//
//===----------------------------------------------------------------------===//
-#include "llvm/Transforms/Scalar.h"
-#include "InstCombine.h"
+#include "llvm/Transforms/InstCombine/InstCombine.h"
+#include "InstCombineInternal.h"
#include "llvm-c/Initialization.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringSwitch.h"
+#include "llvm/Analysis/AssumptionCache.h"
+#include "llvm/Analysis/CFG.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/LibCallSemantics.h"
+#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/MemoryBuiltins.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Dominators.h"
#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
-#include "llvm/Target/TargetLibraryInfo.h"
+#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/Local.h"
#include <algorithm>
#include <climits>
STATISTIC(NumFactor , "Number of factorizations");
STATISTIC(NumReassoc , "Number of reassociations");
-static cl::opt<bool> UnsafeFPShrink("enable-double-float-shrink", cl::Hidden,
- cl::init(false),
- cl::desc("Enable unsafe double to float "
- "shrinking for math lib calls"));
-
-// Initialization Routines
-void llvm::initializeInstCombine(PassRegistry &Registry) {
- initializeInstCombinerPass(Registry);
-}
-
-void LLVMInitializeInstCombine(LLVMPassRegistryRef R) {
- initializeInstCombine(*unwrap(R));
-}
-
-char InstCombiner::ID = 0;
-INITIALIZE_PASS_BEGIN(InstCombiner, "instcombine",
- "Combine redundant instructions", false, false)
-INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
-INITIALIZE_PASS_END(InstCombiner, "instcombine",
- "Combine redundant instructions", false, false)
-
-void InstCombiner::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesCFG();
- AU.addRequired<TargetLibraryInfo>();
-}
-
-
Value *InstCombiner::EmitGEPOffset(User *GEP) {
return llvm::EmitGEPOffset(Builder, *getDataLayout(), GEP);
}
Instruction::BinaryOps ROp) {
if (Instruction::isCommutative(ROp))
return LeftDistributesOverRight(ROp, LOp);
+
+ switch (LOp) {
+ default:
+ return false;
+ // (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts.
+ // (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.
+ // (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts.
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ switch (ROp) {
+ default:
+ return false;
+ case Instruction::Shl:
+ case Instruction::LShr:
+ case Instruction::AShr:
+ return true;
+ }
+ }
// TODO: It would be nice to handle division, aka "(X + Y)/Z = X/Z + Y/Z",
// but this requires knowing that the addition does not overflow and other
// such subtleties.
}
/// This function factors binary ops which can be combined using distributive
-/// laws. This also factor SHL as MUL e.g. SHL(X, 2) ==> MUL(X, 4).
+/// laws. This function tries to transform 'Op' based TopLevelOpcode to enable
+/// factorization e.g for ADD(SHL(X , 2), MUL(X, 5)), When this function called
+/// with TopLevelOpcode == Instruction::Add and Op = SHL(X, 2), transforms
+/// SHL(X, 2) to MUL(X, 4) i.e. returns Instruction::Mul with LHS set to 'X' and
+/// RHS to 4.
static Instruction::BinaryOps
-getBinOpsForFactorization(BinaryOperator *Op, Value *&LHS, Value *&RHS) {
+getBinOpsForFactorization(Instruction::BinaryOps TopLevelOpcode,
+ BinaryOperator *Op, Value *&LHS, Value *&RHS) {
if (!Op)
return Instruction::BinaryOpsEnd;
- if (Op->getOpcode() == Instruction::Shl) {
- if (Constant *CST = dyn_cast<Constant>(Op->getOperand(1))) {
- // The multiplier is really 1 << CST.
- RHS = ConstantExpr::getShl(ConstantInt::get(Op->getType(), 1), CST);
- LHS = Op->getOperand(0);
- return Instruction::Mul;
+ LHS = Op->getOperand(0);
+ RHS = Op->getOperand(1);
+
+ switch (TopLevelOpcode) {
+ default:
+ return Op->getOpcode();
+
+ case Instruction::Add:
+ case Instruction::Sub:
+ if (Op->getOpcode() == Instruction::Shl) {
+ if (Constant *CST = dyn_cast<Constant>(Op->getOperand(1))) {
+ // The multiplier is really 1 << CST.
+ RHS = ConstantExpr::getShl(ConstantInt::get(Op->getType(), 1), CST);
+ return Instruction::Mul;
+ }
}
+ return Op->getOpcode();
}
// TODO: We can add other conversions e.g. shr => div etc.
-
- LHS = Op->getOperand(0);
- RHS = Op->getOperand(1);
- return Op->getOpcode();
}
/// This tries to simplify binary operations by factorizing out common terms
// Factorization.
Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
- Instruction::BinaryOps LHSOpcode = getBinOpsForFactorization(Op0, A, B);
- Instruction::BinaryOps RHSOpcode = getBinOpsForFactorization(Op1, C, D);
+ auto TopLevelOpcode = I.getOpcode();
+ auto LHSOpcode = getBinOpsForFactorization(TopLevelOpcode, Op0, A, B);
+ auto RHSOpcode = getBinOpsForFactorization(TopLevelOpcode, Op1, C, D);
// The instruction has the form "(A op' B) op (C op' D)". Try to factorize
// a common term.
return V;
// Expansion.
- Instruction::BinaryOps TopLevelOpcode = I.getOpcode();
if (Op0 && RightDistributesOverLeft(Op0->getOpcode(), TopLevelOpcode)) {
// The instruction has the form "(A op' B) op C". See if expanding it out
// to "(A op C) op' (B op C)" results in simplifications.
// If the incoming non-constant value is in I's block, we will remove one
// instruction, but insert another equivalent one, leading to infinite
// instcombine.
- if (NonConstBB == I.getParent())
+ if (isPotentiallyReachable(I.getParent(), NonConstBB, DT, LI))
return nullptr;
}
// If there is exactly one non-constant value, we can insert a copy of the
// operation in that block. However, if this is a critical edge, we would be
- // inserting the computation one some other paths (e.g. inside a loop). Only
+ // inserting the computation on some other paths (e.g. inside a loop). Only
// do this if the pred block is unconditionally branching into the phi block.
if (NonConstBB != nullptr) {
BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
SmallVector<Value*, 8> Ops(GEP.op_begin(), GEP.op_end());
- if (Value *V = SimplifyGEPInst(Ops, DL))
+ if (Value *V = SimplifyGEPInst(Ops, DL, TLI, DT, AC))
return ReplaceInstUsesWith(GEP, V);
Value *PtrOp = GEP.getOperand(0);
if (DI == -1) {
// All the GEPs feeding the PHI are identical. Clone one down into our
// BB so that it can be merged with the current GEP.
- GEP.getParent()->getInstList().insert(GEP.getParent()->getFirstNonPHI(),
- NewGEP);
+ GEP.getParent()->getInstList().insert(
+ GEP.getParent()->getFirstInsertionPt(), NewGEP);
} else {
// All the GEPs feeding the PHI differ at a single offset. Clone a GEP
// into the current block so it can be merged, and create a new PHI to
PN->getIncomingBlock(I));
NewGEP->setOperand(DI, NewPN);
- GEP.getParent()->getInstList().insert(GEP.getParent()->getFirstNonPHI(),
- NewGEP);
+ GEP.getParent()->getInstList().insert(
+ GEP.getParent()->getFirstInsertionPt(), NewGEP);
NewGEP->setOperand(DI, NewPN);
}
GetElementPtrInst::Create(Src->getOperand(0), Indices, GEP.getName());
}
- // Canonicalize (gep i8* X, -(ptrtoint Y)) to (sub (ptrtoint X), (ptrtoint Y))
- // The GEP pattern is emitted by the SCEV expander for certain kinds of
- // pointer arithmetic.
- if (DL && GEP.getNumIndices() == 1 &&
- match(GEP.getOperand(1), m_Neg(m_PtrToInt(m_Value())))) {
+ if (DL && GEP.getNumIndices() == 1) {
unsigned AS = GEP.getPointerAddressSpace();
- if (GEP.getType() == Builder->getInt8PtrTy(AS) &&
- GEP.getOperand(1)->getType()->getScalarSizeInBits() ==
+ if (GEP.getOperand(1)->getType()->getScalarSizeInBits() ==
DL->getPointerSizeInBits(AS)) {
- Operator *Index = cast<Operator>(GEP.getOperand(1));
- Value *PtrToInt = Builder->CreatePtrToInt(PtrOp, Index->getType());
- Value *NewSub = Builder->CreateSub(PtrToInt, Index->getOperand(1));
- return CastInst::Create(Instruction::IntToPtr, NewSub, GEP.getType());
+ Type *PtrTy = GEP.getPointerOperandType();
+ Type *Ty = PtrTy->getPointerElementType();
+ uint64_t TyAllocSize = DL->getTypeAllocSize(Ty);
+
+ bool Matched = false;
+ uint64_t C;
+ Value *V = nullptr;
+ if (TyAllocSize == 1) {
+ V = GEP.getOperand(1);
+ Matched = true;
+ } else if (match(GEP.getOperand(1),
+ m_AShr(m_Value(V), m_ConstantInt(C)))) {
+ if (TyAllocSize == 1ULL << C)
+ Matched = true;
+ } else if (match(GEP.getOperand(1),
+ m_SDiv(m_Value(V), m_ConstantInt(C)))) {
+ if (TyAllocSize == C)
+ Matched = true;
+ }
+
+ if (Matched) {
+ // Canonicalize (gep i8* X, -(ptrtoint Y))
+ // to (inttoptr (sub (ptrtoint X), (ptrtoint Y)))
+ // The GEP pattern is emitted by the SCEV expander for certain kinds of
+ // pointer arithmetic.
+ if (match(V, m_Neg(m_PtrToInt(m_Value())))) {
+ Operator *Index = cast<Operator>(V);
+ Value *PtrToInt = Builder->CreatePtrToInt(PtrOp, Index->getType());
+ Value *NewSub = Builder->CreateSub(PtrToInt, Index->getOperand(1));
+ return CastInst::Create(Instruction::IntToPtr, NewSub, GEP.getType());
+ }
+ // Canonicalize (gep i8* X, (ptrtoint Y)-(ptrtoint X))
+ // to (bitcast Y)
+ Value *Y;
+ if (match(V, m_Sub(m_PtrToInt(m_Value(Y)),
+ m_PtrToInt(m_Specific(GEP.getOperand(0)))))) {
+ return CastInst::CreatePointerBitCastOrAddrSpaceCast(Y,
+ GEP.getType());
+ }
+ }
}
}
if (!DL)
return nullptr;
+ // addrspacecast between types is canonicalized as a bitcast, then an
+ // addrspacecast. To take advantage of the below bitcast + struct GEP, look
+ // through the addrspacecast.
+ if (AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(PtrOp)) {
+ // X = bitcast A addrspace(1)* to B addrspace(1)*
+ // Y = addrspacecast A addrspace(1)* to B addrspace(2)*
+ // Z = gep Y, <...constant indices...>
+ // Into an addrspacecasted GEP of the struct.
+ if (BitCastInst *BC = dyn_cast<BitCastInst>(ASC->getOperand(0)))
+ PtrOp = BC;
+ }
+
/// See if we can simplify:
/// X = bitcast A* to B*
/// Y = gep X, <...constant indices...>
if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) {
Value *Operand = BCI->getOperand(0);
PointerType *OpType = cast<PointerType>(Operand->getType());
- unsigned OffsetBits = DL->getPointerTypeSizeInBits(OpType);
+ unsigned OffsetBits = DL->getPointerTypeSizeInBits(GEP.getType());
APInt Offset(OffsetBits, 0);
if (!isa<BitCastInst>(Operand) &&
- GEP.accumulateConstantOffset(*DL, Offset) &&
- StrippedPtrTy->getAddressSpace() == GEP.getPointerAddressSpace()) {
+ GEP.accumulateConstantOffset(*DL, Offset)) {
// If this GEP instruction doesn't move the pointer, just replace the GEP
// with a bitcast of the real input to the dest type.
return &GEP;
}
}
+
+ if (Operand->getType()->getPointerAddressSpace() != GEP.getAddressSpace())
+ return new AddrSpaceCastInst(Operand, GEP.getType());
return new BitCastInst(Operand, GEP.getType());
}
if (NGEP->getType() == GEP.getType())
return ReplaceInstUsesWith(GEP, NGEP);
NGEP->takeName(&GEP);
+
+ if (NGEP->getType()->getPointerAddressSpace() != GEP.getAddressSpace())
+ return new AddrSpaceCastInst(NGEP, GEP.getType());
return new BitCastInst(NGEP, GEP.getType());
}
}
return nullptr;
}
+Instruction *InstCombiner::visitReturnInst(ReturnInst &RI) {
+ if (RI.getNumOperands() == 0) // ret void
+ return nullptr;
+
+ Value *ResultOp = RI.getOperand(0);
+ Type *VTy = ResultOp->getType();
+ if (!VTy->isIntegerTy())
+ return nullptr;
+ // There might be assume intrinsics dominating this return that completely
+ // determine the value. If so, constant fold it.
+ unsigned BitWidth = VTy->getPrimitiveSizeInBits();
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ computeKnownBits(ResultOp, KnownZero, KnownOne, 0, &RI);
+ if ((KnownZero|KnownOne).isAllOnesValue())
+ RI.setOperand(0, Constant::getIntegerValue(VTy, KnownOne));
+
+ return nullptr;
+}
Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
// Change br (not X), label True, label False to: br X, label False, True
Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
Value *Cond = SI.getCondition();
+ unsigned BitWidth = cast<IntegerType>(Cond->getType())->getBitWidth();
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ computeKnownBits(Cond, KnownZero, KnownOne);
+ unsigned LeadingKnownZeros = KnownZero.countLeadingOnes();
+ unsigned LeadingKnownOnes = KnownOne.countLeadingOnes();
+
+ // Compute the number of leading bits we can ignore.
+ for (auto &C : SI.cases()) {
+ LeadingKnownZeros = std::min(
+ LeadingKnownZeros, C.getCaseValue()->getValue().countLeadingZeros());
+ LeadingKnownOnes = std::min(
+ LeadingKnownOnes, C.getCaseValue()->getValue().countLeadingOnes());
+ }
+
+ unsigned NewWidth = BitWidth - std::max(LeadingKnownZeros, LeadingKnownOnes);
+
+ // Truncate the condition operand if the new type is equal to or larger than
+ // the largest legal integer type. We need to be conservative here since
+ // x86 generates redundant zero-extenstion instructions if the operand is
+ // truncated to i8 or i16.
+ bool TruncCond = false;
+ if (DL && BitWidth > NewWidth &&
+ NewWidth >= DL->getLargestLegalIntTypeSize()) {
+ TruncCond = true;
+ IntegerType *Ty = IntegerType::get(SI.getContext(), NewWidth);
+ Builder->SetInsertPoint(&SI);
+ Value *NewCond = Builder->CreateTrunc(SI.getCondition(), Ty, "trunc");
+ SI.setCondition(NewCond);
+
+ for (auto &C : SI.cases())
+ static_cast<SwitchInst::CaseIt *>(&C)->setValue(ConstantInt::get(
+ SI.getContext(), C.getCaseValue()->getValue().trunc(NewWidth)));
+ }
+
if (Instruction *I = dyn_cast<Instruction>(Cond)) {
if (I->getOpcode() == Instruction::Add)
if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
for (SwitchInst::CaseIt i = SI.case_begin(), e = SI.case_end();
i != e; ++i) {
ConstantInt* CaseVal = i.getCaseValue();
- Constant* NewCaseVal = ConstantExpr::getSub(cast<Constant>(CaseVal),
- AddRHS);
+ Constant *LHS = CaseVal;
+ if (TruncCond)
+ LHS = LeadingKnownZeros
+ ? ConstantExpr::getZExt(CaseVal, Cond->getType())
+ : ConstantExpr::getSExt(CaseVal, Cond->getType());
+ Constant* NewCaseVal = ConstantExpr::getSub(LHS, AddRHS);
assert(isa<ConstantInt>(NewCaseVal) &&
"Result of expression should be constant");
i.setValue(cast<ConstantInt>(NewCaseVal));
return &SI;
}
}
- return nullptr;
+
+ return TruncCond ? &SI : nullptr;
}
Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) {
return nullptr;
}
-enum Personality_Type {
- Unknown_Personality,
- GNU_Ada_Personality,
- GNU_CXX_Personality,
- GNU_ObjC_Personality
-};
-
-/// RecognizePersonality - See if the given exception handling personality
-/// function is one that we understand. If so, return a description of it;
-/// otherwise return Unknown_Personality.
-static Personality_Type RecognizePersonality(Value *Pers) {
- Function *F = dyn_cast<Function>(Pers->stripPointerCasts());
- if (!F)
- return Unknown_Personality;
- return StringSwitch<Personality_Type>(F->getName())
- .Case("__gnat_eh_personality", GNU_Ada_Personality)
- .Case("__gxx_personality_v0", GNU_CXX_Personality)
- .Case("__objc_personality_v0", GNU_ObjC_Personality)
- .Default(Unknown_Personality);
-}
-
/// isCatchAll - Return 'true' if the given typeinfo will match anything.
-static bool isCatchAll(Personality_Type Personality, Constant *TypeInfo) {
+static bool isCatchAll(EHPersonality Personality, Constant *TypeInfo) {
switch (Personality) {
- case Unknown_Personality:
+ case EHPersonality::GNU_C:
+ // The GCC C EH personality only exists to support cleanups, so it's not
+ // clear what the semantics of catch clauses are.
return false;
- case GNU_Ada_Personality:
+ case EHPersonality::Unknown:
+ return false;
+ case EHPersonality::GNU_Ada:
// While __gnat_all_others_value will match any Ada exception, it doesn't
// match foreign exceptions (or didn't, before gcc-4.7).
return false;
- case GNU_CXX_Personality:
- case GNU_ObjC_Personality:
+ case EHPersonality::GNU_CXX:
+ case EHPersonality::GNU_ObjC:
+ case EHPersonality::MSVC_X86SEH:
+ case EHPersonality::MSVC_Win64SEH:
+ case EHPersonality::MSVC_CXX:
return TypeInfo->isNullValue();
}
- llvm_unreachable("Unknown personality!");
+ llvm_unreachable("invalid enum");
}
static bool shorter_filter(const Value *LHS, const Value *RHS) {
// The logic here should be correct for any real-world personality function.
// However if that turns out not to be true, the offending logic can always
// be conditioned on the personality function, like the catch-all logic is.
- Personality_Type Personality = RecognizePersonality(LI.getPersonalityFn());
+ EHPersonality Personality = classifyEHPersonality(LI.getPersonalityFn());
// Simplify the list of clauses, eg by removing repeated catch clauses
// (these are often created by inlining).
// If we already saw this clause, there is no point in having a second
// copy of it.
- if (AlreadyCaught.insert(TypeInfo)) {
+ if (AlreadyCaught.insert(TypeInfo).second) {
// This catch clause was not already seen.
NewClauses.push_back(CatchClause);
} else {
continue;
// There is no point in having multiple copies of the same typeinfo in
// a filter, so only add it if we didn't already.
- if (SeenInFilter.insert(TypeInfo))
+ if (SeenInFilter.insert(TypeInfo).second)
NewFilterElts.push_back(cast<Constant>(Elt));
}
// A filter containing a catch-all cannot match anything by definition.
return nullptr;
}
-
-
-
/// TryToSinkInstruction - Try to move the specified instruction from its
/// current block into the beginning of DestBlock, which can only happen if it's
/// safe to move the instruction past all of the instructions between it and the
return true;
}
+bool InstCombiner::run() {
+ while (!Worklist.isEmpty()) {
+ Instruction *I = Worklist.RemoveOne();
+ if (I == nullptr) continue; // skip null values.
+
+ // Check to see if we can DCE the instruction.
+ if (isInstructionTriviallyDead(I, TLI)) {
+ DEBUG(dbgs() << "IC: DCE: " << *I << '\n');
+ EraseInstFromFunction(*I);
+ ++NumDeadInst;
+ MadeIRChange = true;
+ continue;
+ }
+
+ // Instruction isn't dead, see if we can constant propagate it.
+ if (!I->use_empty() && isa<Constant>(I->getOperand(0)))
+ if (Constant *C = ConstantFoldInstruction(I, DL, TLI)) {
+ DEBUG(dbgs() << "IC: ConstFold to: " << *C << " from: " << *I << '\n');
+
+ // Add operands to the worklist.
+ ReplaceInstUsesWith(*I, C);
+ ++NumConstProp;
+ EraseInstFromFunction(*I);
+ MadeIRChange = true;
+ continue;
+ }
+
+ // See if we can trivially sink this instruction to a successor basic block.
+ if (I->hasOneUse()) {
+ BasicBlock *BB = I->getParent();
+ Instruction *UserInst = cast<Instruction>(*I->user_begin());
+ BasicBlock *UserParent;
+
+ // Get the block the use occurs in.
+ if (PHINode *PN = dyn_cast<PHINode>(UserInst))
+ UserParent = PN->getIncomingBlock(*I->use_begin());
+ else
+ UserParent = UserInst->getParent();
+
+ if (UserParent != BB) {
+ bool UserIsSuccessor = false;
+ // See if the user is one of our successors.
+ for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
+ if (*SI == UserParent) {
+ UserIsSuccessor = true;
+ break;
+ }
+
+ // If the user is one of our immediate successors, and if that successor
+ // only has us as a predecessors (we'd have to split the critical edge
+ // otherwise), we can keep going.
+ if (UserIsSuccessor && UserParent->getSinglePredecessor()) {
+ // Okay, the CFG is simple enough, try to sink this instruction.
+ if (TryToSinkInstruction(I, UserParent)) {
+ MadeIRChange = true;
+ // We'll add uses of the sunk instruction below, but since sinking
+ // can expose opportunities for it's *operands* add them to the
+ // worklist
+ for (Use &U : I->operands())
+ if (Instruction *OpI = dyn_cast<Instruction>(U.get()))
+ Worklist.Add(OpI);
+ }
+ }
+ }
+ }
+
+ // Now that we have an instruction, try combining it to simplify it.
+ Builder->SetInsertPoint(I->getParent(), I);
+ Builder->SetCurrentDebugLocation(I->getDebugLoc());
+
+#ifndef NDEBUG
+ std::string OrigI;
+#endif
+ DEBUG(raw_string_ostream SS(OrigI); I->print(SS); OrigI = SS.str(););
+ DEBUG(dbgs() << "IC: Visiting: " << OrigI << '\n');
+
+ if (Instruction *Result = visit(*I)) {
+ ++NumCombined;
+ // Should we replace the old instruction with a new one?
+ if (Result != I) {
+ DEBUG(dbgs() << "IC: Old = " << *I << '\n'
+ << " New = " << *Result << '\n');
+
+ if (!I->getDebugLoc().isUnknown())
+ Result->setDebugLoc(I->getDebugLoc());
+ // Everything uses the new instruction now.
+ I->replaceAllUsesWith(Result);
+
+ // Move the name to the new instruction first.
+ Result->takeName(I);
+
+ // Push the new instruction and any users onto the worklist.
+ Worklist.Add(Result);
+ Worklist.AddUsersToWorkList(*Result);
+
+ // Insert the new instruction into the basic block...
+ BasicBlock *InstParent = I->getParent();
+ BasicBlock::iterator InsertPos = I;
+
+ // If we replace a PHI with something that isn't a PHI, fix up the
+ // insertion point.
+ if (!isa<PHINode>(Result) && isa<PHINode>(InsertPos))
+ InsertPos = InstParent->getFirstInsertionPt();
+
+ InstParent->getInstList().insert(InsertPos, Result);
+
+ EraseInstFromFunction(*I);
+ } else {
+#ifndef NDEBUG
+ DEBUG(dbgs() << "IC: Mod = " << OrigI << '\n'
+ << " New = " << *I << '\n');
+#endif
+
+ // If the instruction was modified, it's possible that it is now dead.
+ // if so, remove it.
+ if (isInstructionTriviallyDead(I, TLI)) {
+ EraseInstFromFunction(*I);
+ } else {
+ Worklist.Add(I);
+ Worklist.AddUsersToWorkList(*I);
+ }
+ }
+ MadeIRChange = true;
+ }
+ }
+
+ Worklist.Zap();
+ return MadeIRChange;
+}
/// AddReachableCodeToWorklist - Walk the function in depth-first order, adding
/// all reachable code to the worklist.
/// whose condition is a known constant, we only visit the reachable successors.
///
static bool AddReachableCodeToWorklist(BasicBlock *BB,
- SmallPtrSet<BasicBlock*, 64> &Visited,
- InstCombiner &IC,
+ SmallPtrSetImpl<BasicBlock*> &Visited,
+ InstCombineWorklist &ICWorklist,
const DataLayout *DL,
const TargetLibraryInfo *TLI) {
bool MadeIRChange = false;
BB = Worklist.pop_back_val();
// We have now visited this block! If we've already been here, ignore it.
- if (!Visited.insert(BB)) continue;
+ if (!Visited.insert(BB).second)
+ continue;
for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
Instruction *Inst = BBI++;
// of the function down. This jives well with the way that it adds all uses
// of instructions to the worklist after doing a transformation, thus avoiding
// some N^2 behavior in pathological cases.
- IC.Worklist.AddInitialGroup(&InstrsForInstCombineWorklist[0],
- InstrsForInstCombineWorklist.size());
+ ICWorklist.AddInitialGroup(&InstrsForInstCombineWorklist[0],
+ InstrsForInstCombineWorklist.size());
return MadeIRChange;
}
-bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
- MadeIRChange = false;
-
- DEBUG(dbgs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
- << F.getName() << "\n");
-
- {
- // Do a depth-first traversal of the function, populate the worklist with
- // the reachable instructions. Ignore blocks that are not reachable. Keep
- // track of which blocks we visit.
- SmallPtrSet<BasicBlock*, 64> Visited;
- MadeIRChange |= AddReachableCodeToWorklist(F.begin(), Visited, *this, DL,
- TLI);
-
- // Do a quick scan over the function. If we find any blocks that are
- // unreachable, remove any instructions inside of them. This prevents
- // the instcombine code from having to deal with some bad special cases.
- for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
- if (Visited.count(BB)) continue;
-
- // Delete the instructions backwards, as it has a reduced likelihood of
- // having to update as many def-use and use-def chains.
- Instruction *EndInst = BB->getTerminator(); // Last not to be deleted.
- while (EndInst != BB->begin()) {
- // Delete the next to last instruction.
- BasicBlock::iterator I = EndInst;
- Instruction *Inst = --I;
- if (!Inst->use_empty())
- Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
- if (isa<LandingPadInst>(Inst)) {
- EndInst = Inst;
- continue;
- }
- if (!isa<DbgInfoIntrinsic>(Inst)) {
- ++NumDeadInst;
- MadeIRChange = true;
- }
- Inst->eraseFromParent();
- }
- }
- }
-
- while (!Worklist.isEmpty()) {
- Instruction *I = Worklist.RemoveOne();
- if (I == nullptr) continue; // skip null values.
+/// \brief Populate the IC worklist from a function, and prune any dead basic
+/// blocks discovered in the process.
+///
+/// This also does basic constant propagation and other forward fixing to make
+/// the combiner itself run much faster.
+static bool prepareICWorklistFromFunction(Function &F, const DataLayout *DL,
+ TargetLibraryInfo *TLI,
+ InstCombineWorklist &ICWorklist) {
+ bool MadeIRChange = false;
- // Check to see if we can DCE the instruction.
- if (isInstructionTriviallyDead(I, TLI)) {
- DEBUG(dbgs() << "IC: DCE: " << *I << '\n');
- EraseInstFromFunction(*I);
- ++NumDeadInst;
- MadeIRChange = true;
+ // Do a depth-first traversal of the function, populate the worklist with
+ // the reachable instructions. Ignore blocks that are not reachable. Keep
+ // track of which blocks we visit.
+ SmallPtrSet<BasicBlock *, 64> Visited;
+ MadeIRChange |=
+ AddReachableCodeToWorklist(F.begin(), Visited, ICWorklist, DL, TLI);
+
+ // Do a quick scan over the function. If we find any blocks that are
+ // unreachable, remove any instructions inside of them. This prevents
+ // the instcombine code from having to deal with some bad special cases.
+ for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
+ if (Visited.count(BB))
continue;
- }
- // Instruction isn't dead, see if we can constant propagate it.
- if (!I->use_empty() && isa<Constant>(I->getOperand(0)))
- if (Constant *C = ConstantFoldInstruction(I, DL, TLI)) {
- DEBUG(dbgs() << "IC: ConstFold to: " << *C << " from: " << *I << '\n');
-
- // Add operands to the worklist.
- ReplaceInstUsesWith(*I, C);
- ++NumConstProp;
- EraseInstFromFunction(*I);
- MadeIRChange = true;
+ // Delete the instructions backwards, as it has a reduced likelihood of
+ // having to update as many def-use and use-def chains.
+ Instruction *EndInst = BB->getTerminator(); // Last not to be deleted.
+ while (EndInst != BB->begin()) {
+ // Delete the next to last instruction.
+ BasicBlock::iterator I = EndInst;
+ Instruction *Inst = --I;
+ if (!Inst->use_empty())
+ Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
+ if (isa<LandingPadInst>(Inst)) {
+ EndInst = Inst;
continue;
}
-
- // See if we can trivially sink this instruction to a successor basic block.
- if (I->hasOneUse()) {
- BasicBlock *BB = I->getParent();
- Instruction *UserInst = cast<Instruction>(*I->user_begin());
- BasicBlock *UserParent;
-
- // Get the block the use occurs in.
- if (PHINode *PN = dyn_cast<PHINode>(UserInst))
- UserParent = PN->getIncomingBlock(*I->use_begin());
- else
- UserParent = UserInst->getParent();
-
- if (UserParent != BB) {
- bool UserIsSuccessor = false;
- // See if the user is one of our successors.
- for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
- if (*SI == UserParent) {
- UserIsSuccessor = true;
- break;
- }
-
- // If the user is one of our immediate successors, and if that successor
- // only has us as a predecessors (we'd have to split the critical edge
- // otherwise), we can keep going.
- if (UserIsSuccessor && UserParent->getSinglePredecessor()) {
- // Okay, the CFG is simple enough, try to sink this instruction.
- if (TryToSinkInstruction(I, UserParent)) {
- MadeIRChange = true;
- // We'll add uses of the sunk instruction below, but since sinking
- // can expose opportunities for it's *operands* add them to the
- // worklist
- for (Use &U : I->operands())
- if (Instruction *OpI = dyn_cast<Instruction>(U.get()))
- Worklist.Add(OpI);
- }
- }
+ if (!isa<DbgInfoIntrinsic>(Inst)) {
+ ++NumDeadInst;
+ MadeIRChange = true;
}
+ Inst->eraseFromParent();
}
+ }
- // Now that we have an instruction, try combining it to simplify it.
- Builder->SetInsertPoint(I->getParent(), I);
- Builder->SetCurrentDebugLocation(I->getDebugLoc());
+ return MadeIRChange;
+}
-#ifndef NDEBUG
- std::string OrigI;
-#endif
- DEBUG(raw_string_ostream SS(OrigI); I->print(SS); OrigI = SS.str(););
- DEBUG(dbgs() << "IC: Visiting: " << OrigI << '\n');
+static bool
+combineInstructionsOverFunction(Function &F, InstCombineWorklist &Worklist,
+ AssumptionCache &AC, TargetLibraryInfo &TLI,
+ DominatorTree &DT, LoopInfo *LI = nullptr) {
+ // Minimizing size?
+ bool MinimizeSize = F.hasFnAttribute(Attribute::MinSize);
+ const DataLayout &DL = F.getParent()->getDataLayout();
- if (Instruction *Result = visit(*I)) {
- ++NumCombined;
- // Should we replace the old instruction with a new one?
- if (Result != I) {
- DEBUG(dbgs() << "IC: Old = " << *I << '\n'
- << " New = " << *Result << '\n');
+ /// Builder - This is an IRBuilder that automatically inserts new
+ /// instructions into the worklist when they are created.
+ IRBuilder<true, TargetFolder, InstCombineIRInserter> Builder(
+ F.getContext(), TargetFolder(&DL), InstCombineIRInserter(Worklist, &AC));
- if (!I->getDebugLoc().isUnknown())
- Result->setDebugLoc(I->getDebugLoc());
- // Everything uses the new instruction now.
- I->replaceAllUsesWith(Result);
+ // Lower dbg.declare intrinsics otherwise their value may be clobbered
+ // by instcombiner.
+ bool DbgDeclaresChanged = LowerDbgDeclare(F);
- // Move the name to the new instruction first.
- Result->takeName(I);
+ // Iterate while there is work to do.
+ int Iteration = 0;
+ for (;;) {
+ ++Iteration;
+ DEBUG(dbgs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
+ << F.getName() << "\n");
- // Push the new instruction and any users onto the worklist.
- Worklist.Add(Result);
- Worklist.AddUsersToWorkList(*Result);
+ bool Changed = false;
+ if (prepareICWorklistFromFunction(F, &DL, &TLI, Worklist))
+ Changed = true;
- // Insert the new instruction into the basic block...
- BasicBlock *InstParent = I->getParent();
- BasicBlock::iterator InsertPos = I;
+ InstCombiner IC(Worklist, &Builder, MinimizeSize, &AC, &TLI, &DT, &DL, LI);
+ if (IC.run())
+ Changed = true;
- // If we replace a PHI with something that isn't a PHI, fix up the
- // insertion point.
- if (!isa<PHINode>(Result) && isa<PHINode>(InsertPos))
- InsertPos = InstParent->getFirstInsertionPt();
+ if (!Changed)
+ break;
+ }
- InstParent->getInstList().insert(InsertPos, Result);
+ return DbgDeclaresChanged || Iteration > 1;
+}
- EraseInstFromFunction(*I);
- } else {
-#ifndef NDEBUG
- DEBUG(dbgs() << "IC: Mod = " << OrigI << '\n'
- << " New = " << *I << '\n');
-#endif
+PreservedAnalyses InstCombinePass::run(Function &F,
+ AnalysisManager<Function> *AM) {
+ auto &AC = AM->getResult<AssumptionAnalysis>(F);
+ auto &DT = AM->getResult<DominatorTreeAnalysis>(F);
+ auto &TLI = AM->getResult<TargetLibraryAnalysis>(F);
- // If the instruction was modified, it's possible that it is now dead.
- // if so, remove it.
- if (isInstructionTriviallyDead(I, TLI)) {
- EraseInstFromFunction(*I);
- } else {
- Worklist.Add(I);
- Worklist.AddUsersToWorkList(*I);
- }
- }
- MadeIRChange = true;
- }
- }
+ auto *LI = AM->getCachedResult<LoopAnalysis>(F);
- Worklist.Zap();
- return MadeIRChange;
+ if (!combineInstructionsOverFunction(F, Worklist, AC, TLI, DT, LI))
+ // No changes, all analyses are preserved.
+ return PreservedAnalyses::all();
+
+ // Mark all the analyses that instcombine updates as preserved.
+ // FIXME: Need a way to preserve CFG analyses here!
+ PreservedAnalyses PA;
+ PA.preserve<DominatorTreeAnalysis>();
+ return PA;
}
namespace {
-class InstCombinerLibCallSimplifier : public LibCallSimplifier {
- InstCombiner *IC;
+/// \brief The legacy pass manager's instcombine pass.
+///
+/// This is a basic whole-function wrapper around the instcombine utility. It
+/// will try to combine all instructions in the function.
+class InstructionCombiningPass : public FunctionPass {
+ InstCombineWorklist Worklist;
+
public:
- InstCombinerLibCallSimplifier(const DataLayout *DL,
- const TargetLibraryInfo *TLI,
- InstCombiner *IC)
- : LibCallSimplifier(DL, TLI, UnsafeFPShrink) {
- this->IC = IC;
- }
+ static char ID; // Pass identification, replacement for typeid
- /// replaceAllUsesWith - override so that instruction replacement
- /// can be defined in terms of the instruction combiner framework.
- void replaceAllUsesWith(Instruction *I, Value *With) const override {
- IC->ReplaceInstUsesWith(*I, With);
+ InstructionCombiningPass() : FunctionPass(ID) {
+ initializeInstructionCombiningPassPass(*PassRegistry::getPassRegistry());
}
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+ bool runOnFunction(Function &F) override;
};
}
-bool InstCombiner::runOnFunction(Function &F) {
+void InstructionCombiningPass::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesCFG();
+ AU.addRequired<AssumptionCacheTracker>();
+ AU.addRequired<TargetLibraryInfoWrapperPass>();
+ AU.addRequired<DominatorTreeWrapperPass>();
+ AU.addPreserved<DominatorTreeWrapperPass>();
+}
+
+bool InstructionCombiningPass::runOnFunction(Function &F) {
if (skipOptnoneFunction(F))
return false;
- DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
- DL = DLP ? &DLP->getDataLayout() : nullptr;
- TLI = &getAnalysis<TargetLibraryInfo>();
- // Minimizing size?
- MinimizeSize = F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
- Attribute::MinSize);
+ // Required analyses.
+ auto &AC = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
+ auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
+ auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
- /// Builder - This is an IRBuilder that automatically inserts new
- /// instructions into the worklist when they are created.
- IRBuilder<true, TargetFolder, InstCombineIRInserter>
- TheBuilder(F.getContext(), TargetFolder(DL),
- InstCombineIRInserter(Worklist));
- Builder = &TheBuilder;
-
- InstCombinerLibCallSimplifier TheSimplifier(DL, TLI, this);
- Simplifier = &TheSimplifier;
+ // Optional analyses.
+ auto *LIWP = getAnalysisIfAvailable<LoopInfoWrapperPass>();
+ auto *LI = LIWP ? &LIWP->getLoopInfo() : nullptr;
- bool EverMadeChange = false;
+ return combineInstructionsOverFunction(F, Worklist, AC, TLI, DT, LI);
+}
- // Lower dbg.declare intrinsics otherwise their value may be clobbered
- // by instcombiner.
- EverMadeChange = LowerDbgDeclare(F);
+char InstructionCombiningPass::ID = 0;
+INITIALIZE_PASS_BEGIN(InstructionCombiningPass, "instcombine",
+ "Combine redundant instructions", false, false)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
+INITIALIZE_PASS_END(InstructionCombiningPass, "instcombine",
+ "Combine redundant instructions", false, false)
- // Iterate while there is work to do.
- unsigned Iteration = 0;
- while (DoOneIteration(F, Iteration++))
- EverMadeChange = true;
+// Initialization Routines
+void llvm::initializeInstCombine(PassRegistry &Registry) {
+ initializeInstructionCombiningPassPass(Registry);
+}
- Builder = nullptr;
- return EverMadeChange;
+void LLVMInitializeInstCombine(LLVMPassRegistryRef R) {
+ initializeInstructionCombiningPassPass(*unwrap(R));
}
FunctionPass *llvm::createInstructionCombiningPass() {
- return new InstCombiner();
+ return new InstructionCombiningPass();
}
projects / oota-llvm.git / blobdiff