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will make it more obvious what it represents, and stop it being confused with the StoreSize. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71349 91177308-0d34-0410-b5e6-96231b3b80d8
1816 lines
72 KiB
C++
1816 lines
72 KiB
C++
//===- ScalarReplAggregates.cpp - Scalar Replacement of Aggregates --------===//
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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 transformation implements the well known scalar replacement of
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// aggregates transformation. This xform breaks up alloca instructions of
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// aggregate type (structure or array) into individual alloca instructions for
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// each member (if possible). Then, if possible, it transforms the individual
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// alloca instructions into nice clean scalar SSA form.
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//
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// This combines a simple SRoA algorithm with the Mem2Reg algorithm because
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// often interact, especially for C++ programs. As such, iterating between
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// SRoA, then Mem2Reg until we run out of things to promote works well.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "scalarrepl"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Constants.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Function.h"
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#include "llvm/GlobalVariable.h"
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#include "llvm/Instructions.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/Pass.h"
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#include "llvm/Analysis/Dominators.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Transforms/Utils/PromoteMemToReg.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/GetElementPtrTypeIterator.h"
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#include "llvm/Support/IRBuilder.h"
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#include "llvm/Support/MathExtras.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/ADT/StringExtras.h"
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using namespace llvm;
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STATISTIC(NumReplaced, "Number of allocas broken up");
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STATISTIC(NumPromoted, "Number of allocas promoted");
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STATISTIC(NumConverted, "Number of aggregates converted to scalar");
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STATISTIC(NumGlobals, "Number of allocas copied from constant global");
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namespace {
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struct VISIBILITY_HIDDEN SROA : public FunctionPass {
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static char ID; // Pass identification, replacement for typeid
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explicit SROA(signed T = -1) : FunctionPass(&ID) {
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if (T == -1)
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SRThreshold = 128;
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else
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SRThreshold = T;
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}
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bool runOnFunction(Function &F);
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bool performScalarRepl(Function &F);
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bool performPromotion(Function &F);
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// getAnalysisUsage - This pass does not require any passes, but we know it
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// will not alter the CFG, so say so.
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequired<DominatorTree>();
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AU.addRequired<DominanceFrontier>();
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AU.addRequired<TargetData>();
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AU.setPreservesCFG();
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}
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private:
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TargetData *TD;
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/// AllocaInfo - When analyzing uses of an alloca instruction, this captures
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/// information about the uses. All these fields are initialized to false
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/// and set to true when something is learned.
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struct AllocaInfo {
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/// isUnsafe - This is set to true if the alloca cannot be SROA'd.
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bool isUnsafe : 1;
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/// needsCleanup - This is set to true if there is some use of the alloca
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/// that requires cleanup.
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bool needsCleanup : 1;
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/// isMemCpySrc - This is true if this aggregate is memcpy'd from.
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bool isMemCpySrc : 1;
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/// isMemCpyDst - This is true if this aggregate is memcpy'd into.
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bool isMemCpyDst : 1;
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AllocaInfo()
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: isUnsafe(false), needsCleanup(false),
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isMemCpySrc(false), isMemCpyDst(false) {}
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};
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unsigned SRThreshold;
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void MarkUnsafe(AllocaInfo &I) { I.isUnsafe = true; }
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int isSafeAllocaToScalarRepl(AllocationInst *AI);
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void isSafeUseOfAllocation(Instruction *User, AllocationInst *AI,
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AllocaInfo &Info);
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void isSafeElementUse(Value *Ptr, bool isFirstElt, AllocationInst *AI,
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AllocaInfo &Info);
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void isSafeMemIntrinsicOnAllocation(MemIntrinsic *MI, AllocationInst *AI,
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unsigned OpNo, AllocaInfo &Info);
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void isSafeUseOfBitCastedAllocation(BitCastInst *User, AllocationInst *AI,
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AllocaInfo &Info);
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void DoScalarReplacement(AllocationInst *AI,
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std::vector<AllocationInst*> &WorkList);
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void CleanupGEP(GetElementPtrInst *GEP);
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void CleanupAllocaUsers(AllocationInst *AI);
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AllocaInst *AddNewAlloca(Function &F, const Type *Ty, AllocationInst *Base);
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void RewriteBitCastUserOfAlloca(Instruction *BCInst, AllocationInst *AI,
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SmallVector<AllocaInst*, 32> &NewElts);
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void RewriteMemIntrinUserOfAlloca(MemIntrinsic *MI, Instruction *BCInst,
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AllocationInst *AI,
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SmallVector<AllocaInst*, 32> &NewElts);
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void RewriteStoreUserOfWholeAlloca(StoreInst *SI, AllocationInst *AI,
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SmallVector<AllocaInst*, 32> &NewElts);
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void RewriteLoadUserOfWholeAlloca(LoadInst *LI, AllocationInst *AI,
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SmallVector<AllocaInst*, 32> &NewElts);
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bool CanConvertToScalar(Value *V, bool &IsNotTrivial, const Type *&VecTy,
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bool &SawVec, uint64_t Offset, unsigned AllocaSize);
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void ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, uint64_t Offset);
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Value *ConvertScalar_ExtractValue(Value *NV, const Type *ToType,
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uint64_t Offset, IRBuilder<> &Builder);
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Value *ConvertScalar_InsertValue(Value *StoredVal, Value *ExistingVal,
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uint64_t Offset, IRBuilder<> &Builder);
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static Instruction *isOnlyCopiedFromConstantGlobal(AllocationInst *AI);
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};
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}
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char SROA::ID = 0;
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static RegisterPass<SROA> X("scalarrepl", "Scalar Replacement of Aggregates");
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// Public interface to the ScalarReplAggregates pass
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FunctionPass *llvm::createScalarReplAggregatesPass(signed int Threshold) {
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return new SROA(Threshold);
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}
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bool SROA::runOnFunction(Function &F) {
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TD = &getAnalysis<TargetData>();
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bool Changed = performPromotion(F);
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while (1) {
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bool LocalChange = performScalarRepl(F);
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if (!LocalChange) break; // No need to repromote if no scalarrepl
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Changed = true;
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LocalChange = performPromotion(F);
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if (!LocalChange) break; // No need to re-scalarrepl if no promotion
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}
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return Changed;
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}
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bool SROA::performPromotion(Function &F) {
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std::vector<AllocaInst*> Allocas;
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DominatorTree &DT = getAnalysis<DominatorTree>();
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DominanceFrontier &DF = getAnalysis<DominanceFrontier>();
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BasicBlock &BB = F.getEntryBlock(); // Get the entry node for the function
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bool Changed = false;
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while (1) {
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Allocas.clear();
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// Find allocas that are safe to promote, by looking at all instructions in
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// the entry node
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for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I)
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if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) // Is it an alloca?
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if (isAllocaPromotable(AI))
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Allocas.push_back(AI);
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if (Allocas.empty()) break;
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PromoteMemToReg(Allocas, DT, DF);
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NumPromoted += Allocas.size();
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Changed = true;
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}
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return Changed;
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}
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/// getNumSAElements - Return the number of elements in the specific struct or
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/// array.
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static uint64_t getNumSAElements(const Type *T) {
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if (const StructType *ST = dyn_cast<StructType>(T))
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return ST->getNumElements();
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return cast<ArrayType>(T)->getNumElements();
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}
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// performScalarRepl - This algorithm is a simple worklist driven algorithm,
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// which runs on all of the malloc/alloca instructions in the function, removing
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// them if they are only used by getelementptr instructions.
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//
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bool SROA::performScalarRepl(Function &F) {
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std::vector<AllocationInst*> WorkList;
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// Scan the entry basic block, adding any alloca's and mallocs to the worklist
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BasicBlock &BB = F.getEntryBlock();
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for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
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if (AllocationInst *A = dyn_cast<AllocationInst>(I))
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WorkList.push_back(A);
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// Process the worklist
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bool Changed = false;
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while (!WorkList.empty()) {
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AllocationInst *AI = WorkList.back();
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WorkList.pop_back();
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// Handle dead allocas trivially. These can be formed by SROA'ing arrays
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// with unused elements.
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if (AI->use_empty()) {
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AI->eraseFromParent();
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continue;
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}
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// If this alloca is impossible for us to promote, reject it early.
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if (AI->isArrayAllocation() || !AI->getAllocatedType()->isSized())
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continue;
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// Check to see if this allocation is only modified by a memcpy/memmove from
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// a constant global. If this is the case, we can change all users to use
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// the constant global instead. This is commonly produced by the CFE by
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// constructs like "void foo() { int A[] = {1,2,3,4,5,6,7,8,9...}; }" if 'A'
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// is only subsequently read.
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if (Instruction *TheCopy = isOnlyCopiedFromConstantGlobal(AI)) {
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DOUT << "Found alloca equal to global: " << *AI;
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DOUT << " memcpy = " << *TheCopy;
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Constant *TheSrc = cast<Constant>(TheCopy->getOperand(2));
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AI->replaceAllUsesWith(ConstantExpr::getBitCast(TheSrc, AI->getType()));
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TheCopy->eraseFromParent(); // Don't mutate the global.
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AI->eraseFromParent();
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++NumGlobals;
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Changed = true;
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continue;
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}
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// Check to see if we can perform the core SROA transformation. We cannot
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// transform the allocation instruction if it is an array allocation
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// (allocations OF arrays are ok though), and an allocation of a scalar
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// value cannot be decomposed at all.
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uint64_t AllocaSize = TD->getTypeAllocSize(AI->getAllocatedType());
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// Do not promote any struct whose size is too big.
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if (AllocaSize > SRThreshold) continue;
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if ((isa<StructType>(AI->getAllocatedType()) ||
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isa<ArrayType>(AI->getAllocatedType())) &&
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// Do not promote any struct into more than "32" separate vars.
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getNumSAElements(AI->getAllocatedType()) <= SRThreshold/4) {
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// Check that all of the users of the allocation are capable of being
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// transformed.
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switch (isSafeAllocaToScalarRepl(AI)) {
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default: assert(0 && "Unexpected value!");
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case 0: // Not safe to scalar replace.
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break;
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case 1: // Safe, but requires cleanup/canonicalizations first
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CleanupAllocaUsers(AI);
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// FALL THROUGH.
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case 3: // Safe to scalar replace.
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DoScalarReplacement(AI, WorkList);
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Changed = true;
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continue;
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}
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}
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// If we can turn this aggregate value (potentially with casts) into a
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// simple scalar value that can be mem2reg'd into a register value.
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// IsNotTrivial tracks whether this is something that mem2reg could have
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// promoted itself. If so, we don't want to transform it needlessly. Note
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// that we can't just check based on the type: the alloca may be of an i32
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// but that has pointer arithmetic to set byte 3 of it or something.
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bool IsNotTrivial = false;
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const Type *VectorTy = 0;
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bool HadAVector = false;
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if (CanConvertToScalar(AI, IsNotTrivial, VectorTy, HadAVector,
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0, unsigned(AllocaSize)) && IsNotTrivial) {
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AllocaInst *NewAI;
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// If we were able to find a vector type that can handle this with
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// insert/extract elements, and if there was at least one use that had
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// a vector type, promote this to a vector. We don't want to promote
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// random stuff that doesn't use vectors (e.g. <9 x double>) because then
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// we just get a lot of insert/extracts. If at least one vector is
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// involved, then we probably really do have a union of vector/array.
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if (VectorTy && isa<VectorType>(VectorTy) && HadAVector) {
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DOUT << "CONVERT TO VECTOR: " << *AI << " TYPE = " << *VectorTy <<"\n";
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// Create and insert the vector alloca.
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NewAI = new AllocaInst(VectorTy, 0, "", AI->getParent()->begin());
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ConvertUsesToScalar(AI, NewAI, 0);
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} else {
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DOUT << "CONVERT TO SCALAR INTEGER: " << *AI << "\n";
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// Create and insert the integer alloca.
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const Type *NewTy = IntegerType::get(AllocaSize*8);
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NewAI = new AllocaInst(NewTy, 0, "", AI->getParent()->begin());
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ConvertUsesToScalar(AI, NewAI, 0);
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}
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NewAI->takeName(AI);
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AI->eraseFromParent();
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++NumConverted;
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Changed = true;
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continue;
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}
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// Otherwise, couldn't process this alloca.
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}
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return Changed;
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}
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/// DoScalarReplacement - This alloca satisfied the isSafeAllocaToScalarRepl
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/// predicate, do SROA now.
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void SROA::DoScalarReplacement(AllocationInst *AI,
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std::vector<AllocationInst*> &WorkList) {
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DOUT << "Found inst to SROA: " << *AI;
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SmallVector<AllocaInst*, 32> ElementAllocas;
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if (const StructType *ST = dyn_cast<StructType>(AI->getAllocatedType())) {
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ElementAllocas.reserve(ST->getNumContainedTypes());
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for (unsigned i = 0, e = ST->getNumContainedTypes(); i != e; ++i) {
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AllocaInst *NA = new AllocaInst(ST->getContainedType(i), 0,
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AI->getAlignment(),
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AI->getName() + "." + utostr(i), AI);
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ElementAllocas.push_back(NA);
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WorkList.push_back(NA); // Add to worklist for recursive processing
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}
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} else {
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const ArrayType *AT = cast<ArrayType>(AI->getAllocatedType());
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ElementAllocas.reserve(AT->getNumElements());
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const Type *ElTy = AT->getElementType();
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for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) {
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AllocaInst *NA = new AllocaInst(ElTy, 0, AI->getAlignment(),
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AI->getName() + "." + utostr(i), AI);
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ElementAllocas.push_back(NA);
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WorkList.push_back(NA); // Add to worklist for recursive processing
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}
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}
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// Now that we have created the alloca instructions that we want to use,
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// expand the getelementptr instructions to use them.
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//
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while (!AI->use_empty()) {
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Instruction *User = cast<Instruction>(AI->use_back());
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if (BitCastInst *BCInst = dyn_cast<BitCastInst>(User)) {
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RewriteBitCastUserOfAlloca(BCInst, AI, ElementAllocas);
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BCInst->eraseFromParent();
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continue;
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}
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// Replace:
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// %res = load { i32, i32 }* %alloc
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// with:
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// %load.0 = load i32* %alloc.0
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// %insert.0 insertvalue { i32, i32 } zeroinitializer, i32 %load.0, 0
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// %load.1 = load i32* %alloc.1
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// %insert = insertvalue { i32, i32 } %insert.0, i32 %load.1, 1
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// (Also works for arrays instead of structs)
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if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
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Value *Insert = UndefValue::get(LI->getType());
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for (unsigned i = 0, e = ElementAllocas.size(); i != e; ++i) {
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Value *Load = new LoadInst(ElementAllocas[i], "load", LI);
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Insert = InsertValueInst::Create(Insert, Load, i, "insert", LI);
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}
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LI->replaceAllUsesWith(Insert);
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LI->eraseFromParent();
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continue;
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}
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// Replace:
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// store { i32, i32 } %val, { i32, i32 }* %alloc
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// with:
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// %val.0 = extractvalue { i32, i32 } %val, 0
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// store i32 %val.0, i32* %alloc.0
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// %val.1 = extractvalue { i32, i32 } %val, 1
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// store i32 %val.1, i32* %alloc.1
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// (Also works for arrays instead of structs)
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if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
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Value *Val = SI->getOperand(0);
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for (unsigned i = 0, e = ElementAllocas.size(); i != e; ++i) {
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Value *Extract = ExtractValueInst::Create(Val, i, Val->getName(), SI);
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new StoreInst(Extract, ElementAllocas[i], SI);
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}
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SI->eraseFromParent();
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continue;
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}
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GetElementPtrInst *GEPI = cast<GetElementPtrInst>(User);
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// We now know that the GEP is of the form: GEP <ptr>, 0, <cst>
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unsigned Idx =
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(unsigned)cast<ConstantInt>(GEPI->getOperand(2))->getZExtValue();
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assert(Idx < ElementAllocas.size() && "Index out of range?");
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AllocaInst *AllocaToUse = ElementAllocas[Idx];
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Value *RepValue;
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if (GEPI->getNumOperands() == 3) {
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// Do not insert a new getelementptr instruction with zero indices, only
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// to have it optimized out later.
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RepValue = AllocaToUse;
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} else {
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// We are indexing deeply into the structure, so we still need a
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// getelement ptr instruction to finish the indexing. This may be
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// expanded itself once the worklist is rerun.
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//
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SmallVector<Value*, 8> NewArgs;
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NewArgs.push_back(Constant::getNullValue(Type::Int32Ty));
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NewArgs.append(GEPI->op_begin()+3, GEPI->op_end());
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RepValue = GetElementPtrInst::Create(AllocaToUse, NewArgs.begin(),
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NewArgs.end(), "", GEPI);
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RepValue->takeName(GEPI);
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}
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// If this GEP is to the start of the aggregate, check for memcpys.
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if (Idx == 0 && GEPI->hasAllZeroIndices())
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RewriteBitCastUserOfAlloca(GEPI, AI, ElementAllocas);
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// Move all of the users over to the new GEP.
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GEPI->replaceAllUsesWith(RepValue);
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// Delete the old GEP
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GEPI->eraseFromParent();
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}
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// Finally, delete the Alloca instruction
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AI->eraseFromParent();
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NumReplaced++;
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}
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/// isSafeElementUse - Check to see if this use is an allowed use for a
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/// getelementptr instruction of an array aggregate allocation. isFirstElt
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/// indicates whether Ptr is known to the start of the aggregate.
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///
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void SROA::isSafeElementUse(Value *Ptr, bool isFirstElt, AllocationInst *AI,
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AllocaInfo &Info) {
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for (Value::use_iterator I = Ptr->use_begin(), E = Ptr->use_end();
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I != E; ++I) {
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Instruction *User = cast<Instruction>(*I);
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switch (User->getOpcode()) {
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case Instruction::Load: break;
|
|
case Instruction::Store:
|
|
// Store is ok if storing INTO the pointer, not storing the pointer
|
|
if (User->getOperand(0) == Ptr) return MarkUnsafe(Info);
|
|
break;
|
|
case Instruction::GetElementPtr: {
|
|
GetElementPtrInst *GEP = cast<GetElementPtrInst>(User);
|
|
bool AreAllZeroIndices = isFirstElt;
|
|
if (GEP->getNumOperands() > 1) {
|
|
if (!isa<ConstantInt>(GEP->getOperand(1)) ||
|
|
!cast<ConstantInt>(GEP->getOperand(1))->isZero())
|
|
// Using pointer arithmetic to navigate the array.
|
|
return MarkUnsafe(Info);
|
|
|
|
if (AreAllZeroIndices)
|
|
AreAllZeroIndices = GEP->hasAllZeroIndices();
|
|
}
|
|
isSafeElementUse(GEP, AreAllZeroIndices, AI, Info);
|
|
if (Info.isUnsafe) return;
|
|
break;
|
|
}
|
|
case Instruction::BitCast:
|
|
if (isFirstElt) {
|
|
isSafeUseOfBitCastedAllocation(cast<BitCastInst>(User), AI, Info);
|
|
if (Info.isUnsafe) return;
|
|
break;
|
|
}
|
|
DOUT << " Transformation preventing inst: " << *User;
|
|
return MarkUnsafe(Info);
|
|
case Instruction::Call:
|
|
if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(User)) {
|
|
if (isFirstElt) {
|
|
isSafeMemIntrinsicOnAllocation(MI, AI, I.getOperandNo(), Info);
|
|
if (Info.isUnsafe) return;
|
|
break;
|
|
}
|
|
}
|
|
DOUT << " Transformation preventing inst: " << *User;
|
|
return MarkUnsafe(Info);
|
|
default:
|
|
DOUT << " Transformation preventing inst: " << *User;
|
|
return MarkUnsafe(Info);
|
|
}
|
|
}
|
|
return; // All users look ok :)
|
|
}
|
|
|
|
/// AllUsersAreLoads - Return true if all users of this value are loads.
|
|
static bool AllUsersAreLoads(Value *Ptr) {
|
|
for (Value::use_iterator I = Ptr->use_begin(), E = Ptr->use_end();
|
|
I != E; ++I)
|
|
if (cast<Instruction>(*I)->getOpcode() != Instruction::Load)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
/// isSafeUseOfAllocation - Check to see if this user is an allowed use for an
|
|
/// aggregate allocation.
|
|
///
|
|
void SROA::isSafeUseOfAllocation(Instruction *User, AllocationInst *AI,
|
|
AllocaInfo &Info) {
|
|
if (BitCastInst *C = dyn_cast<BitCastInst>(User))
|
|
return isSafeUseOfBitCastedAllocation(C, AI, Info);
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(User))
|
|
if (!LI->isVolatile())
|
|
return;// Loads (returning a first class aggregrate) are always rewritable
|
|
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(User))
|
|
if (!SI->isVolatile() && SI->getOperand(0) != AI)
|
|
return;// Store is ok if storing INTO the pointer, not storing the pointer
|
|
|
|
GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User);
|
|
if (GEPI == 0)
|
|
return MarkUnsafe(Info);
|
|
|
|
gep_type_iterator I = gep_type_begin(GEPI), E = gep_type_end(GEPI);
|
|
|
|
// The GEP is not safe to transform if not of the form "GEP <ptr>, 0, <cst>".
|
|
if (I == E ||
|
|
I.getOperand() != Constant::getNullValue(I.getOperand()->getType())) {
|
|
return MarkUnsafe(Info);
|
|
}
|
|
|
|
++I;
|
|
if (I == E) return MarkUnsafe(Info); // ran out of GEP indices??
|
|
|
|
bool IsAllZeroIndices = true;
|
|
|
|
// If the first index is a non-constant index into an array, see if we can
|
|
// handle it as a special case.
|
|
if (const ArrayType *AT = dyn_cast<ArrayType>(*I)) {
|
|
if (!isa<ConstantInt>(I.getOperand())) {
|
|
IsAllZeroIndices = 0;
|
|
uint64_t NumElements = AT->getNumElements();
|
|
|
|
// If this is an array index and the index is not constant, we cannot
|
|
// promote... that is unless the array has exactly one or two elements in
|
|
// it, in which case we CAN promote it, but we have to canonicalize this
|
|
// out if this is the only problem.
|
|
if ((NumElements == 1 || NumElements == 2) &&
|
|
AllUsersAreLoads(GEPI)) {
|
|
Info.needsCleanup = true;
|
|
return; // Canonicalization required!
|
|
}
|
|
return MarkUnsafe(Info);
|
|
}
|
|
}
|
|
|
|
// Walk through the GEP type indices, checking the types that this indexes
|
|
// into.
|
|
for (; I != E; ++I) {
|
|
// Ignore struct elements, no extra checking needed for these.
|
|
if (isa<StructType>(*I))
|
|
continue;
|
|
|
|
ConstantInt *IdxVal = dyn_cast<ConstantInt>(I.getOperand());
|
|
if (!IdxVal) return MarkUnsafe(Info);
|
|
|
|
// Are all indices still zero?
|
|
IsAllZeroIndices &= IdxVal->isZero();
|
|
|
|
if (const ArrayType *AT = dyn_cast<ArrayType>(*I)) {
|
|
// This GEP indexes an array. Verify that this is an in-range constant
|
|
// integer. Specifically, consider A[0][i]. We cannot know that the user
|
|
// isn't doing invalid things like allowing i to index an out-of-range
|
|
// subscript that accesses A[1]. Because of this, we have to reject SROA
|
|
// of any accesses into structs where any of the components are variables.
|
|
if (IdxVal->getZExtValue() >= AT->getNumElements())
|
|
return MarkUnsafe(Info);
|
|
} else if (const VectorType *VT = dyn_cast<VectorType>(*I)) {
|
|
if (IdxVal->getZExtValue() >= VT->getNumElements())
|
|
return MarkUnsafe(Info);
|
|
}
|
|
}
|
|
|
|
// If there are any non-simple uses of this getelementptr, make sure to reject
|
|
// them.
|
|
return isSafeElementUse(GEPI, IsAllZeroIndices, AI, Info);
|
|
}
|
|
|
|
/// isSafeMemIntrinsicOnAllocation - Return true if the specified memory
|
|
/// intrinsic can be promoted by SROA. At this point, we know that the operand
|
|
/// of the memintrinsic is a pointer to the beginning of the allocation.
|
|
void SROA::isSafeMemIntrinsicOnAllocation(MemIntrinsic *MI, AllocationInst *AI,
|
|
unsigned OpNo, AllocaInfo &Info) {
|
|
// If not constant length, give up.
|
|
ConstantInt *Length = dyn_cast<ConstantInt>(MI->getLength());
|
|
if (!Length) return MarkUnsafe(Info);
|
|
|
|
// If not the whole aggregate, give up.
|
|
if (Length->getZExtValue() !=
|
|
TD->getTypeAllocSize(AI->getType()->getElementType()))
|
|
return MarkUnsafe(Info);
|
|
|
|
// We only know about memcpy/memset/memmove.
|
|
if (!isa<MemIntrinsic>(MI))
|
|
return MarkUnsafe(Info);
|
|
|
|
// Otherwise, we can transform it. Determine whether this is a memcpy/set
|
|
// into or out of the aggregate.
|
|
if (OpNo == 1)
|
|
Info.isMemCpyDst = true;
|
|
else {
|
|
assert(OpNo == 2);
|
|
Info.isMemCpySrc = true;
|
|
}
|
|
}
|
|
|
|
/// isSafeUseOfBitCastedAllocation - Return true if all users of this bitcast
|
|
/// are
|
|
void SROA::isSafeUseOfBitCastedAllocation(BitCastInst *BC, AllocationInst *AI,
|
|
AllocaInfo &Info) {
|
|
for (Value::use_iterator UI = BC->use_begin(), E = BC->use_end();
|
|
UI != E; ++UI) {
|
|
if (BitCastInst *BCU = dyn_cast<BitCastInst>(UI)) {
|
|
isSafeUseOfBitCastedAllocation(BCU, AI, Info);
|
|
} else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(UI)) {
|
|
isSafeMemIntrinsicOnAllocation(MI, AI, UI.getOperandNo(), Info);
|
|
} else if (StoreInst *SI = dyn_cast<StoreInst>(UI)) {
|
|
if (SI->isVolatile())
|
|
return MarkUnsafe(Info);
|
|
|
|
// If storing the entire alloca in one chunk through a bitcasted pointer
|
|
// to integer, we can transform it. This happens (for example) when you
|
|
// cast a {i32,i32}* to i64* and store through it. This is similar to the
|
|
// memcpy case and occurs in various "byval" cases and emulated memcpys.
|
|
if (isa<IntegerType>(SI->getOperand(0)->getType()) &&
|
|
TD->getTypeAllocSize(SI->getOperand(0)->getType()) ==
|
|
TD->getTypeAllocSize(AI->getType()->getElementType())) {
|
|
Info.isMemCpyDst = true;
|
|
continue;
|
|
}
|
|
return MarkUnsafe(Info);
|
|
} else if (LoadInst *LI = dyn_cast<LoadInst>(UI)) {
|
|
if (LI->isVolatile())
|
|
return MarkUnsafe(Info);
|
|
|
|
// If loading the entire alloca in one chunk through a bitcasted pointer
|
|
// to integer, we can transform it. This happens (for example) when you
|
|
// cast a {i32,i32}* to i64* and load through it. This is similar to the
|
|
// memcpy case and occurs in various "byval" cases and emulated memcpys.
|
|
if (isa<IntegerType>(LI->getType()) &&
|
|
TD->getTypeAllocSize(LI->getType()) ==
|
|
TD->getTypeAllocSize(AI->getType()->getElementType())) {
|
|
Info.isMemCpySrc = true;
|
|
continue;
|
|
}
|
|
return MarkUnsafe(Info);
|
|
} else if (isa<DbgInfoIntrinsic>(UI)) {
|
|
// If one user is DbgInfoIntrinsic then check if all users are
|
|
// DbgInfoIntrinsics.
|
|
if (OnlyUsedByDbgInfoIntrinsics(BC)) {
|
|
Info.needsCleanup = true;
|
|
return;
|
|
}
|
|
else
|
|
MarkUnsafe(Info);
|
|
}
|
|
else {
|
|
return MarkUnsafe(Info);
|
|
}
|
|
if (Info.isUnsafe) return;
|
|
}
|
|
}
|
|
|
|
/// RewriteBitCastUserOfAlloca - BCInst (transitively) bitcasts AI, or indexes
|
|
/// to its first element. Transform users of the cast to use the new values
|
|
/// instead.
|
|
void SROA::RewriteBitCastUserOfAlloca(Instruction *BCInst, AllocationInst *AI,
|
|
SmallVector<AllocaInst*, 32> &NewElts) {
|
|
Value::use_iterator UI = BCInst->use_begin(), UE = BCInst->use_end();
|
|
while (UI != UE) {
|
|
Instruction *User = cast<Instruction>(*UI++);
|
|
if (BitCastInst *BCU = dyn_cast<BitCastInst>(User)) {
|
|
RewriteBitCastUserOfAlloca(BCU, AI, NewElts);
|
|
if (BCU->use_empty()) BCU->eraseFromParent();
|
|
continue;
|
|
}
|
|
|
|
if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(User)) {
|
|
// This must be memcpy/memmove/memset of the entire aggregate.
|
|
// Split into one per element.
|
|
RewriteMemIntrinUserOfAlloca(MI, BCInst, AI, NewElts);
|
|
continue;
|
|
}
|
|
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
|
|
// If this is a store of the entire alloca from an integer, rewrite it.
|
|
RewriteStoreUserOfWholeAlloca(SI, AI, NewElts);
|
|
continue;
|
|
}
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
|
|
// If this is a load of the entire alloca to an integer, rewrite it.
|
|
RewriteLoadUserOfWholeAlloca(LI, AI, NewElts);
|
|
continue;
|
|
}
|
|
|
|
// Otherwise it must be some other user of a gep of the first pointer. Just
|
|
// leave these alone.
|
|
continue;
|
|
}
|
|
}
|
|
|
|
/// RewriteMemIntrinUserOfAlloca - MI is a memcpy/memset/memmove from or to AI.
|
|
/// Rewrite it to copy or set the elements of the scalarized memory.
|
|
void SROA::RewriteMemIntrinUserOfAlloca(MemIntrinsic *MI, Instruction *BCInst,
|
|
AllocationInst *AI,
|
|
SmallVector<AllocaInst*, 32> &NewElts) {
|
|
|
|
// If this is a memcpy/memmove, construct the other pointer as the
|
|
// appropriate type. The "Other" pointer is the pointer that goes to memory
|
|
// that doesn't have anything to do with the alloca that we are promoting. For
|
|
// memset, this Value* stays null.
|
|
Value *OtherPtr = 0;
|
|
unsigned MemAlignment = MI->getAlignment();
|
|
if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) { // memmove/memcopy
|
|
if (BCInst == MTI->getRawDest())
|
|
OtherPtr = MTI->getRawSource();
|
|
else {
|
|
assert(BCInst == MTI->getRawSource());
|
|
OtherPtr = MTI->getRawDest();
|
|
}
|
|
}
|
|
|
|
// If there is an other pointer, we want to convert it to the same pointer
|
|
// type as AI has, so we can GEP through it safely.
|
|
if (OtherPtr) {
|
|
// It is likely that OtherPtr is a bitcast, if so, remove it.
|
|
if (BitCastInst *BC = dyn_cast<BitCastInst>(OtherPtr))
|
|
OtherPtr = BC->getOperand(0);
|
|
// All zero GEPs are effectively bitcasts.
|
|
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(OtherPtr))
|
|
if (GEP->hasAllZeroIndices())
|
|
OtherPtr = GEP->getOperand(0);
|
|
|
|
if (ConstantExpr *BCE = dyn_cast<ConstantExpr>(OtherPtr))
|
|
if (BCE->getOpcode() == Instruction::BitCast)
|
|
OtherPtr = BCE->getOperand(0);
|
|
|
|
// If the pointer is not the right type, insert a bitcast to the right
|
|
// type.
|
|
if (OtherPtr->getType() != AI->getType())
|
|
OtherPtr = new BitCastInst(OtherPtr, AI->getType(), OtherPtr->getName(),
|
|
MI);
|
|
}
|
|
|
|
// Process each element of the aggregate.
|
|
Value *TheFn = MI->getOperand(0);
|
|
const Type *BytePtrTy = MI->getRawDest()->getType();
|
|
bool SROADest = MI->getRawDest() == BCInst;
|
|
|
|
Constant *Zero = Constant::getNullValue(Type::Int32Ty);
|
|
|
|
for (unsigned i = 0, e = NewElts.size(); i != e; ++i) {
|
|
// If this is a memcpy/memmove, emit a GEP of the other element address.
|
|
Value *OtherElt = 0;
|
|
unsigned OtherEltAlign = MemAlignment;
|
|
|
|
if (OtherPtr) {
|
|
Value *Idx[2] = { Zero, ConstantInt::get(Type::Int32Ty, i) };
|
|
OtherElt = GetElementPtrInst::Create(OtherPtr, Idx, Idx + 2,
|
|
OtherPtr->getNameStr()+"."+utostr(i),
|
|
MI);
|
|
uint64_t EltOffset;
|
|
const PointerType *OtherPtrTy = cast<PointerType>(OtherPtr->getType());
|
|
if (const StructType *ST =
|
|
dyn_cast<StructType>(OtherPtrTy->getElementType())) {
|
|
EltOffset = TD->getStructLayout(ST)->getElementOffset(i);
|
|
} else {
|
|
const Type *EltTy =
|
|
cast<SequentialType>(OtherPtr->getType())->getElementType();
|
|
EltOffset = TD->getTypeAllocSize(EltTy)*i;
|
|
}
|
|
|
|
// The alignment of the other pointer is the guaranteed alignment of the
|
|
// element, which is affected by both the known alignment of the whole
|
|
// mem intrinsic and the alignment of the element. If the alignment of
|
|
// the memcpy (f.e.) is 32 but the element is at a 4-byte offset, then the
|
|
// known alignment is just 4 bytes.
|
|
OtherEltAlign = (unsigned)MinAlign(OtherEltAlign, EltOffset);
|
|
}
|
|
|
|
Value *EltPtr = NewElts[i];
|
|
const Type *EltTy = cast<PointerType>(EltPtr->getType())->getElementType();
|
|
|
|
// If we got down to a scalar, insert a load or store as appropriate.
|
|
if (EltTy->isSingleValueType()) {
|
|
if (isa<MemTransferInst>(MI)) {
|
|
if (SROADest) {
|
|
// From Other to Alloca.
|
|
Value *Elt = new LoadInst(OtherElt, "tmp", false, OtherEltAlign, MI);
|
|
new StoreInst(Elt, EltPtr, MI);
|
|
} else {
|
|
// From Alloca to Other.
|
|
Value *Elt = new LoadInst(EltPtr, "tmp", MI);
|
|
new StoreInst(Elt, OtherElt, false, OtherEltAlign, MI);
|
|
}
|
|
continue;
|
|
}
|
|
assert(isa<MemSetInst>(MI));
|
|
|
|
// If the stored element is zero (common case), just store a null
|
|
// constant.
|
|
Constant *StoreVal;
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(MI->getOperand(2))) {
|
|
if (CI->isZero()) {
|
|
StoreVal = Constant::getNullValue(EltTy); // 0.0, null, 0, <0,0>
|
|
} else {
|
|
// If EltTy is a vector type, get the element type.
|
|
const Type *ValTy = EltTy;
|
|
if (const VectorType *VTy = dyn_cast<VectorType>(ValTy))
|
|
ValTy = VTy->getElementType();
|
|
|
|
// Construct an integer with the right value.
|
|
unsigned EltSize = TD->getTypeSizeInBits(ValTy);
|
|
APInt OneVal(EltSize, CI->getZExtValue());
|
|
APInt TotalVal(OneVal);
|
|
// Set each byte.
|
|
for (unsigned i = 0; 8*i < EltSize; ++i) {
|
|
TotalVal = TotalVal.shl(8);
|
|
TotalVal |= OneVal;
|
|
}
|
|
|
|
// Convert the integer value to the appropriate type.
|
|
StoreVal = ConstantInt::get(TotalVal);
|
|
if (isa<PointerType>(ValTy))
|
|
StoreVal = ConstantExpr::getIntToPtr(StoreVal, ValTy);
|
|
else if (ValTy->isFloatingPoint())
|
|
StoreVal = ConstantExpr::getBitCast(StoreVal, ValTy);
|
|
assert(StoreVal->getType() == ValTy && "Type mismatch!");
|
|
|
|
// If the requested value was a vector constant, create it.
|
|
if (EltTy != ValTy) {
|
|
unsigned NumElts = cast<VectorType>(ValTy)->getNumElements();
|
|
SmallVector<Constant*, 16> Elts(NumElts, StoreVal);
|
|
StoreVal = ConstantVector::get(&Elts[0], NumElts);
|
|
}
|
|
}
|
|
new StoreInst(StoreVal, EltPtr, MI);
|
|
continue;
|
|
}
|
|
// Otherwise, if we're storing a byte variable, use a memset call for
|
|
// this element.
|
|
}
|
|
|
|
// Cast the element pointer to BytePtrTy.
|
|
if (EltPtr->getType() != BytePtrTy)
|
|
EltPtr = new BitCastInst(EltPtr, BytePtrTy, EltPtr->getNameStr(), MI);
|
|
|
|
// Cast the other pointer (if we have one) to BytePtrTy.
|
|
if (OtherElt && OtherElt->getType() != BytePtrTy)
|
|
OtherElt = new BitCastInst(OtherElt, BytePtrTy,OtherElt->getNameStr(),
|
|
MI);
|
|
|
|
unsigned EltSize = TD->getTypeAllocSize(EltTy);
|
|
|
|
// Finally, insert the meminst for this element.
|
|
if (isa<MemTransferInst>(MI)) {
|
|
Value *Ops[] = {
|
|
SROADest ? EltPtr : OtherElt, // Dest ptr
|
|
SROADest ? OtherElt : EltPtr, // Src ptr
|
|
ConstantInt::get(MI->getOperand(3)->getType(), EltSize), // Size
|
|
ConstantInt::get(Type::Int32Ty, OtherEltAlign) // Align
|
|
};
|
|
CallInst::Create(TheFn, Ops, Ops + 4, "", MI);
|
|
} else {
|
|
assert(isa<MemSetInst>(MI));
|
|
Value *Ops[] = {
|
|
EltPtr, MI->getOperand(2), // Dest, Value,
|
|
ConstantInt::get(MI->getOperand(3)->getType(), EltSize), // Size
|
|
Zero // Align
|
|
};
|
|
CallInst::Create(TheFn, Ops, Ops + 4, "", MI);
|
|
}
|
|
}
|
|
MI->eraseFromParent();
|
|
}
|
|
|
|
/// RewriteStoreUserOfWholeAlloca - We found an store of an integer that
|
|
/// overwrites the entire allocation. Extract out the pieces of the stored
|
|
/// integer and store them individually.
|
|
void SROA::RewriteStoreUserOfWholeAlloca(StoreInst *SI,
|
|
AllocationInst *AI,
|
|
SmallVector<AllocaInst*, 32> &NewElts){
|
|
// Extract each element out of the integer according to its structure offset
|
|
// and store the element value to the individual alloca.
|
|
Value *SrcVal = SI->getOperand(0);
|
|
const Type *AllocaEltTy = AI->getType()->getElementType();
|
|
uint64_t AllocaSizeBits = TD->getTypeAllocSizeInBits(AllocaEltTy);
|
|
|
|
// If this isn't a store of an integer to the whole alloca, it may be a store
|
|
// to the first element. Just ignore the store in this case and normal SROA
|
|
// will handle it. We don't handle types here that have tail padding, like
|
|
// an alloca of type {i1}.
|
|
if (!isa<IntegerType>(SrcVal->getType()) ||
|
|
TD->getTypeSizeInBits(SrcVal->getType()) != AllocaSizeBits)
|
|
return;
|
|
|
|
DOUT << "PROMOTING STORE TO WHOLE ALLOCA: " << *AI << *SI;
|
|
|
|
// There are two forms here: AI could be an array or struct. Both cases
|
|
// have different ways to compute the element offset.
|
|
if (const StructType *EltSTy = dyn_cast<StructType>(AllocaEltTy)) {
|
|
const StructLayout *Layout = TD->getStructLayout(EltSTy);
|
|
|
|
for (unsigned i = 0, e = NewElts.size(); i != e; ++i) {
|
|
// Get the number of bits to shift SrcVal to get the value.
|
|
const Type *FieldTy = EltSTy->getElementType(i);
|
|
uint64_t Shift = Layout->getElementOffsetInBits(i);
|
|
|
|
if (TD->isBigEndian())
|
|
Shift = AllocaSizeBits-Shift-TD->getTypeAllocSizeInBits(FieldTy);
|
|
|
|
Value *EltVal = SrcVal;
|
|
if (Shift) {
|
|
Value *ShiftVal = ConstantInt::get(EltVal->getType(), Shift);
|
|
EltVal = BinaryOperator::CreateLShr(EltVal, ShiftVal,
|
|
"sroa.store.elt", SI);
|
|
}
|
|
|
|
// Truncate down to an integer of the right size.
|
|
uint64_t FieldSizeBits = TD->getTypeSizeInBits(FieldTy);
|
|
|
|
// Ignore zero sized fields like {}, they obviously contain no data.
|
|
if (FieldSizeBits == 0) continue;
|
|
|
|
if (FieldSizeBits != AllocaSizeBits)
|
|
EltVal = new TruncInst(EltVal, IntegerType::get(FieldSizeBits), "", SI);
|
|
Value *DestField = NewElts[i];
|
|
if (EltVal->getType() == FieldTy) {
|
|
// Storing to an integer field of this size, just do it.
|
|
} else if (FieldTy->isFloatingPoint() || isa<VectorType>(FieldTy)) {
|
|
// Bitcast to the right element type (for fp/vector values).
|
|
EltVal = new BitCastInst(EltVal, FieldTy, "", SI);
|
|
} else {
|
|
// Otherwise, bitcast the dest pointer (for aggregates).
|
|
DestField = new BitCastInst(DestField,
|
|
PointerType::getUnqual(EltVal->getType()),
|
|
"", SI);
|
|
}
|
|
new StoreInst(EltVal, DestField, SI);
|
|
}
|
|
|
|
} else {
|
|
const ArrayType *ATy = cast<ArrayType>(AllocaEltTy);
|
|
const Type *ArrayEltTy = ATy->getElementType();
|
|
uint64_t ElementOffset = TD->getTypeAllocSizeInBits(ArrayEltTy);
|
|
uint64_t ElementSizeBits = TD->getTypeSizeInBits(ArrayEltTy);
|
|
|
|
uint64_t Shift;
|
|
|
|
if (TD->isBigEndian())
|
|
Shift = AllocaSizeBits-ElementOffset;
|
|
else
|
|
Shift = 0;
|
|
|
|
for (unsigned i = 0, e = NewElts.size(); i != e; ++i) {
|
|
// Ignore zero sized fields like {}, they obviously contain no data.
|
|
if (ElementSizeBits == 0) continue;
|
|
|
|
Value *EltVal = SrcVal;
|
|
if (Shift) {
|
|
Value *ShiftVal = ConstantInt::get(EltVal->getType(), Shift);
|
|
EltVal = BinaryOperator::CreateLShr(EltVal, ShiftVal,
|
|
"sroa.store.elt", SI);
|
|
}
|
|
|
|
// Truncate down to an integer of the right size.
|
|
if (ElementSizeBits != AllocaSizeBits)
|
|
EltVal = new TruncInst(EltVal, IntegerType::get(ElementSizeBits),"",SI);
|
|
Value *DestField = NewElts[i];
|
|
if (EltVal->getType() == ArrayEltTy) {
|
|
// Storing to an integer field of this size, just do it.
|
|
} else if (ArrayEltTy->isFloatingPoint() || isa<VectorType>(ArrayEltTy)) {
|
|
// Bitcast to the right element type (for fp/vector values).
|
|
EltVal = new BitCastInst(EltVal, ArrayEltTy, "", SI);
|
|
} else {
|
|
// Otherwise, bitcast the dest pointer (for aggregates).
|
|
DestField = new BitCastInst(DestField,
|
|
PointerType::getUnqual(EltVal->getType()),
|
|
"", SI);
|
|
}
|
|
new StoreInst(EltVal, DestField, SI);
|
|
|
|
if (TD->isBigEndian())
|
|
Shift -= ElementOffset;
|
|
else
|
|
Shift += ElementOffset;
|
|
}
|
|
}
|
|
|
|
SI->eraseFromParent();
|
|
}
|
|
|
|
/// RewriteLoadUserOfWholeAlloca - We found an load of the entire allocation to
|
|
/// an integer. Load the individual pieces to form the aggregate value.
|
|
void SROA::RewriteLoadUserOfWholeAlloca(LoadInst *LI, AllocationInst *AI,
|
|
SmallVector<AllocaInst*, 32> &NewElts) {
|
|
// Extract each element out of the NewElts according to its structure offset
|
|
// and form the result value.
|
|
const Type *AllocaEltTy = AI->getType()->getElementType();
|
|
uint64_t AllocaSizeBits = TD->getTypeAllocSizeInBits(AllocaEltTy);
|
|
|
|
// If this isn't a load of the whole alloca to an integer, it may be a load
|
|
// of the first element. Just ignore the load in this case and normal SROA
|
|
// will handle it. We don't handle types here that have tail padding, like
|
|
// an alloca of type {i1}.
|
|
if (!isa<IntegerType>(LI->getType()) ||
|
|
TD->getTypeSizeInBits(LI->getType()) != AllocaSizeBits)
|
|
return;
|
|
|
|
DOUT << "PROMOTING LOAD OF WHOLE ALLOCA: " << *AI << *LI;
|
|
|
|
// There are two forms here: AI could be an array or struct. Both cases
|
|
// have different ways to compute the element offset.
|
|
const StructLayout *Layout = 0;
|
|
uint64_t ArrayEltBitOffset = 0;
|
|
if (const StructType *EltSTy = dyn_cast<StructType>(AllocaEltTy)) {
|
|
Layout = TD->getStructLayout(EltSTy);
|
|
} else {
|
|
const Type *ArrayEltTy = cast<ArrayType>(AllocaEltTy)->getElementType();
|
|
ArrayEltBitOffset = TD->getTypeAllocSizeInBits(ArrayEltTy);
|
|
}
|
|
|
|
Value *ResultVal = Constant::getNullValue(LI->getType());
|
|
|
|
for (unsigned i = 0, e = NewElts.size(); i != e; ++i) {
|
|
// Load the value from the alloca. If the NewElt is an aggregate, cast
|
|
// the pointer to an integer of the same size before doing the load.
|
|
Value *SrcField = NewElts[i];
|
|
const Type *FieldTy =
|
|
cast<PointerType>(SrcField->getType())->getElementType();
|
|
uint64_t FieldSizeBits = TD->getTypeSizeInBits(FieldTy);
|
|
|
|
// Ignore zero sized fields like {}, they obviously contain no data.
|
|
if (FieldSizeBits == 0) continue;
|
|
|
|
const IntegerType *FieldIntTy = IntegerType::get(FieldSizeBits);
|
|
if (!isa<IntegerType>(FieldTy) && !FieldTy->isFloatingPoint() &&
|
|
!isa<VectorType>(FieldTy))
|
|
SrcField = new BitCastInst(SrcField, PointerType::getUnqual(FieldIntTy),
|
|
"", LI);
|
|
SrcField = new LoadInst(SrcField, "sroa.load.elt", LI);
|
|
|
|
// If SrcField is a fp or vector of the right size but that isn't an
|
|
// integer type, bitcast to an integer so we can shift it.
|
|
if (SrcField->getType() != FieldIntTy)
|
|
SrcField = new BitCastInst(SrcField, FieldIntTy, "", LI);
|
|
|
|
// Zero extend the field to be the same size as the final alloca so that
|
|
// we can shift and insert it.
|
|
if (SrcField->getType() != ResultVal->getType())
|
|
SrcField = new ZExtInst(SrcField, ResultVal->getType(), "", LI);
|
|
|
|
// Determine the number of bits to shift SrcField.
|
|
uint64_t Shift;
|
|
if (Layout) // Struct case.
|
|
Shift = Layout->getElementOffsetInBits(i);
|
|
else // Array case.
|
|
Shift = i*ArrayEltBitOffset;
|
|
|
|
if (TD->isBigEndian())
|
|
Shift = AllocaSizeBits-Shift-FieldIntTy->getBitWidth();
|
|
|
|
if (Shift) {
|
|
Value *ShiftVal = ConstantInt::get(SrcField->getType(), Shift);
|
|
SrcField = BinaryOperator::CreateShl(SrcField, ShiftVal, "", LI);
|
|
}
|
|
|
|
ResultVal = BinaryOperator::CreateOr(SrcField, ResultVal, "", LI);
|
|
}
|
|
|
|
LI->replaceAllUsesWith(ResultVal);
|
|
LI->eraseFromParent();
|
|
}
|
|
|
|
|
|
/// HasPadding - Return true if the specified type has any structure or
|
|
/// alignment padding, false otherwise.
|
|
static bool HasPadding(const Type *Ty, const TargetData &TD) {
|
|
if (const StructType *STy = dyn_cast<StructType>(Ty)) {
|
|
const StructLayout *SL = TD.getStructLayout(STy);
|
|
unsigned PrevFieldBitOffset = 0;
|
|
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
|
|
unsigned FieldBitOffset = SL->getElementOffsetInBits(i);
|
|
|
|
// Padding in sub-elements?
|
|
if (HasPadding(STy->getElementType(i), TD))
|
|
return true;
|
|
|
|
// Check to see if there is any padding between this element and the
|
|
// previous one.
|
|
if (i) {
|
|
unsigned PrevFieldEnd =
|
|
PrevFieldBitOffset+TD.getTypeSizeInBits(STy->getElementType(i-1));
|
|
if (PrevFieldEnd < FieldBitOffset)
|
|
return true;
|
|
}
|
|
|
|
PrevFieldBitOffset = FieldBitOffset;
|
|
}
|
|
|
|
// Check for tail padding.
|
|
if (unsigned EltCount = STy->getNumElements()) {
|
|
unsigned PrevFieldEnd = PrevFieldBitOffset +
|
|
TD.getTypeSizeInBits(STy->getElementType(EltCount-1));
|
|
if (PrevFieldEnd < SL->getSizeInBits())
|
|
return true;
|
|
}
|
|
|
|
} else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
|
|
return HasPadding(ATy->getElementType(), TD);
|
|
} else if (const VectorType *VTy = dyn_cast<VectorType>(Ty)) {
|
|
return HasPadding(VTy->getElementType(), TD);
|
|
}
|
|
return TD.getTypeSizeInBits(Ty) != TD.getTypeAllocSizeInBits(Ty);
|
|
}
|
|
|
|
/// isSafeStructAllocaToScalarRepl - Check to see if the specified allocation of
|
|
/// an aggregate can be broken down into elements. Return 0 if not, 3 if safe,
|
|
/// or 1 if safe after canonicalization has been performed.
|
|
///
|
|
int SROA::isSafeAllocaToScalarRepl(AllocationInst *AI) {
|
|
// Loop over the use list of the alloca. We can only transform it if all of
|
|
// the users are safe to transform.
|
|
AllocaInfo Info;
|
|
|
|
for (Value::use_iterator I = AI->use_begin(), E = AI->use_end();
|
|
I != E; ++I) {
|
|
isSafeUseOfAllocation(cast<Instruction>(*I), AI, Info);
|
|
if (Info.isUnsafe) {
|
|
DOUT << "Cannot transform: " << *AI << " due to user: " << **I;
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
// Okay, we know all the users are promotable. If the aggregate is a memcpy
|
|
// source and destination, we have to be careful. In particular, the memcpy
|
|
// could be moving around elements that live in structure padding of the LLVM
|
|
// types, but may actually be used. In these cases, we refuse to promote the
|
|
// struct.
|
|
if (Info.isMemCpySrc && Info.isMemCpyDst &&
|
|
HasPadding(AI->getType()->getElementType(), *TD))
|
|
return 0;
|
|
|
|
// If we require cleanup, return 1, otherwise return 3.
|
|
return Info.needsCleanup ? 1 : 3;
|
|
}
|
|
|
|
/// CleanupGEP - GEP is used by an Alloca, which can be prompted after the GEP
|
|
/// is canonicalized here.
|
|
void SROA::CleanupGEP(GetElementPtrInst *GEPI) {
|
|
gep_type_iterator I = gep_type_begin(GEPI);
|
|
++I;
|
|
|
|
const ArrayType *AT = dyn_cast<ArrayType>(*I);
|
|
if (!AT)
|
|
return;
|
|
|
|
uint64_t NumElements = AT->getNumElements();
|
|
|
|
if (isa<ConstantInt>(I.getOperand()))
|
|
return;
|
|
|
|
if (NumElements == 1) {
|
|
GEPI->setOperand(2, Constant::getNullValue(Type::Int32Ty));
|
|
return;
|
|
}
|
|
|
|
assert(NumElements == 2 && "Unhandled case!");
|
|
// All users of the GEP must be loads. At each use of the GEP, insert
|
|
// two loads of the appropriate indexed GEP and select between them.
|
|
Value *IsOne = new ICmpInst(ICmpInst::ICMP_NE, I.getOperand(),
|
|
Constant::getNullValue(I.getOperand()->getType()),
|
|
"isone", GEPI);
|
|
// Insert the new GEP instructions, which are properly indexed.
|
|
SmallVector<Value*, 8> Indices(GEPI->op_begin()+1, GEPI->op_end());
|
|
Indices[1] = Constant::getNullValue(Type::Int32Ty);
|
|
Value *ZeroIdx = GetElementPtrInst::Create(GEPI->getOperand(0),
|
|
Indices.begin(),
|
|
Indices.end(),
|
|
GEPI->getName()+".0", GEPI);
|
|
Indices[1] = ConstantInt::get(Type::Int32Ty, 1);
|
|
Value *OneIdx = GetElementPtrInst::Create(GEPI->getOperand(0),
|
|
Indices.begin(),
|
|
Indices.end(),
|
|
GEPI->getName()+".1", GEPI);
|
|
// Replace all loads of the variable index GEP with loads from both
|
|
// indexes and a select.
|
|
while (!GEPI->use_empty()) {
|
|
LoadInst *LI = cast<LoadInst>(GEPI->use_back());
|
|
Value *Zero = new LoadInst(ZeroIdx, LI->getName()+".0", LI);
|
|
Value *One = new LoadInst(OneIdx , LI->getName()+".1", LI);
|
|
Value *R = SelectInst::Create(IsOne, One, Zero, LI->getName(), LI);
|
|
LI->replaceAllUsesWith(R);
|
|
LI->eraseFromParent();
|
|
}
|
|
GEPI->eraseFromParent();
|
|
}
|
|
|
|
|
|
/// CleanupAllocaUsers - If SROA reported that it can promote the specified
|
|
/// allocation, but only if cleaned up, perform the cleanups required.
|
|
void SROA::CleanupAllocaUsers(AllocationInst *AI) {
|
|
// At this point, we know that the end result will be SROA'd and promoted, so
|
|
// we can insert ugly code if required so long as sroa+mem2reg will clean it
|
|
// up.
|
|
for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
|
|
UI != E; ) {
|
|
User *U = *UI++;
|
|
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(U))
|
|
CleanupGEP(GEPI);
|
|
else if (Instruction *I = dyn_cast<Instruction>(U)) {
|
|
SmallVector<DbgInfoIntrinsic *, 2> DbgInUses;
|
|
if (!isa<StoreInst>(I) && OnlyUsedByDbgInfoIntrinsics(I, &DbgInUses)) {
|
|
// Safe to remove debug info uses.
|
|
while (!DbgInUses.empty()) {
|
|
DbgInfoIntrinsic *DI = DbgInUses.back(); DbgInUses.pop_back();
|
|
DI->eraseFromParent();
|
|
}
|
|
I->eraseFromParent();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// MergeInType - Add the 'In' type to the accumulated type (Accum) so far at
|
|
/// the offset specified by Offset (which is specified in bytes).
|
|
///
|
|
/// There are two cases we handle here:
|
|
/// 1) A union of vector types of the same size and potentially its elements.
|
|
/// Here we turn element accesses into insert/extract element operations.
|
|
/// This promotes a <4 x float> with a store of float to the third element
|
|
/// into a <4 x float> that uses insert element.
|
|
/// 2) A fully general blob of memory, which we turn into some (potentially
|
|
/// large) integer type with extract and insert operations where the loads
|
|
/// and stores would mutate the memory.
|
|
static void MergeInType(const Type *In, uint64_t Offset, const Type *&VecTy,
|
|
unsigned AllocaSize, const TargetData &TD) {
|
|
// If this could be contributing to a vector, analyze it.
|
|
if (VecTy != Type::VoidTy) { // either null or a vector type.
|
|
|
|
// If the In type is a vector that is the same size as the alloca, see if it
|
|
// matches the existing VecTy.
|
|
if (const VectorType *VInTy = dyn_cast<VectorType>(In)) {
|
|
if (VInTy->getBitWidth()/8 == AllocaSize && Offset == 0) {
|
|
// If we're storing/loading a vector of the right size, allow it as a
|
|
// vector. If this the first vector we see, remember the type so that
|
|
// we know the element size.
|
|
if (VecTy == 0)
|
|
VecTy = VInTy;
|
|
return;
|
|
}
|
|
} else if (In == Type::FloatTy || In == Type::DoubleTy ||
|
|
(isa<IntegerType>(In) && In->getPrimitiveSizeInBits() >= 8 &&
|
|
isPowerOf2_32(In->getPrimitiveSizeInBits()))) {
|
|
// If we're accessing something that could be an element of a vector, see
|
|
// if the implied vector agrees with what we already have and if Offset is
|
|
// compatible with it.
|
|
unsigned EltSize = In->getPrimitiveSizeInBits()/8;
|
|
if (Offset % EltSize == 0 &&
|
|
AllocaSize % EltSize == 0 &&
|
|
(VecTy == 0 ||
|
|
cast<VectorType>(VecTy)->getElementType()
|
|
->getPrimitiveSizeInBits()/8 == EltSize)) {
|
|
if (VecTy == 0)
|
|
VecTy = VectorType::get(In, AllocaSize/EltSize);
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Otherwise, we have a case that we can't handle with an optimized vector
|
|
// form. We can still turn this into a large integer.
|
|
VecTy = Type::VoidTy;
|
|
}
|
|
|
|
/// CanConvertToScalar - V is a pointer. If we can convert the pointee and all
|
|
/// its accesses to use a to single vector type, return true, and set VecTy to
|
|
/// the new type. If we could convert the alloca into a single promotable
|
|
/// integer, return true but set VecTy to VoidTy. Further, if the use is not a
|
|
/// completely trivial use that mem2reg could promote, set IsNotTrivial. Offset
|
|
/// is the current offset from the base of the alloca being analyzed.
|
|
///
|
|
/// If we see at least one access to the value that is as a vector type, set the
|
|
/// SawVec flag.
|
|
///
|
|
bool SROA::CanConvertToScalar(Value *V, bool &IsNotTrivial, const Type *&VecTy,
|
|
bool &SawVec, uint64_t Offset,
|
|
unsigned AllocaSize) {
|
|
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI!=E; ++UI) {
|
|
Instruction *User = cast<Instruction>(*UI);
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
|
|
// Don't break volatile loads.
|
|
if (LI->isVolatile())
|
|
return false;
|
|
MergeInType(LI->getType(), Offset, VecTy, AllocaSize, *TD);
|
|
SawVec |= isa<VectorType>(LI->getType());
|
|
continue;
|
|
}
|
|
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
|
|
// Storing the pointer, not into the value?
|
|
if (SI->getOperand(0) == V || SI->isVolatile()) return 0;
|
|
MergeInType(SI->getOperand(0)->getType(), Offset, VecTy, AllocaSize, *TD);
|
|
SawVec |= isa<VectorType>(SI->getOperand(0)->getType());
|
|
continue;
|
|
}
|
|
|
|
if (BitCastInst *BCI = dyn_cast<BitCastInst>(User)) {
|
|
if (!CanConvertToScalar(BCI, IsNotTrivial, VecTy, SawVec, Offset,
|
|
AllocaSize))
|
|
return false;
|
|
IsNotTrivial = true;
|
|
continue;
|
|
}
|
|
|
|
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(User)) {
|
|
// If this is a GEP with a variable indices, we can't handle it.
|
|
if (!GEP->hasAllConstantIndices())
|
|
return false;
|
|
|
|
// Compute the offset that this GEP adds to the pointer.
|
|
SmallVector<Value*, 8> Indices(GEP->op_begin()+1, GEP->op_end());
|
|
uint64_t GEPOffset = TD->getIndexedOffset(GEP->getOperand(0)->getType(),
|
|
&Indices[0], Indices.size());
|
|
// See if all uses can be converted.
|
|
if (!CanConvertToScalar(GEP, IsNotTrivial, VecTy, SawVec,Offset+GEPOffset,
|
|
AllocaSize))
|
|
return false;
|
|
IsNotTrivial = true;
|
|
continue;
|
|
}
|
|
|
|
// If this is a constant sized memset of a constant value (e.g. 0) we can
|
|
// handle it.
|
|
if (MemSetInst *MSI = dyn_cast<MemSetInst>(User)) {
|
|
// Store of constant value and constant size.
|
|
if (isa<ConstantInt>(MSI->getValue()) &&
|
|
isa<ConstantInt>(MSI->getLength())) {
|
|
IsNotTrivial = true;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// If this is a memcpy or memmove into or out of the whole allocation, we
|
|
// can handle it like a load or store of the scalar type.
|
|
if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(User)) {
|
|
if (ConstantInt *Len = dyn_cast<ConstantInt>(MTI->getLength()))
|
|
if (Len->getZExtValue() == AllocaSize && Offset == 0) {
|
|
IsNotTrivial = true;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// Ignore dbg intrinsic.
|
|
if (isa<DbgInfoIntrinsic>(User))
|
|
continue;
|
|
|
|
// Otherwise, we cannot handle this!
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
/// ConvertUsesToScalar - Convert all of the users of Ptr to use the new alloca
|
|
/// directly. This happens when we are converting an "integer union" to a
|
|
/// single integer scalar, or when we are converting a "vector union" to a
|
|
/// vector with insert/extractelement instructions.
|
|
///
|
|
/// Offset is an offset from the original alloca, in bits that need to be
|
|
/// shifted to the right. By the end of this, there should be no uses of Ptr.
|
|
void SROA::ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, uint64_t Offset) {
|
|
while (!Ptr->use_empty()) {
|
|
Instruction *User = cast<Instruction>(Ptr->use_back());
|
|
|
|
if (BitCastInst *CI = dyn_cast<BitCastInst>(User)) {
|
|
ConvertUsesToScalar(CI, NewAI, Offset);
|
|
CI->eraseFromParent();
|
|
continue;
|
|
}
|
|
|
|
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(User)) {
|
|
// Compute the offset that this GEP adds to the pointer.
|
|
SmallVector<Value*, 8> Indices(GEP->op_begin()+1, GEP->op_end());
|
|
uint64_t GEPOffset = TD->getIndexedOffset(GEP->getOperand(0)->getType(),
|
|
&Indices[0], Indices.size());
|
|
ConvertUsesToScalar(GEP, NewAI, Offset+GEPOffset*8);
|
|
GEP->eraseFromParent();
|
|
continue;
|
|
}
|
|
|
|
IRBuilder<> Builder(User->getParent(), User);
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
|
|
// The load is a bit extract from NewAI shifted right by Offset bits.
|
|
Value *LoadedVal = Builder.CreateLoad(NewAI, "tmp");
|
|
Value *NewLoadVal
|
|
= ConvertScalar_ExtractValue(LoadedVal, LI->getType(), Offset, Builder);
|
|
LI->replaceAllUsesWith(NewLoadVal);
|
|
LI->eraseFromParent();
|
|
continue;
|
|
}
|
|
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
|
|
assert(SI->getOperand(0) != Ptr && "Consistency error!");
|
|
Value *Old = Builder.CreateLoad(NewAI, (NewAI->getName()+".in").c_str());
|
|
Value *New = ConvertScalar_InsertValue(SI->getOperand(0), Old, Offset,
|
|
Builder);
|
|
Builder.CreateStore(New, NewAI);
|
|
SI->eraseFromParent();
|
|
continue;
|
|
}
|
|
|
|
// If this is a constant sized memset of a constant value (e.g. 0) we can
|
|
// transform it into a store of the expanded constant value.
|
|
if (MemSetInst *MSI = dyn_cast<MemSetInst>(User)) {
|
|
assert(MSI->getRawDest() == Ptr && "Consistency error!");
|
|
unsigned NumBytes = cast<ConstantInt>(MSI->getLength())->getZExtValue();
|
|
if (NumBytes != 0) {
|
|
unsigned Val = cast<ConstantInt>(MSI->getValue())->getZExtValue();
|
|
|
|
// Compute the value replicated the right number of times.
|
|
APInt APVal(NumBytes*8, Val);
|
|
|
|
// Splat the value if non-zero.
|
|
if (Val)
|
|
for (unsigned i = 1; i != NumBytes; ++i)
|
|
APVal |= APVal << 8;
|
|
|
|
Value *Old = Builder.CreateLoad(NewAI, (NewAI->getName()+".in").c_str());
|
|
Value *New = ConvertScalar_InsertValue(ConstantInt::get(APVal), Old,
|
|
Offset, Builder);
|
|
Builder.CreateStore(New, NewAI);
|
|
}
|
|
MSI->eraseFromParent();
|
|
continue;
|
|
}
|
|
|
|
// If this is a memcpy or memmove into or out of the whole allocation, we
|
|
// can handle it like a load or store of the scalar type.
|
|
if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(User)) {
|
|
assert(Offset == 0 && "must be store to start of alloca");
|
|
|
|
// If the source and destination are both to the same alloca, then this is
|
|
// a noop copy-to-self, just delete it. Otherwise, emit a load and store
|
|
// as appropriate.
|
|
AllocaInst *OrigAI = cast<AllocaInst>(Ptr->getUnderlyingObject());
|
|
|
|
if (MTI->getSource()->getUnderlyingObject() != OrigAI) {
|
|
// Dest must be OrigAI, change this to be a load from the original
|
|
// pointer (bitcasted), then a store to our new alloca.
|
|
assert(MTI->getRawDest() == Ptr && "Neither use is of pointer?");
|
|
Value *SrcPtr = MTI->getSource();
|
|
SrcPtr = Builder.CreateBitCast(SrcPtr, NewAI->getType());
|
|
|
|
LoadInst *SrcVal = Builder.CreateLoad(SrcPtr, "srcval");
|
|
SrcVal->setAlignment(MTI->getAlignment());
|
|
Builder.CreateStore(SrcVal, NewAI);
|
|
} else if (MTI->getDest()->getUnderlyingObject() != OrigAI) {
|
|
// Src must be OrigAI, change this to be a load from NewAI then a store
|
|
// through the original dest pointer (bitcasted).
|
|
assert(MTI->getRawSource() == Ptr && "Neither use is of pointer?");
|
|
LoadInst *SrcVal = Builder.CreateLoad(NewAI, "srcval");
|
|
|
|
Value *DstPtr = Builder.CreateBitCast(MTI->getDest(), NewAI->getType());
|
|
StoreInst *NewStore = Builder.CreateStore(SrcVal, DstPtr);
|
|
NewStore->setAlignment(MTI->getAlignment());
|
|
} else {
|
|
// Noop transfer. Src == Dst
|
|
}
|
|
|
|
|
|
MTI->eraseFromParent();
|
|
continue;
|
|
}
|
|
|
|
// If user is a dbg info intrinsic then it is safe to remove it.
|
|
if (isa<DbgInfoIntrinsic>(User)) {
|
|
User->eraseFromParent();
|
|
continue;
|
|
}
|
|
|
|
assert(0 && "Unsupported operation!");
|
|
abort();
|
|
}
|
|
}
|
|
|
|
/// ConvertScalar_ExtractValue - Extract a value of type ToType from an integer
|
|
/// or vector value FromVal, extracting the bits from the offset specified by
|
|
/// Offset. This returns the value, which is of type ToType.
|
|
///
|
|
/// This happens when we are converting an "integer union" to a single
|
|
/// integer scalar, or when we are converting a "vector union" to a vector with
|
|
/// insert/extractelement instructions.
|
|
///
|
|
/// Offset is an offset from the original alloca, in bits that need to be
|
|
/// shifted to the right.
|
|
Value *SROA::ConvertScalar_ExtractValue(Value *FromVal, const Type *ToType,
|
|
uint64_t Offset, IRBuilder<> &Builder) {
|
|
// If the load is of the whole new alloca, no conversion is needed.
|
|
if (FromVal->getType() == ToType && Offset == 0)
|
|
return FromVal;
|
|
|
|
// If the result alloca is a vector type, this is either an element
|
|
// access or a bitcast to another vector type of the same size.
|
|
if (const VectorType *VTy = dyn_cast<VectorType>(FromVal->getType())) {
|
|
if (isa<VectorType>(ToType))
|
|
return Builder.CreateBitCast(FromVal, ToType, "tmp");
|
|
|
|
// Otherwise it must be an element access.
|
|
unsigned Elt = 0;
|
|
if (Offset) {
|
|
unsigned EltSize = TD->getTypeAllocSizeInBits(VTy->getElementType());
|
|
Elt = Offset/EltSize;
|
|
assert(EltSize*Elt == Offset && "Invalid modulus in validity checking");
|
|
}
|
|
// Return the element extracted out of it.
|
|
Value *V = Builder.CreateExtractElement(FromVal,
|
|
ConstantInt::get(Type::Int32Ty,Elt),
|
|
"tmp");
|
|
if (V->getType() != ToType)
|
|
V = Builder.CreateBitCast(V, ToType, "tmp");
|
|
return V;
|
|
}
|
|
|
|
// If ToType is a first class aggregate, extract out each of the pieces and
|
|
// use insertvalue's to form the FCA.
|
|
if (const StructType *ST = dyn_cast<StructType>(ToType)) {
|
|
const StructLayout &Layout = *TD->getStructLayout(ST);
|
|
Value *Res = UndefValue::get(ST);
|
|
for (unsigned i = 0, e = ST->getNumElements(); i != e; ++i) {
|
|
Value *Elt = ConvertScalar_ExtractValue(FromVal, ST->getElementType(i),
|
|
Offset+Layout.getElementOffsetInBits(i),
|
|
Builder);
|
|
Res = Builder.CreateInsertValue(Res, Elt, i, "tmp");
|
|
}
|
|
return Res;
|
|
}
|
|
|
|
if (const ArrayType *AT = dyn_cast<ArrayType>(ToType)) {
|
|
uint64_t EltSize = TD->getTypeAllocSizeInBits(AT->getElementType());
|
|
Value *Res = UndefValue::get(AT);
|
|
for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) {
|
|
Value *Elt = ConvertScalar_ExtractValue(FromVal, AT->getElementType(),
|
|
Offset+i*EltSize, Builder);
|
|
Res = Builder.CreateInsertValue(Res, Elt, i, "tmp");
|
|
}
|
|
return Res;
|
|
}
|
|
|
|
// Otherwise, this must be a union that was converted to an integer value.
|
|
const IntegerType *NTy = cast<IntegerType>(FromVal->getType());
|
|
|
|
// If this is a big-endian system and the load is narrower than the
|
|
// full alloca type, we need to do a shift to get the right bits.
|
|
int ShAmt = 0;
|
|
if (TD->isBigEndian()) {
|
|
// On big-endian machines, the lowest bit is stored at the bit offset
|
|
// from the pointer given by getTypeStoreSizeInBits. This matters for
|
|
// integers with a bitwidth that is not a multiple of 8.
|
|
ShAmt = TD->getTypeStoreSizeInBits(NTy) -
|
|
TD->getTypeStoreSizeInBits(ToType) - Offset;
|
|
} else {
|
|
ShAmt = Offset;
|
|
}
|
|
|
|
// Note: we support negative bitwidths (with shl) which are not defined.
|
|
// We do this to support (f.e.) loads off the end of a structure where
|
|
// only some bits are used.
|
|
if (ShAmt > 0 && (unsigned)ShAmt < NTy->getBitWidth())
|
|
FromVal = Builder.CreateLShr(FromVal, ConstantInt::get(FromVal->getType(),
|
|
ShAmt), "tmp");
|
|
else if (ShAmt < 0 && (unsigned)-ShAmt < NTy->getBitWidth())
|
|
FromVal = Builder.CreateShl(FromVal, ConstantInt::get(FromVal->getType(),
|
|
-ShAmt), "tmp");
|
|
|
|
// Finally, unconditionally truncate the integer to the right width.
|
|
unsigned LIBitWidth = TD->getTypeSizeInBits(ToType);
|
|
if (LIBitWidth < NTy->getBitWidth())
|
|
FromVal = Builder.CreateTrunc(FromVal, IntegerType::get(LIBitWidth), "tmp");
|
|
else if (LIBitWidth > NTy->getBitWidth())
|
|
FromVal = Builder.CreateZExt(FromVal, IntegerType::get(LIBitWidth), "tmp");
|
|
|
|
// If the result is an integer, this is a trunc or bitcast.
|
|
if (isa<IntegerType>(ToType)) {
|
|
// Should be done.
|
|
} else if (ToType->isFloatingPoint() || isa<VectorType>(ToType)) {
|
|
// Just do a bitcast, we know the sizes match up.
|
|
FromVal = Builder.CreateBitCast(FromVal, ToType, "tmp");
|
|
} else {
|
|
// Otherwise must be a pointer.
|
|
FromVal = Builder.CreateIntToPtr(FromVal, ToType, "tmp");
|
|
}
|
|
assert(FromVal->getType() == ToType && "Didn't convert right?");
|
|
return FromVal;
|
|
}
|
|
|
|
|
|
/// ConvertScalar_InsertValue - Insert the value "SV" into the existing integer
|
|
/// or vector value "Old" at the offset specified by Offset.
|
|
///
|
|
/// This happens when we are converting an "integer union" to a
|
|
/// single integer scalar, or when we are converting a "vector union" to a
|
|
/// vector with insert/extractelement instructions.
|
|
///
|
|
/// Offset is an offset from the original alloca, in bits that need to be
|
|
/// shifted to the right.
|
|
Value *SROA::ConvertScalar_InsertValue(Value *SV, Value *Old,
|
|
uint64_t Offset, IRBuilder<> &Builder) {
|
|
|
|
// Convert the stored type to the actual type, shift it left to insert
|
|
// then 'or' into place.
|
|
const Type *AllocaType = Old->getType();
|
|
|
|
if (const VectorType *VTy = dyn_cast<VectorType>(AllocaType)) {
|
|
uint64_t VecSize = TD->getTypeAllocSizeInBits(VTy);
|
|
uint64_t ValSize = TD->getTypeAllocSizeInBits(SV->getType());
|
|
|
|
// Changing the whole vector with memset or with an access of a different
|
|
// vector type?
|
|
if (ValSize == VecSize)
|
|
return Builder.CreateBitCast(SV, AllocaType, "tmp");
|
|
|
|
uint64_t EltSize = TD->getTypeAllocSizeInBits(VTy->getElementType());
|
|
|
|
// Must be an element insertion.
|
|
unsigned Elt = Offset/EltSize;
|
|
|
|
if (SV->getType() != VTy->getElementType())
|
|
SV = Builder.CreateBitCast(SV, VTy->getElementType(), "tmp");
|
|
|
|
SV = Builder.CreateInsertElement(Old, SV,
|
|
ConstantInt::get(Type::Int32Ty, Elt),
|
|
"tmp");
|
|
return SV;
|
|
}
|
|
|
|
// If SV is a first-class aggregate value, insert each value recursively.
|
|
if (const StructType *ST = dyn_cast<StructType>(SV->getType())) {
|
|
const StructLayout &Layout = *TD->getStructLayout(ST);
|
|
for (unsigned i = 0, e = ST->getNumElements(); i != e; ++i) {
|
|
Value *Elt = Builder.CreateExtractValue(SV, i, "tmp");
|
|
Old = ConvertScalar_InsertValue(Elt, Old,
|
|
Offset+Layout.getElementOffsetInBits(i),
|
|
Builder);
|
|
}
|
|
return Old;
|
|
}
|
|
|
|
if (const ArrayType *AT = dyn_cast<ArrayType>(SV->getType())) {
|
|
uint64_t EltSize = TD->getTypeAllocSizeInBits(AT->getElementType());
|
|
for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) {
|
|
Value *Elt = Builder.CreateExtractValue(SV, i, "tmp");
|
|
Old = ConvertScalar_InsertValue(Elt, Old, Offset+i*EltSize, Builder);
|
|
}
|
|
return Old;
|
|
}
|
|
|
|
// If SV is a float, convert it to the appropriate integer type.
|
|
// If it is a pointer, do the same.
|
|
unsigned SrcWidth = TD->getTypeSizeInBits(SV->getType());
|
|
unsigned DestWidth = TD->getTypeSizeInBits(AllocaType);
|
|
unsigned SrcStoreWidth = TD->getTypeStoreSizeInBits(SV->getType());
|
|
unsigned DestStoreWidth = TD->getTypeStoreSizeInBits(AllocaType);
|
|
if (SV->getType()->isFloatingPoint() || isa<VectorType>(SV->getType()))
|
|
SV = Builder.CreateBitCast(SV, IntegerType::get(SrcWidth), "tmp");
|
|
else if (isa<PointerType>(SV->getType()))
|
|
SV = Builder.CreatePtrToInt(SV, TD->getIntPtrType(), "tmp");
|
|
|
|
// Zero extend or truncate the value if needed.
|
|
if (SV->getType() != AllocaType) {
|
|
if (SV->getType()->getPrimitiveSizeInBits() <
|
|
AllocaType->getPrimitiveSizeInBits())
|
|
SV = Builder.CreateZExt(SV, AllocaType, "tmp");
|
|
else {
|
|
// Truncation may be needed if storing more than the alloca can hold
|
|
// (undefined behavior).
|
|
SV = Builder.CreateTrunc(SV, AllocaType, "tmp");
|
|
SrcWidth = DestWidth;
|
|
SrcStoreWidth = DestStoreWidth;
|
|
}
|
|
}
|
|
|
|
// If this is a big-endian system and the store is narrower than the
|
|
// full alloca type, we need to do a shift to get the right bits.
|
|
int ShAmt = 0;
|
|
if (TD->isBigEndian()) {
|
|
// On big-endian machines, the lowest bit is stored at the bit offset
|
|
// from the pointer given by getTypeStoreSizeInBits. This matters for
|
|
// integers with a bitwidth that is not a multiple of 8.
|
|
ShAmt = DestStoreWidth - SrcStoreWidth - Offset;
|
|
} else {
|
|
ShAmt = Offset;
|
|
}
|
|
|
|
// Note: we support negative bitwidths (with shr) which are not defined.
|
|
// We do this to support (f.e.) stores off the end of a structure where
|
|
// only some bits in the structure are set.
|
|
APInt Mask(APInt::getLowBitsSet(DestWidth, SrcWidth));
|
|
if (ShAmt > 0 && (unsigned)ShAmt < DestWidth) {
|
|
SV = Builder.CreateShl(SV, ConstantInt::get(SV->getType(), ShAmt), "tmp");
|
|
Mask <<= ShAmt;
|
|
} else if (ShAmt < 0 && (unsigned)-ShAmt < DestWidth) {
|
|
SV = Builder.CreateLShr(SV, ConstantInt::get(SV->getType(), -ShAmt), "tmp");
|
|
Mask = Mask.lshr(-ShAmt);
|
|
}
|
|
|
|
// Mask out the bits we are about to insert from the old value, and or
|
|
// in the new bits.
|
|
if (SrcWidth != DestWidth) {
|
|
assert(DestWidth > SrcWidth);
|
|
Old = Builder.CreateAnd(Old, ConstantInt::get(~Mask), "mask");
|
|
SV = Builder.CreateOr(Old, SV, "ins");
|
|
}
|
|
return SV;
|
|
}
|
|
|
|
|
|
|
|
/// PointsToConstantGlobal - Return true if V (possibly indirectly) points to
|
|
/// some part of a constant global variable. This intentionally only accepts
|
|
/// constant expressions because we don't can't rewrite arbitrary instructions.
|
|
static bool PointsToConstantGlobal(Value *V) {
|
|
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
|
|
return GV->isConstant();
|
|
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
|
|
if (CE->getOpcode() == Instruction::BitCast ||
|
|
CE->getOpcode() == Instruction::GetElementPtr)
|
|
return PointsToConstantGlobal(CE->getOperand(0));
|
|
return false;
|
|
}
|
|
|
|
/// isOnlyCopiedFromConstantGlobal - Recursively walk the uses of a (derived)
|
|
/// pointer to an alloca. Ignore any reads of the pointer, return false if we
|
|
/// see any stores or other unknown uses. If we see pointer arithmetic, keep
|
|
/// track of whether it moves the pointer (with isOffset) but otherwise traverse
|
|
/// the uses. If we see a memcpy/memmove that targets an unoffseted pointer to
|
|
/// the alloca, and if the source pointer is a pointer to a constant global, we
|
|
/// can optimize this.
|
|
static bool isOnlyCopiedFromConstantGlobal(Value *V, Instruction *&TheCopy,
|
|
bool isOffset) {
|
|
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI!=E; ++UI) {
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(*UI))
|
|
// Ignore non-volatile loads, they are always ok.
|
|
if (!LI->isVolatile())
|
|
continue;
|
|
|
|
if (BitCastInst *BCI = dyn_cast<BitCastInst>(*UI)) {
|
|
// If uses of the bitcast are ok, we are ok.
|
|
if (!isOnlyCopiedFromConstantGlobal(BCI, TheCopy, isOffset))
|
|
return false;
|
|
continue;
|
|
}
|
|
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(*UI)) {
|
|
// If the GEP has all zero indices, it doesn't offset the pointer. If it
|
|
// doesn't, it does.
|
|
if (!isOnlyCopiedFromConstantGlobal(GEP, TheCopy,
|
|
isOffset || !GEP->hasAllZeroIndices()))
|
|
return false;
|
|
continue;
|
|
}
|
|
|
|
// If this is isn't our memcpy/memmove, reject it as something we can't
|
|
// handle.
|
|
if (!isa<MemTransferInst>(*UI))
|
|
return false;
|
|
|
|
// If we already have seen a copy, reject the second one.
|
|
if (TheCopy) return false;
|
|
|
|
// If the pointer has been offset from the start of the alloca, we can't
|
|
// safely handle this.
|
|
if (isOffset) return false;
|
|
|
|
// If the memintrinsic isn't using the alloca as the dest, reject it.
|
|
if (UI.getOperandNo() != 1) return false;
|
|
|
|
MemIntrinsic *MI = cast<MemIntrinsic>(*UI);
|
|
|
|
// If the source of the memcpy/move is not a constant global, reject it.
|
|
if (!PointsToConstantGlobal(MI->getOperand(2)))
|
|
return false;
|
|
|
|
// Otherwise, the transform is safe. Remember the copy instruction.
|
|
TheCopy = MI;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// isOnlyCopiedFromConstantGlobal - Return true if the specified alloca is only
|
|
/// modified by a copy from a constant global. If we can prove this, we can
|
|
/// replace any uses of the alloca with uses of the global directly.
|
|
Instruction *SROA::isOnlyCopiedFromConstantGlobal(AllocationInst *AI) {
|
|
Instruction *TheCopy = 0;
|
|
if (::isOnlyCopiedFromConstantGlobal(AI, TheCopy, false))
|
|
return TheCopy;
|
|
return 0;
|
|
}
|