linux-kernel - Re: [PATCH v5 8/8] LoongArch: Add ORC stack unwinder support

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Message-ID: <e860c6d42dc67e2c662c732ce56309874456f21b.camel@xry111.site>
Date:   Sun, 03 Dec 2023 21:20:07 +0800
From:   Xi Ruoyao <xry111@...111.site>
To:     Tiezhu Yang <yangtiezhu@...ngson.cn>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Huacai Chen <chenhuacai@...nel.org>
Cc:     loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 8/8] LoongArch: Add ORC stack unwinder support

On Wed, 2023-11-29 at 21:07 +0800, Tiezhu Yang wrote:
> +KBUILD_AFLAGS			+= $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma)-mthin-add-sub)
> +KBUILD_CFLAGS			+= $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma)-mthin-add-sub)
> +
> +ifdef CONFIG_OBJTOOL
> +KBUILD_CFLAGS			+= -fno-optimize-sibling-calls -fno-jump-tables -falign-functions=4 -falign-labels=4
> +endif

I still hate regressing the optimization with a passion.

And -falign-labels=4 implies -falign-functions=4 so at least we can
remove -falign-functions=4.

And in GCC >= 14 the defaults are -falign-labels=16 and -falign-
functions=32.  These values are determined by benchmarking on LA464 so
I'd suggest using them (maybe unless CONFIG_CC_OPTIMIZE_FOR_SIZE).

-- 
Xi Ruoyao <xry111@...111.site>
School of Aerospace Science and Technology, Xidian University