Allow scalarrepl to treat an all-zero GEP just as bitcast.
This includes not marking a GEP involving a vector as unsafe, but only when it
has all zero indices. This allows scalarrepl to work in a few more cases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57177 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/ScalarReplAggregates.cpp b/lib/Transforms/Scalar/ScalarReplAggregates.cpp
index c292028..b319d8d 100644
--- a/lib/Transforms/Scalar/ScalarReplAggregates.cpp
+++ b/lib/Transforms/Scalar/ScalarReplAggregates.cpp
@@ -530,7 +530,8 @@
return MarkUnsafe(Info);
}
}
-
+
+ bool hasVector = false;
// Walk through the GEP type indices, checking the types that this indexes
// into.
@@ -539,22 +540,30 @@
if (isa<StructType>(*I))
continue;
- // Don't SROA pointers into vectors.
- if (isa<VectorType>(*I))
- return MarkUnsafe(Info);
-
- // Otherwise, we must have an index into an array type. Verify that this is
- // an in-range constant integer. Specifically, consider A[0][i]. We
- // cannot know that the user isn't doing invalid things like allowing i to
- // index an out-of-range subscript that accesses A[1]. Because of this, we
- // have to reject SROA of any accesses into structs where any of the
- // components are variables.
ConstantInt *IdxVal = dyn_cast<ConstantInt>(I.getOperand());
if (!IdxVal) return MarkUnsafe(Info);
- if (IdxVal->getZExtValue() >= cast<ArrayType>(*I)->getNumElements())
- return MarkUnsafe(Info);
-
+
+ // Are all indices still zero?
IsAllZeroIndices &= IdxVal->isZero();
+
+ if (const ArrayType *AT = dyn_cast<ArrayType>(*I)) {
+ // This GEP indexes an array. Verify that this is an in-range constant
+ // integer. Specifically, consider A[0][i]. We cannot know that the user
+ // isn't doing invalid things like allowing i to index an out-of-range
+ // subscript that accesses A[1]. Because of this, we have to reject SROA
+ // of any accesses into structs where any of the components are variables.
+ if (IdxVal->getZExtValue() >= AT->getNumElements())
+ return MarkUnsafe(Info);
+ }
+
+ // Note if we've seen a vector type yet
+ hasVector |= isa<VectorType>(*I);
+
+ // Don't SROA pointers into vectors, unless all indices are zero. When all
+ // indices are zero, we only consider this GEP as a bitcast, but will still
+ // not consider breaking up the vector.
+ if (hasVector && !IsAllZeroIndices)
+ return MarkUnsafe(Info);
}
// If there are any non-simple uses of this getelementptr, make sure to reject
@@ -661,6 +670,11 @@
// It is likely that OtherPtr is a bitcast, if so, remove it.
if (BitCastInst *BC = dyn_cast<BitCastInst>(OtherPtr))
OtherPtr = BC->getOperand(0);
+ // All zero GEPs are effectively casts
+ if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(OtherPtr))
+ if (GEP->hasAllZeroIndices())
+ OtherPtr = GEP->getOperand(0);
+
if (ConstantExpr *BCE = dyn_cast<ConstantExpr>(OtherPtr))
if (BCE->getOpcode() == Instruction::BitCast)
OtherPtr = BCE->getOperand(0);