mirror of
https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64811 91177308-0d34-0410-b5e6-96231b3b80d8
1200 lines
42 KiB
C++
1200 lines
42 KiB
C++
//===- 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 is distributed under the University of Illinois Open Source
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// 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. This pass handles three
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// kinds of loops.
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//
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// [1] Loop is eliminated when loop body is executed only once. For example,
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// for (i = 0; i < N; ++i) {
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// if ( i == X) {
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// ...
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// }
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// }
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//
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// [2] Loop's iteration space is shrunk if loop body is executed for certain
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// range only. For example,
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//
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// for (i = 0; i < N; ++i) {
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// if ( i > A && i < B) {
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// ...
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// }
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// }
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// is trnasformed to iterators from A to B, if A > 0 and B < N.
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//
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// [3] Loop is split if the loop body is dominated by an branch. For example,
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//
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// for (i = LB; i < UB; ++i) { if (i < SV) A; else B; }
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//
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// is transformed into
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// AEV = BSV = SV
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// for (i = LB; i < min(UB, AEV); ++i)
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// A;
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// for (i = max(LB, BSV); i < UB; ++i);
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// B;
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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/IntrinsicInst.h"
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#include "llvm/Analysis/LoopPass.h"
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#include "llvm/Analysis/ScalarEvolution.h"
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#include "llvm/Analysis/Dominators.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/Cloning.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/ADT/DepthFirstIterator.h"
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#include "llvm/ADT/Statistic.h"
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using namespace llvm;
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STATISTIC(NumIndexSplit, "Number of loop index split");
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STATISTIC(NumIndexSplitRemoved, "Number of loops eliminated by loop index split");
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STATISTIC(NumRestrictBounds, "Number of loop iteration space restricted");
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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(&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.addPreserved<ScalarEvolution>();
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AU.addRequiredID(LCSSAID);
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AU.addPreservedID(LCSSAID);
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AU.addRequired<LoopInfo>();
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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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AU.addRequired<DominatorTree>();
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AU.addRequired<DominanceFrontier>();
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AU.addPreserved<DominatorTree>();
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AU.addPreserved<DominanceFrontier>();
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}
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private:
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/// processOneIterationLoop -- Eliminate loop if loop body is executed
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/// only once. For example,
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/// for (i = 0; i < N; ++i) {
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/// if ( i == X) {
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/// ...
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/// }
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/// }
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///
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bool processOneIterationLoop();
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// -- Routines used by updateLoopIterationSpace();
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/// updateLoopIterationSpace -- Update loop's iteration space if loop
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/// body is executed for certain IV range only. For example,
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///
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/// for (i = 0; i < N; ++i) {
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/// if ( i > A && i < B) {
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/// ...
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/// }
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/// }
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/// is transformed to iterators from A to B, if A > 0 and B < N.
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///
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bool updateLoopIterationSpace();
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/// restrictLoopBound - Op dominates loop body. Op compares an IV based value
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/// with a loop invariant value. Update loop's lower and upper bound based on
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/// the loop invariant value.
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bool restrictLoopBound(ICmpInst &Op);
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// --- Routines used by splitLoop(). --- /
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bool splitLoop();
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/// removeBlocks - Remove basic block DeadBB and all blocks dominated by
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/// DeadBB. This routine is used to remove split condition's dead branch,
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/// dominated by DeadBB. LiveBB dominates split conidition's other branch.
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void removeBlocks(BasicBlock *DeadBB, Loop *LP, BasicBlock *LiveBB);
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/// moveExitCondition - Move exit condition EC into split condition block.
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void moveExitCondition(BasicBlock *CondBB, BasicBlock *ActiveBB,
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BasicBlock *ExitBB, ICmpInst *EC, ICmpInst *SC,
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PHINode *IV, Instruction *IVAdd, Loop *LP,
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unsigned);
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/// updatePHINodes - CFG has been changed.
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/// Before
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/// - ExitBB's single predecessor was Latch
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/// - Latch's second successor was Header
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/// Now
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/// - ExitBB's single predecessor was Header
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/// - Latch's one and only successor was Header
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///
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/// Update ExitBB PHINodes' to reflect this change.
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void updatePHINodes(BasicBlock *ExitBB, BasicBlock *Latch,
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BasicBlock *Header,
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PHINode *IV, Instruction *IVIncrement, Loop *LP);
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// --- Utility routines --- /
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/// cleanBlock - A block is considered clean if all non terminal
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/// instructions are either PHINodes or IV based values.
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bool cleanBlock(BasicBlock *BB);
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/// IVisLT - If Op is comparing IV based value with an loop invariant and
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/// IV based value is less than the loop invariant then return the loop
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/// invariant. Otherwise return NULL.
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Value * IVisLT(ICmpInst &Op);
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/// IVisLE - If Op is comparing IV based value with an loop invariant and
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/// IV based value is less than or equal to the loop invariant then
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/// return the loop invariant. Otherwise return NULL.
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Value * IVisLE(ICmpInst &Op);
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/// IVisGT - If Op is comparing IV based value with an loop invariant and
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/// IV based value is greater than the loop invariant then return the loop
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/// invariant. Otherwise return NULL.
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Value * IVisGT(ICmpInst &Op);
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/// IVisGE - If Op is comparing IV based value with an loop invariant and
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/// IV based value is greater than or equal to the loop invariant then
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/// return the loop invariant. Otherwise return NULL.
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Value * IVisGE(ICmpInst &Op);
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private:
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// Current Loop information.
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Loop *L;
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LPPassManager *LPM;
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LoopInfo *LI;
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DominatorTree *DT;
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DominanceFrontier *DF;
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PHINode *IndVar;
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ICmpInst *ExitCondition;
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ICmpInst *SplitCondition;
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Value *IVStartValue;
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Value *IVExitValue;
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Instruction *IVIncrement;
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SmallPtrSet<Value *, 4> IVBasedValues;
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};
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}
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char LoopIndexSplit::ID = 0;
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static RegisterPass<LoopIndexSplit>
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X("loop-index-split", "Index Split Loops");
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Pass *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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bool LoopIndexSplit::runOnLoop(Loop *IncomingLoop, LPPassManager &LPM_Ref) {
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L = IncomingLoop;
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LPM = &LPM_Ref;
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// FIXME - Nested loops make dominator info updates tricky.
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if (!L->getSubLoops().empty())
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return false;
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DT = &getAnalysis<DominatorTree>();
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LI = &getAnalysis<LoopInfo>();
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DF = &getAnalysis<DominanceFrontier>();
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// Initialize loop data.
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IndVar = L->getCanonicalInductionVariable();
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if (!IndVar) return false;
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bool P1InLoop = L->contains(IndVar->getIncomingBlock(1));
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IVStartValue = IndVar->getIncomingValue(!P1InLoop);
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IVIncrement = dyn_cast<Instruction>(IndVar->getIncomingValue(P1InLoop));
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if (!IVIncrement) return false;
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IVBasedValues.clear();
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IVBasedValues.insert(IndVar);
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IVBasedValues.insert(IVIncrement);
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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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for(BasicBlock::iterator BI = (*I)->begin(), BE = (*I)->end();
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BI != BE; ++BI) {
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if (BinaryOperator *BO = dyn_cast<BinaryOperator>(BI))
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if (BO != IVIncrement
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&& (BO->getOpcode() == Instruction::Add
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|| BO->getOpcode() == Instruction::Sub))
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if (IVBasedValues.count(BO->getOperand(0))
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&& L->isLoopInvariant(BO->getOperand(1)))
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IVBasedValues.insert(BO);
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}
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// Reject loop if loop exit condition is not suitable.
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BasicBlock *ExitingBlock = L->getExitingBlock();
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if (!ExitingBlock)
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return false;
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BranchInst *EBR = dyn_cast<BranchInst>(ExitingBlock->getTerminator());
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if (!EBR) return false;
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ExitCondition = dyn_cast<ICmpInst>(EBR->getCondition());
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if (!ExitCondition) return false;
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if (ExitingBlock != L->getLoopLatch()) return false;
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IVExitValue = ExitCondition->getOperand(1);
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if (!L->isLoopInvariant(IVExitValue))
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IVExitValue = ExitCondition->getOperand(0);
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if (!L->isLoopInvariant(IVExitValue))
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return false;
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// If start value is more then exit value where induction variable
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// increments by 1 then we are potentially dealing with an infinite loop.
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// Do not index split this loop.
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if (ConstantInt *SV = dyn_cast<ConstantInt>(IVStartValue))
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if (ConstantInt *EV = dyn_cast<ConstantInt>(IVExitValue))
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if (SV->getSExtValue() > EV->getSExtValue())
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return false;
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if (processOneIterationLoop())
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return true;
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if (updateLoopIterationSpace())
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return true;
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if (splitLoop())
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return true;
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return false;
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}
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// --- Helper routines ---
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// isUsedOutsideLoop - Returns true iff V is used outside the loop L.
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static bool isUsedOutsideLoop(Value *V, Loop *L) {
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for(Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
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if (!L->contains(cast<Instruction>(*UI)->getParent()))
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return true;
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return false;
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}
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// Return V+1
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static Value *getPlusOne(Value *V, bool Sign, Instruction *InsertPt) {
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ConstantInt *One = ConstantInt::get(V->getType(), 1, Sign);
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return BinaryOperator::CreateAdd(V, One, "lsp", InsertPt);
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}
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// Return V-1
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static Value *getMinusOne(Value *V, bool Sign, Instruction *InsertPt) {
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ConstantInt *One = ConstantInt::get(V->getType(), 1, Sign);
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return BinaryOperator::CreateSub(V, One, "lsp", InsertPt);
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}
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// Return min(V1, V1)
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static Value *getMin(Value *V1, Value *V2, bool Sign, Instruction *InsertPt) {
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Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
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V1, V2, "lsp", InsertPt);
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return SelectInst::Create(C, V1, V2, "lsp", InsertPt);
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}
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// Return max(V1, V2)
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static Value *getMax(Value *V1, Value *V2, bool Sign, Instruction *InsertPt) {
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Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
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V1, V2, "lsp", InsertPt);
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return SelectInst::Create(C, V2, V1, "lsp", InsertPt);
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}
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/// processOneIterationLoop -- Eliminate loop if loop body is executed
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/// only once. For example,
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/// for (i = 0; i < N; ++i) {
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/// if ( i == X) {
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/// ...
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/// }
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/// }
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///
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bool LoopIndexSplit::processOneIterationLoop() {
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SplitCondition = NULL;
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BasicBlock *Latch = L->getLoopLatch();
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BasicBlock *Header = L->getHeader();
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BranchInst *BR = dyn_cast<BranchInst>(Header->getTerminator());
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if (!BR) return false;
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if (!isa<BranchInst>(Latch->getTerminator())) return false;
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if (BR->isUnconditional()) return false;
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SplitCondition = dyn_cast<ICmpInst>(BR->getCondition());
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if (!SplitCondition) return false;
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if (SplitCondition == ExitCondition) return false;
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if (SplitCondition->getPredicate() != ICmpInst::ICMP_EQ) return false;
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if (BR->getOperand(1) != Latch) return false;
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if (!IVBasedValues.count(SplitCondition->getOperand(0))
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&& !IVBasedValues.count(SplitCondition->getOperand(1)))
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return false;
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// If IV is used outside the loop then this loop traversal is required.
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// FIXME: Calculate and use last IV value.
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if (isUsedOutsideLoop(IVIncrement, L))
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return false;
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// If BR operands are not IV or not loop invariants then skip this loop.
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Value *OPV = SplitCondition->getOperand(0);
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Value *SplitValue = SplitCondition->getOperand(1);
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if (!L->isLoopInvariant(SplitValue)) {
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Value *T = SplitValue;
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SplitValue = OPV;
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OPV = T;
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}
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if (!L->isLoopInvariant(SplitValue))
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return false;
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Instruction *OPI = dyn_cast<Instruction>(OPV);
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if (!OPI) return false;
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if (OPI->getParent() != Header || isUsedOutsideLoop(OPI, L))
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return false;
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if (!cleanBlock(Header))
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return false;
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if (!cleanBlock(Latch))
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return false;
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// If the merge point for BR is not loop latch then skip this loop.
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if (BR->getSuccessor(0) != Latch) {
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DominanceFrontier::iterator DF0 = DF->find(BR->getSuccessor(0));
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assert (DF0 != DF->end() && "Unable to find dominance frontier");
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if (!DF0->second.count(Latch))
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return false;
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}
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if (BR->getSuccessor(1) != Latch) {
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DominanceFrontier::iterator DF1 = DF->find(BR->getSuccessor(1));
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assert (DF1 != DF->end() && "Unable to find dominance frontier");
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if (!DF1->second.count(Latch))
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return false;
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}
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// Now, Current loop L contains compare instruction
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// that compares induction variable, IndVar, against loop invariant. And
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// entire (i.e. meaningful) loop body is dominated by this compare
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// instruction. In such case eliminate
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// loop structure surrounding this loop body. For example,
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// for (int i = start; i < end; ++i) {
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// if ( i == somevalue) {
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// loop_body
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// }
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// }
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// can be transformed into
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// if (somevalue >= start && somevalue < end) {
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// i = somevalue;
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// loop_body
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// }
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// Replace index variable with split value in loop body. Loop body is executed
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// only when index variable is equal to split value.
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IndVar->replaceAllUsesWith(SplitValue);
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// Replace split condition in header.
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// Transform
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// SplitCondition : icmp eq i32 IndVar, SplitValue
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// into
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// c1 = icmp uge i32 SplitValue, StartValue
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// c2 = icmp ult i32 SplitValue, ExitValue
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// and i32 c1, c2
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Instruction *C1 = new ICmpInst(ExitCondition->isSignedPredicate() ?
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ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE,
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SplitValue, IVStartValue, "lisplit", BR);
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CmpInst::Predicate C2P = ExitCondition->getPredicate();
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BranchInst *LatchBR = cast<BranchInst>(Latch->getTerminator());
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if (LatchBR->getOperand(0) != Header)
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C2P = CmpInst::getInversePredicate(C2P);
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Instruction *C2 = new ICmpInst(C2P, SplitValue, IVExitValue, "lisplit", BR);
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Instruction *NSplitCond = BinaryOperator::CreateAnd(C1, C2, "lisplit", BR);
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SplitCondition->replaceAllUsesWith(NSplitCond);
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SplitCondition->eraseFromParent();
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// Remove Latch to Header edge.
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BasicBlock *LatchSucc = NULL;
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Header->removePredecessor(Latch);
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for (succ_iterator SI = succ_begin(Latch), E = succ_end(Latch);
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SI != E; ++SI) {
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if (Header != *SI)
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LatchSucc = *SI;
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}
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LatchBR->setUnconditionalDest(LatchSucc);
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// Remove IVIncrement
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IVIncrement->replaceAllUsesWith(UndefValue::get(IVIncrement->getType()));
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IVIncrement->eraseFromParent();
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LPM->deleteLoopFromQueue(L);
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// Update Dominator Info.
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// Only CFG change done is to remove Latch to Header edge. This
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// does not change dominator tree because Latch did not dominate
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// Header.
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if (DF) {
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DominanceFrontier::iterator HeaderDF = DF->find(Header);
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if (HeaderDF != DF->end())
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DF->removeFromFrontier(HeaderDF, Header);
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DominanceFrontier::iterator LatchDF = DF->find(Latch);
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if (LatchDF != DF->end())
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DF->removeFromFrontier(LatchDF, Header);
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}
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++NumIndexSplitRemoved;
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return true;
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}
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/// restrictLoopBound - Op dominates loop body. Op compares an IV based value
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/// with a loop invariant value. Update loop's lower and upper bound based on
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/// the loop invariant value.
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bool LoopIndexSplit::restrictLoopBound(ICmpInst &Op) {
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bool Sign = Op.isSignedPredicate();
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Instruction *PHTerm = L->getLoopPreheader()->getTerminator();
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if (IVisGT(*ExitCondition) || IVisGE(*ExitCondition)) {
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BranchInst *EBR =
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cast<BranchInst>(ExitCondition->getParent()->getTerminator());
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ExitCondition->setPredicate(ExitCondition->getInversePredicate());
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BasicBlock *T = EBR->getSuccessor(0);
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EBR->setSuccessor(0, EBR->getSuccessor(1));
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EBR->setSuccessor(1, T);
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}
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// New upper and lower bounds.
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Value *NLB = NULL;
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Value *NUB = NULL;
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if (Value *V = IVisLT(Op)) {
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// Restrict upper bound.
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if (IVisLE(*ExitCondition))
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V = getMinusOne(V, Sign, PHTerm);
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NUB = getMin(V, IVExitValue, Sign, PHTerm);
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} else if (Value *V = IVisLE(Op)) {
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// Restrict upper bound.
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if (IVisLT(*ExitCondition))
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V = getPlusOne(V, Sign, PHTerm);
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NUB = getMin(V, IVExitValue, Sign, PHTerm);
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} else if (Value *V = IVisGT(Op)) {
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// Restrict lower bound.
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V = getPlusOne(V, Sign, PHTerm);
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NLB = getMax(V, IVStartValue, Sign, PHTerm);
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} else if (Value *V = IVisGE(Op))
|
|
// Restrict lower bound.
|
|
NLB = getMax(V, IVStartValue, Sign, PHTerm);
|
|
|
|
if (!NLB && !NUB)
|
|
return false;
|
|
|
|
if (NLB) {
|
|
unsigned i = IndVar->getBasicBlockIndex(L->getLoopPreheader());
|
|
IndVar->setIncomingValue(i, NLB);
|
|
}
|
|
|
|
if (NUB) {
|
|
unsigned i = (ExitCondition->getOperand(0) != IVExitValue);
|
|
ExitCondition->setOperand(i, NUB);
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// updateLoopIterationSpace -- Update loop's iteration space if loop
|
|
/// body is executed for certain IV range only. For example,
|
|
///
|
|
/// for (i = 0; i < N; ++i) {
|
|
/// if ( i > A && i < B) {
|
|
/// ...
|
|
/// }
|
|
/// }
|
|
/// is transformed to iterators from A to B, if A > 0 and B < N.
|
|
///
|
|
bool LoopIndexSplit::updateLoopIterationSpace() {
|
|
SplitCondition = NULL;
|
|
if (ExitCondition->getPredicate() == ICmpInst::ICMP_NE
|
|
|| ExitCondition->getPredicate() == ICmpInst::ICMP_EQ)
|
|
return false;
|
|
BasicBlock *Latch = L->getLoopLatch();
|
|
BasicBlock *Header = L->getHeader();
|
|
BranchInst *BR = dyn_cast<BranchInst>(Header->getTerminator());
|
|
if (!BR) return false;
|
|
if (!isa<BranchInst>(Latch->getTerminator())) return false;
|
|
if (BR->isUnconditional()) return false;
|
|
BinaryOperator *AND = dyn_cast<BinaryOperator>(BR->getCondition());
|
|
if (!AND) return false;
|
|
if (AND->getOpcode() != Instruction::And) return false;
|
|
ICmpInst *Op0 = dyn_cast<ICmpInst>(AND->getOperand(0));
|
|
ICmpInst *Op1 = dyn_cast<ICmpInst>(AND->getOperand(1));
|
|
if (!Op0 || !Op1)
|
|
return false;
|
|
IVBasedValues.insert(AND);
|
|
IVBasedValues.insert(Op0);
|
|
IVBasedValues.insert(Op1);
|
|
if (!cleanBlock(Header)) return false;
|
|
BasicBlock *ExitingBlock = ExitCondition->getParent();
|
|
if (!cleanBlock(ExitingBlock)) return false;
|
|
|
|
// Verify that loop exiting block has only two predecessor, where one pred
|
|
// 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 (Header == BB)
|
|
continue;
|
|
if (ExitingBBPred)
|
|
return false;
|
|
else
|
|
ExitingBBPred = BB;
|
|
}
|
|
|
|
if (!restrictLoopBound(*Op0))
|
|
return false;
|
|
|
|
if (!restrictLoopBound(*Op1))
|
|
return false;
|
|
|
|
// Update CFG.
|
|
if (BR->getSuccessor(0) == ExitingBlock)
|
|
BR->setUnconditionalDest(BR->getSuccessor(1));
|
|
else
|
|
BR->setUnconditionalDest(BR->getSuccessor(0));
|
|
|
|
AND->eraseFromParent();
|
|
if (Op0->use_empty())
|
|
Op0->eraseFromParent();
|
|
if (Op1->use_empty())
|
|
Op1->eraseFromParent();
|
|
|
|
// Update domiantor info. Now, ExitingBlock has only one predecessor,
|
|
// ExitingBBPred, and it is ExitingBlock's immediate domiantor.
|
|
DT->changeImmediateDominator(ExitingBlock, ExitingBBPred);
|
|
|
|
BasicBlock *ExitBlock = ExitingBlock->getTerminator()->getSuccessor(1);
|
|
if (L->contains(ExitBlock))
|
|
ExitBlock = ExitingBlock->getTerminator()->getSuccessor(0);
|
|
|
|
// If ExitingBlock is a member of the loop basic blocks' DF list then
|
|
// replace ExitingBlock with header and exit block in the DF list
|
|
DominanceFrontier::iterator ExitingBlockDF = DF->find(ExitingBlock);
|
|
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);
|
|
for (DominanceFrontier::DomSetType::iterator
|
|
EBI = ExitingBlockDF->second.begin(),
|
|
EBE = ExitingBlockDF->second.end(); EBI != EBE; ++EBI)
|
|
BBDF->second.insert(*EBI);
|
|
}
|
|
}
|
|
}
|
|
NumRestrictBounds++;
|
|
return true;
|
|
}
|
|
|
|
/// 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) {
|
|
|
|
// First update DeadBB's dominance frontier.
|
|
SmallVector<BasicBlock *, 8> FrontierBBs;
|
|
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;
|
|
FrontierBBs.push_back(FrontierBB);
|
|
|
|
// 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);
|
|
}
|
|
|
|
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);
|
|
}
|
|
}
|
|
else
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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);
|
|
BB->replaceAllUsesWith(UndefValue::get(Type::LabelTy));
|
|
}
|
|
|
|
while (!WorkList.empty()) {
|
|
BasicBlock *BB = WorkList.back(); WorkList.pop_back();
|
|
for(BasicBlock::iterator BBI = BB->begin(), BBE = BB->end();
|
|
BBI != BBE; ) {
|
|
Instruction *I = BBI;
|
|
++BBI;
|
|
I->replaceAllUsesWith(UndefValue::get(I->getType()));
|
|
I->eraseFromParent();
|
|
}
|
|
LPM->deleteSimpleAnalysisValue(BB, LP);
|
|
DT->eraseNode(BB);
|
|
DF->removeBlock(BB);
|
|
LI->removeBlock(BB);
|
|
BB->eraseFromParent();
|
|
}
|
|
|
|
// 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);
|
|
}
|
|
|
|
}
|
|
|
|
// moveExitCondition - Move exit condition EC into split condition block CondBB.
|
|
void LoopIndexSplit::moveExitCondition(BasicBlock *CondBB, BasicBlock *ActiveBB,
|
|
BasicBlock *ExitBB, ICmpInst *EC,
|
|
ICmpInst *SC, PHINode *IV,
|
|
Instruction *IVAdd, Loop *LP,
|
|
unsigned ExitValueNum) {
|
|
|
|
BasicBlock *ExitingBB = EC->getParent();
|
|
Instruction *CurrentBR = CondBB->getTerminator();
|
|
|
|
// Move exit condition into split condition block.
|
|
EC->moveBefore(CurrentBR);
|
|
EC->setOperand(ExitValueNum == 0 ? 1 : 0, IV);
|
|
|
|
// Move exiting block's branch into split condition block. Update its branch
|
|
// destination.
|
|
BranchInst *ExitingBR = cast<BranchInst>(ExitingBB->getTerminator());
|
|
ExitingBR->moveBefore(CurrentBR);
|
|
BasicBlock *OrigDestBB = NULL;
|
|
if (ExitingBR->getSuccessor(0) == ExitBB) {
|
|
OrigDestBB = ExitingBR->getSuccessor(1);
|
|
ExitingBR->setSuccessor(1, ActiveBB);
|
|
}
|
|
else {
|
|
OrigDestBB = ExitingBR->getSuccessor(0);
|
|
ExitingBR->setSuccessor(0, ActiveBB);
|
|
}
|
|
|
|
// Remove split condition and current split condition branch.
|
|
SC->eraseFromParent();
|
|
CurrentBR->eraseFromParent();
|
|
|
|
// Connect exiting block to original destination.
|
|
BranchInst::Create(OrigDestBB, ExitingBB);
|
|
|
|
// Update PHINodes
|
|
updatePHINodes(ExitBB, ExitingBB, CondBB, IV, IVAdd, LP);
|
|
|
|
// Fix dominator info.
|
|
// ExitBB is now dominated by CondBB
|
|
DT->changeImmediateDominator(ExitBB, CondBB);
|
|
DF->changeImmediateDominator(ExitBB, CondBB, DT);
|
|
|
|
// Basicblocks dominated by ActiveBB may have ExitingBB or
|
|
// a basic block outside the loop in their DF list. If so,
|
|
// replace it with CondBB.
|
|
DomTreeNode *Node = DT->getNode(ActiveBB);
|
|
for (df_iterator<DomTreeNode *> DI = df_begin(Node), DE = df_end(Node);
|
|
DI != DE; ++DI) {
|
|
BasicBlock *BB = DI->getBlock();
|
|
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 == ExitingBB || !L->contains(DFBB)) {
|
|
BBDF->second.erase(DFBB);
|
|
BBDF->second.insert(CondBB);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// updatePHINodes - CFG has been changed.
|
|
/// Before
|
|
/// - ExitBB's single predecessor was Latch
|
|
/// - Latch's second successor was Header
|
|
/// Now
|
|
/// - ExitBB's single predecessor is Header
|
|
/// - Latch's one and only successor is Header
|
|
///
|
|
/// Update ExitBB PHINodes' to reflect this change.
|
|
void LoopIndexSplit::updatePHINodes(BasicBlock *ExitBB, BasicBlock *Latch,
|
|
BasicBlock *Header,
|
|
PHINode *IV, Instruction *IVIncrement,
|
|
Loop *LP) {
|
|
|
|
for (BasicBlock::iterator BI = ExitBB->begin(), BE = ExitBB->end();
|
|
BI != BE; ) {
|
|
PHINode *PN = dyn_cast<PHINode>(BI);
|
|
++BI;
|
|
if (!PN)
|
|
break;
|
|
|
|
Value *V = PN->getIncomingValueForBlock(Latch);
|
|
if (PHINode *PHV = dyn_cast<PHINode>(V)) {
|
|
// PHV is in Latch. PHV has one use is in ExitBB PHINode. And one use
|
|
// in Header which is new incoming value for PN.
|
|
Value *NewV = NULL;
|
|
for (Value::use_iterator UI = PHV->use_begin(), E = PHV->use_end();
|
|
UI != E; ++UI)
|
|
if (PHINode *U = dyn_cast<PHINode>(*UI))
|
|
if (LP->contains(U->getParent())) {
|
|
NewV = U;
|
|
break;
|
|
}
|
|
|
|
// Add incoming value from header only if PN has any use inside the loop.
|
|
if (NewV)
|
|
PN->addIncoming(NewV, Header);
|
|
|
|
} else if (Instruction *PHI = dyn_cast<Instruction>(V)) {
|
|
// If this instruction is IVIncrement then IV is new incoming value
|
|
// from header otherwise this instruction must be incoming value from
|
|
// header because loop is in LCSSA form.
|
|
if (PHI == IVIncrement)
|
|
PN->addIncoming(IV, Header);
|
|
else
|
|
PN->addIncoming(V, Header);
|
|
} else
|
|
// Otherwise this is an incoming value from header because loop is in
|
|
// LCSSA form.
|
|
PN->addIncoming(V, Header);
|
|
|
|
// Remove incoming value from Latch.
|
|
PN->removeIncomingValue(Latch);
|
|
}
|
|
}
|
|
|
|
bool LoopIndexSplit::splitLoop() {
|
|
SplitCondition = NULL;
|
|
if (ExitCondition->getPredicate() == ICmpInst::ICMP_NE
|
|
|| ExitCondition->getPredicate() == ICmpInst::ICMP_EQ)
|
|
return false;
|
|
BasicBlock *Header = L->getHeader();
|
|
BasicBlock *Latch = L->getLoopLatch();
|
|
BranchInst *SBR = NULL; // Split Condition Branch
|
|
BranchInst *EBR = cast<BranchInst>(ExitCondition->getParent()->getTerminator());
|
|
// If Exiting block includes loop variant instructions then this
|
|
// loop may not be split safely.
|
|
BasicBlock *ExitingBlock = ExitCondition->getParent();
|
|
if (!cleanBlock(ExitingBlock)) return false;
|
|
|
|
for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
|
|
I != E; ++I) {
|
|
BranchInst *BR = dyn_cast<BranchInst>((*I)->getTerminator());
|
|
if (!BR || BR->isUnconditional()) continue;
|
|
ICmpInst *CI = dyn_cast<ICmpInst>(BR->getCondition());
|
|
if (!CI || CI == ExitCondition
|
|
|| CI->getPredicate() == ICmpInst::ICMP_NE
|
|
|| CI->getPredicate() == ICmpInst::ICMP_EQ)
|
|
continue;
|
|
|
|
// Unable to handle triangle loops at the moment.
|
|
// 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().
|
|
if (Header == (*I)
|
|
&& (Latch == BR->getSuccessor(0) || Latch == BR->getSuccessor(1)))
|
|
continue;
|
|
|
|
// If the block does not dominate the latch then this is not a diamond.
|
|
// Such loop may not benefit from index split.
|
|
if (!DT->dominates((*I), Latch))
|
|
continue;
|
|
|
|
// If split condition branches heads do not have single predecessor,
|
|
// SplitCondBlock, then is not possible to remove inactive branch.
|
|
if (!BR->getSuccessor(0)->getSinglePredecessor()
|
|
|| !BR->getSuccessor(1)->getSinglePredecessor())
|
|
return false;
|
|
|
|
// If the merge point for BR is not loop latch then skip this condition.
|
|
if (BR->getSuccessor(0) != Latch) {
|
|
DominanceFrontier::iterator DF0 = DF->find(BR->getSuccessor(0));
|
|
assert (DF0 != DF->end() && "Unable to find dominance frontier");
|
|
if (!DF0->second.count(Latch))
|
|
continue;
|
|
}
|
|
|
|
if (BR->getSuccessor(1) != Latch) {
|
|
DominanceFrontier::iterator DF1 = DF->find(BR->getSuccessor(1));
|
|
assert (DF1 != DF->end() && "Unable to find dominance frontier");
|
|
if (!DF1->second.count(Latch))
|
|
continue;
|
|
}
|
|
SplitCondition = CI;
|
|
SBR = BR;
|
|
break;
|
|
}
|
|
|
|
if (!SplitCondition)
|
|
return false;
|
|
|
|
// If the predicate sign does not match then skip.
|
|
if (ExitCondition->isSignedPredicate() != SplitCondition->isSignedPredicate())
|
|
return false;
|
|
|
|
unsigned EVOpNum = (ExitCondition->getOperand(1) == IVExitValue);
|
|
unsigned SVOpNum = IVBasedValues.count(SplitCondition->getOperand(0));
|
|
Value *SplitValue = SplitCondition->getOperand(SVOpNum);
|
|
if (!L->isLoopInvariant(SplitValue))
|
|
return false;
|
|
if (!IVBasedValues.count(SplitCondition->getOperand(!SVOpNum)))
|
|
return false;
|
|
|
|
// Normalize loop conditions so that it is easier to calculate new loop
|
|
// bounds.
|
|
if (IVisGT(*ExitCondition) || IVisGE(*ExitCondition)) {
|
|
ExitCondition->setPredicate(ExitCondition->getInversePredicate());
|
|
BasicBlock *T = EBR->getSuccessor(0);
|
|
EBR->setSuccessor(0, EBR->getSuccessor(1));
|
|
EBR->setSuccessor(1, T);
|
|
}
|
|
|
|
if (IVisGT(*SplitCondition) || IVisGE(*SplitCondition)) {
|
|
SplitCondition->setPredicate(SplitCondition->getInversePredicate());
|
|
BasicBlock *T = SBR->getSuccessor(0);
|
|
SBR->setSuccessor(0, SBR->getSuccessor(1));
|
|
SBR->setSuccessor(1, T);
|
|
}
|
|
|
|
//[*] Calculate new loop bounds.
|
|
Value *AEV = SplitValue;
|
|
Value *BSV = SplitValue;
|
|
bool Sign = SplitCondition->isSignedPredicate();
|
|
Instruction *PHTerm = L->getLoopPreheader()->getTerminator();
|
|
|
|
if (IVisLT(*ExitCondition)) {
|
|
if (IVisLT(*SplitCondition)) {
|
|
/* Do nothing */
|
|
}
|
|
else if (IVisLE(*SplitCondition)) {
|
|
AEV = getPlusOne(SplitValue, Sign, PHTerm);
|
|
BSV = getPlusOne(SplitValue, Sign, PHTerm);
|
|
} else {
|
|
assert (0 && "Unexpected split condition!");
|
|
}
|
|
}
|
|
else if (IVisLE(*ExitCondition)) {
|
|
if (IVisLT(*SplitCondition)) {
|
|
AEV = getMinusOne(SplitValue, Sign, PHTerm);
|
|
}
|
|
else if (IVisLE(*SplitCondition)) {
|
|
BSV = getPlusOne(SplitValue, Sign, PHTerm);
|
|
} else {
|
|
assert (0 && "Unexpected split condition!");
|
|
}
|
|
} else {
|
|
assert (0 && "Unexpected exit condition!");
|
|
}
|
|
AEV = getMin(AEV, IVExitValue, Sign, PHTerm);
|
|
BSV = getMax(BSV, IVStartValue, Sign, PHTerm);
|
|
|
|
// [*] Clone Loop
|
|
DenseMap<const Value *, Value *> ValueMap;
|
|
Loop *BLoop = CloneLoop(L, LPM, LI, ValueMap, this);
|
|
Loop *ALoop = L;
|
|
|
|
// [*] ALoop's exiting edge enters 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);
|
|
BasicBlock *B_Header = BLoop->getHeader();
|
|
if (ALoop->contains(B_ExitBlock)) {
|
|
B_ExitBlock = A_ExitInsn->getSuccessor(0);
|
|
A_ExitInsn->setSuccessor(0, B_Header);
|
|
} else
|
|
A_ExitInsn->setSuccessor(1, B_Header);
|
|
|
|
// [*] Update ALoop's exit value using new exit value.
|
|
ExitCondition->setOperand(EVOpNum, AEV);
|
|
|
|
// [*] 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.
|
|
|
|
// Collect inverse map of Header PHINodes.
|
|
DenseMap<Value *, Value *> InverseMap;
|
|
for (BasicBlock::iterator BI = ALoop->getHeader()->begin(),
|
|
BE = ALoop->getHeader()->end(); BI != BE; ++BI) {
|
|
if (PHINode *PN = dyn_cast<PHINode>(BI)) {
|
|
PHINode *PNClone = cast<PHINode>(ValueMap[PN]);
|
|
InverseMap[PNClone] = PN;
|
|
} else
|
|
break;
|
|
}
|
|
|
|
BasicBlock *A_Preheader = ALoop->getLoopPreheader();
|
|
for (BasicBlock::iterator BI = B_Header->begin(), BE = B_Header->end();
|
|
BI != BE; ++BI) {
|
|
if (PHINode *PN = dyn_cast<PHINode>(BI)) {
|
|
// Remove incoming value from original preheader.
|
|
PN->removeIncomingValue(A_Preheader);
|
|
|
|
// Add incoming value from A_ExitingBlock.
|
|
if (PN == B_IndVar)
|
|
PN->addIncoming(BSV, A_ExitingBlock);
|
|
else {
|
|
PHINode *OrigPN = cast<PHINode>(InverseMap[PN]);
|
|
Value *V2 = NULL;
|
|
// If loop header is also loop exiting block then
|
|
// OrigPN is incoming value for B loop header.
|
|
if (A_ExitingBlock == ALoop->getHeader())
|
|
V2 = OrigPN;
|
|
else
|
|
V2 = OrigPN->getIncomingValueForBlock(A_ExitingBlock);
|
|
PN->addIncoming(V2, A_ExitingBlock);
|
|
}
|
|
} else
|
|
break;
|
|
}
|
|
|
|
DT->changeImmediateDominator(B_Header, A_ExitingBlock);
|
|
DF->changeImmediateDominator(B_Header, A_ExitingBlock, DT);
|
|
|
|
// [*] 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();
|
|
BI != BE; ++BI) {
|
|
if (PHINode *PN = dyn_cast<PHINode>(BI)) {
|
|
PN->addIncoming(ValueMap[PN->getIncomingValueForBlock(A_ExitingBlock)],
|
|
B_ExitingBlock);
|
|
PN->removeIncomingValue(A_ExitingBlock);
|
|
} else
|
|
break;
|
|
}
|
|
|
|
DT->changeImmediateDominator(B_ExitBlock, B_ExitingBlock);
|
|
DF->changeImmediateDominator(B_ExitBlock, B_ExitingBlock, DT);
|
|
|
|
//[*] 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);
|
|
|
|
//[*] 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();
|
|
BI != BE; ++BI) {
|
|
if (PHINode *PN = dyn_cast<PHINode>(BI)) {
|
|
Value *V1 = PN->getIncomingValueForBlock(A_ExitBlock);
|
|
PHINode *newPHI = PHINode::Create(PN->getType(), PN->getName());
|
|
newPHI->addIncoming(V1, A_ExitingBlock);
|
|
A_ExitBlock->getInstList().push_front(newPHI);
|
|
PN->removeIncomingValue(A_ExitBlock);
|
|
PN->addIncoming(newPHI, A_ExitBlock);
|
|
} else
|
|
break;
|
|
}
|
|
|
|
//[*] Eliminate split condition's inactive branch from ALoop.
|
|
BasicBlock *A_SplitCondBlock = SplitCondition->getParent();
|
|
BranchInst *A_BR = cast<BranchInst>(A_SplitCondBlock->getTerminator());
|
|
BasicBlock *A_InactiveBranch = NULL;
|
|
BasicBlock *A_ActiveBranch = NULL;
|
|
A_ActiveBranch = A_BR->getSuccessor(0);
|
|
A_InactiveBranch = A_BR->getSuccessor(1);
|
|
A_BR->setUnconditionalDest(A_ActiveBranch);
|
|
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 = NULL;
|
|
BasicBlock *B_ActiveBranch = NULL;
|
|
B_ActiveBranch = B_BR->getSuccessor(1);
|
|
B_InactiveBranch = B_BR->getSuccessor(0);
|
|
B_BR->setUnconditionalDest(B_ActiveBranch);
|
|
removeBlocks(B_InactiveBranch, BLoop, B_ActiveBranch);
|
|
|
|
BasicBlock *A_Header = ALoop->getHeader();
|
|
if (A_ExitingBlock == A_Header)
|
|
return true;
|
|
|
|
//[*] Move exit condition into split condition block to avoid
|
|
// executing dead loop iteration.
|
|
ICmpInst *B_ExitCondition = cast<ICmpInst>(ValueMap[ExitCondition]);
|
|
Instruction *B_IndVarIncrement = cast<Instruction>(ValueMap[IVIncrement]);
|
|
ICmpInst *B_SplitCondition = cast<ICmpInst>(ValueMap[SplitCondition]);
|
|
|
|
moveExitCondition(A_SplitCondBlock, A_ActiveBranch, A_ExitBlock, ExitCondition,
|
|
cast<ICmpInst>(SplitCondition), IndVar, IVIncrement,
|
|
ALoop, EVOpNum);
|
|
|
|
moveExitCondition(B_SplitCondBlock, B_ActiveBranch,
|
|
B_ExitBlock, B_ExitCondition,
|
|
B_SplitCondition, B_IndVar, B_IndVarIncrement,
|
|
BLoop, EVOpNum);
|
|
|
|
NumIndexSplit++;
|
|
return true;
|
|
}
|
|
|
|
/// cleanBlock - A block is considered clean if all non terminal instructions
|
|
/// are either, PHINodes, IV based.
|
|
bool LoopIndexSplit::cleanBlock(BasicBlock *BB) {
|
|
Instruction *Terminator = BB->getTerminator();
|
|
for(BasicBlock::iterator BI = BB->begin(), BE = BB->end();
|
|
BI != BE; ++BI) {
|
|
Instruction *I = BI;
|
|
|
|
if (isa<PHINode>(I) || I == Terminator || I == ExitCondition
|
|
|| I == SplitCondition || IVBasedValues.count(I)
|
|
|| isa<DbgInfoIntrinsic>(I))
|
|
continue;
|
|
|
|
if (I->mayWriteToMemory())
|
|
return false;
|
|
|
|
// I is used only inside this block then it is OK.
|
|
bool usedOutsideBB = false;
|
|
for (Value::use_iterator UI = I->use_begin(), UE = I->use_end();
|
|
UI != UE; ++UI) {
|
|
Instruction *U = cast<Instruction>(UI);
|
|
if (U->getParent() != BB)
|
|
usedOutsideBB = true;
|
|
}
|
|
if (!usedOutsideBB)
|
|
continue;
|
|
|
|
// Otherwise we have a instruction that may not allow loop spliting.
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// IVisLT - If Op is comparing IV based value with an loop invariant and
|
|
/// IV based value is less than the loop invariant then return the loop
|
|
/// invariant. Otherwise return NULL.
|
|
Value * LoopIndexSplit::IVisLT(ICmpInst &Op) {
|
|
ICmpInst::Predicate P = Op.getPredicate();
|
|
if ((P == ICmpInst::ICMP_SLT || P == ICmpInst::ICMP_ULT)
|
|
&& IVBasedValues.count(Op.getOperand(0))
|
|
&& L->isLoopInvariant(Op.getOperand(1)))
|
|
return Op.getOperand(1);
|
|
|
|
if ((P == ICmpInst::ICMP_SGT || P == ICmpInst::ICMP_UGT)
|
|
&& IVBasedValues.count(Op.getOperand(1))
|
|
&& L->isLoopInvariant(Op.getOperand(0)))
|
|
return Op.getOperand(0);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/// IVisLE - If Op is comparing IV based value with an loop invariant and
|
|
/// IV based value is less than or equal to the loop invariant then
|
|
/// return the loop invariant. Otherwise return NULL.
|
|
Value * LoopIndexSplit::IVisLE(ICmpInst &Op) {
|
|
ICmpInst::Predicate P = Op.getPredicate();
|
|
if ((P == ICmpInst::ICMP_SLE || P == ICmpInst::ICMP_ULE)
|
|
&& IVBasedValues.count(Op.getOperand(0))
|
|
&& L->isLoopInvariant(Op.getOperand(1)))
|
|
return Op.getOperand(1);
|
|
|
|
if ((P == ICmpInst::ICMP_SGE || P == ICmpInst::ICMP_UGE)
|
|
&& IVBasedValues.count(Op.getOperand(1))
|
|
&& L->isLoopInvariant(Op.getOperand(0)))
|
|
return Op.getOperand(0);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/// IVisGT - If Op is comparing IV based value with an loop invariant and
|
|
/// IV based value is greater than the loop invariant then return the loop
|
|
/// invariant. Otherwise return NULL.
|
|
Value * LoopIndexSplit::IVisGT(ICmpInst &Op) {
|
|
ICmpInst::Predicate P = Op.getPredicate();
|
|
if ((P == ICmpInst::ICMP_SGT || P == ICmpInst::ICMP_UGT)
|
|
&& IVBasedValues.count(Op.getOperand(0))
|
|
&& L->isLoopInvariant(Op.getOperand(1)))
|
|
return Op.getOperand(1);
|
|
|
|
if ((P == ICmpInst::ICMP_SLT || P == ICmpInst::ICMP_ULT)
|
|
&& IVBasedValues.count(Op.getOperand(1))
|
|
&& L->isLoopInvariant(Op.getOperand(0)))
|
|
return Op.getOperand(0);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/// IVisGE - If Op is comparing IV based value with an loop invariant and
|
|
/// IV based value is greater than or equal to the loop invariant then
|
|
/// return the loop invariant. Otherwise return NULL.
|
|
Value * LoopIndexSplit::IVisGE(ICmpInst &Op) {
|
|
ICmpInst::Predicate P = Op.getPredicate();
|
|
if ((P == ICmpInst::ICMP_SGE || P == ICmpInst::ICMP_UGE)
|
|
&& IVBasedValues.count(Op.getOperand(0))
|
|
&& L->isLoopInvariant(Op.getOperand(1)))
|
|
return Op.getOperand(1);
|
|
|
|
if ((P == ICmpInst::ICMP_SLE || P == ICmpInst::ICMP_ULE)
|
|
&& IVBasedValues.count(Op.getOperand(1))
|
|
&& L->isLoopInvariant(Op.getOperand(0)))
|
|
return Op.getOperand(0);
|
|
|
|
return NULL;
|
|
}
|
|
|