Re: [PATCH] x86: LLVMLinux: Wrap -mno-80387 with cc-option

From: Ingo Molnar
Date: Tue Apr 22 2014 - 05:42:32 EST



* Behan Webster <behanw@xxxxxxxxxxxxxxxxxx> wrote:

> On 04/21/14 23:05, Ingo Molnar wrote:
> >* behanw@xxxxxxxxxxxxxxxxxx <behanw@xxxxxxxxxxxxxxxxxx> wrote:
> >
> >>From: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx>
> >>
> >>Wrap -mno-80387 gcc options with cc-option so they don't break clang.
> >>
> >>Signed-off-by: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx>
> >>---
> >> arch/x86/Makefile | 4 +++-
> >> 1 file changed, 3 insertions(+), 1 deletion(-)
> >>
> >>diff --git a/arch/x86/Makefile b/arch/x86/Makefile
> >>index d1b7c37..ce6ad7e 100644
> >>--- a/arch/x86/Makefile
> >>+++ b/arch/x86/Makefile
> >>@@ -83,7 +83,9 @@ else
> >> KBUILD_CFLAGS += -m64
> >> # Don't autogenerate traditional x87, MMX or SSE instructions
> >>- KBUILD_CFLAGS += -mno-mmx -mno-sse -mno-80387 -mno-fp-ret-in-387
> >>+ KBUILD_CFLAGS += -mno-mmx -mno-sse
> >>+ KBUILD_CFLAGS += $(call cc-option,-mno-80387)
> >>+ KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)
> >Is there a clang equivalent option that inhibits all things FPU opcode
> >generation by the compiler?
> Not that I've found yet. Still investigating.
>
> >That's the general purpose of -no-80387.
> Yes, I understand what this is trying to accomplish. At this point
> I'd just like this new code not to break the use of clang with
> v3.15.

Agreed.

> I will submit another patch which adds similar functionality when
> compiled with clang once I have that answer.

Thanks!

Ingo
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