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From: "miladfarca at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/107736] New: call to a function, generated by inline asm, is
 off by one byte
Date: Thu, 17 Nov 2022 19:21:34 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: c
X-Bugzilla-Version: 12.2.0
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X-Bugzilla-Severity: normal
X-Bugzilla-Who: miladfarca at gmail dot com
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107736

            Bug ID: 107736
           Summary: call to a function, generated by inline asm, is off by
                    one byte
           Product: gcc
           Version: 12.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: miladfarca at gmail dot com
  Target Milestone: ---

Tested on Arm64, PPC64 and s390x with gcc 12.

```
const char num =3D 0;

void call();
asm( ".globl call            \n"
     ".type call, %function  \n"
     ".hidden call           \n"
     "call:                  \n"
     // Just return.
     "ret                    \n");

int main(){
 call();
 return 0;
}
```
TL;DR:
The instruction generated for `call();` is jumping to the address of `num` =
and
causing a crash as `num` is not an instruction, seems to be an alignment is=
sue?

Details:
- This doesn't happen on x64 and call is made to the correct address. It al=
so
does not happen with clang on either platforms (tested with version 6.0).

- gcc is putting "call" into .rodata section of memory including on x64. Not
sure if this is a separate bug or intentional. clang is putting it under
".text" as expected.

- gcc is incorrectly assuming `&num` is the address of `call` and jumping t=
o it
which is off by 1 byte.

- Workarounds include adding either ".text \n" or ".align 8" to the inline =
asm,
tho call should be made to the correct address even without them?=