george.burgess.iv added inline comments.
================
Comment at: lib/AST/ExprConstant.cpp:4763
@@ +4762,3 @@
+ /// arithmetic.
+ bool UseStrictCastingRules;
+
----------------
rsmith wrote:
> This should be handled as an `EvaluationMode`.
Works for me.
================
Comment at: lib/AST/ExprConstant.cpp:4879-4907
@@ +4878,31 @@
+ // We need to adjust the array index we're handing off in that case.
+ QualType ArrayTy = Result.Designator.MostDerivedType;
+ if (!ArrayTy.isNull() && !ArrayTy->isIncompleteType() && ArrayTy != Pointee)
{
+ CharUnits PointeeEltSize;
+ if (!HandleSizeof(Info, PExp->getExprLoc(), Pointee, PointeeEltSize))
+ return false;
+
+ CharUnits ArrayEltSize;
+ if (!HandleSizeof(Info, PExp->getExprLoc(), ArrayTy, ArrayEltSize))
+ return false;
+
+ // Additionally, because LValuePathEntry wasn't made to really handle byte
+ // offsets, we need to keep the LValue Offset up-to-date (so casting e.g.
+ // BaseToDerived works as intended), but we also need to lie a bit about
the
+ // array index.
+ //
+ // Example:
+ // (char*)Foo.Bar[1] + 2 // (assuming sizeof(Foo.Bar[1]) > 2)
+ // Will have an index of 1 and an offset of offsetof(Foo.Bar[1]) + 2.
+ if (PointeeEltSize != ArrayEltSize) {
+ CharUnits ByteOffset = IndexOffset * PointeeEltSize + AddedOffset;
+ CharUnits Rem = CharUnits::fromQuantity(ByteOffset % ArrayEltSize);
+ Result.Offset += Rem - AddedOffset;
+ AddedOffset = Rem;
+ IndexOffset = ByteOffset / ArrayEltSize;
+ }
+
+ // HandleLValueArrayAdjustment takes the type of the array
+ Pointee = ArrayTy;
+ }
+
----------------
rsmith wrote:
> We should not do this except in your special new mode, and I'm not entirely
> convinced we should support this case at all. Just discarding the designator
> (as we would do anyway in constant-folding mode) seems like an acceptable
> response here. We really don't know what subobject is being referenced any
> more.
We need some way to support `BOS((char*)&Foo.Bar + 1, N)`, so this needs to go
somewhere. I originally had it in its own method that was super similar to this
one, and the duplication made me sad. Will re-duplicate and see how that looks.
FYI, if you'll look at the diff at L194 in p2-0x.cpp, we have an interesting
feature in the non-patched impl where `B *b = (B*)((A*)&b + 1)` is at an offset
of sizeof(A), but Designator says it's at b[1]. I assumed this behavior is a
bug, and this kinda-fixes it. If it's intended behavior, I'll absolutely find a
better way to handle this.
================
Comment at: lib/AST/ExprConstant.cpp:6355-6356
@@ +6354,4 @@
+bool OutermostMemberEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) {
+ Result = E->getType();
+ return true;
+}
----------------
rsmith wrote:
> I think handling this through the normal pointer evaluator, but with a
> different `EvaluationMode`, is a better approach. (We need some
> representation for an `LValueBase` to represent "unknown base", but
> everything else should fall through pretty naturally.)
Sounds great to me -- I thought another visitor seemed heavyweight, but didn't
consider adding another `EvaluationMode`. Will look into swapping approaches.
http://reviews.llvm.org/D12169
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