Revert the part of r107257 which introduced new logic for using
nsw and nuw flags from IR Instructions. On further consideration,
this isn't valid.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107298 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 358d591..d541b55 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -2760,38 +2760,6 @@
return getUnknown(PN);
}
-/// UseFlag - When creating an operator with operands L and R based on an
-/// LLVM IR instruction in basic block BB where the instruction has
-/// nsw, nuw, or inbounds, test whether the corresponding flag can be
-/// set for the resulting SCEV.
-static bool
-UseFlag(bool Flag, const SCEV *L, const SCEV *R, const Value *Inst) {
- // If the flag is not set, don't use it. This is included here to reduce
- // clutter in the callers.
- if (!Flag)
- return false;
-
- // Determine the block which contains the instruction with the flag.
- const Instruction *I = dyn_cast<Instruction>(Inst);
- if (!I)
- return false;
- const BasicBlock *BB = I->getParent();
-
- // Handle an easy case: test if exactly one of the operands is an addrec
- // and that the instruction is trivially control-equivalent to the addrec's
- // loop's header.
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(L)) {
- if (!isa<SCEVAddRecExpr>(R) &&
- AR->getLoop()->getHeader() == BB)
- return true;
- } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(R)) {
- if (AR->getLoop()->getHeader() == BB)
- return true;
- }
-
- return false;
-}
-
/// createNodeForGEP - Expand GEP instructions into add and multiply
/// operations. This allows them to be analyzed by regular SCEV code.
///
@@ -2800,9 +2768,7 @@
// Don't blindly transfer the inbounds flag from the GEP instruction to the
// Add expression, because the Instruction may be guarded by control flow
// and the no-overflow bits may not be valid for the expression in any
- // context. However, in the special case where the GEP is in the loop header,
- // we know it's trivially control-equivalent to any addrecs for that loop.
- bool InBounds = GEP->isInBounds();
+ // context.
const Type *IntPtrTy = getEffectiveSCEVType(GEP->getType());
Value *Base = GEP->getOperand(0);
@@ -2821,13 +2787,8 @@
unsigned FieldNo = cast<ConstantInt>(Index)->getZExtValue();
const SCEV *FieldOffset = getOffsetOfExpr(STy, FieldNo);
- // Test if the GEP has the inbounds keyword and is control-equivalent
- // to the addrec.
- bool HasNUW = UseFlag(InBounds, TotalOffset, FieldOffset, GEP);
-
// Add the field offset to the running total offset.
- TotalOffset = getAddExpr(TotalOffset, FieldOffset,
- HasNUW, /*HasNSW=*/false);
+ TotalOffset = getAddExpr(TotalOffset, FieldOffset);
} else {
// For an array, add the element offset, explicitly scaled.
const SCEV *ElementSize = getSizeOfExpr(*GTI);
@@ -2835,33 +2796,19 @@
// Getelementptr indices are signed.
IndexS = getTruncateOrSignExtend(IndexS, IntPtrTy);
- // Test if the GEP has the inbounds keyword and is control-equivalent
- // to the addrec.
- bool HasNUW = UseFlag(InBounds, IndexS, ElementSize, GEP);
-
// Multiply the index by the element size to compute the element offset.
- const SCEV *LocalOffset = getMulExpr(IndexS, ElementSize,
- HasNUW, /*HasNSW=*/false);
-
- // Test if the GEP has the inbounds keyword and is control-equivalent
- // to the addrec.
- HasNUW = UseFlag(InBounds, TotalOffset, LocalOffset, GEP);
+ const SCEV *LocalOffset = getMulExpr(IndexS, ElementSize);
// Add the element offset to the running total offset.
- TotalOffset = getAddExpr(TotalOffset, LocalOffset,
- HasNUW, /*HasNSW=*/false);
+ TotalOffset = getAddExpr(TotalOffset, LocalOffset);
}
}
// Get the SCEV for the GEP base.
const SCEV *BaseS = getSCEV(Base);
- // Test if the GEP has the inbounds keyword and is control-equivalent
- // to the addrec.
- bool HasNUW = UseFlag(InBounds, BaseS, TotalOffset, GEP);
-
// Add the total offset from all the GEP indices to the base.
- return getAddExpr(BaseS, TotalOffset, HasNUW, /*HasNSW=*/false);
+ return getAddExpr(BaseS, TotalOffset);
}
/// GetMinTrailingZeros - Determine the minimum number of zero bits that S is
@@ -3253,30 +3200,12 @@
Operator *U = cast<Operator>(V);
switch (Opcode) {
- case Instruction::Add: {
- const SCEV *LHS = getSCEV(U->getOperand(0));
- const SCEV *RHS = getSCEV(U->getOperand(1));
-
- // Don't transfer the NSW and NUW bits from the Add instruction to the
- // Add expression unless we can prove that it's safe.
- AddOperator *Add = cast<AddOperator>(U);
- bool HasNUW = UseFlag(Add->hasNoUnsignedWrap(), LHS, RHS, Add);
- bool HasNSW = UseFlag(Add->hasNoSignedWrap(), LHS, RHS, Add);
-
- return getAddExpr(LHS, RHS, HasNUW, HasNSW);
- }
- case Instruction::Mul: {
- const SCEV *LHS = getSCEV(U->getOperand(0));
- const SCEV *RHS = getSCEV(U->getOperand(1));
-
- // Don't transfer the NSW and NUW bits from the Mul instruction to the
- // Mul expression unless we can prove that it's safe.
- MulOperator *Mul = cast<MulOperator>(U);
- bool HasNUW = UseFlag(Mul->hasNoUnsignedWrap(), LHS, RHS, Mul);
- bool HasNSW = UseFlag(Mul->hasNoSignedWrap(), LHS, RHS, Mul);
-
- return getMulExpr(LHS, RHS, HasNUW, HasNSW);
- }
+ case Instruction::Add:
+ return getAddExpr(getSCEV(U->getOperand(0)),
+ getSCEV(U->getOperand(1)));
+ case Instruction::Mul:
+ return getMulExpr(getSCEV(U->getOperand(0)),
+ getSCEV(U->getOperand(1)));
case Instruction::UDiv:
return getUDivExpr(getSCEV(U->getOperand(0)),
getSCEV(U->getOperand(1)));