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//===- ScopHelper.cpp - Some Helper Functions for Scop. ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Small functions that help with Scop and LLVM-IR.
//
//===----------------------------------------------------------------------===//
#include "polly/Support/ScopHelper.h"
#include "polly/ScopInfo.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/RegionInfo.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/IR/CFG.h"
#include "llvm/Support/Debug.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
using namespace llvm;
#define DEBUG_TYPE "polly-scop-helper"
// Helper function for Scop
// TODO: Add assertion to not allow parameter to be null
//===----------------------------------------------------------------------===//
// Temporary Hack for extended region tree.
// Cast the region to loop if there is a loop have the same header and exit.
Loop *polly::castToLoop(const Region &R, LoopInfo &LI) {
BasicBlock *entry = R.getEntry();
if (!LI.isLoopHeader(entry))
return 0;
Loop *L = LI.getLoopFor(entry);
BasicBlock *exit = L->getExitBlock();
// Is the loop with multiple exits?
if (!exit)
return 0;
if (exit != R.getExit()) {
// SubRegion/ParentRegion with the same entry.
assert((R.getNode(R.getEntry())->isSubRegion() ||
R.getParent()->getEntry() == entry) &&
"Expect the loop is the smaller or bigger region");
return 0;
}
return L;
}
Value *polly::getPointerOperand(Instruction &Inst) {
if (LoadInst *load = dyn_cast<LoadInst>(&Inst))
return load->getPointerOperand();
else if (StoreInst *store = dyn_cast<StoreInst>(&Inst))
return store->getPointerOperand();
else if (GetElementPtrInst *gep = dyn_cast<GetElementPtrInst>(&Inst))
return gep->getPointerOperand();
return 0;
}
Type *polly::getAccessInstType(Instruction *AccInst) {
if (StoreInst *Store = dyn_cast<StoreInst>(AccInst))
return Store->getValueOperand()->getType();
return AccInst->getType();
}
bool polly::hasInvokeEdge(const PHINode *PN) {
for (unsigned i = 0, e = PN->getNumIncomingValues(); i < e; ++i)
if (InvokeInst *II = dyn_cast<InvokeInst>(PN->getIncomingValue(i)))
if (II->getParent() == PN->getIncomingBlock(i))
return true;
return false;
}
BasicBlock *polly::createSingleExitEdge(Region *R, Pass *P) {
BasicBlock *BB = R->getExit();
SmallVector<BasicBlock *, 4> Preds;
for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI)
if (R->contains(*PI))
Preds.push_back(*PI);
auto *AA = P->getAnalysisIfAvailable<AliasAnalysis>();
auto *DTWP = P->getAnalysisIfAvailable<DominatorTreeWrapperPass>();
auto *DT = DTWP ? &DTWP->getDomTree() : nullptr;
auto *LIWP = P->getAnalysisIfAvailable<LoopInfoWrapperPass>();
auto *LI = LIWP ? &LIWP->getLoopInfo() : nullptr;
return SplitBlockPredecessors(BB, Preds, ".region", AA, DT, LI);
}
static void replaceScopAndRegionEntry(polly::Scop *S, BasicBlock *OldEntry,
BasicBlock *NewEntry) {
if (polly::ScopStmt *Stmt = S->getStmtForBasicBlock(OldEntry))
Stmt->setBasicBlock(NewEntry);
S->getRegion().replaceEntryRecursive(NewEntry);
}
BasicBlock *polly::simplifyRegion(Scop *S, Pass *P) {
Region *R = &S->getRegion();
// The entering block for the region.
BasicBlock *EnteringBB = R->getEnteringBlock();
BasicBlock *OldEntry = R->getEntry();
BasicBlock *NewEntry = nullptr;
// Create single entry edge if the region has multiple entry edges.
if (!EnteringBB) {
auto *DTWP = P->getAnalysisIfAvailable<DominatorTreeWrapperPass>();
auto *DT = DTWP ? &DTWP->getDomTree() : nullptr;
auto *LIWP = P->getAnalysisIfAvailable<LoopInfoWrapperPass>();
auto *LI = LIWP ? &LIWP->getLoopInfo() : nullptr;
NewEntry = SplitBlock(OldEntry, OldEntry->begin(), DT, LI);
EnteringBB = OldEntry;
}
// Create an unconditional entry edge.
if (EnteringBB->getTerminator()->getNumSuccessors() != 1) {
BasicBlock *EntryBB = NewEntry ? NewEntry : OldEntry;
BasicBlock *SplitEdgeBB = SplitEdge(EnteringBB, EntryBB, P);
// Once the edge between EnteringBB and EntryBB is split, two cases arise.
// The first is simple. The new block is inserted between EnteringBB and
// EntryBB. In this case no further action is needed. However it might
// happen (if the splitted edge is not critical) that the new block is
// inserted __after__ EntryBB causing the following situation:
//
// EnteringBB
// _|_
// | |
// | \-> some_other_BB_not_in_R
// V
// EntryBB
// |
// V
// SplitEdgeBB
//
// In this case we need to swap the role of EntryBB and SplitEdgeBB.
// Check which case SplitEdge produced:
if (SplitEdgeBB->getTerminator()->getSuccessor(0) == EntryBB) {
// First (simple) case.
EnteringBB = SplitEdgeBB;
} else {
// Second (complicated) case.
NewEntry = SplitEdgeBB;
EnteringBB = EntryBB;
}
EnteringBB->setName("polly.entering.block");
}
if (NewEntry)
replaceScopAndRegionEntry(S, OldEntry, NewEntry);
// Create single exit edge if the region has multiple exit edges.
if (!R->getExitingBlock()) {
BasicBlock *NewExit = createSingleExitEdge(R, P);
for (auto &&SubRegion : *R)
SubRegion->replaceExitRecursive(NewExit);
}
return EnteringBB;
}
void polly::splitEntryBlockForAlloca(BasicBlock *EntryBlock, Pass *P) {
// Find first non-alloca instruction. Every basic block has a non-alloc
// instruction, as every well formed basic block has a terminator.
BasicBlock::iterator I = EntryBlock->begin();
while (isa<AllocaInst>(I))
++I;
auto *DTWP = P->getAnalysisIfAvailable<DominatorTreeWrapperPass>();
auto *DT = DTWP ? &DTWP->getDomTree() : nullptr;
auto *LIWP = P->getAnalysisIfAvailable<LoopInfoWrapperPass>();
auto *LI = LIWP ? &LIWP->getLoopInfo() : nullptr;
// SplitBlock updates DT, DF and LI.
BasicBlock *NewEntry = SplitBlock(EntryBlock, I, DT, LI);
if (RegionInfoPass *RIP = P->getAnalysisIfAvailable<RegionInfoPass>())
RIP->getRegionInfo().splitBlock(NewEntry, EntryBlock);
}
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