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Generalize the ChangeCompareStride code, in preparation for
handling non-constant strides. No functionality change. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65363 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
parent
d0a90b9876
commit
c34fea3935
@ -2133,15 +2133,12 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
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return Cond;
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const SCEVConstant *SC = dyn_cast<SCEVConstant>(*CondStride);
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if (!SC) return Cond;
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ConstantInt *C = dyn_cast<ConstantInt>(Cond->getOperand(1));
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if (!C) return Cond;
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ICmpInst::Predicate Predicate = Cond->getPredicate();
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int64_t CmpSSInt = SC->getValue()->getSExtValue();
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int64_t CmpVal = C->getValue().getSExtValue();
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unsigned BitWidth = C->getValue().getBitWidth();
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unsigned BitWidth = (*CondStride)->getBitWidth();
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uint64_t SignBit = 1ULL << (BitWidth-1);
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const Type *CmpTy = C->getType();
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const Type *CmpTy = Cond->getOperand(0)->getType();
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const Type *NewCmpTy = NULL;
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unsigned TyBits = CmpTy->getPrimitiveSizeInBits();
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unsigned NewTyBits = 0;
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@ -2149,102 +2146,112 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
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Value *NewCmpLHS = NULL;
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Value *NewCmpRHS = NULL;
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int64_t Scale = 1;
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// Check stride constant and the comparision constant signs to detect
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// overflow.
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if ((CmpVal & SignBit) != (CmpSSInt & SignBit))
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return Cond;
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// Look for a suitable stride / iv as replacement.
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SCEVHandle NewOffset = SE->getIntegerSCEV(0, UIntPtrTy);
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std::stable_sort(StrideOrder.begin(), StrideOrder.end(), StrideCompare());
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for (unsigned i = 0, e = StrideOrder.size(); i != e; ++i) {
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std::map<SCEVHandle, IVUsersOfOneStride>::iterator SI =
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IVUsesByStride.find(StrideOrder[i]);
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if (!isa<SCEVConstant>(SI->first))
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continue;
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int64_t SSInt = cast<SCEVConstant>(SI->first)->getValue()->getSExtValue();
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if (abs(SSInt) <= abs(CmpSSInt) || (SSInt % CmpSSInt) != 0)
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continue;
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Scale = SSInt / CmpSSInt;
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int64_t NewCmpVal = CmpVal * Scale;
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APInt Mul = APInt(BitWidth, NewCmpVal);
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// Check for overflow.
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if (Mul.getSExtValue() != NewCmpVal)
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continue;
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if (ConstantInt *C = dyn_cast<ConstantInt>(Cond->getOperand(1))) {
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int64_t CmpVal = C->getValue().getSExtValue();
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// Watch out for overflow.
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if (ICmpInst::isSignedPredicate(Predicate) &&
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(CmpVal & SignBit) != (NewCmpVal & SignBit))
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continue;
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// Check stride constant and the comparision constant signs to detect
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// overflow.
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if ((CmpVal & SignBit) != (CmpSSInt & SignBit))
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return Cond;
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if (NewCmpVal == CmpVal)
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continue;
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// Pick the best iv to use trying to avoid a cast.
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NewCmpLHS = NULL;
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for (std::vector<IVStrideUse>::iterator UI = SI->second.Users.begin(),
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E = SI->second.Users.end(); UI != E; ++UI) {
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NewCmpLHS = UI->OperandValToReplace;
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if (NewCmpLHS->getType() == CmpTy)
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break;
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}
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if (!NewCmpLHS)
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continue;
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NewCmpTy = NewCmpLHS->getType();
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NewTyBits = isa<PointerType>(NewCmpTy)
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? UIntPtrTy->getPrimitiveSizeInBits()
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: NewCmpTy->getPrimitiveSizeInBits();
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if (RequiresTypeConversion(NewCmpTy, CmpTy)) {
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// Check if it is possible to rewrite it using
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// an iv / stride of a smaller integer type.
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bool TruncOk = false;
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if (NewCmpTy->isInteger()) {
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unsigned Bits = NewTyBits;
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if (ICmpInst::isSignedPredicate(Predicate))
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--Bits;
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uint64_t Mask = (1ULL << Bits) - 1;
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if (((uint64_t)NewCmpVal & Mask) == (uint64_t)NewCmpVal)
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TruncOk = true;
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}
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if (!TruncOk)
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// Look for a suitable stride / iv as replacement.
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for (unsigned i = 0, e = StrideOrder.size(); i != e; ++i) {
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std::map<SCEVHandle, IVUsersOfOneStride>::iterator SI =
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IVUsesByStride.find(StrideOrder[i]);
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if (!isa<SCEVConstant>(SI->first))
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continue;
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int64_t SSInt = cast<SCEVConstant>(SI->first)->getValue()->getSExtValue();
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if (abs(SSInt) <= abs(CmpSSInt) || (SSInt % CmpSSInt) != 0)
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continue;
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Scale = SSInt / CmpSSInt;
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int64_t NewCmpVal = CmpVal * Scale;
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APInt Mul = APInt(BitWidth, NewCmpVal);
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// Check for overflow.
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if (Mul.getSExtValue() != NewCmpVal)
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continue;
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// Watch out for overflow.
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if (ICmpInst::isSignedPredicate(Predicate) &&
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(CmpVal & SignBit) != (NewCmpVal & SignBit))
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continue;
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if (NewCmpVal == CmpVal)
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continue;
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// Pick the best iv to use trying to avoid a cast.
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NewCmpLHS = NULL;
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for (std::vector<IVStrideUse>::iterator UI = SI->second.Users.begin(),
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E = SI->second.Users.end(); UI != E; ++UI) {
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NewCmpLHS = UI->OperandValToReplace;
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if (NewCmpLHS->getType() == CmpTy)
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break;
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}
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if (!NewCmpLHS)
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continue;
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NewCmpTy = NewCmpLHS->getType();
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NewTyBits = isa<PointerType>(NewCmpTy)
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? UIntPtrTy->getPrimitiveSizeInBits()
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: NewCmpTy->getPrimitiveSizeInBits();
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if (RequiresTypeConversion(NewCmpTy, CmpTy)) {
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// Check if it is possible to rewrite it using
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// an iv / stride of a smaller integer type.
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bool TruncOk = false;
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if (NewCmpTy->isInteger()) {
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unsigned Bits = NewTyBits;
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if (ICmpInst::isSignedPredicate(Predicate))
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--Bits;
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uint64_t Mask = (1ULL << Bits) - 1;
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if (((uint64_t)NewCmpVal & Mask) == (uint64_t)NewCmpVal)
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TruncOk = true;
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}
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if (!TruncOk)
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continue;
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}
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// Don't rewrite if use offset is non-constant and the new type is
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// of a different type.
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// FIXME: too conservative?
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if (NewTyBits != TyBits && !isa<SCEVConstant>(CondUse->Offset))
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continue;
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bool AllUsesAreAddresses = true;
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bool AllUsesAreOutsideLoop = true;
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std::vector<BasedUser> UsersToProcess;
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SCEVHandle CommonExprs = CollectIVUsers(SI->first, SI->second, L,
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AllUsesAreAddresses,
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AllUsesAreOutsideLoop,
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UsersToProcess);
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// Avoid rewriting the compare instruction with an iv of new stride
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// if it's likely the new stride uses will be rewritten using the
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// stride of the compare instruction.
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if (AllUsesAreAddresses &&
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ValidStride(!CommonExprs->isZero(), Scale, UsersToProcess))
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continue;
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// If scale is negative, use swapped predicate unless it's testing
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// for equality.
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if (Scale < 0 && !Cond->isEquality())
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Predicate = ICmpInst::getSwappedPredicate(Predicate);
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NewStride = &StrideOrder[i];
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if (!isa<PointerType>(NewCmpTy))
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NewCmpRHS = ConstantInt::get(NewCmpTy, NewCmpVal);
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else {
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NewCmpRHS = ConstantInt::get(UIntPtrTy, NewCmpVal);
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NewCmpRHS = SCEVExpander::InsertCastOfTo(Instruction::IntToPtr,
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NewCmpRHS, NewCmpTy);
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}
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NewOffset = TyBits == NewTyBits
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? SE->getMulExpr(CondUse->Offset,
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SE->getConstant(ConstantInt::get(CmpTy, Scale)))
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: SE->getConstant(ConstantInt::get(NewCmpTy,
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cast<SCEVConstant>(CondUse->Offset)->getValue()->getSExtValue()*Scale));
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break;
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}
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// Don't rewrite if use offset is non-constant and the new type is
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// of a different type.
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// FIXME: too conservative?
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if (NewTyBits != TyBits && !isa<SCEVConstant>(CondUse->Offset))
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continue;
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bool AllUsesAreAddresses = true;
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bool AllUsesAreOutsideLoop = true;
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std::vector<BasedUser> UsersToProcess;
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SCEVHandle CommonExprs = CollectIVUsers(SI->first, SI->second, L,
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AllUsesAreAddresses,
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AllUsesAreOutsideLoop,
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UsersToProcess);
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// Avoid rewriting the compare instruction with an iv of new stride
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// if it's likely the new stride uses will be rewritten using the
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// stride of the compare instruction.
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if (AllUsesAreAddresses &&
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ValidStride(!CommonExprs->isZero(), Scale, UsersToProcess))
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continue;
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// If scale is negative, use swapped predicate unless it's testing
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// for equality.
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if (Scale < 0 && !Cond->isEquality())
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Predicate = ICmpInst::getSwappedPredicate(Predicate);
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NewStride = &StrideOrder[i];
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if (!isa<PointerType>(NewCmpTy))
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NewCmpRHS = ConstantInt::get(NewCmpTy, NewCmpVal);
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else {
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NewCmpRHS = ConstantInt::get(UIntPtrTy, NewCmpVal);
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NewCmpRHS = SCEVExpander::InsertCastOfTo(Instruction::IntToPtr,
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NewCmpRHS, NewCmpTy);
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}
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break;
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}
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// Forgo this transformation if it the increment happens to be
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@ -2275,11 +2282,6 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
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OldCond->eraseFromParent();
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IVUsesByStride[*CondStride].Users.pop_back();
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SCEVHandle NewOffset = TyBits == NewTyBits
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? SE->getMulExpr(CondUse->Offset,
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SE->getConstant(ConstantInt::get(CmpTy, Scale)))
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: SE->getConstant(ConstantInt::get(NewCmpTy,
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cast<SCEVConstant>(CondUse->Offset)->getValue()->getSExtValue()*Scale));
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IVUsesByStride[*NewStride].addUser(NewOffset, Cond, NewCmpLHS);
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CondUse = &IVUsesByStride[*NewStride].Users.back();
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CondStride = NewStride;
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