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SubjectRe: [PATCH v7 2/2] tty: add rpmsg driver
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On 3/26/20 1:01 AM, Joe Perches wrote:
> On Wed, 2020-03-25 at 14:31 +0100, Jiri Slaby wrote:
>> The question was exactly about that: can a compiler optimize it to a
>> bare number or will strlen call remain there?
>
> $ cat str.c
> #include <string.h>
>
> int foo(void)
> {
> return strlen("abc");
> }
>
> $ gcc -c -O2 str.c
> $ objdump -d str.o
> str.o: file format elf64-x86-64
>
>
> Disassembly of section .text:
>
> 0000000000000000 <foo>:
> 0: f3 0f 1e fa endbr64
> 4: b8 03 00 00 00 mov $0x3,%eax
> 9: c3 retq
>
>
same result with arm gcc using -O1 or -Og:

str.o: file format elf32-littlearm


Disassembly of section .text:

00000000 <foo>:
0: e3a00003 mov r0, #3
4: e12fff1e bx lr

So in conclusion replacing sizeof by srlen even if not optimized in -o0, right?

Thanks,
Arnaud

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