007-08-08 22:25:28 +00:00
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AU.addRequired<DominatorTree>();
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2007-08-15 03:31:47 +00:00
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AU.addRequired<DominanceFrontier>();
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2007-08-08 21:39:47 +00:00
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AU.addPreserved<DominatorTree>();
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AU.addPreserved<DominanceFrontier>();
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2007-08-07 00:25:56 +00:00
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}
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2007-08-08 21:02:17 +00:00
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private:
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class SplitInfo {
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public:
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SplitInfo() : SplitValue(NULL), SplitCondition(NULL) {}
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2007-08-09 01:39:01 +00:00
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2007-08-08 21:02:17 +00:00
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// Induction variable's range is split at this value.
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Value *SplitValue;
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// This compare instruction compares IndVar against SplitValue.
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ICmpInst *SplitCondition;
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2007-08-08 21:18:27 +00:00
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// Clear split info.
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void clear() {
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SplitValue = NULL;
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SplitCondition = NULL;
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}
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2007-08-09 01:39:01 +00:00
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2007-08-08 21:02:17 +00:00
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};
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2007-08-10 00:33:50 +00:00
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2007-08-07 00:25:56 +00:00
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private:
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/// Find condition inside a loop that is suitable candidate for index split.
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void findSplitCondition();
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2007-08-10 00:33:50 +00:00
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/// Find loop's exit condition.
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void findLoopConditionals();
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/// Return induction variable associated with value V.
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void findIndVar(Value *V, Loop *L);
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2007-08-07 00:25:56 +00:00
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/// processOneIterationLoop - Current loop L contains compare instruction
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/// that compares induction variable, IndVar, agains loop invariant. If
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/// entire (i.e. meaningful) loop body is dominated by this compare
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/// instruction then loop body is executed only for one iteration. In
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/// such case eliminate loop structure surrounding this loop body. For
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2007-08-10 18:07:13 +00:00
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bool processOneIterationLoop(SplitInfo &SD);
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2007-08-07 00:25:56 +00:00
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2007-08-08 22:25:28 +00:00
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/// If loop header includes loop variant instruction operands then
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/// this loop may not be eliminated.
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2007-08-08 21:02:17 +00:00
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bool safeHeader(SplitInfo &SD, BasicBlock *BB);
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2007-08-07 00:25:56 +00:00
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2007-08-20 23:51:18 +00:00
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/// If Exiting block includes loop variant instructions then this
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2007-08-08 22:25:28 +00:00
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/// loop may not be eliminated.
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2007-08-20 23:51:18 +00:00
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bool safeExitingBlock(SplitInfo &SD, BasicBlock *BB);
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2007-08-07 00:25:56 +00:00
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2007-08-14 18:35:57 +00:00
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/// removeBlocks - Remove basic block DeadBB and all blocks dominated by DeadBB.
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/// This routine is used to remove split condition's dead branch, dominated by
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/// DeadBB. LiveBB dominates split conidition's other branch.
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void removeBlocks(BasicBlock *DeadBB, Loop *LP, BasicBlock *LiveBB);
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2007-08-12 07:02:51 +00:00
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2007-08-08 22:25:28 +00:00
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/// Find cost of spliting loop L.
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unsigned findSplitCost(Loop *L, SplitInfo &SD);
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2007-08-22 18:27:01 +00:00
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/// safeSplitCondition - Return true if it is possible to
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/// split loop using given split condition.
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bool safeSplitCondition(SplitInfo &SD);
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/// splitLoop - Split current loop L in two loops using split information
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/// SD. Update dominator information. Maintain LCSSA form.
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2007-08-08 21:02:17 +00:00
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bool splitLoop(SplitInfo &SD);
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2007-08-07 00:25:56 +00:00
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2007-08-10 00:33:50 +00:00
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void initialize() {
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IndVar = NULL;
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IndVarIncrement = NULL;
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ExitCondition = NULL;
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2007-08-12 07:02:51 +00:00
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StartValue = NULL;
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ExitValueNum = 0;
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SplitData.clear();
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2007-08-10 00:33:50 +00:00
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}
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2007-08-07 00:25:56 +00:00
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private:
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// Current Loop.
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Loop *L;
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2007-08-10 18:07:13 +00:00
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LPPassManager *LPM;
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LoopInfo *LI;
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2007-08-07 00:25:56 +00:00
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ScalarEvolution *SE;
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2007-08-08 22:25:28 +00:00
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DominatorTree *DT;
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2007-08-13 22:13:24 +00:00
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DominanceFrontier *DF;
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2007-08-08 21:02:17 +00:00
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SmallVector<SplitInfo, 4> SplitData;
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2007-08-10 00:33:50 +00:00
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// Induction variable whose range is being split by this transformation.
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PHINode *IndVar;
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Instruction *IndVarIncrement;
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// Loop exit condition.
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ICmpInst *ExitCondition;
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// Induction variable's initial value.
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Value *StartValue;
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2007-08-12 07:02:51 +00:00
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// Induction variable's final loop exit value operand number in exit condition..
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unsigned ExitValueNum;
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2007-08-07 00:25:56 +00:00
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};
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char LoopIndexSplit::ID = 0;
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RegisterPass<LoopIndexSplit> X ("loop-index-split", "Index Split Loops");
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}
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LoopPass *llvm::createLoopIndexSplitPass() {
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return new LoopIndexSplit();
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}
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// Index split Loop L. Return true if loop is split.
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2007-08-10 18:07:13 +00:00
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bool LoopIndexSplit::runOnLoop(Loop *IncomingLoop, LPPassManager &LPM_Ref) {
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2007-08-07 00:25:56 +00:00
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bool Changed = false;
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L = IncomingLoop;
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2007-08-10 18:07:13 +00:00
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LPM = &LPM_Ref;
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2007-08-14 23:53:57 +00:00
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2007-08-15 02:14:55 +00:00
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// FIXME - Nested loops make dominator info updates tricky.
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2007-08-14 23:53:57 +00:00
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if (!L->getSubLoops().empty())
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return false;
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2007-08-08 21:02:17 +00:00
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2007-08-07 00:25:56 +00:00
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SE = &getAnalysis<ScalarEvolution>();
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2007-08-08 22:25:28 +00:00
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DT = &getAnalysis<DominatorTree>();
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2007-08-10 18:07:13 +00:00
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LI = &getAnalysis<LoopInfo>();
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2007-08-15 03:34:53 +00:00
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DF = &getAnalysis<DominanceFrontier>();
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2007-08-07 00:25:56 +00:00
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2007-08-10 00:33:50 +00:00
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initialize();
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findLoopConditionals();
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if (!ExitCondition)
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return false;
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2007-08-07 00:25:56 +00:00
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findSplitCondition();
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2007-08-08 21:02:17 +00:00
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if (SplitData.empty())
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2007-08-07 00:25:56 +00:00
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return false;
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2007-08-08 21:02:17 +00:00
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// First see if it is possible to eliminate loop itself or not.
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for (SmallVector<SplitInfo, 4>::iterator SI = SplitData.begin(),
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2007-08-20 20:24:15 +00:00
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E = SplitData.end(); SI != E;) {
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2007-08-08 21:02:17 +00:00
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SplitInfo &SD = *SI;
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if (SD.SplitCondition->getPredicate() == ICmpInst::ICMP_EQ) {
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2007-08-10 18:07:13 +00:00
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Changed = processOneIterationLoop(SD);
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2007-08-08 21:02:17 +00:00
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if (Changed) {
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++NumIndexSplit;
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// If is loop is eliminated then nothing else to do here.
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return Changed;
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2007-08-20 20:24:15 +00:00
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} else {
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SmallVector<SplitInfo, 4>::iterator Delete_SI = SI;
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++SI;
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SplitData.erase(Delete_SI);
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2007-08-08 21:02:17 +00:00
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}
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2007-08-20 20:24:15 +00:00
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} else
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++SI;
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2007-08-08 21:02:17 +00:00
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}
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2007-08-08 22:25:28 +00:00
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unsigned MaxCost = 99;
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unsigned Index = 0;
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unsigned MostProfitableSDIndex = 0;
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2007-08-08 21:02:17 +00:00
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for (SmallVector<SplitInfo, 4>::iterator SI = SplitData.begin(),
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2007-08-08 22:25:28 +00:00
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E = SplitData.end(); SI != E; ++SI, ++Index) {
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SplitInfo SD = *SI;
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2007-08-08 21:02:17 +00:00
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// ICM_EQs are already handled above.
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2007-08-20 20:24:15 +00:00
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assert (SD.SplitCondition->getPredicate() != ICmpInst::ICMP_EQ &&
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"Unexpected split condition predicate");
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2007-08-08 22:25:28 +00:00
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unsigned Cost = findSplitCost(L, SD);
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if (Cost < MaxCost)
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MostProfitableSDIndex = Index;
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2007-08-08 21:02:17 +00:00
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}
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2007-08-07 00:25:56 +00:00
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2007-08-08 22:25:28 +00:00
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// Split most profitiable condition.
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2007-08-20 20:24:15 +00:00
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if (!SplitData.empty())
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Changed = splitLoop(SplitData[MostProfitableSDIndex]);
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2007-08-08 22:25:28 +00:00
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2007-08-07 00:25:56 +00:00
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if (Changed)
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++NumIndexSplit;
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2007-08-08 21:02:17 +00:00
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2007-08-07 00:25:56 +00:00
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return Changed;
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}
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2007-08-09 01:39:01 +00:00
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/// Return true if V is a induction variable or induction variable's
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/// increment for loop L.
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2007-08-10 00:33:50 +00:00
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void LoopIndexSplit::findIndVar(Value *V, Loop *L) {
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2007-08-09 01:39:01 +00:00
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Instruction *I = dyn_cast<Instruction>(V);
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if (!I)
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return;
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2007-08-09 01:39:01 +00:00
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// Check if I is a phi node from loop header or not.
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if (PHINode *PN = dyn_cast<PHINode>(V)) {
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if (PN->getParent() == L->getHeader()) {
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2007-08-10 00:33:50 +00:00
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IndVar = PN;
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return;
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2007-08-09 01:39:01 +00:00
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}
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}
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// Check if I is a add instruction whose one operand is
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// phi node from loop header and second operand is constant.
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if (I->getOpcode() != Instruction::Add)
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2007-08-10 00:33:50 +00:00
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return;
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2007-08-09 01:39:01 +00:00
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Value *Op0 = I->getOperand(0);
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Value *Op1 = I->getOperand(1);
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if (PHINode *PN = dyn_cast<PHINode>(Op0)) {
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if (PN->getParent() == L->getHeader()
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&& isa<ConstantInt>(Op1)) {
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IndVar = PN;
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IndVarIncrement = I;
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2007-08-10 00:33:50 +00:00
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return;
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2007-08-09 01:39:01 +00:00
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}
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}
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if (PHINode *PN = dyn_cast<PHINode>(Op1)) {
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if (PN->getParent() == L->getHeader()
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&& isa<ConstantInt>(Op0)) {
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IndVar = PN;
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IndVarIncrement = I;
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2007-08-10 00:33:50 +00:00
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return;
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2007-08-09 01:39:01 +00:00
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}
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}
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2007-08-10 00:33:50 +00:00
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return;
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}
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// Find loop's exit condition and associated induction variable.
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void LoopIndexSplit::findLoopConditionals() {
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2007-08-20 23:51:18 +00:00
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BasicBlock *ExitingBlock = NULL;
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2007-08-10 00:33:50 +00:00
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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 (!L->isLoopExit(BB))
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continue;
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2007-08-20 23:51:18 +00:00
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if (ExitingBlock)
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2007-08-10 00:33:50 +00:00
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return;
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2007-08-20 23:51:18 +00:00
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ExitingBlock = BB;
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2007-08-10 00:33:50 +00:00
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}
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2007-08-20 23:51:18 +00:00
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if (!ExitingBlock)
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2007-08-10 00:33:50 +00:00
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return;
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// If exit block's terminator is conditional branch inst then we have found
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// exit condition.
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2007-08-20 23:51:18 +00:00
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BranchInst *BR = dyn_cast<BranchInst>(ExitingBlock->getTerminator());
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2007-08-10 00:33:50 +00:00
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if (!BR || BR->isUnconditional())
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return;
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ICmpInst *CI = dyn_cast<ICmpInst>(BR->getCondition());
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if (!CI)
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return;
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ExitCondition = CI;
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// Exit condition's one operand is loop invariant exit value and second
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// operand is SCEVAddRecExpr based on induction variable.
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Value *V0 = CI->getOperand(0);
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Value *V1 = CI->getOperand(1);
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SCEVHandle SH0 = SE->getSCEV(V0);
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SCEVHandle SH1 = SE->getSCEV(V1);
|
|
|
|
|
|
|
|
if (SH0->isLoopInvariant(L) && isa<SCEVAddRecExpr>(SH1)) {
|
2007-08-12 07:02:51 +00:00
|
|
|
ExitValueNum = 0;
|
2007-08-10 00:33:50 +00:00
|
|
|
findIndVar(V1, L);
|
|
|
|
}
|
|
|
|
else if (SH1->isLoopInvariant(L) && isa<SCEVAddRecExpr>(SH0)) {
|
2007-08-12 07:02:51 +00:00
|
|
|
ExitValueNum = 1;
|
2007-08-10 00:33:50 +00:00
|
|
|
findIndVar(V0, L);
|
|
|
|
}
|
|
|
|
|
2007-08-12 07:02:51 +00:00
|
|
|
if (!IndVar)
|
2007-08-10 00:33:50 +00:00
|
|
|
ExitCondition = NULL;
|
|
|
|
else if (IndVar) {
|
|
|
|
BasicBlock *Preheader = L->getLoopPreheader();
|
|
|
|
StartValue = IndVar->getIncomingValueForBlock(Preheader);
|
|
|
|
}
|
2007-08-09 01:39:01 +00:00
|
|
|
}
|
|
|
|
|
2007-08-07 00:25:56 +00:00
|
|
|
/// Find condition inside a loop that is suitable candidate for index split.
|
|
|
|
void LoopIndexSplit::findSplitCondition() {
|
|
|
|
|
2007-08-08 21:02:17 +00:00
|
|
|
SplitInfo SD;
|
2007-08-09 01:39:01 +00:00
|
|
|
// Check all basic block's terminators.
|
2007-08-07 00:25:56 +00:00
|
|
|
|
2007-08-09 01:39:01 +00:00
|
|
|
for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
|
|
|
|
I != E; ++I) {
|
|
|
|
BasicBlock *BB = *I;
|
2007-08-07 00:25:56 +00:00
|
|
|
|
2007-08-09 01:39:01 +00:00
|
|
|
// If this basic block does not terminate in a conditional branch
|
|
|
|
// then terminator is not a suitable split condition.
|
|
|
|
BranchInst *BR = dyn_cast<BranchInst>(BB->getTerminator());
|
|
|
|
if (!BR)
|
2007-08-07 00:25:56 +00:00
|
|
|
continue;
|
2007-08-09 01:39:01 +00:00
|
|
|
|
|
|
|
if (BR->isUnconditional())
|
2007-08-07 00:25:56 +00:00
|
|
|
continue;
|
|
|
|
|
2007-08-09 01:39:01 +00:00
|
|
|
ICmpInst *CI = dyn_cast<ICmpInst>(BR->getCondition());
|
2007-08-10 00:33:50 +00:00
|
|
|
if (!CI || CI == ExitCondition)
|
2007-08-09 01:39:01 +00:00
|
|
|
return;
|
2007-08-07 00:25:56 +00:00
|
|
|
|
2007-08-09 01:39:01 +00:00
|
|
|
// If one operand is loop invariant and second operand is SCEVAddRecExpr
|
|
|
|
// based on induction variable then CI is a candidate split condition.
|
|
|
|
Value *V0 = CI->getOperand(0);
|
|
|
|
Value *V1 = CI->getOperand(1);
|
2007-08-07 00:25:56 +00:00
|
|
|
|
2007-08-09 01:39:01 +00:00
|
|
|
SCEVHandle SH0 = SE->getSCEV(V0);
|
|
|
|
SCEVHandle SH1 = SE->getSCEV(V1);
|
|
|
|
|
|
|
|
if (SH0->isLoopInvariant(L) && isa<SCEVAddRecExpr>(SH1)) {
|
|
|
|
SD.SplitValue = V0;
|
|
|
|
SD.SplitCondition = CI;
|
2007-08-10 00:33:50 +00:00
|
|
|
if (PHINode *PN = dyn_cast<PHINode>(V1)) {
|
|
|
|
if (PN == IndVar)
|
|
|
|
SplitData.push_back(SD);
|
|
|
|
}
|
|
|
|
else if (Instruction *Insn = dyn_cast<Instruction>(V1)) {
|
|
|
|
if (IndVarIncrement && IndVarIncrement == Insn)
|
|
|
|
SplitData.push_back(SD);
|
|
|
|
}
|
2007-08-09 01:39:01 +00:00
|
|
|
}
|
|
|
|
else if (SH1->isLoopInvariant(L) && isa<SCEVAddRecExpr>(SH0)) {
|
|
|
|
SD.SplitValue = V1;
|
|
|
|
SD.SplitCondition = CI;
|
2007-08-10 00:33:50 +00:00
|
|
|
if (PHINode *PN = dyn_cast<PHINode>(V0)) {
|
|
|
|
if (PN == IndVar)
|
|
|
|
SplitData.push_back(SD);
|
|
|
|
}
|
|
|
|
else if (Instruction *Insn = dyn_cast<Instruction>(V0)) {
|
|
|
|
if (IndVarIncrement && IndVarIncrement == Insn)
|
|
|
|
SplitData.push_back(SD);
|
|
|
|
}
|
2007-08-07 00:25:56 +00:00
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/// processOneIterationLoop - Current loop L contains compare instruction
|
|
|
|
/// that compares induction variable, IndVar, against loop invariant. If
|
|
|
|
/// entire (i.e. meaningful) loop body is dominated by this compare
|
|
|
|
/// instruction then loop body is executed only once. In such case eliminate
|
|
|
|
/// loop structure surrounding this loop body. For example,
|
|
|
|
/// for (int i = start; i < end; ++i) {
|
|
|
|
/// if ( i == somevalue) {
|
|
|
|
/// loop_body
|
|
|
|
/// }
|
|
|
|
/// }
|
|
|
|
/// can be transformed into
|
|
|
|
/// if (somevalue >= start && somevalue < end) {
|
|
|
|
/// i = somevalue;
|
|
|
|
/// loop_body
|
|
|
|
/// }
|
2007-08-10 18:07:13 +00:00
|
|
|
bool LoopIndexSplit::processOneIterationLoop(SplitInfo &SD) {
|
2007-08-07 00:25:56 +00:00
|
|
|
|
|
|
|
BasicBlock *Header = L->getHeader();
|
|
|
|
|
|
|
|
// First of all, check if SplitCondition dominates entire loop body
|
|
|
|
// or not.
|
|
|
|
|
|
|
|
// If SplitCondition is not in loop header then this loop is not suitable
|
|
|
|
// for this transformation.
|
2007-08-08 21:02:17 +00:00
|
|
|
if (SD.SplitCondition->getParent() != Header)
|
2007-08-07 00:25:56 +00:00
|
|
|
return false;
|
|
|
|
|
|
|
|
// If loop header includes loop variant instruction operands then
|
|
|
|
// this loop may not be eliminated.
|
2007-08-08 21:02:17 +00:00
|
|
|
if (!safeHeader(SD, Header))
|
2007-08-07 00:25:56 +00:00
|
|
|
return false;
|
|
|
|
|
2007-08-20 23:51:18 +00:00
|
|
|
// If Exiting block includes loop variant instructions then this
|
2007-08-07 00:25:56 +00:00
|
|
|
// loop may not be eliminated.
|
2007-08-20 23:51:18 +00:00
|
|
|
if (!safeExitingBlock(SD, ExitCondition->getParent()))
|
2007-08-07 00:25:56 +00:00
|
|
|
return false;
|
|
|
|
|
2007-08-08 01:51:27 +00:00
|
|
|
// Update CFG.
|
|
|
|
|
2007-08-20 20:49:01 +00:00
|
|
|
// Replace index variable with split value in loop body. Loop body is executed
|
|
|
|
// only when index variable is equal to split value.
|
|
|
|
IndVar->replaceAllUsesWith(SD.SplitValue);
|
|
|
|
|
|
|
|
// Remove Latch to Header edge.
|
2007-08-07 00:25:56 +00:00
|
|
|
BasicBlock *Latch = L->getLoopLatch();
|
2007-08-08 01:51:27 +00:00
|
|
|
BasicBlock *LatchSucc = NULL;
|
|
|
|
BranchInst *BR = dyn_cast<BranchInst>(Latch->getTerminator());
|
|
|
|
if (!BR)
|
|
|
|
return false;
|
|
|
|
Header->removePredecessor(Latch);
|
|
|
|
for (succ_iterator SI = succ_begin(Latch), E = succ_end(Latch);
|
|
|
|
SI != E; ++SI) {
|
|
|
|
if (Header != *SI)
|
|
|
|
LatchSucc = *SI;
|
|
|
|
}
|
|
|
|
BR->setUnconditionalDest(LatchSucc);
|
|
|
|
|
2007-08-07 00:25:56 +00:00
|
|
|
Instruction *Terminator = Header->getTerminator();
|
2007-08-14 01:30:57 +00:00
|
|
|
Value *ExitValue = ExitCondition->getOperand(ExitValueNum);
|
2007-08-07 00:25:56 +00:00
|
|
|
|
|
|
|
// Replace split condition in header.
|
|
|
|
// Transform
|
|
|
|
// SplitCondition : icmp eq i32 IndVar, SplitValue
|
|
|
|
// into
|
|
|
|
// c1 = icmp uge i32 SplitValue, StartValue
|
|
|
|
// c2 = icmp ult i32 vSplitValue, ExitValue
|
|
|
|
// and i32 c1, c2
|
2007-08-10 00:33:50 +00:00
|
|
|
bool SignedPredicate = ExitCondition->isSignedPredicate();
|
2007-08-07 00:25:56 +00:00
|
|
|
Instruction *C1 = new ICmpInst(SignedPredicate ?
|
|
|
|
ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE,
|
2007-08-08 21:02:17 +00:00
|
|
|
SD.SplitValue, StartValue, "lisplit",
|
|
|
|
Terminator);
|
2007-08-07 00:25:56 +00:00
|
|
|
Instruction *C2 = new ICmpInst(SignedPredicate ?
|
|
|
|
ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
|
2007-08-14 01:30:57 +00:00
|
|
|
SD.SplitValue, ExitValue, "lisplit",
|
2007-08-08 21:02:17 +00:00
|
|
|
Terminator);
|
|
|
|
Instruction *NSplitCond = BinaryOperator::createAnd(C1, C2, "lisplit",
|
|
|
|
Terminator);
|
|
|
|
SD.SplitCondition->replaceAllUsesWith(NSplitCond);
|
|
|
|
SD.SplitCondition->eraseFromParent();
|
2007-08-07 00:25:56 +00:00
|
|
|
|
|
|
|
// Now, clear latch block. Remove instructions that are responsible
|
|
|
|
// to increment induction variable.
|
|
|
|
Instruction *LTerminator = Latch->getTerminator();
|
|
|
|
for (BasicBlock::iterator LB = Latch->begin(), LE = Latch->end();
|
|
|
|
LB != LE; ) {
|
|
|
|
Instruction *I = LB;
|
|
|
|
++LB;
|
|
|
|
if (isa<PHINode>(I) || I == LTerminator)
|
|
|
|
continue;
|
|
|
|
|
2007-08-14 01:30:57 +00:00
|
|
|
if (I == IndVarIncrement)
|
|
|
|
I->replaceAllUsesWith(ExitValue);
|
|
|
|
else
|
|
|
|
I->replaceAllUsesWith(UndefValue::get(I->getType()));
|
2007-08-07 17:45:35 +00:00
|
|
|
I->eraseFromParent();
|
2007-08-07 00:25:56 +00:00
|
|
|
}
|
|
|
|
|
2007-08-10 18:07:13 +00:00
|
|
|
LPM->deleteLoopFromQueue(L);
|
2007-08-08 21:39:47 +00:00
|
|
|
|
|
|
|
// Update Dominator Info.
|
|
|
|
// Only CFG change done is to remove Latch to Header edge. This
|
|
|
|
// does not change dominator tree because Latch did not dominate
|
|
|
|
// Header.
|
2007-08-13 22:13:24 +00:00
|
|
|
if (DF) {
|
2007-08-08 21:39:47 +00:00
|
|
|
DominanceFrontier::iterator HeaderDF = DF->find(Header);
|
|
|
|
if (HeaderDF != DF->end())
|
|
|
|
DF->removeFromFrontier(HeaderDF, Header);
|
|
|
|
|
|
|
|
DominanceFrontier::iterator LatchDF = DF->find(Latch);
|
|
|
|
if (LatchDF != DF->end())
|
|
|
|
DF->removeFromFrontier(LatchDF, Header);
|
|
|
|
}
|
2007-08-07 00:25:56 +00:00
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
|
|
|
// If loop header includes loop variant instruction operands then
|
|
|
|
// this loop can not be eliminated. This is used by processOneIterationLoop().
|
2007-08-08 21:02:17 +00:00
|
|
|
bool LoopIndexSplit::safeHeader(SplitInfo &SD, BasicBlock *Header) {
|
2007-08-07 00:25:56 +00:00
|
|
|
|
|
|
|
Instruction *Terminator = Header->getTerminator();
|
|
|
|
for(BasicBlock::iterator BI = Header->begin(), BE = Header->end();
|
|
|
|
BI != BE; ++BI) {
|
|
|
|
Instruction *I = BI;
|
|
|
|
|
2007-08-14 01:30:57 +00:00
|
|
|
// PHI Nodes are OK.
|
2007-08-07 00:25:56 +00:00
|
|
|
if (isa<PHINode>(I))
|
|
|
|
continue;
|
|
|
|
|
|
|
|
// SplitCondition itself is OK.
|
2007-08-08 21:02:17 +00:00
|
|
|
if (I == SD.SplitCondition)
|
2007-08-08 01:51:27 +00:00
|
|
|
continue;
|
2007-08-07 00:25:56 +00:00
|
|
|
|
2007-08-09 01:39:01 +00:00
|
|
|
// Induction variable is OK.
|
2007-08-10 00:33:50 +00:00
|
|
|
if (I == IndVar)
|
2007-08-09 01:39:01 +00:00
|
|
|
continue;
|
|
|
|
|
|
|
|
// Induction variable increment is OK.
|
2007-08-10 00:33:50 +00:00
|
|
|
if (I == IndVarIncrement)
|
2007-08-09 01:39:01 +00:00
|
|
|
continue;
|
|
|
|
|
2007-08-07 00:25:56 +00:00
|
|
|
// Terminator is also harmless.
|
|
|
|
if (I == Terminator)
|
|
|
|
continue;
|
|
|
|
|
|
|
|
// Otherwise we have a instruction that may not be safe.
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
|
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
2007-08-20 23:51:18 +00:00
|
|
|
// If Exiting block includes loop variant instructions then this
|
2007-08-07 00:25:56 +00:00
|
|
|
// loop may not be eliminated. This is used by processOneIterationLoop().
|
2007-08-20 23:51:18 +00:00
|
|
|
bool LoopIndexSplit::safeExitingBlock(SplitInfo &SD,
|
|
|
|
BasicBlock *ExitingBlock) {
|
2007-08-07 00:25:56 +00:00
|
|
|
|
2007-08-20 23:51:18 +00:00
|
|
|
for (BasicBlock::iterator BI = ExitingBlock->begin(),
|
|
|
|
BE = ExitingBlock->end(); BI != BE; ++BI) {
|
2007-08-07 00:25:56 +00:00
|
|
|
Instruction *I = BI;
|
|
|
|
|
2007-08-14 01:30:57 +00:00
|
|
|
// PHI Nodes are OK.
|
2007-08-07 00:25:56 +00:00
|
|
|
if (isa<PHINode>(I))
|
|
|
|
continue;
|
|
|
|
|
2007-08-09 01:39:01 +00:00
|
|
|
// Induction variable increment is OK.
|
2007-08-10 00:33:50 +00:00
|
|
|
if (IndVarIncrement && IndVarIncrement == I)
|
2007-08-09 01:39:01 +00:00
|
|
|
continue;
|
|
|
|
|
2007-08-07 00:25:56 +00:00
|
|
|
// Check if I is induction variable increment instruction.
|
2007-08-10 00:33:50 +00:00
|
|
|
if (!IndVarIncrement && I->getOpcode() == Instruction::Add) {
|
2007-08-07 00:25:56 +00:00
|
|
|
|
2007-08-09 01:39:01 +00:00
|
|
|
Value *Op0 = I->getOperand(0);
|
|
|
|
Value *Op1 = I->getOperand(1);
|
2007-08-07 00:25:56 +00:00
|
|
|
PHINode *PN = NULL;
|
|
|
|
ConstantInt *CI = NULL;
|
|
|
|
|
|
|
|
if ((PN = dyn_cast<PHINode>(Op0))) {
|
|
|
|
if ((CI = dyn_cast<ConstantInt>(Op1)))
|
2007-08-10 00:33:50 +00:00
|
|
|
IndVarIncrement = I;
|
2007-08-07 00:25:56 +00:00
|
|
|
} else
|
|
|
|
if ((PN = dyn_cast<PHINode>(Op1))) {
|
|
|
|
if ((CI = dyn_cast<ConstantInt>(Op0)))
|
2007-08-10 00:33:50 +00:00
|
|
|
IndVarIncrement = I;
|
2007-08-07 00:25:56 +00:00
|
|
|
}
|
|
|
|
|
2007-08-10 00:33:50 +00:00
|
|
|
if (IndVarIncrement && PN == IndVar && CI->isOne())
|
2007-08-07 00:25:56 +00:00
|
|
|
continue;
|
|
|
|
}
|
2007-08-08 01:51:27 +00:00
|
|
|
|
2007-08-07 00:25:56 +00:00
|
|
|
// I is an Exit condition if next instruction is block terminator.
|
|
|
|
// Exit condition is OK if it compares loop invariant exit value,
|
|
|
|
// which is checked below.
|
2007-08-07 23:17:52 +00:00
|
|
|
else if (ICmpInst *EC = dyn_cast<ICmpInst>(I)) {
|
2007-08-10 00:33:50 +00:00
|
|
|
if (EC == ExitCondition)
|
2007-08-08 01:51:27 +00:00
|
|
|
continue;
|
2007-08-07 00:25:56 +00:00
|
|
|
}
|
|
|
|
|
2007-08-20 23:51:18 +00:00
|
|
|
if (I == ExitingBlock->getTerminator())
|
2007-08-10 00:33:50 +00:00
|
|
|
continue;
|
|
|
|
|
2007-08-07 00:25:56 +00:00
|
|
|
// Otherwise we have instruction that may not be safe.
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
|
2007-08-20 23:51:18 +00:00
|
|
|
// We could not find any reason to consider ExitingBlock unsafe.
|
2007-08-07 00:25:56 +00:00
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
2007-08-08 22:25:28 +00:00
|
|
|
/// Find cost of spliting loop L. Cost is measured in terms of size growth.
|
|
|
|
/// Size is growth is calculated based on amount of code duplicated in second
|
|
|
|
/// loop.
|
|
|
|
unsigned LoopIndexSplit::findSplitCost(Loop *L, SplitInfo &SD) {
|
|
|
|
|
|
|
|
unsigned Cost = 0;
|
|
|
|
BasicBlock *SDBlock = SD.SplitCondition->getParent();
|
|
|
|
for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
|
|
|
|
I != E; ++I) {
|
|
|
|
BasicBlock *BB = *I;
|
|
|
|
// If a block is not dominated by split condition block then
|
|
|
|
// it must be duplicated in both loops.
|
|
|
|
if (!DT->dominates(SDBlock, BB))
|
|
|
|
Cost += BB->size();
|
|
|
|
}
|
|
|
|
|
|
|
|
return Cost;
|
|
|
|
}
|
|
|
|
|
2007-08-14 18:35:57 +00:00
|
|
|
/// removeBlocks - Remove basic block DeadBB and all blocks dominated by DeadBB.
|
|
|
|
/// This routine is used to remove split condition's dead branch, dominated by
|
|
|
|
/// DeadBB. LiveBB dominates split conidition's other branch.
|
|
|
|
void LoopIndexSplit::removeBlocks(BasicBlock *DeadBB, Loop *LP,
|
|
|
|
BasicBlock *LiveBB) {
|
2007-08-12 07:02:51 +00:00
|
|
|
|
2007-08-15 03:31:47 +00:00
|
|
|
// First update DeadBB's dominance frontier.
|
2007-08-17 21:59:16 +00:00
|
|
|
SmallVector<BasicBlock *, 8> FrontierBBs;
|
2007-08-15 03:31:47 +00:00
|
|
|
DominanceFrontier::iterator DeadBBDF = DF->find(DeadBB);
|
|
|
|
if (DeadBBDF != DF->end()) {
|
|
|
|
SmallVector<BasicBlock *, 8> PredBlocks;
|
|
|
|
|
|
|
|
DominanceFrontier::DomSetType DeadBBSet = DeadBBDF->second;
|
|
|
|
for (DominanceFrontier::DomSetType::iterator DeadBBSetI = DeadBBSet.begin(),
|
|
|
|
DeadBBSetE = DeadBBSet.end(); DeadBBSetI != DeadBBSetE; ++DeadBBSetI) {
|
|
|
|
BasicBlock *FrontierBB = *DeadBBSetI;
|
2007-08-17 21:59:16 +00:00
|
|
|
FrontierBBs.push_back(FrontierBB);
|
|
|
|
|
2007-08-15 03:31:47 +00:00
|
|
|
// Rremove any PHI incoming edge from blocks dominated by DeadBB.
|
|
|
|
PredBlocks.clear();
|
|
|
|
for(pred_iterator PI = pred_begin(FrontierBB), PE = pred_end(FrontierBB);
|
|
|
|
PI != PE; ++PI) {
|
|
|
|
BasicBlock *P = *PI;
|
|
|
|
if (P == DeadBB || DT->dominates(DeadBB, P))
|
|
|
|
PredBlocks.push_back(P);
|
2007-08-12 07:02:51 +00:00
|
|
|
}
|
2007-08-17 21:59:16 +00:00
|
|
|
|
|
|
|
BasicBlock *NewDominator = NULL;
|
2007-08-15 03:31:47 +00:00
|
|
|
for(BasicBlock::iterator FBI = FrontierBB->begin(), FBE = FrontierBB->end();
|
|
|
|
FBI != FBE; ++FBI) {
|
|
|
|
if (PHINode *PN = dyn_cast<PHINode>(FBI)) {
|
|
|
|
for(SmallVector<BasicBlock *, 8>::iterator PI = PredBlocks.begin(),
|
|
|
|
PE = PredBlocks.end(); PI != PE; ++PI) {
|
|
|
|
BasicBlock *P = *PI;
|
|
|
|
PN->removeIncomingValue(P);
|
|
|
|
}
|
2007-08-17 21:59:16 +00:00
|
|
|
// If we have not identified new dominator then see if we can identify
|
|
|
|
// one based on remaining incoming PHINode values.
|
|
|
|
if (NewDominator == NULL && PN->getNumIncomingValues() == 1)
|
|
|
|
NewDominator = PN->getIncomingBlock(0);
|
2007-08-14 18:35:57 +00:00
|
|
|
}
|
2007-08-15 03:31:47 +00:00
|
|
|
else
|
|
|
|
break;
|
2007-08-17 21:59:16 +00:00
|
|
|
}
|
2007-08-15 03:31:47 +00:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// Now remove DeadBB and all nodes dominated by DeadBB in df order.
|
|
|
|
SmallVector<BasicBlock *, 32> WorkList;
|
|
|
|
DomTreeNode *DN = DT->getNode(DeadBB);
|
|
|
|
for (df_iterator<DomTreeNode*> DI = df_begin(DN),
|
|
|
|
E = df_end(DN); DI != E; ++DI) {
|
|
|
|
BasicBlock *BB = DI->getBlock();
|
|
|
|
WorkList.push_back(BB);
|
2007-08-17 21:59:16 +00:00
|
|
|
BB->replaceAllUsesWith(UndefValue::get(Type::LabelTy));
|
2007-08-15 03:31:47 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
while (!WorkList.empty()) {
|
|
|
|
BasicBlock *BB = WorkList.back(); WorkList.pop_back();
|
|
|
|
for(BasicBlock::iterator BBI = BB->begin(), BBE = BB->end();
|
|
|
|
BBI != BBE; ++BBI) {
|
|
|
|
Instruction *I = BBI;
|
|
|
|
I->replaceAllUsesWith(UndefValue::get(I->getType()));
|
|
|
|
I->eraseFromParent();
|
2007-08-12 07:02:51 +00:00
|
|
|
}
|
2007-08-15 03:31:47 +00:00
|
|
|
LPM->deleteSimpleAnalysisValue(BB, LP);
|
|
|
|
DT->eraseNode(BB);
|
|
|
|
DF->removeBlock(BB);
|
|
|
|
LI->removeBlock(BB);
|
|
|
|
BB->eraseFromParent();
|
2007-08-12 07:02:51 +00:00
|
|
|
}
|
2007-08-17 21:59:16 +00:00
|
|
|
|
|
|
|
// Update Frontier BBs' dominator info.
|
|
|
|
while (!FrontierBBs.empty()) {
|
|
|
|
BasicBlock *FBB = FrontierBBs.back(); FrontierBBs.pop_back();
|
|
|
|
BasicBlock *NewDominator = FBB->getSinglePredecessor();
|
|
|
|
if (!NewDominator) {
|
|
|
|
pred_iterator PI = pred_begin(FBB), PE = pred_end(FBB);
|
|
|
|
NewDominator = *PI;
|
|
|
|
++PI;
|
|
|
|
if (NewDominator != LiveBB) {
|
|
|
|
for(; PI != PE; ++PI) {
|
|
|
|
BasicBlock *P = *PI;
|
|
|
|
if (P == LiveBB) {
|
|
|
|
NewDominator = LiveBB;
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
NewDominator = DT->findNearestCommonDominator(NewDominator, P);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
assert (NewDominator && "Unable to fix dominator info.");
|
|
|
|
DT->changeImmediateDominator(FBB, NewDominator);
|
|
|
|
DF->changeImmediateDominator(FBB, NewDominator, DT);
|
|
|
|
}
|
|
|
|
|
2007-08-12 07:02:51 +00:00
|
|
|
}
|
|
|
|
|
2007-08-22 18:27:01 +00:00
|
|
|
/// safeSplitCondition - Return true if it is possible to
|
|
|
|
/// split loop using given split condition.
|
|
|
|
bool LoopIndexSplit::safeSplitCondition(SplitInfo &SD) {
|
2007-08-15 02:14:55 +00:00
|
|
|
|
2007-08-22 18:27:01 +00:00
|
|
|
BasicBlock *SplitCondBlock = SD.SplitCondition->getParent();
|
2007-08-21 21:12:02 +00:00
|
|
|
|
2007-08-22 18:27:01 +00:00
|
|
|
// Unable to handle triange loops at the moment.
|
2007-08-15 02:14:55 +00:00
|
|
|
// In triangle loop, split condition is in header and one of the
|
|
|
|
// the split destination is loop latch. If split condition is EQ
|
|
|
|
// then such loops are already handle in processOneIterationLoop().
|
2007-08-22 18:27:01 +00:00
|
|
|
BasicBlock *Latch = L->getLoopLatch();
|
|
|
|
BranchInst *SplitTerminator =
|
|
|
|
cast<BranchInst>(SplitCondBlock->getTerminator());
|
|
|
|
BasicBlock *Succ0 = SplitTerminator->getSuccessor(0);
|
|
|
|
BasicBlock *Succ1 = SplitTerminator->getSuccessor(1);
|
|
|
|
if (L->getHeader() == SplitCondBlock
|
|
|
|
&& (Latch == Succ0 || Latch == Succ1))
|
2007-08-15 02:14:55 +00:00
|
|
|
return false;
|
2007-08-21 21:12:02 +00:00
|
|
|
|
2007-08-18 00:00:32 +00:00
|
|
|
// If one of the split condition branch is post dominating other then loop
|
|
|
|
// index split is not appropriate.
|
2007-08-22 18:27:01 +00:00
|
|
|
if (DT->dominates(Succ0, Latch) || DT->dominates(Succ1, Latch))
|
2007-08-17 21:59:16 +00:00
|
|
|
return false;
|
2007-08-21 21:12:02 +00:00
|
|
|
|
2007-08-18 00:00:32 +00:00
|
|
|
// If one of the split condition branch is a predecessor of the other
|
|
|
|
// split condition branch head then do not split loop on this condition.
|
2007-08-21 21:12:02 +00:00
|
|
|
for(pred_iterator PI = pred_begin(Succ0), PE = pred_end(Succ0);
|
|
|
|
PI != PE; ++PI)
|
2007-08-18 00:00:32 +00:00
|
|
|
if (Succ1 == *PI)
|
|
|
|
return false;
|
2007-08-21 21:12:02 +00:00
|
|
|
for(pred_iterator PI = pred_begin(Succ1), PE = pred_end(Succ1);
|
|
|
|
PI != PE; ++PI)
|
2007-08-18 00:00:32 +00:00
|
|
|
if (Succ0 == *PI)
|
|
|
|
return false;
|
|
|
|
|
2007-08-22 18:27:01 +00:00
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
|
|
|
/// splitLoop - Split current loop L in two loops using split information
|
|
|
|
/// SD. Update dominator information. Maintain LCSSA form.
|
|
|
|
bool LoopIndexSplit::splitLoop(SplitInfo &SD) {
|
|
|
|
|
|
|
|
if (!safeSplitCondition(SD))
|
|
|
|
return false;
|
|
|
|
|
2007-08-22 19:33:29 +00:00
|
|
|
// After loop is cloned there are two loops.
|
|
|
|
//
|
|
|
|
// First loop, referred as ALoop, executes first part of loop's iteration
|
|
|
|
// space split. Second loop, referred as BLoop, executes remaining
|
|
|
|
// part of loop's iteration space.
|
|
|
|
//
|
|
|
|
// ALoop's exit edge enters BLoop's header through a forwarding block which
|
|
|
|
// acts as a BLoop's preheader.
|
|
|
|
|
|
|
|
//[*] Calculate ALoop induction variable's new exiting value and
|
|
|
|
// BLoop induction variable's new starting value. Calculuate these
|
|
|
|
// values in original loop's preheader.
|
|
|
|
// A_ExitValue = min(SplitValue, OrignalLoopExitValue)
|
|
|
|
// B_StartValue = max(SplitValue, OriginalLoopStartValue)
|
|
|
|
Value *A_ExitValue = NULL;
|
|
|
|
Value *B_StartValue = NULL;
|
2007-08-10 00:53:35 +00:00
|
|
|
if (isa<ConstantInt>(SD.SplitValue)) {
|
2007-08-22 19:33:29 +00:00
|
|
|
A_ExitValue = SD.SplitValue;
|
|
|
|
B_StartValue = SD.SplitValue;
|
2007-08-10 00:53:35 +00:00
|
|
|
}
|
|
|
|
else {
|
2007-08-22 19:33:29 +00:00
|
|
|
BasicBlock *Preheader = L->getLoopPreheader();
|
|
|
|
Instruction *PHTerminator = Preheader->getTerminator();
|
|
|
|
bool SignedPredicate = ExitCondition->isSignedPredicate();
|
2007-08-10 00:53:35 +00:00
|
|
|
Value *C1 = new ICmpInst(SignedPredicate ?
|
|
|
|
ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
|
2007-08-12 07:02:51 +00:00
|
|
|
SD.SplitValue,
|
|
|
|
ExitCondition->getOperand(ExitValueNum),
|
2007-08-22 19:33:29 +00:00
|
|
|
"lsplit.ev", PHTerminator);
|
|
|
|
A_ExitValue = new SelectInst(C1, SD.SplitValue,
|
2007-08-12 07:02:51 +00:00
|
|
|
ExitCondition->getOperand(ExitValueNum),
|
2007-08-22 19:33:29 +00:00
|
|
|
"lsplit.ev", PHTerminator);
|
2007-08-10 00:53:35 +00:00
|
|
|
|
|
|
|
Value *C2 = new ICmpInst(SignedPredicate ?
|
|
|
|
ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
|
|
|
|
SD.SplitValue, StartValue, "lsplit.sv",
|
2007-08-22 19:33:29 +00:00
|
|
|
PHTerminator);
|
|
|
|
B_StartValue = new SelectInst(C2, StartValue, SD.SplitValue,
|
|
|
|
"lsplit.sv", PHTerminator);
|
2007-08-10 00:53:35 +00:00
|
|
|
}
|
2007-08-10 18:07:13 +00:00
|
|
|
|
2007-08-22 19:33:29 +00:00
|
|
|
//[*] Clone loop.
|
2007-08-12 07:02:51 +00:00
|
|
|
DenseMap<const Value *, Value *> ValueMap;
|
2007-08-22 19:33:29 +00:00
|
|
|
Loop *BLoop = CloneLoop(L, LPM, LI, ValueMap, this);
|
|
|
|
BasicBlock *B_Header = BLoop->getHeader();
|
|
|
|
|
|
|
|
//[*] ALoop's exiting edge BLoop's header.
|
|
|
|
// ALoop's original exit block becomes BLoop's exit block.
|
|
|
|
PHINode *B_IndVar = cast<PHINode>(ValueMap[IndVar]);
|
|
|
|
BasicBlock *A_ExitingBlock = ExitCondition->getParent();
|
|
|
|
BranchInst *A_ExitInsn =
|
|
|
|
dyn_cast<BranchInst>(A_ExitingBlock->getTerminator());
|
|
|
|
assert (A_ExitInsn && "Unable to find suitable loop exit branch");
|
|
|
|
BasicBlock *B_ExitBlock = A_ExitInsn->getSuccessor(1);
|
|
|
|
if (L->contains(B_ExitBlock)) {
|
|
|
|
B_ExitBlock = A_ExitInsn->getSuccessor(0);
|
|
|
|
A_ExitInsn->setSuccessor(0, B_Header);
|
2007-08-14 01:30:57 +00:00
|
|
|
} else
|
2007-08-22 19:33:29 +00:00
|
|
|
A_ExitInsn->setSuccessor(1, B_Header);
|
|
|
|
|
|
|
|
//[*] Update ALoop's exit value using new exit value.
|
|
|
|
ExitCondition->setOperand(ExitValueNum, A_ExitValue);
|
2007-08-21 21:12:02 +00:00
|
|
|
|
2007-08-22 19:33:29 +00:00
|
|
|
// [*] Update BLoop's header phi nodes. Remove incoming PHINode's from
|
|
|
|
// original loop's preheader. Add incoming PHINode values from
|
|
|
|
// ALoop's exiting block. Update BLoop header's domiantor info.
|
|
|
|
|
2007-08-14 01:30:57 +00:00
|
|
|
// Collect inverse map of Header PHINodes.
|
|
|
|
DenseMap<Value *, Value *> InverseMap;
|
|
|
|
for (BasicBlock::iterator BI = L->getHeader()->begin(),
|
|
|
|
BE = L->getHeader()->end(); BI != BE; ++BI) {
|
|
|
|
if (PHINode *PN = dyn_cast<PHINode>(BI)) {
|
|
|
|
PHINode *PNClone = cast<PHINode>(ValueMap[PN]);
|
|
|
|
InverseMap[PNClone] = PN;
|
|
|
|
} else
|
|
|
|
break;
|
|
|
|
}
|
2007-08-22 19:33:29 +00:00
|
|
|
BasicBlock *Preheader = L->getLoopPreheader();
|
|
|
|
for (BasicBlock::iterator BI = B_Header->begin(), BE = B_Header->end();
|
2007-08-12 07:02:51 +00:00
|
|
|
BI != BE; ++BI) {
|
|
|
|
if (PHINode *PN = dyn_cast<PHINode>(BI)) {
|
2007-08-22 19:33:29 +00:00
|
|
|
// Remove incoming value from original preheader.
|
|
|
|
PN->removeIncomingValue(Preheader);
|
|
|
|
|
|
|
|
// Add incoming value from A_ExitingBlock.
|
|
|
|
if (PN == B_IndVar)
|
|
|
|
PN->addIncoming(B_StartValue, A_ExitingBlock);
|
2007-08-14 01:30:57 +00:00
|
|
|
else {
|
|
|
|
PHINode *OrigPN = cast<PHINode>(InverseMap[PN]);
|
2007-08-22 19:33:29 +00:00
|
|
|
Value *V2 = OrigPN->getIncomingValueForBlock(A_ExitingBlock);
|
|
|
|
PN->addIncoming(V2, A_ExitingBlock);
|
2007-08-14 01:30:57 +00:00
|
|
|
}
|
|
|
|
} else
|
2007-08-12 07:02:51 +00:00
|
|
|
break;
|
|
|
|
}
|
2007-08-22 19:33:29 +00:00
|
|
|
DT->changeImmediateDominator(B_Header, A_ExitingBlock);
|
|
|
|
DF->changeImmediateDominator(B_Header, A_ExitingBlock, DT);
|
2007-08-21 21:12:02 +00:00
|
|
|
|
2007-08-22 19:33:29 +00:00
|
|
|
// [*] Update BLoop's exit block. Its new predecessor is BLoop's exit
|
|
|
|
// block. Remove incoming PHINode values from ALoop's exiting block.
|
|
|
|
// Add new incoming values from BLoop's incoming exiting value.
|
|
|
|
// Update BLoop exit block's dominator info..
|
|
|
|
BasicBlock *B_ExitingBlock = cast<BasicBlock>(ValueMap[A_ExitingBlock]);
|
|
|
|
for (BasicBlock::iterator BI = B_ExitBlock->begin(), BE = B_ExitBlock->end();
|
2007-08-14 01:30:57 +00:00
|
|
|
BI != BE; ++BI) {
|
|
|
|
if (PHINode *PN = dyn_cast<PHINode>(BI)) {
|
2007-08-22 19:33:29 +00:00
|
|
|
PN->addIncoming(ValueMap[PN->getIncomingValueForBlock(A_ExitingBlock)],
|
|
|
|
B_ExitingBlock);
|
|
|
|
PN->removeIncomingValue(A_ExitingBlock);
|
2007-08-14 01:30:57 +00:00
|
|
|
} else
|
|
|
|
break;
|
|
|
|
}
|
2007-08-12 07:02:51 +00:00
|
|
|
|
2007-08-22 19:33:29 +00:00
|
|
|
DT->changeImmediateDominator(B_ExitBlock, B_ExitingBlock);
|
|
|
|
DF->changeImmediateDominator(B_ExitBlock, B_ExitingBlock, DT);
|
2007-08-10 18:07:13 +00:00
|
|
|
|
2007-08-22 19:33:29 +00:00
|
|
|
//[*] Split ALoop's exit edge. This creates a new block which
|
|
|
|
// serves two purposes. First one is to hold PHINode defnitions
|
|
|
|
// to ensure that ALoop's LCSSA form. Second use it to act
|
|
|
|
// as a preheader for BLoop.
|
|
|
|
BasicBlock *A_ExitBlock = SplitEdge(A_ExitingBlock, B_Header, this);
|
2007-08-12 07:02:51 +00:00
|
|
|
|
2007-08-22 19:33:29 +00:00
|
|
|
//[*] Preserve ALoop's LCSSA form. Create new forwarding PHINodes
|
|
|
|
// in A_ExitBlock to redefine outgoing PHI definitions from ALoop.
|
|
|
|
for(BasicBlock::iterator BI = B_Header->begin(), BE = B_Header->end();
|
2007-08-21 19:47:46 +00:00
|
|
|
BI != BE; ++BI) {
|
|
|
|
if (PHINode *PN = dyn_cast<PHINode>(BI)) {
|
2007-08-22 19:33:29 +00:00
|
|
|
Value *V1 = PN->getIncomingValueForBlock(A_ExitBlock);
|
2007-08-21 19:47:46 +00:00
|
|
|
PHINode *newPHI = new PHINode(PN->getType(), PN->getName());
|
2007-08-22 19:33:29 +00:00
|
|
|
newPHI->addIncoming(V1, A_ExitingBlock);
|
|
|
|
A_ExitBlock->getInstList().push_front(newPHI);
|
|
|
|
PN->removeIncomingValue(A_ExitBlock);
|
|
|
|
PN->addIncoming(newPHI, A_ExitBlock);
|
2007-08-21 19:47:46 +00:00
|
|
|
} else
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
2007-08-22 19:33:29 +00:00
|
|
|
//[*] Eliminate split condition's inactive branch from ALoop.
|
|
|
|
BasicBlock *A_SplitCondBlock = SD.SplitCondition->getParent();
|
|
|
|
BranchInst *A_BR = cast<BranchInst>(A_SplitCondBlock->getTerminator());
|
|
|
|
BasicBlock *A_InactiveBranch = A_BR->getSuccessor(1);
|
|
|
|
BasicBlock *A_ActiveBranch = A_BR->getSuccessor(1);
|
|
|
|
A_BR->setUnconditionalDest(A_BR->getSuccessor(0));
|
|
|
|
removeBlocks(A_InactiveBranch, L, A_ActiveBranch);
|
|
|
|
|
|
|
|
//[*] Eliminate split condition's inactive branch in from BLoop.
|
|
|
|
BasicBlock *B_SplitCondBlock = cast<BasicBlock>(ValueMap[A_SplitCondBlock]);
|
|
|
|
BranchInst *B_BR = cast<BranchInst>(B_SplitCondBlock->getTerminator());
|
|
|
|
BasicBlock *B_InactiveBranch = B_BR->getSuccessor(0);
|
|
|
|
BasicBlock *B_ActiveBranch = B_BR->getSuccessor(1);
|
|
|
|
B_BR->setUnconditionalDest(B_BR->getSuccessor(1));
|
|
|
|
removeBlocks(B_InactiveBranch, BLoop, B_ActiveBranch);
|
|
|
|
|
2007-08-12 07:02:51 +00:00
|
|
|
return true;
|
2007-08-07 00:25:56 +00:00
|
|
|
}
|