#include "llvm/CodeGen/Passes.h"
#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/MemoryLocation.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InlineAsm.h"
+#include "llvm/IR/InstIterator.h"
+#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/MDBuilder.h"
+#include "llvm/IR/NoFolder.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/Statepoint.h"
#include "llvm/IR/ValueHandle.h"
"computations were sunk");
STATISTIC(NumExtsMoved, "Number of [s|z]ext instructions combined with loads");
STATISTIC(NumExtUses, "Number of uses of [s|z]ext instructions optimized");
+STATISTIC(NumAndsAdded,
+ "Number of and mask instructions added to form ext loads");
+STATISTIC(NumAndUses, "Number of uses of and mask instructions optimized");
STATISTIC(NumRetsDup, "Number of return instructions duplicated");
STATISTIC(NumDbgValueMoved, "Number of debug value instructions moved");
STATISTIC(NumSelectsExpanded, "Number of selects turned into branches");
bool optimizeCallInst(CallInst *CI, bool& ModifiedDT);
bool moveExtToFormExtLoad(Instruction *&I);
bool optimizeExtUses(Instruction *I);
+ bool optimizeLoadExt(LoadInst *I);
bool optimizeSelectInst(SelectInst *SI);
bool optimizeShuffleVectorInst(ShuffleVectorInst *SI);
+ bool optimizeSwitchInst(SwitchInst *CI);
bool optimizeExtractElementInst(Instruction *Inst);
bool dupRetToEnableTailCallOpts(BasicBlock *BB);
bool placeDbgValues(Function &F);
return new CodeGenPrepare(TM);
}
+namespace {
+
+bool StoreAddressDependOnValue(StoreInst* SI, Value* DepVal);
+Value* GetUntaintedAddress(Value* CurrentAddress);
+
+// The depth we trace down a variable to look for its dependence set.
+const unsigned kDependenceDepth = 4;
+
+// Recursively looks for variables that 'Val' depends on at the given depth
+// 'Depth', and adds them in 'DepSet'. If 'InsertOnlyLeafNodes' is true, only
+// inserts the leaf node values; otherwise, all visited nodes are included in
+// 'DepSet'. Note that constants will be ignored.
+template <typename SetType>
+void recursivelyFindDependence(SetType* DepSet, Value* Val,
+ bool InsertOnlyLeafNodes = false,
+ unsigned Depth = kDependenceDepth) {
+ if (Val == nullptr) {
+ return;
+ }
+ if (!InsertOnlyLeafNodes && !isa<Constant>(Val)) {
+ DepSet->insert(Val);
+ }
+ if (Depth == 0) {
+ // Cannot go deeper. Insert the leaf nodes.
+ if (InsertOnlyLeafNodes && !isa<Constant>(Val)) {
+ DepSet->insert(Val);
+ }
+ return;
+ }
+
+ // Go one step further to explore the dependence of the operands.
+ Instruction* I = nullptr;
+ if ((I = dyn_cast<Instruction>(Val))) {
+ if (isa<LoadInst>(I)) {
+ // A load is considerd the leaf load of the dependence tree. Done.
+ DepSet->insert(Val);
+ return;
+ } else if (I->isBinaryOp()) {
+ BinaryOperator* I = dyn_cast<BinaryOperator>(Val);
+ Value *Op0 = I->getOperand(0), *Op1 = I->getOperand(1);
+ recursivelyFindDependence(DepSet, Op0, Depth - 1);
+ recursivelyFindDependence(DepSet, Op1, Depth - 1);
+ } else if (I->isCast()) {
+ Value* Op0 = I->getOperand(0);
+ recursivelyFindDependence(DepSet, Op0, Depth - 1);
+ } else if (I->getOpcode() == Instruction::Select) {
+ Value* Op0 = I->getOperand(0);
+ Value* Op1 = I->getOperand(1);
+ Value* Op2 = I->getOperand(2);
+ recursivelyFindDependence(DepSet, Op0, Depth - 1);
+ recursivelyFindDependence(DepSet, Op1, Depth - 1);
+ recursivelyFindDependence(DepSet, Op2, Depth - 1);
+ } else if (I->getOpcode() == Instruction::GetElementPtr) {
+ for (unsigned i = 0; i < I->getNumOperands(); i++) {
+ recursivelyFindDependence(DepSet, I->getOperand(i), Depth - 1);
+ }
+ } else if (I->getOpcode() == Instruction::Store) {
+ auto* SI = dyn_cast<StoreInst>(Val);
+ recursivelyFindDependence(DepSet, SI->getPointerOperand(), Depth - 1);
+ recursivelyFindDependence(DepSet, SI->getValueOperand(), Depth - 1);
+ } else {
+ Value* Op0 = nullptr;
+ Value* Op1 = nullptr;
+ switch (I->getOpcode()) {
+ case Instruction::ICmp:
+ case Instruction::FCmp: {
+ Op0 = I->getOperand(0);
+ Op1 = I->getOperand(1);
+ recursivelyFindDependence(DepSet, Op0, Depth - 1);
+ recursivelyFindDependence(DepSet, Op1, Depth - 1);
+ break;
+ }
+ default: {
+ // Be conservative. Add it and be done with it.
+ DepSet->insert(Val);
+ return;
+ }
+ }
+ }
+ } else if (isa<Constant>(Val)) {
+ // Not interested in constant values. Done.
+ return;
+ } else {
+ // Be conservative. Add it and be done with it.
+ DepSet->insert(Val);
+ return;
+ }
+}
+
+// Helper function to create a Cast instruction.
+Value* createCast(IRBuilder<true, NoFolder>& Builder, Value* DepVal,
+ Type* TargetIntegerType) {
+ Instruction::CastOps CastOp = Instruction::BitCast;
+ switch (DepVal->getType()->getTypeID()) {
+ case Type::IntegerTyID: {
+ CastOp = Instruction::SExt;
+ break;
+ }
+ case Type::FloatTyID:
+ case Type::DoubleTyID: {
+ CastOp = Instruction::FPToSI;
+ break;
+ }
+ case Type::PointerTyID: {
+ CastOp = Instruction::PtrToInt;
+ break;
+ }
+ default: { break; }
+ }
+
+ return Builder.CreateCast(CastOp, DepVal, TargetIntegerType);
+}
+
+// Given a value, if it's a tainted address, this function returns the
+// instruction that ORs the "dependence value" with the "original address".
+// Otherwise, returns nullptr. This instruction is the first OR instruction
+// where one of its operand is an AND instruction with an operand being 0.
+//
+// E.g., it returns '%4 = or i32 %3, %2' given 'CurrentAddress' is '%5'.
+// %0 = load i32, i32* @y, align 4, !tbaa !1
+// %cmp = icmp ne i32 %0, 42 // <== this is like the condition
+// %1 = sext i1 %cmp to i32
+// %2 = ptrtoint i32* @x to i32
+// %3 = and i32 %1, 0
+// %4 = or i32 %3, %2
+// %5 = inttoptr i32 %4 to i32*
+// store i32 1, i32* %5, align 4
+Instruction* getOrAddress(Value* CurrentAddress) {
+ // Is it a cast from integer to pointer type.
+ Instruction* OrAddress = nullptr;
+ Instruction* AndDep = nullptr;
+ Instruction* CastToInt = nullptr;
+ Value* ActualAddress = nullptr;
+ Constant* ZeroConst = nullptr;
+
+ const Instruction* CastToPtr = dyn_cast<Instruction>(CurrentAddress);
+ if (CastToPtr && CastToPtr->getOpcode() == Instruction::IntToPtr) {
+ // Is it an OR instruction: %1 = or %and, %actualAddress.
+ if ((OrAddress = dyn_cast<Instruction>(CastToPtr->getOperand(0))) &&
+ OrAddress->getOpcode() == Instruction::Or) {
+ // The first operand should be and AND instruction.
+ AndDep = dyn_cast<Instruction>(OrAddress->getOperand(0));
+ if (AndDep && AndDep->getOpcode() == Instruction::And) {
+ // Also make sure its first operand of the "AND" is 0, or the "AND" is
+ // marked explicitly by "NoInstCombine".
+ if ((ZeroConst = dyn_cast<Constant>(AndDep->getOperand(1))) &&
+ ZeroConst->isNullValue()) {
+ return OrAddress;
+ }
+ }
+ }
+ }
+ // Looks like it's not been tainted.
+ return nullptr;
+}
+
+// Given a value, if it's a tainted address, this function returns the
+// instruction that taints the "dependence value". Otherwise, returns nullptr.
+// This instruction is the last AND instruction where one of its operand is 0.
+// E.g., it returns '%3' given 'CurrentAddress' is '%5'.
+// %0 = load i32, i32* @y, align 4, !tbaa !1
+// %cmp = icmp ne i32 %0, 42 // <== this is like the condition
+// %1 = sext i1 %cmp to i32
+// %2 = ptrtoint i32* @x to i32
+// %3 = and i32 %1, 0
+// %4 = or i32 %3, %2
+// %5 = inttoptr i32 %4 to i32*
+// store i32 1, i32* %5, align 4
+Instruction* getAndDependence(Value* CurrentAddress) {
+ // If 'CurrentAddress' is tainted, get the OR instruction.
+ auto* OrAddress = getOrAddress(CurrentAddress);
+ if (OrAddress == nullptr) {
+ return nullptr;
+ }
+
+ // No need to check the operands.
+ auto* AndDepInst = dyn_cast<Instruction>(OrAddress->getOperand(0));
+ assert(AndDepInst);
+ return AndDepInst;
+}
+
+// Given a value, if it's a tainted address, this function returns
+// the "dependence value", which is the first operand in the AND instruction.
+// E.g., it returns '%1' given 'CurrentAddress' is '%5'.
+// %0 = load i32, i32* @y, align 4, !tbaa !1
+// %cmp = icmp ne i32 %0, 42 // <== this is like the condition
+// %1 = sext i1 %cmp to i32
+// %2 = ptrtoint i32* @x to i32
+// %3 = and i32 %1, 0
+// %4 = or i32 %3, %2
+// %5 = inttoptr i32 %4 to i32*
+// store i32 1, i32* %5, align 4
+Value* getDependence(Value* CurrentAddress) {
+ auto* AndInst = getAndDependence(CurrentAddress);
+ if (AndInst == nullptr) {
+ return nullptr;
+ }
+ return AndInst->getOperand(0);
+}
+
+// Given an address that has been tainted, returns the only condition it depends
+// on, if any; otherwise, returns nullptr.
+Value* getConditionDependence(Value* Address) {
+ auto* Dep = getDependence(Address);
+ if (Dep == nullptr) {
+ // 'Address' has not been dependence-tainted.
+ return nullptr;
+ }
+
+ Value* Operand = Dep;
+ while (true) {
+ auto* Inst = dyn_cast<Instruction>(Operand);
+ if (Inst == nullptr) {
+ // Non-instruction type does not have condition dependence.
+ return nullptr;
+ }
+ if (Inst->getOpcode() == Instruction::ICmp) {
+ return Inst;
+ } else {
+ if (Inst->getNumOperands() != 1) {
+ return nullptr;
+ } else {
+ Operand = Inst->getOperand(0);
+ }
+ }
+ }
+}
+
+// Conservatively decides whether the dependence set of 'Val1' includes the
+// dependence set of 'Val2'. If 'ExpandSecondValue' is false, we do not expand
+// 'Val2' and use that single value as its dependence set.
+// If it returns true, it means the dependence set of 'Val1' includes that of
+// 'Val2'; otherwise, it only means we cannot conclusively decide it.
+bool dependenceSetInclusion(Value* Val1, Value* Val2,
+ int Val1ExpandLevel = 2 * kDependenceDepth,
+ int Val2ExpandLevel = kDependenceDepth) {
+ typedef SmallSet<Value*, 8> IncludingSet;
+ typedef SmallSet<Value*, 4> IncludedSet;
+
+ IncludingSet DepSet1;
+ IncludedSet DepSet2;
+ // Look for more depths for the including set.
+ recursivelyFindDependence(&DepSet1, Val1, false /*Insert all visited nodes*/,
+ Val1ExpandLevel);
+ recursivelyFindDependence(&DepSet2, Val2, true /*Only insert leaf nodes*/,
+ Val2ExpandLevel);
+
+ auto set_inclusion = [](IncludingSet FullSet, IncludedSet Subset) {
+ for (auto* Dep : Subset) {
+ if (0 == FullSet.count(Dep)) {
+ return false;
+ }
+ }
+ return true;
+ };
+ bool inclusion = set_inclusion(DepSet1, DepSet2);
+ DEBUG(dbgs() << "[dependenceSetInclusion]: " << inclusion << "\n");
+ DEBUG(dbgs() << "Including set for: " << *Val1 << "\n");
+ DEBUG(for (const auto* Dep : DepSet1) { dbgs() << "\t\t" << *Dep << "\n"; });
+ DEBUG(dbgs() << "Included set for: " << *Val2 << "\n");
+ DEBUG(for (const auto* Dep : DepSet2) { dbgs() << "\t\t" << *Dep << "\n"; });
+
+ return inclusion;
+}
+
+// Recursively iterates through the operands spawned from 'DepVal'. If there
+// exists a single value that 'DepVal' only depends on, we call that value the
+// root dependence of 'DepVal' and return it. Otherwise, return 'DepVal'.
+Value* getRootDependence(Value* DepVal) {
+ SmallSet<Value*, 8> DepSet;
+ for (unsigned depth = kDependenceDepth; depth > 0; --depth) {
+ recursivelyFindDependence(&DepSet, DepVal, true /*Only insert leaf nodes*/,
+ depth);
+ if (DepSet.size() == 1) {
+ return *DepSet.begin();
+ }
+ DepSet.clear();
+ }
+ return DepVal;
+}
+
+// This function actually taints 'DepVal' to the address to 'SI'. If the
+// address
+// of 'SI' already depends on whatever 'DepVal' depends on, this function
+// doesn't do anything and returns false. Otherwise, returns true.
+//
+// This effect forces the store and any stores that comes later to depend on
+// 'DepVal'. For example, we have a condition "cond", and a store instruction
+// "s: STORE addr, val". If we want "s" (and any later store) to depend on
+// "cond", we do the following:
+// %conv = sext i1 %cond to i32
+// %addrVal = ptrtoint i32* %addr to i32
+// %andCond = and i32 conv, 0;
+// %orAddr = or i32 %andCond, %addrVal;
+// %NewAddr = inttoptr i32 %orAddr to i32*;
+//
+// This is a more concrete example:
+// ------
+// %0 = load i32, i32* @y, align 4, !tbaa !1
+// %cmp = icmp ne i32 %0, 42 // <== this is like the condition
+// %1 = sext i1 %cmp to i32
+// %2 = ptrtoint i32* @x to i32
+// %3 = and i32 %1, 0
+// %4 = or i32 %3, %2
+// %5 = inttoptr i32 %4 to i32*
+// store i32 1, i32* %5, align 4
+bool taintStoreAddress(StoreInst* SI, Value* DepVal,
+ const char* calling_func = __builtin_FUNCTION()) {
+ DEBUG(dbgs() << "Called from " << calling_func << '\n');
+ // Set the insertion point right after the 'DepVal'.
+ Instruction* Inst = nullptr;
+ IRBuilder<true, NoFolder> Builder(SI);
+ BasicBlock* BB = SI->getParent();
+ Value* Address = SI->getPointerOperand();
+ Type* TargetIntegerType =
+ IntegerType::get(Address->getContext(),
+ BB->getModule()->getDataLayout().getPointerSizeInBits());
+
+ // Does SI's address already depends on whatever 'DepVal' depends on?
+ if (StoreAddressDependOnValue(SI, DepVal)) {
+ return false;
+ }
+
+ // Figure out if there's a root variable 'DepVal' depends on. For example, we
+ // can extract "getelementptr inbounds %struct, %struct* %0, i64 0, i32 123"
+ // to be "%struct* %0" since all other operands are constant.
+ DepVal = getRootDependence(DepVal);
+
+ // Is this already a dependence-tainted store?
+ Value* OldDep = getDependence(Address);
+ if (OldDep) {
+ // The address of 'SI' has already been tainted. Just need to absorb the
+ // DepVal to the existing dependence in the address of SI.
+ Instruction* AndDep = getAndDependence(Address);
+ IRBuilder<true, NoFolder> Builder(AndDep);
+ Value* NewDep = nullptr;
+ if (DepVal->getType() == AndDep->getType()) {
+ NewDep = Builder.CreateAnd(OldDep, DepVal);
+ } else {
+ NewDep = Builder.CreateAnd(
+ OldDep, createCast(Builder, DepVal, TargetIntegerType));
+ }
+
+ auto* NewDepInst = dyn_cast<Instruction>(NewDep);
+
+ // Use the new AND instruction as the dependence
+ AndDep->setOperand(0, NewDep);
+ return true;
+ }
+
+ // SI's address has not been tainted. Now taint it with 'DepVal'.
+ Value* CastDepToInt = createCast(Builder, DepVal, TargetIntegerType);
+ Value* PtrToIntCast = Builder.CreatePtrToInt(Address, TargetIntegerType);
+ Value* AndDepVal =
+ Builder.CreateAnd(CastDepToInt, ConstantInt::get(TargetIntegerType, 0));
+ auto AndInst = dyn_cast<Instruction>(AndDepVal);
+ // XXX-comment: The original IR InstCombiner would change our and instruction
+ // to a select and then the back end optimize the condition out. We attach a
+ // flag to instructions and set it here to inform the InstCombiner to not to
+ // touch this and instruction at all.
+ Value* OrAddr = Builder.CreateOr(AndDepVal, PtrToIntCast);
+ Value* NewAddr = Builder.CreateIntToPtr(OrAddr, Address->getType());
+
+ DEBUG(dbgs() << "[taintStoreAddress]\n"
+ << "Original store: " << *SI << '\n');
+ SI->setOperand(1, NewAddr);
+
+ // Debug output.
+ DEBUG(dbgs() << "\tTargetIntegerType: " << *TargetIntegerType << '\n'
+ << "\tCast dependence value to integer: " << *CastDepToInt
+ << '\n'
+ << "\tCast address to integer: " << *PtrToIntCast << '\n'
+ << "\tAnd dependence value: " << *AndDepVal << '\n'
+ << "\tOr address: " << *OrAddr << '\n'
+ << "\tCast or instruction to address: " << *NewAddr << "\n\n");
+
+ return true;
+}
+
+// Looks for the previous store in the if block --- 'BrBB', which makes the
+// speculative store 'StoreToHoist' safe.
+Value* getSpeculativeStoreInPrevBB(StoreInst* StoreToHoist, BasicBlock* BrBB) {
+ assert(StoreToHoist && "StoreToHoist must be a real store");
+
+ Value* StorePtr = StoreToHoist->getPointerOperand();
+
+ // Look for a store to the same pointer in BrBB.
+ for (BasicBlock::reverse_iterator RI = BrBB->rbegin(), RE = BrBB->rend();
+ RI != RE; ++RI) {
+ Instruction* CurI = &*RI;
+
+ StoreInst* SI = dyn_cast<StoreInst>(CurI);
+ // Found the previous store make sure it stores to the same location.
+ // XXX-update: If the previous store's original untainted address are the
+ // same as 'StorePtr', we are also good to hoist the store.
+ if (SI && (SI->getPointerOperand() == StorePtr ||
+ GetUntaintedAddress(SI->getPointerOperand()) == StorePtr)) {
+ // Found the previous store, return its value operand.
+ return SI;
+ }
+ }
+
+ assert(false &&
+ "We should not reach here since this store is safe to speculate");
+}
+
+// XXX-comment: Returns true if it changes the code, false otherwise (the branch
+// condition already depends on 'DepVal'.
+bool taintConditionalBranch(BranchInst* BI, Value* DepVal) {
+ assert(BI->isConditional());
+ auto* Cond = BI->getOperand(0);
+ if (dependenceSetInclusion(Cond, DepVal)) {
+ // The dependence/ordering is self-evident.
+ return false;
+ }
+
+ IRBuilder<true, NoFolder> Builder(BI);
+ auto* AndDep =
+ Builder.CreateAnd(DepVal, ConstantInt::get(DepVal->getType(), 0));
+ auto* TruncAndDep =
+ Builder.CreateTrunc(AndDep, IntegerType::get(DepVal->getContext(), 1));
+ auto* OrCond = Builder.CreateOr(TruncAndDep, Cond);
+ BI->setOperand(0, OrCond);
+
+ // Debug output.
+ DEBUG(dbgs() << "\tTainted branch condition:\n" << *BI->getParent());
+
+ return true;
+}
+
+bool ConditionalBranchDependsOnValue(BranchInst* BI, Value* DepVal) {
+ assert(BI->isConditional());
+ auto* Cond = BI->getOperand(0);
+ return dependenceSetInclusion(Cond, DepVal);
+}
+
+// XXX-update: For a relaxed load 'LI', find the first immediate atomic store or
+// the first conditional branch. Returns nullptr if there's no such immediately
+// following store/branch instructions, which we can only enforce the load with
+// 'acquire'.
+Instruction* findFirstStoreCondBranchInst(LoadInst* LI) {
+ // In some situations, relaxed loads can be left as is:
+ // 1. The relaxed load is used to calculate the address of the immediate
+ // following store;
+ // 2. The relaxed load is used as a condition in the immediate following
+ // condition, and there are no stores in between. This is actually quite
+ // common. E.g.,
+ // int r1 = x.load(relaxed);
+ // if (r1 != 0) {
+ // y.store(1, relaxed);
+ // }
+ // However, in this function, we don't deal with them directly. Instead, we
+ // just find the immediate following store/condition branch and return it.
+
+ auto* BB = LI->getParent();
+ auto BE = BB->end();
+ auto BBI = BasicBlock::iterator(LI);
+ BBI++;
+ for (; BBI != BE; BBI++) {
+ auto* Inst = dyn_cast<Instruction>(&*BBI);
+ if (Inst == nullptr) {
+ continue;
+ }
+ if (Inst->getOpcode() == Instruction::Store) {
+ return Inst;
+ } else if (Inst->getOpcode() == Instruction::Br) {
+ auto* BrInst = dyn_cast<BranchInst>(Inst);
+ if (BrInst->isConditional()) {
+ return Inst;
+ } else {
+ return nullptr;
+ }
+ }
+ }
+ return nullptr;
+}
+
+// XXX-comment: Returns whether the code has been changed.
+bool taintMonotonicLoads(const SmallVector<LoadInst*, 1>& MonotonicLoadInsts) {
+ bool Changed = false;
+ for (auto* LI : MonotonicLoadInsts) {
+ auto* FirstInst = findFirstStoreCondBranchInst(LI);
+ if (FirstInst == nullptr) {
+ // We don't seem to be able to taint a following store/conditional branch
+ // instruction. Simply make it acquire.
+ DEBUG(dbgs() << "[RelaxedLoad]: Transformed to acquire load\n"
+ << *LI << "\n");
+ LI->setOrdering(Acquire);
+ Changed = true;
+ continue;
+ }
+ // Taint 'FirstInst', which could be a store or a condition branch
+ // instruction.
+ if (FirstInst->getOpcode() == Instruction::Store) {
+ Changed |= taintStoreAddress(dyn_cast<StoreInst>(FirstInst), LI);
+ } else if (FirstInst->getOpcode() == Instruction::Br) {
+ Changed |= taintConditionalBranch(dyn_cast<BranchInst>(FirstInst), LI);
+ } else {
+ assert(false && "findFirstStoreCondBranchInst() should return a "
+ "store/condition branch instruction");
+ }
+ }
+ return Changed;
+}
+
+// Inserts a fake conditional branch right after the instruction 'SplitInst',
+// and the branch condition is 'Condition'. 'SplitInst' will be placed in the
+// newly created block.
+void AddFakeConditionalBranch(Instruction* SplitInst, Value* Condition) {
+ auto* BB = SplitInst->getParent();
+ TerminatorInst* ThenTerm = nullptr;
+ TerminatorInst* ElseTerm = nullptr;
+ SplitBlockAndInsertIfThenElse(Condition, SplitInst, &ThenTerm, &ElseTerm);
+ assert(ThenTerm && ElseTerm &&
+ "Then/Else terminators cannot be empty after basic block spliting");
+ auto* ThenBB = ThenTerm->getParent();
+ auto* ElseBB = ElseTerm->getParent();
+ auto* TailBB = ThenBB->getSingleSuccessor();
+ assert(TailBB && "Tail block cannot be empty after basic block spliting");
+
+ ThenBB->disableCanEliminateBlock();
+ ThenBB->disableCanEliminateBlock();
+ TailBB->disableCanEliminateBlock();
+ ThenBB->setName(BB->getName() + "Then.Fake");
+ ElseBB->setName(BB->getName() + "Else.Fake");
+ DEBUG(dbgs() << "Add fake conditional branch:\n"
+ << "Then Block:\n"
+ << *ThenBB << "Else Block:\n"
+ << *ElseBB << "\n");
+}
+
+// Returns true if the code is changed, and false otherwise.
+void TaintRelaxedLoads(LoadInst* LI) {
+ // For better performance, we can add a "AND X 0" instruction before the
+ // condition.
+ auto* FirstInst = findFirstStoreCondBranchInst(LI);
+ Instruction* InsertPoint = nullptr;
+ if (FirstInst == nullptr) {
+ InsertPoint = LI->getParent()->getTerminator();
+ InsertPoint = LI->getNextNode();
+ } else {
+ InsertPoint = LI->getNextNode();
+ }
+ IRBuilder<true, NoFolder> Builder(InsertPoint);
+ auto* AndZero = dyn_cast<Instruction>(
+ Builder.CreateAnd(LI, Constant::getNullValue(LI->getType())));
+ auto* FakeCondition = dyn_cast<Instruction>(Builder.CreateICmp(
+ CmpInst::ICMP_NE, AndZero, Constant::getNullValue(LI->getType())));
+ AddFakeConditionalBranch(FakeCondition->getNextNode(), FakeCondition);
+}
+
+// XXX-comment: Returns whether the code has been changed.
+bool AddFakeConditionalBranchAfterMonotonicLoads(
+ const SmallVector<LoadInst*, 1>& MonotonicLoadInsts) {
+ bool Changed = false;
+ for (auto* LI : MonotonicLoadInsts) {
+ auto* FirstInst = findFirstStoreCondBranchInst(LI);
+ if (FirstInst != nullptr) {
+ if (FirstInst->getOpcode() == Instruction::Store) {
+ if (StoreAddressDependOnValue(dyn_cast<StoreInst>(FirstInst), LI)) {
+ continue;
+ }
+ } else if (FirstInst->getOpcode() == Instruction::Br &&
+ isa<BranchInst>(FirstInst)) {
+ if (ConditionalBranchDependsOnValue(dyn_cast<BranchInst>(FirstInst),
+ LI)) {
+ continue;
+ }
+ } else {
+ dbgs() << "FirstInst=" << *FirstInst << "\n";
+ assert(false && "findFirstStoreCondBranchInst() should return a "
+ "store/condition branch instruction");
+ }
+ }
+
+ // We really need to process the relaxed load now.
+ StoreInst* SI = nullptr;;
+ if (FirstInst && (SI = dyn_cast<StoreInst>(FirstInst))) {
+ // For immediately coming stores, taint the address of the store.
+ taintStoreAddress(SI, LI);
+ } else {
+ // For immediately coming branch, directly add a fake branch.
+ TaintRelaxedLoads(LI);
+ Changed = true;
+ }
+ }
+ return Changed;
+}
+
+/**** Implementations of public methods for dependence tainting ****/
+Value* GetUntaintedAddress(Value* CurrentAddress) {
+ auto* OrAddress = getOrAddress(CurrentAddress);
+ if (OrAddress == nullptr) {
+ // Is it tainted by a select instruction?
+ auto* Inst = dyn_cast<Instruction>(CurrentAddress);
+ if (nullptr != Inst && Inst->getOpcode() == Instruction::Select) {
+ // A selection instruction.
+ if (Inst->getOperand(1) == Inst->getOperand(2)) {
+ return Inst->getOperand(1);
+ }
+ }
+
+ return CurrentAddress;
+ }
+ Value* ActualAddress = nullptr;
+
+ auto* CastToInt = dyn_cast<Instruction>(OrAddress->getOperand(1));
+ if (CastToInt && CastToInt->getOpcode() == Instruction::PtrToInt) {
+ return CastToInt->getOperand(0);
+ } else {
+ // This should be a IntToPtr constant expression.
+ ConstantExpr* PtrToIntExpr =
+ dyn_cast<ConstantExpr>(OrAddress->getOperand(1));
+ if (PtrToIntExpr && PtrToIntExpr->getOpcode() == Instruction::PtrToInt) {
+ return PtrToIntExpr->getOperand(0);
+ }
+ }
+
+ // Looks like it's not been dependence-tainted. Returns itself.
+ return CurrentAddress;
+}
+
+MemoryLocation GetUntaintedMemoryLocation(StoreInst* SI) {
+ AAMDNodes AATags;
+ SI->getAAMetadata(AATags);
+ const auto& DL = SI->getModule()->getDataLayout();
+ const auto* OriginalAddr = GetUntaintedAddress(SI->getPointerOperand());
+ DEBUG(if (OriginalAddr != SI->getPointerOperand()) {
+ dbgs() << "[GetUntaintedMemoryLocation]\n"
+ << "Storing address: " << *SI->getPointerOperand()
+ << "\nUntainted address: " << *OriginalAddr << "\n";
+ });
+ return MemoryLocation(OriginalAddr,
+ DL.getTypeStoreSize(SI->getValueOperand()->getType()),
+ AATags);
+}
+
+bool TaintDependenceToStore(StoreInst* SI, Value* DepVal) {
+ if (dependenceSetInclusion(SI, DepVal)) {
+ return false;
+ }
+
+ bool tainted = taintStoreAddress(SI, DepVal);
+ assert(tainted);
+ return tainted;
+}
+
+bool TaintDependenceToStoreAddress(StoreInst* SI, Value* DepVal) {
+ if (dependenceSetInclusion(SI->getPointerOperand(), DepVal)) {
+ return false;
+ }
+
+ bool tainted = taintStoreAddress(SI, DepVal);
+ assert(tainted);
+ return tainted;
+}
+
+bool CompressTaintedStore(BasicBlock* BB) {
+ // This function looks for windows of adajcent stores in 'BB' that satisfy the
+ // following condition (and then do optimization):
+ // *Addr(d1) = v1, d1 is a condition and is the only dependence the store's
+ // address depends on && Dep(v1) includes Dep(d1);
+ // *Addr(d2) = v2, d2 is a condition and is the only dependnece the store's
+ // address depends on && Dep(v2) includes Dep(d2) &&
+ // Dep(d2) includes Dep(d1);
+ // ...
+ // *Addr(dN) = vN, dN is a condition and is the only dependence the store's
+ // address depends on && Dep(dN) includes Dep(d"N-1").
+ //
+ // As a result, Dep(dN) includes [Dep(d1) V ... V Dep(d"N-1")], so we can
+ // safely transform the above to the following. In between these stores, we
+ // can omit untainted stores to the same address 'Addr' since they internally
+ // have dependence on the previous stores on the same address.
+ // =>
+ // *Addr = v1
+ // *Addr = v2
+ // *Addr(d3) = v3
+ for (auto BI = BB->begin(), BE = BB->end(); BI != BE; BI++) {
+ // Look for the first store in such a window of adajacent stores.
+ auto* FirstSI = dyn_cast<StoreInst>(&*BI);
+ if (!FirstSI) {
+ continue;
+ }
+
+ // The first store in the window must be tainted.
+ auto* UntaintedAddress = GetUntaintedAddress(FirstSI->getPointerOperand());
+ if (UntaintedAddress == FirstSI->getPointerOperand()) {
+ continue;
+ }
+
+ // The first store's address must directly depend on and only depend on a
+ // condition.
+ auto* FirstSIDepCond = getConditionDependence(FirstSI->getPointerOperand());
+ if (nullptr == FirstSIDepCond) {
+ continue;
+ }
+
+ // Dep(first store's storing value) includes Dep(tainted dependence).
+ if (!dependenceSetInclusion(FirstSI->getValueOperand(), FirstSIDepCond)) {
+ continue;
+ }
+
+ // Look for subsequent stores to the same address that satisfy the condition
+ // of "compressing the dependence".
+ SmallVector<StoreInst*, 8> AdajacentStores;
+ AdajacentStores.push_back(FirstSI);
+ auto BII = BasicBlock::iterator(FirstSI);
+ for (BII++; BII != BE; BII++) {
+ auto* CurrSI = dyn_cast<StoreInst>(&*BII);
+ if (!CurrSI) {
+ if (BII->mayHaveSideEffects()) {
+ // Be conservative. Instructions with side effects are similar to
+ // stores.
+ break;
+ }
+ continue;
+ }
+
+ auto* OrigAddress = GetUntaintedAddress(CurrSI->getPointerOperand());
+ auto* CurrSIDepCond = getConditionDependence(CurrSI->getPointerOperand());
+ // All other stores must satisfy either:
+ // A. 'CurrSI' is an untainted store to the same address, or
+ // B. the combination of the following 5 subconditions:
+ // 1. Tainted;
+ // 2. Untainted address is the same as the group's address;
+ // 3. The address is tainted with a sole value which is a condition;
+ // 4. The storing value depends on the condition in 3.
+ // 5. The condition in 3 depends on the previous stores dependence
+ // condition.
+
+ // Condition A. Should ignore this store directly.
+ if (OrigAddress == CurrSI->getPointerOperand() &&
+ OrigAddress == UntaintedAddress) {
+ continue;
+ }
+ // Check condition B.
+ Value* Cond = nullptr;
+ if (OrigAddress == CurrSI->getPointerOperand() ||
+ OrigAddress != UntaintedAddress || CurrSIDepCond == nullptr ||
+ !dependenceSetInclusion(CurrSI->getValueOperand(), CurrSIDepCond)) {
+ // Check condition 1, 2, 3 & 4.
+ break;
+ }
+
+ // Check condition 5.
+ StoreInst* PrevSI = AdajacentStores[AdajacentStores.size() - 1];
+ auto* PrevSIDepCond = getConditionDependence(PrevSI->getPointerOperand());
+ assert(PrevSIDepCond &&
+ "Store in the group must already depend on a condtion");
+ if (!dependenceSetInclusion(CurrSIDepCond, PrevSIDepCond)) {
+ break;
+ }
+
+ AdajacentStores.push_back(CurrSI);
+ }
+
+ if (AdajacentStores.size() == 1) {
+ // The outer loop should keep looking from the next store.
+ continue;
+ }
+
+ // Now we have such a group of tainted stores to the same address.
+ DEBUG(dbgs() << "[CompressTaintedStore]\n");
+ DEBUG(dbgs() << "Original BB\n");
+ DEBUG(dbgs() << *BB << '\n');
+ auto* LastSI = AdajacentStores[AdajacentStores.size() - 1];
+ for (unsigned i = 0; i < AdajacentStores.size() - 1; ++i) {
+ auto* SI = AdajacentStores[i];
+
+ // Use the original address for stores before the last one.
+ SI->setOperand(1, UntaintedAddress);
+
+ DEBUG(dbgs() << "Store address has been reversed: " << *SI << '\n';);
+ }
+ // XXX-comment: Try to make the last store use fewer registers.
+ // If LastSI's storing value is a select based on the condition with which
+ // its address is tainted, transform the tainted address to a select
+ // instruction, as follows:
+ // r1 = Select Cond ? A : B
+ // r2 = Cond & 0
+ // r3 = Addr | r2
+ // *r3 = r1
+ // ==>
+ // r1 = Select Cond ? A : B
+ // r2 = Select Cond ? Addr : Addr
+ // *r2 = r1
+ // The idea is that both Select instructions depend on the same condition,
+ // so hopefully the backend can generate two cmov instructions for them (and
+ // this saves the number of registers needed).
+ auto* LastSIDep = getConditionDependence(LastSI->getPointerOperand());
+ auto* LastSIValue = dyn_cast<Instruction>(LastSI->getValueOperand());
+ if (LastSIValue && LastSIValue->getOpcode() == Instruction::Select &&
+ LastSIValue->getOperand(0) == LastSIDep) {
+ // XXX-comment: Maybe it's better for us to just leave it as an and/or
+ // dependence pattern.
+ // /*
+ IRBuilder<true, NoFolder> Builder(LastSI);
+ auto* Address =
+ Builder.CreateSelect(LastSIDep, UntaintedAddress, UntaintedAddress);
+ LastSI->setOperand(1, Address);
+ DEBUG(dbgs() << "The last store becomes :" << *LastSI << "\n\n";);
+ // */
+ }
+ }
+
+ return true;
+}
+
+bool PassDependenceToStore(Value* OldAddress, StoreInst* NewStore) {
+ Value* OldDep = getDependence(OldAddress);
+ // Return false when there's no dependence to pass from the OldAddress.
+ if (!OldDep) {
+ return false;
+ }
+
+ // No need to pass the dependence to NewStore's address if it already depends
+ // on whatever 'OldAddress' depends on.
+ if (StoreAddressDependOnValue(NewStore, OldDep)) {
+ return false;
+ }
+ return taintStoreAddress(NewStore, OldAddress);
+}
+
+SmallSet<Value*, 8> FindDependence(Value* Val) {
+ SmallSet<Value*, 8> DepSet;
+ recursivelyFindDependence(&DepSet, Val, true /*Only insert leaf nodes*/);
+ return DepSet;
+}
+
+bool StoreAddressDependOnValue(StoreInst* SI, Value* DepVal) {
+ return dependenceSetInclusion(SI->getPointerOperand(), DepVal);
+}
+
+bool StoreDependOnValue(StoreInst* SI, Value* Dep) {
+ return dependenceSetInclusion(SI, Dep);
+}
+
+} // namespace
+
+
+
bool CodeGenPrepare::runOnFunction(Function &F) {
+ bool EverMadeChange = false;
+
if (skipOptnoneFunction(F))
return false;
DL = &F.getParent()->getDataLayout();
- bool EverMadeChange = false;
// Clear per function information.
InsertedInsts.clear();
PromotedInsts.clear();
if (!OptSize && TLI && TLI->isSlowDivBypassed()) {
const DenseMap<unsigned int, unsigned int> &BypassWidths =
TLI->getBypassSlowDivWidths();
- for (Function::iterator I = F.begin(); I != F.end(); I++)
- EverMadeChange |= bypassSlowDivision(F, I, BypassWidths);
+ BasicBlock* BB = &*F.begin();
+ while (BB != nullptr) {
+ // bypassSlowDivision may create new BBs, but we don't want to reapply the
+ // optimization to those blocks.
+ BasicBlock* Next = BB->getNextNode();
+ EverMadeChange |= bypassSlowDivision(BB, BypassWidths);
+ BB = Next;
+ }
}
// Eliminate blocks that contain only PHI nodes and an
EverMadeChange |= simplifyOffsetableRelocate(*I);
}
+ // XXX-comment: Delay dealing with relaxed loads in this function to avoid
+ // further changes done by other passes (e.g., SimplifyCFG).
+ // Collect all the relaxed loads.
+ SmallVector<LoadInst*, 1> MonotonicLoadInsts;
+ for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
+ if (I->isAtomic()) {
+ switch (I->getOpcode()) {
+ case Instruction::Load: {
+ auto* LI = dyn_cast<LoadInst>(&*I);
+ if (LI->getOrdering() == Monotonic) {
+ MonotonicLoadInsts.push_back(LI);
+ }
+ break;
+ }
+ default: {
+ break;
+ }
+ }
+ }
+ }
+ EverMadeChange |=
+ AddFakeConditionalBranchAfterMonotonicLoads(MonotonicLoadInsts);
+
return EverMadeChange;
}
// Note that this intentionally skips the entry block.
for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {
BasicBlock *BB = &*I++;
-
// If this block doesn't end with an uncond branch, ignore it.
BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
if (!BI || !BI->isUnconditional())
// Computes a map of base pointer relocation instructions to corresponding
// derived pointer relocation instructions given a vector of all relocate calls
static void computeBaseDerivedRelocateMap(
- const SmallVectorImpl<User *> &AllRelocateCalls,
- DenseMap<IntrinsicInst *, SmallVector<IntrinsicInst *, 2>> &
- RelocateInstMap) {
+ const SmallVectorImpl<GCRelocateInst *> &AllRelocateCalls,
+ DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>>
+ &RelocateInstMap) {
// Collect information in two maps: one primarily for locating the base object
// while filling the second map; the second map is the final structure holding
// a mapping between Base and corresponding Derived relocate calls
- DenseMap<std::pair<unsigned, unsigned>, IntrinsicInst *> RelocateIdxMap;
- for (auto &U : AllRelocateCalls) {
- GCRelocateOperands ThisRelocate(U);
- IntrinsicInst *I = cast<IntrinsicInst>(U);
- auto K = std::make_pair(ThisRelocate.getBasePtrIndex(),
- ThisRelocate.getDerivedPtrIndex());
- RelocateIdxMap.insert(std::make_pair(K, I));
+ DenseMap<std::pair<unsigned, unsigned>, GCRelocateInst *> RelocateIdxMap;
+ for (auto *ThisRelocate : AllRelocateCalls) {
+ auto K = std::make_pair(ThisRelocate->getBasePtrIndex(),
+ ThisRelocate->getDerivedPtrIndex());
+ RelocateIdxMap.insert(std::make_pair(K, ThisRelocate));
}
for (auto &Item : RelocateIdxMap) {
std::pair<unsigned, unsigned> Key = Item.first;
// Base relocation: nothing to insert
continue;
- IntrinsicInst *I = Item.second;
+ GCRelocateInst *I = Item.second;
auto BaseKey = std::make_pair(Key.first, Key.first);
// We're iterating over RelocateIdxMap so we cannot modify it.
// Takes a RelocatedBase (base pointer relocation instruction) and Targets to
// replace, computes a replacement, and affects it.
static bool
-simplifyRelocatesOffABase(IntrinsicInst *RelocatedBase,
- const SmallVectorImpl<IntrinsicInst *> &Targets) {
+simplifyRelocatesOffABase(GCRelocateInst *RelocatedBase,
+ const SmallVectorImpl<GCRelocateInst *> &Targets) {
bool MadeChange = false;
- for (auto &ToReplace : Targets) {
- GCRelocateOperands MasterRelocate(RelocatedBase);
- GCRelocateOperands ThisRelocate(ToReplace);
-
- assert(ThisRelocate.getBasePtrIndex() == MasterRelocate.getBasePtrIndex() &&
+ for (GCRelocateInst *ToReplace : Targets) {
+ assert(ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() &&
"Not relocating a derived object of the original base object");
- if (ThisRelocate.getBasePtrIndex() == ThisRelocate.getDerivedPtrIndex()) {
+ if (ToReplace->getBasePtrIndex() == ToReplace->getDerivedPtrIndex()) {
// A duplicate relocate call. TODO: coalesce duplicates.
continue;
}
- Value *Base = ThisRelocate.getBasePtr();
- auto Derived = dyn_cast<GetElementPtrInst>(ThisRelocate.getDerivedPtr());
+ if (RelocatedBase->getParent() != ToReplace->getParent()) {
+ // Base and derived relocates are in different basic blocks.
+ // In this case transform is only valid when base dominates derived
+ // relocate. However it would be too expensive to check dominance
+ // for each such relocate, so we skip the whole transformation.
+ continue;
+ }
+
+ Value *Base = ToReplace->getBasePtr();
+ auto Derived = dyn_cast<GetElementPtrInst>(ToReplace->getDerivedPtr());
if (!Derived || Derived->getPointerOperand() != Base)
continue;
// In this case, we can not find the bitcast any more. So we insert a new bitcast
// no matter there is already one or not. In this way, we can handle all cases, and
// the extra bitcast should be optimized away in later passes.
- Instruction *ActualRelocatedBase = RelocatedBase;
+ Value *ActualRelocatedBase = RelocatedBase;
if (RelocatedBase->getType() != Base->getType()) {
ActualRelocatedBase =
- cast<Instruction>(Builder.CreateBitCast(RelocatedBase, Base->getType()));
+ Builder.CreateBitCast(RelocatedBase, Base->getType());
}
Value *Replacement = Builder.CreateGEP(
Derived->getSourceElementType(), ActualRelocatedBase, makeArrayRef(OffsetV));
- Instruction *ReplacementInst = cast<Instruction>(Replacement);
Replacement->takeName(ToReplace);
// If the newly generated derived pointer's type does not match the original derived
// pointer's type, cast the new derived pointer to match it. Same reasoning as above.
- Instruction *ActualReplacement = ReplacementInst;
- if (ReplacementInst->getType() != ToReplace->getType()) {
+ Value *ActualReplacement = Replacement;
+ if (Replacement->getType() != ToReplace->getType()) {
ActualReplacement =
- cast<Instruction>(Builder.CreateBitCast(ReplacementInst, ToReplace->getType()));
+ Builder.CreateBitCast(Replacement, ToReplace->getType());
}
ToReplace->replaceAllUsesWith(ActualReplacement);
ToReplace->eraseFromParent();
// %val = load %ptr'
bool CodeGenPrepare::simplifyOffsetableRelocate(Instruction &I) {
bool MadeChange = false;
- SmallVector<User *, 2> AllRelocateCalls;
+ SmallVector<GCRelocateInst *, 2> AllRelocateCalls;
for (auto *U : I.users())
- if (isGCRelocate(dyn_cast<Instruction>(U)))
+ if (GCRelocateInst *Relocate = dyn_cast<GCRelocateInst>(U))
// Collect all the relocate calls associated with a statepoint
- AllRelocateCalls.push_back(U);
+ AllRelocateCalls.push_back(Relocate);
// We need atleast one base pointer relocation + one derived pointer
// relocation to mangle
// RelocateInstMap is a mapping from the base relocate instruction to the
// corresponding derived relocate instructions
- DenseMap<IntrinsicInst *, SmallVector<IntrinsicInst *, 2>> RelocateInstMap;
+ DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>> RelocateInstMap;
computeBaseDerivedRelocateMap(AllRelocateCalls, RelocateInstMap);
if (RelocateInstMap.empty())
return false;
// Preincrement use iterator so we don't invalidate it.
++UI;
+ // If the block selected to receive the cast is an EH pad that does not
+ // allow non-PHI instructions before the terminator, we can't sink the
+ // cast.
+ if (UserBB->getTerminator()->isEHPad())
+ continue;
+
// If this user is in the same block as the cast, don't change the cast.
if (UserBB == DefBB) continue;
assert(*AddI->user_begin() == CI && "expected!");
#endif
- Module *M = CI->getParent()->getParent()->getParent();
+ Module *M = CI->getModule();
Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, Ty);
auto *InsertPt = AddI->hasOneUse() ? CI : AddI;
// <16 x i1> %mask, <16 x i32> %passthru)
// to a chain of basic blocks, with loading element one-by-one if
// the appropriate mask bit is set
-//
+//
// %1 = bitcast i8* %addr to i32*
// %2 = extractelement <16 x i1> %mask, i32 0
// %3 = icmp eq i1 %2, true
//
static void ScalarizeMaskedLoad(CallInst *CI) {
Value *Ptr = CI->getArgOperand(0);
- Value *Src0 = CI->getArgOperand(3);
+ Value *Alignment = CI->getArgOperand(1);
Value *Mask = CI->getArgOperand(2);
- VectorType *VecType = dyn_cast<VectorType>(CI->getType());
- Type *EltTy = VecType->getElementType();
+ Value *Src0 = CI->getArgOperand(3);
+ unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
+ VectorType *VecType = dyn_cast<VectorType>(CI->getType());
assert(VecType && "Unexpected return type of masked load intrinsic");
+ Type *EltTy = CI->getType()->getVectorElementType();
+
IRBuilder<> Builder(CI->getContext());
Instruction *InsertPt = CI;
BasicBlock *IfBlock = CI->getParent();
BasicBlock *CondBlock = nullptr;
BasicBlock *PrevIfBlock = CI->getParent();
- Builder.SetInsertPoint(InsertPt);
+ Builder.SetInsertPoint(InsertPt);
Builder.SetCurrentDebugLocation(CI->getDebugLoc());
+ // Short-cut if the mask is all-true.
+ bool IsAllOnesMask = isa<Constant>(Mask) &&
+ cast<Constant>(Mask)->isAllOnesValue();
+
+ if (IsAllOnesMask) {
+ Value *NewI = Builder.CreateAlignedLoad(Ptr, AlignVal);
+ CI->replaceAllUsesWith(NewI);
+ CI->eraseFromParent();
+ return;
+ }
+
+ // Adjust alignment for the scalar instruction.
+ AlignVal = std::min(AlignVal, VecType->getScalarSizeInBits()/8);
// Bitcast %addr fron i8* to EltTy*
Type *NewPtrType =
EltTy->getPointerTo(cast<PointerType>(Ptr->getType())->getAddressSpace());
Value *FirstEltPtr = Builder.CreateBitCast(Ptr, NewPtrType);
+ unsigned VectorWidth = VecType->getNumElements();
+
Value *UndefVal = UndefValue::get(VecType);
// The result vector
Value *VResult = UndefVal;
+ if (isa<ConstantVector>(Mask)) {
+ for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
+ if (cast<ConstantVector>(Mask)->getOperand(Idx)->isNullValue())
+ continue;
+ Value *Gep =
+ Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
+ LoadInst* Load = Builder.CreateAlignedLoad(Gep, AlignVal);
+ VResult = Builder.CreateInsertElement(VResult, Load,
+ Builder.getInt32(Idx));
+ }
+ Value *NewI = Builder.CreateSelect(Mask, VResult, Src0);
+ CI->replaceAllUsesWith(NewI);
+ CI->eraseFromParent();
+ return;
+ }
+
PHINode *Phi = nullptr;
Value *PrevPhi = UndefVal;
- unsigned VectorWidth = VecType->getNumElements();
for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
// Fill the "else" block, created in the previous iteration
Value *Gep =
Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
- LoadInst* Load = Builder.CreateLoad(Gep, false);
+ LoadInst *Load = Builder.CreateAlignedLoad(Gep, AlignVal);
VResult = Builder.CreateInsertElement(VResult, Load, Builder.getInt32(Idx));
// Create "else" block, fill it in the next iteration
// %5 = getelementptr i32* %1, i32 0
// store i32 %4, i32* %5
// br label %else
-//
+//
// else: ; preds = %0, %cond.store
// %6 = extractelement <16 x i1> %mask, i32 1
// %7 = icmp eq i1 %6, true
// br i1 %7, label %cond.store1, label %else2
-//
+//
// cond.store1: ; preds = %else
// %8 = extractelement <16 x i32> %val, i32 1
// %9 = getelementptr i32* %1, i32 1
// br label %else2
// . . .
static void ScalarizeMaskedStore(CallInst *CI) {
- Value *Ptr = CI->getArgOperand(1);
Value *Src = CI->getArgOperand(0);
+ Value *Ptr = CI->getArgOperand(1);
+ Value *Alignment = CI->getArgOperand(2);
Value *Mask = CI->getArgOperand(3);
+ unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
VectorType *VecType = dyn_cast<VectorType>(Src->getType());
- Type *EltTy = VecType->getElementType();
-
assert(VecType && "Unexpected data type in masked store intrinsic");
+ Type *EltTy = VecType->getElementType();
+
IRBuilder<> Builder(CI->getContext());
Instruction *InsertPt = CI;
BasicBlock *IfBlock = CI->getParent();
Builder.SetInsertPoint(InsertPt);
Builder.SetCurrentDebugLocation(CI->getDebugLoc());
+ // Short-cut if the mask is all-true.
+ bool IsAllOnesMask = isa<Constant>(Mask) &&
+ cast<Constant>(Mask)->isAllOnesValue();
+
+ if (IsAllOnesMask) {
+ Builder.CreateAlignedStore(Src, Ptr, AlignVal);
+ CI->eraseFromParent();
+ return;
+ }
+
+ // Adjust alignment for the scalar instruction.
+ AlignVal = std::max(AlignVal, VecType->getScalarSizeInBits()/8);
// Bitcast %addr fron i8* to EltTy*
Type *NewPtrType =
EltTy->getPointerTo(cast<PointerType>(Ptr->getType())->getAddressSpace());
Value *FirstEltPtr = Builder.CreateBitCast(Ptr, NewPtrType);
-
unsigned VectorWidth = VecType->getNumElements();
+
+ if (isa<ConstantVector>(Mask)) {
+ for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
+ if (cast<ConstantVector>(Mask)->getOperand(Idx)->isNullValue())
+ continue;
+ Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx));
+ Value *Gep =
+ Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
+ Builder.CreateAlignedStore(OneElt, Gep, AlignVal);
+ }
+ CI->eraseFromParent();
+ return;
+ }
+
for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
// Fill the "else" block, created in the previous iteration
//
// %mask_1 = extractelement <16 x i1> %mask, i32 Idx
// %to_store = icmp eq i1 %mask_1, true
- // br i1 %to_load, label %cond.store, label %else
+ // br i1 %to_store, label %cond.store, label %else
//
Value *Predicate = Builder.CreateExtractElement(Mask, Builder.getInt32(Idx));
Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate,
Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx));
Value *Gep =
Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
- Builder.CreateStore(OneElt, Gep);
+ Builder.CreateAlignedStore(OneElt, Gep, AlignVal);
// Create "else" block, fill it in the next iteration
BasicBlock *NewIfBlock =
CI->eraseFromParent();
}
+// Translate a masked gather intrinsic like
+// <16 x i32 > @llvm.masked.gather.v16i32( <16 x i32*> %Ptrs, i32 4,
+// <16 x i1> %Mask, <16 x i32> %Src)
+// to a chain of basic blocks, with loading element one-by-one if
+// the appropriate mask bit is set
+//
+// % Ptrs = getelementptr i32, i32* %base, <16 x i64> %ind
+// % Mask0 = extractelement <16 x i1> %Mask, i32 0
+// % ToLoad0 = icmp eq i1 % Mask0, true
+// br i1 % ToLoad0, label %cond.load, label %else
+//
+// cond.load:
+// % Ptr0 = extractelement <16 x i32*> %Ptrs, i32 0
+// % Load0 = load i32, i32* % Ptr0, align 4
+// % Res0 = insertelement <16 x i32> undef, i32 % Load0, i32 0
+// br label %else
+//
+// else:
+// %res.phi.else = phi <16 x i32>[% Res0, %cond.load], [undef, % 0]
+// % Mask1 = extractelement <16 x i1> %Mask, i32 1
+// % ToLoad1 = icmp eq i1 % Mask1, true
+// br i1 % ToLoad1, label %cond.load1, label %else2
+//
+// cond.load1:
+// % Ptr1 = extractelement <16 x i32*> %Ptrs, i32 1
+// % Load1 = load i32, i32* % Ptr1, align 4
+// % Res1 = insertelement <16 x i32> %res.phi.else, i32 % Load1, i32 1
+// br label %else2
+// . . .
+// % Result = select <16 x i1> %Mask, <16 x i32> %res.phi.select, <16 x i32> %Src
+// ret <16 x i32> %Result
+static void ScalarizeMaskedGather(CallInst *CI) {
+ Value *Ptrs = CI->getArgOperand(0);
+ Value *Alignment = CI->getArgOperand(1);
+ Value *Mask = CI->getArgOperand(2);
+ Value *Src0 = CI->getArgOperand(3);
+
+ VectorType *VecType = dyn_cast<VectorType>(CI->getType());
+
+ assert(VecType && "Unexpected return type of masked load intrinsic");
+
+ IRBuilder<> Builder(CI->getContext());
+ Instruction *InsertPt = CI;
+ BasicBlock *IfBlock = CI->getParent();
+ BasicBlock *CondBlock = nullptr;
+ BasicBlock *PrevIfBlock = CI->getParent();
+ Builder.SetInsertPoint(InsertPt);
+ unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
+
+ Builder.SetCurrentDebugLocation(CI->getDebugLoc());
+
+ Value *UndefVal = UndefValue::get(VecType);
+
+ // The result vector
+ Value *VResult = UndefVal;
+ unsigned VectorWidth = VecType->getNumElements();
+
+ // Shorten the way if the mask is a vector of constants.
+ bool IsConstMask = isa<ConstantVector>(Mask);
+
+ if (IsConstMask) {
+ for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
+ if (cast<ConstantVector>(Mask)->getOperand(Idx)->isNullValue())
+ continue;
+ Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
+ "Ptr" + Twine(Idx));
+ LoadInst *Load = Builder.CreateAlignedLoad(Ptr, AlignVal,
+ "Load" + Twine(Idx));
+ VResult = Builder.CreateInsertElement(VResult, Load,
+ Builder.getInt32(Idx),
+ "Res" + Twine(Idx));
+ }
+ Value *NewI = Builder.CreateSelect(Mask, VResult, Src0);
+ CI->replaceAllUsesWith(NewI);
+ CI->eraseFromParent();
+ return;
+ }
+
+ PHINode *Phi = nullptr;
+ Value *PrevPhi = UndefVal;
+
+ for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
+
+ // Fill the "else" block, created in the previous iteration
+ //
+ // %Mask1 = extractelement <16 x i1> %Mask, i32 1
+ // %ToLoad1 = icmp eq i1 %Mask1, true
+ // br i1 %ToLoad1, label %cond.load, label %else
+ //
+ if (Idx > 0) {
+ Phi = Builder.CreatePHI(VecType, 2, "res.phi.else");
+ Phi->addIncoming(VResult, CondBlock);
+ Phi->addIncoming(PrevPhi, PrevIfBlock);
+ PrevPhi = Phi;
+ VResult = Phi;
+ }
+
+ Value *Predicate = Builder.CreateExtractElement(Mask,
+ Builder.getInt32(Idx),
+ "Mask" + Twine(Idx));
+ Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate,
+ ConstantInt::get(Predicate->getType(), 1),
+ "ToLoad" + Twine(Idx));
+
+ // Create "cond" block
+ //
+ // %EltAddr = getelementptr i32* %1, i32 0
+ // %Elt = load i32* %EltAddr
+ // VResult = insertelement <16 x i32> VResult, i32 %Elt, i32 Idx
+ //
+ CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.load");
+ Builder.SetInsertPoint(InsertPt);
+
+ Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
+ "Ptr" + Twine(Idx));
+ LoadInst *Load = Builder.CreateAlignedLoad(Ptr, AlignVal,
+ "Load" + Twine(Idx));
+ VResult = Builder.CreateInsertElement(VResult, Load, Builder.getInt32(Idx),
+ "Res" + Twine(Idx));
+
+ // Create "else" block, fill it in the next iteration
+ BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else");
+ Builder.SetInsertPoint(InsertPt);
+ Instruction *OldBr = IfBlock->getTerminator();
+ BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr);
+ OldBr->eraseFromParent();
+ PrevIfBlock = IfBlock;
+ IfBlock = NewIfBlock;
+ }
+
+ Phi = Builder.CreatePHI(VecType, 2, "res.phi.select");
+ Phi->addIncoming(VResult, CondBlock);
+ Phi->addIncoming(PrevPhi, PrevIfBlock);
+ Value *NewI = Builder.CreateSelect(Mask, Phi, Src0);
+ CI->replaceAllUsesWith(NewI);
+ CI->eraseFromParent();
+}
+
+// Translate a masked scatter intrinsic, like
+// void @llvm.masked.scatter.v16i32(<16 x i32> %Src, <16 x i32*>* %Ptrs, i32 4,
+// <16 x i1> %Mask)
+// to a chain of basic blocks, that stores element one-by-one if
+// the appropriate mask bit is set.
+//
+// % Ptrs = getelementptr i32, i32* %ptr, <16 x i64> %ind
+// % Mask0 = extractelement <16 x i1> % Mask, i32 0
+// % ToStore0 = icmp eq i1 % Mask0, true
+// br i1 %ToStore0, label %cond.store, label %else
+//
+// cond.store:
+// % Elt0 = extractelement <16 x i32> %Src, i32 0
+// % Ptr0 = extractelement <16 x i32*> %Ptrs, i32 0
+// store i32 %Elt0, i32* % Ptr0, align 4
+// br label %else
+//
+// else:
+// % Mask1 = extractelement <16 x i1> % Mask, i32 1
+// % ToStore1 = icmp eq i1 % Mask1, true
+// br i1 % ToStore1, label %cond.store1, label %else2
+//
+// cond.store1:
+// % Elt1 = extractelement <16 x i32> %Src, i32 1
+// % Ptr1 = extractelement <16 x i32*> %Ptrs, i32 1
+// store i32 % Elt1, i32* % Ptr1, align 4
+// br label %else2
+// . . .
+static void ScalarizeMaskedScatter(CallInst *CI) {
+ Value *Src = CI->getArgOperand(0);
+ Value *Ptrs = CI->getArgOperand(1);
+ Value *Alignment = CI->getArgOperand(2);
+ Value *Mask = CI->getArgOperand(3);
+
+ assert(isa<VectorType>(Src->getType()) &&
+ "Unexpected data type in masked scatter intrinsic");
+ assert(isa<VectorType>(Ptrs->getType()) &&
+ isa<PointerType>(Ptrs->getType()->getVectorElementType()) &&
+ "Vector of pointers is expected in masked scatter intrinsic");
+
+ IRBuilder<> Builder(CI->getContext());
+ Instruction *InsertPt = CI;
+ BasicBlock *IfBlock = CI->getParent();
+ Builder.SetInsertPoint(InsertPt);
+ Builder.SetCurrentDebugLocation(CI->getDebugLoc());
+
+ unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
+ unsigned VectorWidth = Src->getType()->getVectorNumElements();
+
+ // Shorten the way if the mask is a vector of constants.
+ bool IsConstMask = isa<ConstantVector>(Mask);
+
+ if (IsConstMask) {
+ for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
+ if (cast<ConstantVector>(Mask)->getOperand(Idx)->isNullValue())
+ continue;
+ Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx),
+ "Elt" + Twine(Idx));
+ Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
+ "Ptr" + Twine(Idx));
+ Builder.CreateAlignedStore(OneElt, Ptr, AlignVal);
+ }
+ CI->eraseFromParent();
+ return;
+ }
+ for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
+ // Fill the "else" block, created in the previous iteration
+ //
+ // % Mask1 = extractelement <16 x i1> % Mask, i32 Idx
+ // % ToStore = icmp eq i1 % Mask1, true
+ // br i1 % ToStore, label %cond.store, label %else
+ //
+ Value *Predicate = Builder.CreateExtractElement(Mask,
+ Builder.getInt32(Idx),
+ "Mask" + Twine(Idx));
+ Value *Cmp =
+ Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate,
+ ConstantInt::get(Predicate->getType(), 1),
+ "ToStore" + Twine(Idx));
+
+ // Create "cond" block
+ //
+ // % Elt1 = extractelement <16 x i32> %Src, i32 1
+ // % Ptr1 = extractelement <16 x i32*> %Ptrs, i32 1
+ // %store i32 % Elt1, i32* % Ptr1
+ //
+ BasicBlock *CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.store");
+ Builder.SetInsertPoint(InsertPt);
+
+ Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx),
+ "Elt" + Twine(Idx));
+ Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
+ "Ptr" + Twine(Idx));
+ Builder.CreateAlignedStore(OneElt, Ptr, AlignVal);
+
+ // Create "else" block, fill it in the next iteration
+ BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else");
+ Builder.SetInsertPoint(InsertPt);
+ Instruction *OldBr = IfBlock->getTerminator();
+ BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr);
+ OldBr->eraseFromParent();
+ IfBlock = NewIfBlock;
+ }
+ CI->eraseFromParent();
+}
+
+/// If counting leading or trailing zeros is an expensive operation and a zero
+/// input is defined, add a check for zero to avoid calling the intrinsic.
+///
+/// We want to transform:
+/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 false)
+///
+/// into:
+/// entry:
+/// %cmpz = icmp eq i64 %A, 0
+/// br i1 %cmpz, label %cond.end, label %cond.false
+/// cond.false:
+/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 true)
+/// br label %cond.end
+/// cond.end:
+/// %ctz = phi i64 [ 64, %entry ], [ %z, %cond.false ]
+///
+/// If the transform is performed, return true and set ModifiedDT to true.
+static bool despeculateCountZeros(IntrinsicInst *CountZeros,
+ const TargetLowering *TLI,
+ const DataLayout *DL,
+ bool &ModifiedDT) {
+ if (!TLI || !DL)
+ return false;
+
+ // If a zero input is undefined, it doesn't make sense to despeculate that.
+ if (match(CountZeros->getOperand(1), m_One()))
+ return false;
+
+ // If it's cheap to speculate, there's nothing to do.
+ auto IntrinsicID = CountZeros->getIntrinsicID();
+ if ((IntrinsicID == Intrinsic::cttz && TLI->isCheapToSpeculateCttz()) ||
+ (IntrinsicID == Intrinsic::ctlz && TLI->isCheapToSpeculateCtlz()))
+ return false;
+
+ // Only handle legal scalar cases. Anything else requires too much work.
+ Type *Ty = CountZeros->getType();
+ unsigned SizeInBits = Ty->getPrimitiveSizeInBits();
+ if (Ty->isVectorTy() || SizeInBits > DL->getLargestLegalIntTypeSize())
+ return false;
+
+ // The intrinsic will be sunk behind a compare against zero and branch.
+ BasicBlock *StartBlock = CountZeros->getParent();
+ BasicBlock *CallBlock = StartBlock->splitBasicBlock(CountZeros, "cond.false");
+
+ // Create another block after the count zero intrinsic. A PHI will be added
+ // in this block to select the result of the intrinsic or the bit-width
+ // constant if the input to the intrinsic is zero.
+ BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(CountZeros));
+ BasicBlock *EndBlock = CallBlock->splitBasicBlock(SplitPt, "cond.end");
+
+ // Set up a builder to create a compare, conditional branch, and PHI.
+ IRBuilder<> Builder(CountZeros->getContext());
+ Builder.SetInsertPoint(StartBlock->getTerminator());
+ Builder.SetCurrentDebugLocation(CountZeros->getDebugLoc());
+
+ // Replace the unconditional branch that was created by the first split with
+ // a compare against zero and a conditional branch.
+ Value *Zero = Constant::getNullValue(Ty);
+ Value *Cmp = Builder.CreateICmpEQ(CountZeros->getOperand(0), Zero, "cmpz");
+ Builder.CreateCondBr(Cmp, EndBlock, CallBlock);
+ StartBlock->getTerminator()->eraseFromParent();
+
+ // Create a PHI in the end block to select either the output of the intrinsic
+ // or the bit width of the operand.
+ Builder.SetInsertPoint(&EndBlock->front());
+ PHINode *PN = Builder.CreatePHI(Ty, 2, "ctz");
+ CountZeros->replaceAllUsesWith(PN);
+ Value *BitWidth = Builder.getInt(APInt(SizeInBits, SizeInBits));
+ PN->addIncoming(BitWidth, StartBlock);
+ PN->addIncoming(CountZeros, CallBlock);
+
+ // We are explicitly handling the zero case, so we can set the intrinsic's
+ // undefined zero argument to 'true'. This will also prevent reprocessing the
+ // intrinsic; we only despeculate when a zero input is defined.
+ CountZeros->setArgOperand(1, Builder.getTrue());
+ ModifiedDT = true;
+ return true;
+}
+
bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool& ModifiedDT) {
BasicBlock *BB = CI->getParent();
// over-aligning global variables that have an explicit section is
// forbidden.
GlobalVariable *GV;
- if ((GV = dyn_cast<GlobalVariable>(Val)) && GV->hasUniqueInitializer() &&
- !GV->hasSection() && GV->getAlignment() < PrefAlign &&
+ if ((GV = dyn_cast<GlobalVariable>(Val)) && GV->canIncreaseAlignment() &&
+ GV->getAlignment() < PrefAlign &&
DL->getTypeAllocSize(GV->getType()->getElementType()) >=
MinSize + Offset2)
GV->setAlignment(PrefAlign);
}
case Intrinsic::masked_load: {
// Scalarize unsupported vector masked load
- if (!TTI->isLegalMaskedLoad(CI->getType(), 1)) {
+ if (!TTI->isLegalMaskedLoad(CI->getType())) {
ScalarizeMaskedLoad(CI);
ModifiedDT = true;
return true;
return false;
}
case Intrinsic::masked_store: {
- if (!TTI->isLegalMaskedStore(CI->getArgOperand(0)->getType(), 1)) {
+ if (!TTI->isLegalMaskedStore(CI->getArgOperand(0)->getType())) {
ScalarizeMaskedStore(CI);
ModifiedDT = true;
return true;
}
return false;
}
+ case Intrinsic::masked_gather: {
+ if (!TTI->isLegalMaskedGather(CI->getType())) {
+ ScalarizeMaskedGather(CI);
+ ModifiedDT = true;
+ return true;
+ }
+ return false;
+ }
+ case Intrinsic::masked_scatter: {
+ if (!TTI->isLegalMaskedScatter(CI->getArgOperand(0)->getType())) {
+ ScalarizeMaskedScatter(CI);
+ ModifiedDT = true;
+ return true;
+ }
+ return false;
+ }
case Intrinsic::aarch64_stlxr:
case Intrinsic::aarch64_stxr: {
ZExtInst *ExtVal = dyn_cast<ZExtInst>(CI->getArgOperand(0));
II->replaceAllUsesWith(II->getArgOperand(0));
II->eraseFromParent();
return true;
+
+ case Intrinsic::cttz:
+ case Intrinsic::ctlz:
+ // If counting zeros is expensive, try to avoid it.
+ return despeculateCountZeros(II, TLI, DL, ModifiedDT);
}
if (TLI) {
/// \brief Utility function to determine if \p OpIdx should be promoted when
/// promoting \p Inst.
static bool shouldExtOperand(const Instruction *Inst, int OpIdx) {
- if (isa<SelectInst>(Inst) && OpIdx == 0)
- return false;
- return true;
+ return !(isa<SelectInst>(Inst) && OpIdx == 0);
}
/// \brief Utility function to promote the operand of \p Ext when this
return false;
// #2 check that the truncate just drops extended bits.
- if (Inst->getType()->getIntegerBitWidth() >= OpndType->getIntegerBitWidth())
- return true;
-
- return false;
+ return Inst->getType()->getIntegerBitWidth() >=
+ OpndType->getIntegerBitWidth();
}
TypePromotionHelper::Action TypePromotionHelper::getAction(
return MadeChange;
}
+// Find loads whose uses only use some of the loaded value's bits. Add an "and"
+// just after the load if the target can fold this into one extload instruction,
+// with the hope of eliminating some of the other later "and" instructions using
+// the loaded value. "and"s that are made trivially redundant by the insertion
+// of the new "and" are removed by this function, while others (e.g. those whose
+// path from the load goes through a phi) are left for isel to potentially
+// remove.
+//
+// For example:
+//
+// b0:
+// x = load i32
+// ...
+// b1:
+// y = and x, 0xff
+// z = use y
+//
+// becomes:
+//
+// b0:
+// x = load i32
+// x' = and x, 0xff
+// ...
+// b1:
+// z = use x'
+//
+// whereas:
+//
+// b0:
+// x1 = load i32
+// ...
+// b1:
+// x2 = load i32
+// ...
+// b2:
+// x = phi x1, x2
+// y = and x, 0xff
+//
+// becomes (after a call to optimizeLoadExt for each load):
+//
+// b0:
+// x1 = load i32
+// x1' = and x1, 0xff
+// ...
+// b1:
+// x2 = load i32
+// x2' = and x2, 0xff
+// ...
+// b2:
+// x = phi x1', x2'
+// y = and x, 0xff
+//
+
+bool CodeGenPrepare::optimizeLoadExt(LoadInst *Load) {
+
+ if (!Load->isSimple() ||
+ !(Load->getType()->isIntegerTy() || Load->getType()->isPointerTy()))
+ return false;
+
+ // Skip loads we've already transformed or have no reason to transform.
+ if (Load->hasOneUse()) {
+ User *LoadUser = *Load->user_begin();
+ if (cast<Instruction>(LoadUser)->getParent() == Load->getParent() &&
+ !dyn_cast<PHINode>(LoadUser))
+ return false;
+ }
+
+ // Look at all uses of Load, looking through phis, to determine how many bits
+ // of the loaded value are needed.
+ SmallVector<Instruction *, 8> WorkList;
+ SmallPtrSet<Instruction *, 16> Visited;
+ SmallVector<Instruction *, 8> AndsToMaybeRemove;
+ for (auto *U : Load->users())
+ WorkList.push_back(cast<Instruction>(U));
+
+ EVT LoadResultVT = TLI->getValueType(*DL, Load->getType());
+ unsigned BitWidth = LoadResultVT.getSizeInBits();
+ APInt DemandBits(BitWidth, 0);
+ APInt WidestAndBits(BitWidth, 0);
+
+ while (!WorkList.empty()) {
+ Instruction *I = WorkList.back();
+ WorkList.pop_back();
+
+ // Break use-def graph loops.
+ if (!Visited.insert(I).second)
+ continue;
+
+ // For a PHI node, push all of its users.
+ if (auto *Phi = dyn_cast<PHINode>(I)) {
+ for (auto *U : Phi->users())
+ WorkList.push_back(cast<Instruction>(U));
+ continue;
+ }
+
+ switch (I->getOpcode()) {
+ case llvm::Instruction::And: {
+ auto *AndC = dyn_cast<ConstantInt>(I->getOperand(1));
+ if (!AndC)
+ return false;
+ APInt AndBits = AndC->getValue();
+ DemandBits |= AndBits;
+ // Keep track of the widest and mask we see.
+ if (AndBits.ugt(WidestAndBits))
+ WidestAndBits = AndBits;
+ if (AndBits == WidestAndBits && I->getOperand(0) == Load)
+ AndsToMaybeRemove.push_back(I);
+ break;
+ }
+
+ case llvm::Instruction::Shl: {
+ auto *ShlC = dyn_cast<ConstantInt>(I->getOperand(1));
+ if (!ShlC)
+ return false;
+ uint64_t ShiftAmt = ShlC->getLimitedValue(BitWidth - 1);
+ auto ShlDemandBits = APInt::getAllOnesValue(BitWidth).lshr(ShiftAmt);
+ DemandBits |= ShlDemandBits;
+ break;
+ }
+
+ case llvm::Instruction::Trunc: {
+ EVT TruncVT = TLI->getValueType(*DL, I->getType());
+ unsigned TruncBitWidth = TruncVT.getSizeInBits();
+ auto TruncBits = APInt::getAllOnesValue(TruncBitWidth).zext(BitWidth);
+ DemandBits |= TruncBits;
+ break;
+ }
+
+ default:
+ return false;
+ }
+ }
+
+ uint32_t ActiveBits = DemandBits.getActiveBits();
+ // Avoid hoisting (and (load x) 1) since it is unlikely to be folded by the
+ // target even if isLoadExtLegal says an i1 EXTLOAD is valid. For example,
+ // for the AArch64 target isLoadExtLegal(ZEXTLOAD, i32, i1) returns true, but
+ // (and (load x) 1) is not matched as a single instruction, rather as a LDR
+ // followed by an AND.
+ // TODO: Look into removing this restriction by fixing backends to either
+ // return false for isLoadExtLegal for i1 or have them select this pattern to
+ // a single instruction.
+ //
+ // Also avoid hoisting if we didn't see any ands with the exact DemandBits
+ // mask, since these are the only ands that will be removed by isel.
+ if (ActiveBits <= 1 || !APIntOps::isMask(ActiveBits, DemandBits) ||
+ WidestAndBits != DemandBits)
+ return false;
+
+ LLVMContext &Ctx = Load->getType()->getContext();
+ Type *TruncTy = Type::getIntNTy(Ctx, ActiveBits);
+ EVT TruncVT = TLI->getValueType(*DL, TruncTy);
+
+ // Reject cases that won't be matched as extloads.
+ if (!LoadResultVT.bitsGT(TruncVT) || !TruncVT.isRound() ||
+ !TLI->isLoadExtLegal(ISD::ZEXTLOAD, LoadResultVT, TruncVT))
+ return false;
+
+ IRBuilder<> Builder(Load->getNextNode());
+ auto *NewAnd = dyn_cast<Instruction>(
+ Builder.CreateAnd(Load, ConstantInt::get(Ctx, DemandBits)));
+
+ // Replace all uses of load with new and (except for the use of load in the
+ // new and itself).
+ Load->replaceAllUsesWith(NewAnd);
+ NewAnd->setOperand(0, Load);
+
+ // Remove any and instructions that are now redundant.
+ for (auto *And : AndsToMaybeRemove)
+ // Check that the and mask is the same as the one we decided to put on the
+ // new and.
+ if (cast<ConstantInt>(And->getOperand(1))->getValue() == DemandBits) {
+ And->replaceAllUsesWith(NewAnd);
+ if (&*CurInstIterator == And)
+ CurInstIterator = std::next(And->getIterator());
+ And->eraseFromParent();
+ ++NumAndUses;
+ }
+
+ ++NumAndsAdded;
+ return true;
+}
+
/// Check if V (an operand of a select instruction) is an expensive instruction
/// that is only used once.
static bool sinkSelectOperand(const TargetTransformInfo *TTI, Value *V) {
auto *I = dyn_cast<Instruction>(V);
- if (I && I->hasOneUse() &&
- TTI->getUserCost(I) == TargetTransformInfo::TCC_Expensive)
- return true;
-
- return false;
+ // If it's safe to speculatively execute, then it should not have side
+ // effects; therefore, it's safe to sink and possibly *not* execute.
+ return I && I->hasOneUse() && isSafeToSpeculativelyExecute(I) &&
+ TTI->getUserCost(I) >= TargetTransformInfo::TCC_Expensive;
}
/// Returns true if a SelectInst should be turned into an explicit branch.
return MadeChange;
}
+bool CodeGenPrepare::optimizeSwitchInst(SwitchInst *SI) {
+ if (!TLI || !DL)
+ return false;
+
+ Value *Cond = SI->getCondition();
+ Type *OldType = Cond->getType();
+ LLVMContext &Context = Cond->getContext();
+ MVT RegType = TLI->getRegisterType(Context, TLI->getValueType(*DL, OldType));
+ unsigned RegWidth = RegType.getSizeInBits();
+
+ if (RegWidth <= cast<IntegerType>(OldType)->getBitWidth())
+ return false;
+
+ // If the register width is greater than the type width, expand the condition
+ // of the switch instruction and each case constant to the width of the
+ // register. By widening the type of the switch condition, subsequent
+ // comparisons (for case comparisons) will not need to be extended to the
+ // preferred register width, so we will potentially eliminate N-1 extends,
+ // where N is the number of cases in the switch.
+ auto *NewType = Type::getIntNTy(Context, RegWidth);
+
+ // Zero-extend the switch condition and case constants unless the switch
+ // condition is a function argument that is already being sign-extended.
+ // In that case, we can avoid an unnecessary mask/extension by sign-extending
+ // everything instead.
+ Instruction::CastOps ExtType = Instruction::ZExt;
+ if (auto *Arg = dyn_cast<Argument>(Cond))
+ if (Arg->hasSExtAttr())
+ ExtType = Instruction::SExt;
+
+ auto *ExtInst = CastInst::Create(ExtType, Cond, NewType);
+ ExtInst->insertBefore(SI);
+ SI->setCondition(ExtInst);
+ for (SwitchInst::CaseIt Case : SI->cases()) {
+ APInt NarrowConst = Case.getCaseValue()->getValue();
+ APInt WideConst = (ExtType == Instruction::ZExt) ?
+ NarrowConst.zext(RegWidth) : NarrowConst.sext(RegWidth);
+ Case.setValue(ConstantInt::get(Context, WideConst));
+ }
+
+ return true;
+}
+
namespace {
/// \brief Helper class to promote a scalar operation to a vector one.
/// This class is used to move downward extractelement transition.
if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
stripInvariantGroupMetadata(*LI);
if (TLI) {
+ bool Modified = optimizeLoadExt(LI);
unsigned AS = LI->getPointerAddressSpace();
- return optimizeMemoryInst(I, I->getOperand(0), LI->getType(), AS);
+ Modified |= optimizeMemoryInst(I, I->getOperand(0), LI->getType(), AS);
+ return Modified;
}
return false;
}
if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I))
return optimizeShuffleVectorInst(SVI);
+ if (auto *Switch = dyn_cast<SwitchInst>(I))
+ return optimizeSwitchInst(Switch);
+
if (isa<ExtractElementInst>(I))
return optimizeExtractElementInst(I);
return false;
}
+/// Given an OR instruction, check to see if this is a bitreverse
+/// idiom. If so, insert the new intrinsic and return true.
+static bool makeBitReverse(Instruction &I, const DataLayout &DL,
+ const TargetLowering &TLI) {
+ if (!I.getType()->isIntegerTy() ||
+ !TLI.isOperationLegalOrCustom(ISD::BITREVERSE,
+ TLI.getValueType(DL, I.getType(), true)))
+ return false;
+
+ SmallVector<Instruction*, 4> Insts;
+ if (!recognizeBitReverseOrBSwapIdiom(&I, false, true, Insts))
+ return false;
+ Instruction *LastInst = Insts.back();
+ I.replaceAllUsesWith(LastInst);
+ RecursivelyDeleteTriviallyDeadInstructions(&I);
+ return true;
+}
+
// In this pass we look for GEP and cast instructions that are used
// across basic blocks and rewrite them to improve basic-block-at-a-time
// selection.
if (ModifiedDT)
return true;
}
- MadeChange |= dupRetToEnableTailCallOpts(&BB);
+ bool MadeBitReverse = true;
+ while (TLI && MadeBitReverse) {
+ MadeBitReverse = false;
+ for (auto &I : reverse(BB)) {
+ if (makeBitReverse(I, *DL, *TLI)) {
+ MadeBitReverse = MadeChange = true;
+ break;
+ }
+ }
+ }
+ MadeChange |= dupRetToEnableTailCallOpts(&BB);
+
return MadeChange;
}
Instruction *VI = dyn_cast_or_null<Instruction>(DVI->getValue());
if (VI && VI != PrevNonDbgInst && !VI->isTerminator()) {
+ // If VI is a phi in a block with an EHPad terminator, we can't insert
+ // after it.
+ if (isa<PHINode>(VI) && VI->getParent()->getTerminator()->isEHPad())
+ continue;
DEBUG(dbgs() << "Moving Debug Value before :\n" << *DVI << ' ' << *VI);
DVI->removeFromParent();
if (isa<PHINode>(VI))
projects / oota-llvm.git / blobdiff