[PATCH] D87607: [clang][aarch64] Support implicit casts between GNU and SVE vectors

[Cullen Rhodes via Phabricator via cfe-commits]

c-rhodes added inline comments.


================
Comment at: clang/test/Sema/attr-arm-sve-vector-bits.c:233-234
 
+svint64_t to_svint64_t__from_gnu_int32_t(gnu_int32_t x) { return x; } // expected-error-re {{returning 'gnu_int32_t' (vector of {{[0-9]+}} 'int32_t' values) from a function with incompatible result type 'svint64_t' (aka '__SVInt64_t')}}
+gnu_int32_t from_svint64_t__to_gnu_int32_t(svint64_t x) { return x; } // expected-error-re {{returning 'svint64_t' (aka '__SVInt64_t') from a function with incompatible result type 'gnu_int32_t' (vector of {{[0-9]+}} 'int32_t' values)}}
+
----------------
c-rhodes wrote:
> I expected similar diagnostics when casting between GNU and fixed-length SVE vectors where the element type doesn't match but the vector size is equal but that wasn't the case. Since no functional changes were necessary to support casting between these types I tried the following:
> ```#include <stdint.h>
> 
> #define N 128
> 
> typedef float float32_t;
> typedef double float64_t;
> 
> typedef float32_t gnu_float32_t __attribute__((vector_size(N/8)));
> typedef float64_t gnu_float64_t __attribute__((vector_size(N/8)));
> 
> gnu_float32_t foo(gnu_float64_t x) { return (gnu_float32_t)x; }
> gnu_float64_t bar(gnu_float32_t x) { return (gnu_float64_t)x; }```
> 
> It seems Clang considers this implicit cast valid whereas GCC doesn't, even with lax vector conversions enabled.
I pasted the wrong example, the explicit cast shouldn't be there:
```#include <stdint.h>

#define N 128

typedef float float32_t;
typedef double float64_t;

typedef float32_t gnu_float32_t __attribute__((vector_size(N/8)));
typedef float64_t gnu_float64_t __attribute__((vector_size(N/8)));

gnu_float32_t foo(gnu_float64_t x) { return x; }
gnu_float64_t bar(gnu_float32_t x) { return x; }```


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D87607/new/

https://reviews.llvm.org/D87607