efriedma added inline comments.
================
Comment at: clang/lib/AST/ASTContext.cpp:8522
+ return VT->getElementType().getCanonicalType() ==
+ getBuiltinVectorTypeInfo(BT).ElementType;
}
----------------
c-rhodes wrote:
> efriedma wrote:
> > We allow casting SVE fixed-width vectors only if the element type is
> > identical, but we allow casting to GNU fixed-width vectors if the vector
> > width is the same? That seems sort of loose; could allow weird casts,
> > particularly when bool vectors are involved.
> > We allow casting SVE fixed-width vectors only if the element type is
> > identical, but we allow casting to GNU fixed-width vectors if the vector
> > width is the same? That seems sort of loose; could allow weird casts,
> > particularly when bool vectors are involved.
>
> Fixed-length SVE vectors are created with the attribute and the vector width
> must match `-msve-vector-bits`, which should guarantee consistent vector
> widths for a given input. This is checking the vector width is the same and
> the element type matches when casting between GNU and SVE vectors, although
> since neither of those types are created by the attribute it's necessary to
> check the vector width to validate `__ARM_FEATURE_SVE_BITS==N`.
>
> Predicates are treated differently in the ACLE and it doesn't mention
> supporting casts between GNU bool vectors and SVE VLS/VLA predicates. I'm
> also not sure the GNU vector_size extension is defined for bool elements yet,
> but I did notice Simon Moll is working on this (D81083).
I think you need to check both the size and the element type here?
================
Comment at: clang/test/Sema/attr-arm-sve-vector-bits.c:237
+// Test implicit conversion between SVE and GNU vector is invalid when
+// __ARM_FEATURE_SVE_BITS != N
+#if defined(__ARM_FEATURE_SVE_BITS) && __ARM_FEATURE_SVE_BITS == 512
----------------
This test isn't checking what it says it is; int4 and svint64_t have different
element types.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D87607/new/
https://reviews.llvm.org/D87607
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