On Mon, Jan 18, 2021 at 11:56 AM Adrian Ratiu <adrian.ratiu@xxxxxxxxxxxxx> wrote:
From: Nathan Chancellor <natechancellor@xxxxxxxxx>
Drop warning because kernel now requires GCC >= v4.9 after commit 6ec4476ac825 ("Raise gcc version requirement to 4.9") and clarify that -ftree-vectorize now always needs enabling for GCC by directly testing the presence of CONFIG_CC_IS_GCC.
Another reason to remove the warning is that Clang exposes itself as GCC < 4.6 so it triggers the warning about GCC which doesn't make much sense and risks misleading users.
As a side-note remark, -fttree-vectorize is on by default in Clang, but it currently does not work (see linked issues).
Link: https://github.com/ClangBuiltLinux/linux/issues/496 Link: https://github.com/ClangBuiltLinux/linux/issues/503 Reported-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx> Signed-off-by: Adrian Ratiu <adrian.ratiu@xxxxxxxxxxxxx>
Shouldn't there be a check for whatever minimum version of clang produces optimized code now? As I understand it, the warning was originally meant to complain about both old gcc and any version of clang, while waiting for a new version of clang to produce vectorized code.
Has that happened now?
Arnd