From: Dave.Martin@arm.com (Dave Martin)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: asm/unified.h: guard the IT macros against redefinition when using LTO
Date: Mon, 27 Jul 2015 12:16:15 +0100 [thread overview]
Message-ID: <20150727111613.GL10670@e103592.cambridge.arm.com> (raw)
In-Reply-To: <alpine.LFD.2.20.1507241739280.1806@knanqh.ubzr>
On Fri, Jul 24, 2015 at 05:42:15PM -0400, Nicolas Pitre wrote:
>
> With LTO, the intermediate representation for each .c file contains those
> global assembly macro definitions. When the lot is merged together during
> the final link, we get duplicate definition errors:
>
> [...]
> /tmp/cc48fUMp.s:42352: Error: Macro `it' was already defined
> /tmp/cc48fUMp.s:42354: Error: Macro `itt' was already defined
> /tmp/cc48fUMp.s:42356: Error: Macro `ite' was already defined
> [...]
>
> Guard those against redefinitions.
>
> Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
I have a vague memory of hitting this before, but LTO had other problems
at the time...
Another scary thing with LTO is asms that use directives like
.arch_extension, .fpu etc. that will stay active for the rest of the LTO
unit of nothing is done about it.
I can't remember whether that was resolved somehow.
Cheers
---Dave
> diff --git a/arch/arm/include/asm/unified.h b/arch/arm/include/asm/unified.h
> index a91ae49961..ee257a3de7 100644
> --- a/arch/arm/include/asm/unified.h
> +++ b/arch/arm/include/asm/unified.h
> @@ -103,6 +103,8 @@
> .endm
> #else /* !__ASSEMBLY__ */
> __asm__(
> +/* the .L_it_macros_defined guards against redefinition in the LTO case */
> +" .ifndef .L_it_macros_defined\n"
> " .macro it, cond\n"
> " .endm\n"
> " .macro itt, cond\n"
> @@ -132,7 +134,9 @@ __asm__(
> " .macro iteet, cond\n"
> " .endm\n"
> " .macro iteee, cond\n"
> -" .endm\n");
> +" .endm\n"
> +" .set .L_it_macros_defined,1\n"
> +" .endif");
> #endif /* __ASSEMBLY__ */
>
> #endif /* CONFIG_ARM_ASM_UNIFIED */
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2015-07-27 11:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-24 21:42 [PATCH] ARM: asm/unified.h: guard the IT macros against redefinition when using LTO Nicolas Pitre
2015-07-27 11:16 ` Dave Martin [this message]
2015-07-27 11:21 ` Russell King - ARM Linux
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