Re: GCC Inline assembly - immediate integer operand emit without $

[Sam <samueldotj@xxxxxxxxx>]

On Fri, Aug 31, 2012 at 3:08 PM, Segher Boessenkool
<segher@xxxxxxxxxxxxxxxxxxx> wrote:
>> The following example tries to create an elf section with three
>> integers using inline assembly.
>>     asm (".pushsection .test\n"
>>          ".long 0, %0, %1\n"
>>          ".popsection"
>>          :: "i"(ENUM_VAL2), "i"(2));
>>
>> But it fails because gcc emits the assembly code with $.
>> Is there a way to instruct gcc to avoid emitting $?
>>     .pushsection .test
>>      .long 0, $1, $2 <<<<<<
>>      .popsection
>
>
>     asm (".pushsection .test\n"
>          ".long 0, %P0, %P1\n"
>
>          ".popsection"
>          :: "i"(ENUM_VAL2), "i"(2));
>
> but this is quite hackish, %P isn't meant for this.  On newer GCC
> versions there is %p, which is better.

Thanks - it is what exactly I wanted.

$ objdump -s -j .test

a.out:     file format elf64-x86-64

Contents of section .test:
 0000 00000000 01000000 02000000           ............

>
> Can't you just do this with attribute((section(".test")))?
No. That actual asm block pushes  text location along with the constant passed.
something like
    asm ("0:\n"
         "nop\n"
         ".pushsection .test\n"
         ".long 0b, %P0\n"
         ".popsection"
         :: "i"(ENUM_VAL2));