[llvm] r363147 - [NFC][SCEV] Add NoWrapFlag argument to InsertBinOp
Sam Parker via llvm-commits
llvm-commits at lists.llvm.org
Wed Jun 12 04:53:55 PDT 2019
Author: sam_parker
Date: Wed Jun 12 04:53:55 2019
New Revision: 363147
URL: http://llvm.org/viewvc/llvm-project?rev=363147&view=rev
Log:
[NFC][SCEV] Add NoWrapFlag argument to InsertBinOp
'Use wrap flags in InsertBinop' (rL362687) was reverted due to
miscompiles. This patch introduces the previous change to pass
no-wrap flags but now only FlagAnyWrap is passed.
Differential Revision: https://reviews.llvm.org/D61934
Modified:
llvm/trunk/include/llvm/Analysis/ScalarEvolutionExpander.h
llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp
Modified: llvm/trunk/include/llvm/Analysis/ScalarEvolutionExpander.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ScalarEvolutionExpander.h?rev=363147&r1=363146&r2=363147&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/ScalarEvolutionExpander.h (original)
+++ llvm/trunk/include/llvm/Analysis/ScalarEvolutionExpander.h Wed Jun 12 04:53:55 2019
@@ -318,7 +318,7 @@ namespace llvm {
/// avoid inserting an obviously redundant operation, and hoisting to an
/// outer loop when the opportunity is there and it is safe.
Value *InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, Value *RHS,
- bool IsSafeToHoist);
+ SCEV::NoWrapFlags Flags, bool IsSafeToHoist);
/// Arrange for there to be a cast of V to Ty at IP, reusing an existing
/// cast if a suitable one exists, moving an existing cast if a suitable one
Modified: llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp?rev=363147&r1=363146&r2=363147&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp Wed Jun 12 04:53:55 2019
@@ -169,7 +169,8 @@ Value *SCEVExpander::InsertNoopCastOfTo(
/// of work to avoid inserting an obviously redundant operation, and hoisting
/// to an outer loop when the opportunity is there and it is safe.
Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode,
- Value *LHS, Value *RHS, bool IsSafeToHoist) {
+ Value *LHS, Value *RHS,
+ SCEV::NoWrapFlags Flags, bool IsSafeToHoist) {
// Fold a binop with constant operands.
if (Constant *CLHS = dyn_cast<Constant>(LHS))
if (Constant *CRHS = dyn_cast<Constant>(RHS))
@@ -188,20 +189,22 @@ Value *SCEVExpander::InsertBinop(Instruc
if (isa<DbgInfoIntrinsic>(IP))
ScanLimit++;
- // Conservatively, do not use any instruction which has any of wrap/exact
- // flags installed.
- // TODO: Instead of simply disable poison instructions we can be clever
- // here and match SCEV to this instruction.
- auto canGeneratePoison = [](Instruction *I) {
- if (isa<OverflowingBinaryOperator>(I) &&
- (I->hasNoSignedWrap() || I->hasNoUnsignedWrap()))
- return true;
+ auto canGenerateIncompatiblePoison = [&Flags](Instruction *I) {
+ // Ensure that no-wrap flags match.
+ if (isa<OverflowingBinaryOperator>(I)) {
+ if (I->hasNoSignedWrap() != (Flags & SCEV::FlagNSW))
+ return true;
+ if (I->hasNoUnsignedWrap() != (Flags & SCEV::FlagNUW))
+ return true;
+ }
+ // Conservatively, do not use any instruction which has any of exact
+ // flags installed.
if (isa<PossiblyExactOperator>(I) && I->isExact())
return true;
return false;
};
if (IP->getOpcode() == (unsigned)Opcode && IP->getOperand(0) == LHS &&
- IP->getOperand(1) == RHS && !canGeneratePoison(&*IP))
+ IP->getOperand(1) == RHS && !canGenerateIncompatiblePoison(&*IP))
return &*IP;
if (IP == BlockBegin) break;
}
@@ -226,6 +229,10 @@ Value *SCEVExpander::InsertBinop(Instruc
// If we haven't found this binop, insert it.
Instruction *BO = cast<Instruction>(Builder.CreateBinOp(Opcode, LHS, RHS));
BO->setDebugLoc(Loc);
+ if (Flags & SCEV::FlagNUW)
+ BO->setHasNoUnsignedWrap();
+ if (Flags & SCEV::FlagNSW)
+ BO->setHasNoSignedWrap();
rememberInstruction(BO);
return BO;
@@ -737,7 +744,8 @@ Value *SCEVExpander::visitAddExpr(const
// Instead of doing a negate and add, just do a subtract.
Value *W = expandCodeFor(SE.getNegativeSCEV(Op), Ty);
Sum = InsertNoopCastOfTo(Sum, Ty);
- Sum = InsertBinop(Instruction::Sub, Sum, W, /*IsSafeToHoist*/ true);
+ Sum = InsertBinop(Instruction::Sub, Sum, W, SCEV::FlagAnyWrap,
+ /*IsSafeToHoist*/ true);
++I;
} else {
// A simple add.
@@ -745,7 +753,8 @@ Value *SCEVExpander::visitAddExpr(const
Sum = InsertNoopCastOfTo(Sum, Ty);
// Canonicalize a constant to the RHS.
if (isa<Constant>(Sum)) std::swap(Sum, W);
- Sum = InsertBinop(Instruction::Add, Sum, W, /*IsSafeToHoist*/ true);
+ Sum = InsertBinop(Instruction::Add, Sum, W, SCEV::FlagAnyWrap,
+ /*IsSafeToHoist*/ true);
++I;
}
}
@@ -774,7 +783,7 @@ Value *SCEVExpander::visitMulExpr(const
// Expand the calculation of X pow N in the following manner:
// Let N = P1 + P2 + ... + PK, where all P are powers of 2. Then:
// X pow N = (X pow P1) * (X pow P2) * ... * (X pow PK).
- const auto ExpandOpBinPowN = [this, &I, &OpsAndLoops, &Ty]() {
+ const auto ExpandOpBinPowN = [this, &I, &OpsAndLoops, &Ty, &S]() {
auto E = I;
// Calculate how many times the same operand from the same loop is included
// into this power.
@@ -797,9 +806,11 @@ Value *SCEVExpander::visitMulExpr(const
if (Exponent & 1)
Result = P;
for (uint64_t BinExp = 2; BinExp <= Exponent; BinExp <<= 1) {
- P = InsertBinop(Instruction::Mul, P, P, /*IsSafeToHoist*/ true);
+ P = InsertBinop(Instruction::Mul, P, P, SCEV::FlagAnyWrap,
+ /*IsSafeToHoist*/ true);
if (Exponent & BinExp)
Result = Result ? InsertBinop(Instruction::Mul, Result, P,
+ SCEV::FlagAnyWrap,
/*IsSafeToHoist*/ true)
: P;
}
@@ -817,7 +828,7 @@ Value *SCEVExpander::visitMulExpr(const
// Instead of doing a multiply by negative one, just do a negate.
Prod = InsertNoopCastOfTo(Prod, Ty);
Prod = InsertBinop(Instruction::Sub, Constant::getNullValue(Ty), Prod,
- /*IsSafeToHoist*/ true);
+ SCEV::FlagAnyWrap, /*IsSafeToHoist*/ true);
++I;
} else {
// A simple mul.
@@ -831,9 +842,10 @@ Value *SCEVExpander::visitMulExpr(const
assert(!Ty->isVectorTy() && "vector types are not SCEVable");
Prod = InsertBinop(Instruction::Shl, Prod,
ConstantInt::get(Ty, RHS->logBase2()),
- /*IsSafeToHoist*/ true);
+ SCEV::FlagAnyWrap, /*IsSafeToHoist*/ true);
} else {
- Prod = InsertBinop(Instruction::Mul, Prod, W, /*IsSafeToHoist*/ true);
+ Prod = InsertBinop(Instruction::Mul, Prod, W, SCEV::FlagAnyWrap,
+ /*IsSafeToHoist*/ true);
}
}
}
@@ -850,11 +862,11 @@ Value *SCEVExpander::visitUDivExpr(const
if (RHS.isPowerOf2())
return InsertBinop(Instruction::LShr, LHS,
ConstantInt::get(Ty, RHS.logBase2()),
- /*IsSafeToHoist*/ true);
+ SCEV::FlagAnyWrap, /*IsSafeToHoist*/ true);
}
Value *RHS = expandCodeFor(S->getRHS(), Ty);
- return InsertBinop(Instruction::UDiv, LHS, RHS,
+ return InsertBinop(Instruction::UDiv, LHS, RHS, SCEV::FlagAnyWrap,
/*IsSafeToHoist*/ SE.isKnownNonZero(S->getRHS()));
}
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