On 10/07/2020 09:20, Xi Ruoyao wrote:
> On 2020-07-09 17:11 +0100, Jonny Grant wrote:
>> Due to the const' on the 'int i = 1;' gcc removes all the other branches
>> unfortunately.
>> (I'd rather not use any special build macro to remove the 'const' just to see
>> all the generated redundant assembler.)
>>
>> main:
>> push rbp
>> mov rbp, rsp
>> mov DWORD PTR [rbp-4], 1
>> mov eax, 1
>> pop rbp
>> ret
>
> Use -O0.
>
> It's nothing to do with that `const`. With something like -O2 it would be
> optimized away even if there is no `const`. `i` is a local variable and the
> compiler can determine that nobody can modify it.
Hello
Today's trunk on godbolt.org, shows same optimised out with -O0
#1 with x86-64 gcc (trunk)
g++ (Compiler-Explorer-Build) 11.0.0 20200709 (experimental)
main:
push rbp
mov rbp, rsp
mov DWORD PTR [rbp-4], 1
mov eax, 1
pop rbp
ret
Maybe I am misunderstanding. Is there a way to keep all redundant assembler in gcc latest version trunk?
Thank you
Jonny
