[LoopDist/LoopVer] Move LoopVersioning to a new module, NFC
Summary:
The class will obviously need improvement down the road. For one, there
is no reason that addPHINodes would have to be exposed like that. I
will make this and other improvements in follow-up patches.
The main goal is to be able to share this functionality. The
LoopLoadElimination pass I am working on needs it too. Later we can
move other clients as well (LV and Ashutosh's LICMVer).
Reviewers: hfinkel, ashutosh.nema
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D10577
llvm-svn: 241932
diff --git a/llvm/lib/Transforms/Scalar/LoopDistribute.cpp b/llvm/lib/Transforms/Scalar/LoopDistribute.cpp
index 9a10817..7598322 100644
--- a/llvm/lib/Transforms/Scalar/LoopDistribute.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopDistribute.cpp
@@ -34,6 +34,7 @@
#include "llvm/Support/Debug.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Transforms/Utils/LoopVersioning.h"
#include <list>
#define LDIST_NAME "loop-distribute"
@@ -567,121 +568,6 @@
AccessesType Accesses;
};
-/// \brief Handles the loop versioning based on memchecks.
-class LoopVersioning {
-public:
- LoopVersioning(const LoopAccessInfo &LAI, Loop *L, LoopInfo *LI,
- DominatorTree *DT,
- const SmallVector<int, 8> *PtrToPartition = nullptr)
- : VersionedLoop(L), NonVersionedLoop(nullptr),
- PtrToPartition(PtrToPartition), LAI(LAI), LI(LI), DT(DT) {}
-
- /// \brief Returns true if we need memchecks to disambiguate may-aliasing
- /// accesses.
- bool needsRuntimeChecks() const {
- return LAI.getRuntimePointerCheck()->needsAnyChecking(PtrToPartition);
- }
-
- /// \brief Performs the CFG manipulation part of versioning the loop including
- /// the DominatorTree and LoopInfo updates.
- void versionLoop(Pass *P) {
- Instruction *FirstCheckInst;
- Instruction *MemRuntimeCheck;
- // Add the memcheck in the original preheader (this is empty initially).
- BasicBlock *MemCheckBB = VersionedLoop->getLoopPreheader();
- std::tie(FirstCheckInst, MemRuntimeCheck) =
- LAI.addRuntimeCheck(MemCheckBB->getTerminator(), PtrToPartition);
- assert(MemRuntimeCheck && "called even though needsAnyChecking = false");
-
- // Rename the block to make the IR more readable.
- MemCheckBB->setName(VersionedLoop->getHeader()->getName() +
- ".lver.memcheck");
-
- // Create empty preheader for the loop (and after cloning for the
- // non-versioned loop).
- BasicBlock *PH =
- SplitBlock(MemCheckBB, MemCheckBB->getTerminator(), DT, LI);
- PH->setName(VersionedLoop->getHeader()->getName() + ".ph");
-
- // Clone the loop including the preheader.
- //
- // FIXME: This does not currently preserve SimplifyLoop because the exit
- // block is a join between the two loops.
- SmallVector<BasicBlock *, 8> NonVersionedLoopBlocks;
- NonVersionedLoop =
- cloneLoopWithPreheader(PH, MemCheckBB, VersionedLoop, VMap,
- ".lver.orig", LI, DT, NonVersionedLoopBlocks);
- remapInstructionsInBlocks(NonVersionedLoopBlocks, VMap);
-
- // Insert the conditional branch based on the result of the memchecks.
- Instruction *OrigTerm = MemCheckBB->getTerminator();
- BranchInst::Create(NonVersionedLoop->getLoopPreheader(),
- VersionedLoop->getLoopPreheader(), MemRuntimeCheck,
- OrigTerm);
- OrigTerm->eraseFromParent();
-
- // The loops merge in the original exit block. This is now dominated by the
- // memchecking block.
- DT->changeImmediateDominator(VersionedLoop->getExitBlock(), MemCheckBB);
- }
-
- /// \brief Adds the necessary PHI nodes for the versioned loops based on the
- /// loop-defined values used outside of the loop.
- void addPHINodes(const SmallVectorImpl<Instruction *> &DefsUsedOutside) {
- BasicBlock *PHIBlock = VersionedLoop->getExitBlock();
- assert(PHIBlock && "No single successor to loop exit block");
-
- for (auto *Inst : DefsUsedOutside) {
- auto *NonVersionedLoopInst = cast<Instruction>(VMap[Inst]);
- PHINode *PN;
-
- // First see if we have a single-operand PHI with the value defined by the
- // original loop.
- for (auto I = PHIBlock->begin(); (PN = dyn_cast<PHINode>(I)); ++I) {
- assert(PN->getNumOperands() == 1 &&
- "Exit block should only have on predecessor");
- if (PN->getIncomingValue(0) == Inst)
- break;
- }
- // If not create it.
- if (!PN) {
- PN = PHINode::Create(Inst->getType(), 2, Inst->getName() + ".lver",
- PHIBlock->begin());
- for (auto *User : Inst->users())
- if (!VersionedLoop->contains(cast<Instruction>(User)->getParent()))
- User->replaceUsesOfWith(Inst, PN);
- PN->addIncoming(Inst, VersionedLoop->getExitingBlock());
- }
- // Add the new incoming value from the non-versioned loop.
- PN->addIncoming(NonVersionedLoopInst,
- NonVersionedLoop->getExitingBlock());
- }
- }
-
-private:
- /// \brief The original loop. This becomes the "versioned" one, i.e. control
- /// goes if the memchecks all pass.
- Loop *VersionedLoop;
- /// \brief The fall-back loop, i.e. if any of the memchecks fail.
- Loop *NonVersionedLoop;
-
- /// \brief For each memory pointer it contains the partitionId it is used in.
- /// If nullptr, no partitioning is used.
- ///
- /// The I-th entry corresponds to I-th entry in LAI.getRuntimePointerCheck().
- /// If the pointer is used in multiple partitions the entry is set to -1.
- const SmallVector<int, 8> *PtrToPartition;
-
- /// \brief This maps the instructions from VersionedLoop to their counterpart
- /// in NonVersionedLoop.
- ValueToValueMapTy VMap;
-
- /// \brief Analyses used.
- const LoopAccessInfo &LAI;
- LoopInfo *LI;
- DominatorTree *DT;
-};
-
/// \brief Returns the instructions that use values defined in the loop.
static SmallVector<Instruction *, 8> findDefsUsedOutsideOfLoop(Loop *L) {
SmallVector<Instruction *, 8> UsedOutside;