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List:       perl5-porters
Subject:    Re: Inlining Perl_foldEQ_locale and Perl_foldEQ_latin1
From:       Tomasz Konojacki <me () xenu ! pl>
Date:       2017-02-28 1:31:04
Message-ID: 20170228023102.1E5E.5C4F47F8 () xenu ! pl
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On Wed, 22 Feb 2017 23:12:35 -0600
Andy Lester <andy@petdance.com> wrote:

(...)
> they're only called via function pointers, so they can't be inlined.

Out of curiosity, I played with function inlining a bit. I simply
compiled following snippets with "gcc -S -O2" and inspected their
assembly outputs.

My gcc version is "gcc version 5.3.1 [DragonFly] Release/2015-12-04".

Here are my results:

=== CASE 1. foobar() was inlined ===

static __inline__ void foobar(void) {
        puts("foo");
        return;
}

int main() {
        void (*foobar_ptr)(void) = foobar;
	foobar_ptr(); 
        return 0;
}

=== CASE 2. foobar() wasn't inlined ===

static __inline__ void foobar(void) {
        puts("foo");
        return;
}

int main() {
        void (*foobar_ptr)(void) = NULL;

        /* condition that can't be resolved at compile-time */
        if (getc(stdin) == 'a')
                foobar_ptr = foobar;

        if (foobar_ptr)
                foobar_ptr();

        return 0;
}
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