On Mon, Jun 18, 2018 at 08:43:04AM -0500, Siddhesh Poyarekar wrote:
> r217431 changed X30 as caller-saved in CALL_USE_REGISTERS because of
> which this comment about X30 not being marked as call-clobbered is no
> longer accurate.
Is the second paragraph is still relevant to how we define EPILOGUE_USES?
Possibly I'd rewrite the comment to explain the behaviour around calls and
how they interact with x30.
It seems like the right thing to do, but I can't shake the feeling we'd be
losing useful information here.
James
> * config/aarch64/aarch64.h: Remove obsolete comment.
> ---
> diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
> index 976f9afae54..df9fb31aa64 100644
> --- a/gcc/config/aarch64/aarch64.h
> +++ b/gcc/config/aarch64/aarch64.h
> @@ -303,15 +303,6 @@ extern unsigned aarch64_architecture_version;
> register. GCC internally uses the poly_int variable aarch64_sve_vg
> instead. */
>
> -/* Note that we don't mark X30 as a call-clobbered register. The idea is
> - that it's really the call instructions themselves which clobber X30.
> - We don't care what the called function does with it afterwards.
> -
> - This approach makes it easier to implement sibcalls. Unlike normal
> - calls, sibcalls don't clobber X30, so the register reaches the
> - called function intact. EPILOGUE_USES says that X30 is useful
> - to the called function. */
> -
> #define FIXED_REGISTERS \
> { \
> 0, 0, 0, 0, 0, 0, 0, 0, /* R0 - R7 */ \
> --
> 2.14.4
>
