c-rhodes added inline comments.
================
Comment at: clang/lib/AST/ASTContext.cpp:8522
+ return VT->getElementType().getCanonicalType() ==
+ getBuiltinVectorTypeInfo(BT).ElementType;
}
----------------
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).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D87607/new/
https://reviews.llvm.org/D87607
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