[Bug c/95652] New: GCC 8.3.1 generates syntactically incorrect assembly code

[Bug c/95652] New: GCC 8.3.1 generates syntactically incorrect assembly code

[teo.samarzija at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95652

            Bug ID: 95652
           Summary: GCC 8.3.1 generates syntactically incorrect assembly
                    code
           Product: gcc
           Version: 8.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: teo.samarzija at gmail dot com
  Target Milestone: ---

Hey, guys!

So, I think I've found a bug in GCC 8.3.1 that occurs on Linux. Here is a
simple test case:

int printf(const char*,...);

float eax;

int main() {
    eax=7;
    printf("%lf\n",eax);
}

When compiled with "gcc -masm=intel -o test test.c", I get the error messages:

/tmp/ccGiemfM.s: Assembler messages:
/tmp/ccGiemfM.s:20: Error: invalid use of register
/tmp/ccGiemfM.s:21: Error: invalid use of register

It appears as though GCC 8.3.1 generates syntactically incorrect assembly code
for that.
Possibly related: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52554

[Bug c/95652] GCC 8.3.1 generates syntactically incorrect assembly code

[teo.samarzija at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95652

--- Comment #1 from Teo Samarzija <teo.samarzija at gmail dot com> ---
Possibly related, "as --version" prints:

GNU assembler (GNU Binutils) 2.33.1
Copyright (C) 2019 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or later.
This program has absolutely no warranty.
This assembler was configured for a target of `x86_64-pc-linux-gnu'.

[Bug target/95652] GCC 8.3.1 generates syntactically incorrect assembly code with -masm=intel

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95652

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|GCC 8.3.1 generates         |GCC 8.3.1 generates
                   |syntactically incorrect     |syntactically incorrect
                   |assembly code               |assembly code with
                   |                            |-masm=intel
         Depends on|                            |87986

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This looks closer to a dup of bug 87986.

Basically -masm=intel is not always working.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87986
[Bug 87986] Assembler errors w/ -masm=intel

[Bug target/95652] GCC 8.3.1 generates syntactically incorrect assembly code with -masm=intel

[teo.samarzija at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95652

--- Comment #3 from Teo Samarzija <teo.samarzija at gmail dot com> ---
(In reply to Andrew Pinski from comment #2)
> This looks closer to a dup of bug 87986.
> 
> Basically -masm=intel is not always working.

When does it occur? Maybe we can determine when it can occur and warn about it?
As far I can tell, it occurs when you use a reserved word in assembly as the
name of the global variable, and only under Linux (not under Windows, since the
names of global variables on Windows get prepended '_').
Why exactly does GCC use such a different convention for Windows and Linux?
Perhaps you can change that.
Besides, how does CLANG compile that same code fine, also under Linux and with
"-masm=intel"? Maybe you can copy the way CLANG does that.

[Bug target/95652] GCC 8.3.1 generates syntactically incorrect assembly code with -masm=intel

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95652

--- Comment #4 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Teo Samarzija from comment #3)
> Besides, how does CLANG compile that same code fine, also under Linux and
> with "-masm=intel"? Maybe you can copy the way CLANG does that.

Clang outputs:

        mov     dword ptr [rip + eax], 1088421888

which gld does't understand:

pr95652.s: Assembler messages:
pr95652.s:17: Error: `dword ptr [rip+eax]' is not a valid base/index expression

[Bug target/95652] GCC 8.3.1 generates syntactically incorrect assembly code with -masm=intel

[teo.samarzija at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95652

--- Comment #5 from Teo Samarzija <teo.samarzija at gmail dot com> ---
(In reply to Uroš Bizjak from comment #4)
> (In reply to Teo Samarzija from comment #3)
> > Besides, how does CLANG compile that same code fine, also under Linux and
> > with "-masm=intel"? Maybe you can copy the way CLANG does that.
> 
> Clang outputs:
> 
> 	mov	dword ptr [rip + eax], 1088421888
> 
> which gld does't understand:
> 
> pr95652.s: Assembler messages:
> pr95652.s:17: Error: `dword ptr [rip+eax]' is not a valid base/index
> expression

Which version of CLANG? CLANG 9.0 compiles the code in the opening post
correctly (under Linux and using Intel Syntax).

[Bug target/95652] GCC 8.3.1 generates syntactically incorrect assembly code with -masm=intel

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95652

--- Comment #6 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Teo Samarzija from comment #5)
> (In reply to Uroš Bizjak from comment #4)
> > (In reply to Teo Samarzija from comment #3)
> > > Besides, how does CLANG compile that same code fine, also under Linux and
> > > with "-masm=intel"? Maybe you can copy the way CLANG does that.
> > 
> > Clang outputs:
> > 
> > 	mov	dword ptr [rip + eax], 1088421888
> > 
> > which gld does't understand:
> > 
> > pr95652.s: Assembler messages:
> > pr95652.s:17: Error: `dword ptr [rip+eax]' is not a valid base/index
> > expression
> 
> Which version of CLANG? CLANG 9.0 compiles the code in the opening post
> correctly (under Linux and using Intel Syntax).

Try to assemble the produced assembly with gas.

[Bug target/95652] GCC 8.3.1 generates syntactically incorrect assembly code with -masm=intel

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95652
Bug 95652 depends on bug 87986, which changed state.

Bug 87986 Summary: Assembler errors w/ -masm=intel
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87986

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |DUPLICATE

[Bug target/95652] GCC 8.3.1 generates syntactically incorrect assembly code with -masm=intel

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95652

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |DUPLICATE

--- Comment #7 from H.J. Lu <hjl.tools at gmail dot com> ---
dup.

*** This bug has been marked as a duplicate of bug 53929 ***