| Issue |
86711
|
| Summary |
[AArch64] Wrong code for i64 to f32 vector conversion
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
hvdijk
|
Please consider:
```c++
#include <stdio.h>
typedef unsigned long ul;
typedef float f;
typedef unsigned long ul1 __attribute__((ext_vector_type(1)));
typedef float f1 __attribute__((ext_vector_type(1)));
__attribute__((noinline))
f converts(ul v) { return (f)v; }
__attribute__((noinline))
f1 convertv(ul1 v) { return __builtin_convertvector(v, f1); }
int main(void) {
ul s = 0xffffff7fffffffff;
ul1 v = 0xffffff7fffffffff;
printf("%A %A\n", converts(s), convertv(v)[0]);
}
```
Expected output, and actual output with `clang -O0`:
```
0X1.FFFFFEP+63 0X1.FFFFFEP+63
```
Actual output with `clang -O3`:
```
0X1.FFFFFEP+63 0X1P+64
```
This happens because the vector conversion from i64 to f32 is performed as a vector conversion from i64 to f64, and then a conversion from f64 to f32. But both of these conversions round, and the first conversion does not preserve enough information for the second conversion to produce the correct result.
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