| Issue |
64632
|
| Summary |
[clang] -msse2, -mavx, (etc) do not fail when not supported by the target
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
nekopsykose
|
on aarch64:
clang:
```console
/ # clang main.c -msse2
clang-16: warning: argument unused during compilation: '-msse2' [-Wunused-command-line-argument]
```
gcc:
```console
/ # gcc main.c -msse2
gcc: error: unrecognized command-line option '-msse2'
```
i don't know which one is actually meant to be correct. but for configure tests that don't use -Werror ([like here](https://github.com/kdave/btrfs-progs/blob/bb0ca35245858f17a6ced97aade1dd8d70f9c9d7/configure.ac#L52)) this makes the build system think this is actually supported, and later sets a define that isn't actually then valid.
that's perhaps weird use (i never found other breakage aside from this case, so i assume usually one tests such things slightly differently or at least paired with Werror), but this specific -m value use doesn't seem like it has value being ignored instead of hard-failing?
the challenge here is disambiguating "-msse not used for some reason on x86_64 where it exists" and "-msse not used because platform doesn't have it whatsoever (different -m args for platform simd entirely)"
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