joechrisellis added inline comments.
================
Comment at: clang/lib/Sema/SemaCast.cpp:2222-2227
+ // Allow bitcasting if either the source or destination is a scalable
+ // vector.
+ if (SrcType->isSizelessBuiltinType() || DestType->isSizelessBuiltinType())
{
+ Kind = CK_BitCast;
+ return TC_Success;
+ }
----------------
c-rhodes wrote:
> This is a bit ambiguous, it'll allow bitcasting between things like a fixed
> predicate and any sizeless type which I don't think makes sense. I think
> it'll also allow bitcasting between any scalable and GNU vectors regardless
> of vector length, e.g.:
>
> ```
> typedef int32_t int32x4_t __attribute__((vector_size(16)));
>
> void foo() {
> svint32_t s32;
> int32x4_t g32;
> g32 = (int32x4_t)s32;
> s32 = (svint32_t)g32;
> }
> ```
>
> the above should only work when `-msve-vector-bits=128` but will currently be
> allowed for any N.
Ah, you're dead right. I think the next diff should fix this, but if there are
any more inconsistencies/ambiguities I'll fix them too. :)
================
Comment at: clang/test/Sema/aarch64-sve-explicit-casts.cpp:1-36
+// RUN: %clang_cc1 -triple aarch64-none-linux-gnu -target-feature +sve
-msve-vector-bits=512 -flax-vector-conversions=none
-fallow-half-arguments-and-returns -ffreestanding -fsyntax-only -verify %s
+
+#include <arm_sve.h>
+
+// SVE types cannot be C-style casted to one another.
+// "To avoid any ambiguity [between the two operations], the ACLE does not
allow C-style casting from one
+// vector type to another." ~ACLE Section 3.4 (Vector Types)
----------------
c-rhodes wrote:
> `clang/test/SemaCXX/sizeless-1.cpp` already contains a test checking C-style
> casts between distinct sizeless types aren't supported, I'm not sure if
> adding this is necessary.
ACK -- removed. :)
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D91262/new/
https://reviews.llvm.org/D91262
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