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Re: Using __builtin_expect (likely/unlikely macros)

From: Konstantin Kharlamov
Subject: Re: Using __builtin_expect (likely/unlikely macros)
Date: Thu, 18 Apr 2019 11:43:33 +0300

Thanks. I wonder if "AVOID" macro may sound more clear about its intended use as "NEVER_RETURN" or "DIE"?

On Чт, Apr 18, 2019 at 01:25, Paul Eggert <address@hidden> wrote:
Konstantin Kharlamov wrote:
I was told that e.g. "cold" attribute can sometimes produce unbearably slow code https://gcc.gnu.org/ml/gcc-help/2019-01/msg00035.html

Although cold functions can be slow, it appears that overall it's a win for Emacs to mark _Noreturn error function declarations as cold: on my platform, 'make compile-always' ran about 1.3% faster. So I installed the attached patch into master. (Like Stefan, I'm wary of marking functions 'hot' so I didn't do that.)

This patch also adds a convenience macro AVOID for the now-common pattern '_Noreturn ATTRIBUTE_COLD void'.

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