teach SCEV that the scale and addition of an inbounds gep don't NSW.
This fixes a FIXME in scev-aa.ll (allowing a new no-alias result) and
generally makes things more precise.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125449 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index aab95ae..62244cc 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -2870,6 +2870,7 @@
// 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.
+ bool isInBounds = GEP->isInBounds();
const Type *IntPtrTy = getEffectiveSCEVType(GEP->getType());
Value *Base = GEP->getOperand(0);
@@ -2898,7 +2899,8 @@
IndexS = getTruncateOrSignExtend(IndexS, IntPtrTy);
// Multiply the index by the element size to compute the element offset.
- const SCEV *LocalOffset = getMulExpr(IndexS, ElementSize);
+ const SCEV *LocalOffset = getMulExpr(IndexS, ElementSize, /*NUW*/ false,
+ /*NSW*/ isInBounds);
// Add the element offset to the running total offset.
TotalOffset = getAddExpr(TotalOffset, LocalOffset);
@@ -2909,7 +2911,8 @@
const SCEV *BaseS = getSCEV(Base);
// Add the total offset from all the GEP indices to the base.
- return getAddExpr(BaseS, TotalOffset);
+ return getAddExpr(BaseS, TotalOffset, /*NUW*/ false,
+ /*NSW*/ isInBounds);
}
/// GetMinTrailingZeros - Determine the minimum number of zero bits that S is