[Bug target/114910] New: can't build a c6x cross compiler

[Bug target/114910] New: can't build a c6x cross compiler

[dkm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114910

            Bug ID: 114910
           Summary: can't build a c6x cross compiler
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dkm at gcc dot gnu.org
  Target Milestone: ---

Hello,

I'm building a c6x cross compiler using crosstool-ng (with newlib).

Configured with:

configure --build=x86_64-build_pc-linux-gnu --host=x86_64-build_pc-linux-gnu
--target=tic6x-elf --prefix=/root/crosstool-scratch/tic6x-elf
--exec_prefix=/root/crosstool-scratch/tic6x-elf
--with-local-prefix=/root/crosstool-scratch/tic6x-elf/tic6x-elf
--with-headers=/root/crosstool-scratch/tic6x-elf/tic6x-elf/include
--with-newlib --enable-threads=no --disable-shared
--with-pkgversion=crosstool-NG 1.26.0.72_810021d --enable-__cxa_atexit
--disable-libgomp --disable-libmudflap --disable-libmpx --disable-libssp
--disable-libquadmath --disable-libquadmath-support
--with-gmp=/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/buildtools
--with-mpfr=/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/buildtools
--with-mpc=/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/buildtools
--with-isl=/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/buildtools --enable-lto
--enable-target-optspace --disable-nls --enable-multiarch
--enable-languages=c,c++


The failing command:
/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/build/build-cc-gcc-final/./gcc/xgcc
-B/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/build/build-cc-gcc-final/./gcc/
-B/root/crosstool-scratch/tic6x-elf/tic6x-elf/bin/
-B/root/crosstool-scratch/tic6x-elf/tic6x-elf/lib/ -isystem
/root/crosstool-scratch/tic6x-elf/tic6x-elf/include -isystem
/root/crosstool-scratch/tic6x-elf/tic6x-elf/sys-include    -g -O2 -idirafter
/root/crosstool-scratch/tic6x-elf/tic6x-elf/include -g -Os -mbig-endian -O2  -g
-O2  -idirafter /root/crosstool-scratch/tic6x-elf/tic6x-elf/include -g -Os
-DIN_GCC -DCROSS_DIRECTORY_STRUCTURE  -W -Wall -Wno-narrowing -Wwrite-strings
-Wcast-qual -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition 
-isystem ./include  -msdata=none -g -DIN_LIBGCC2 -fbuilding-libgcc
-fno-stack-protector  -msdata=none -I. -I. -I../../.././gcc
-I/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/src/gcc/libgcc
-I/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/src/gcc/libgcc/.
-I/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/src/gcc/libgcc/../gcc
-I/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/src/gcc/libgcc/../include 
-DHAVE_CC_TLS -DUSE_EMUTLS  -o hardcfr.o -MT hardcfr.o -MD -MP -MF hardcfr.dep 
-c /mnt/dkm/git/crosstool-ng/.build/tic6x-elf/src/gcc/libgcc/hardcfr.c
-fvisibility=hidden -DHIDE_EXPORTS -save-temps --verbose-asm
hardcfr.s: Assembler messages:                                                  
hardcfr.s:164: Error: label not at start of execute packet                      
hardcfr.s:335: Error: label not at start of execute packet                      
hardcfr.s:340: Error: label not at start of execute packet                      
hardcfr.s:357: Error: label not at start of execute packet                      
hardcfr.s:381: Error: label not at start of execute packet  

with corresponding assembly:

 161   │     .loc 1 165 3 is_stmt 0
 162   │         callp   .s2 (consume_seq), B3   ;#
 163   │ .LVL9:
 164   │     ||  stw .d1t1   A7, *A4 ;# cfg_it__lsm.31, *cfg_it_8(D)
 165   │ ;#
/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/src/gcc/libgcc/hardcfr.c:167:  
return true;
 166   │     .loc 1 167 9

 335   │     ||  add .l1x    12, B15, A4 ;#,,
 336   │ ;#
/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/src/gcc/libgcc/hardcfr.c:287:   
consume_seq (&cfg_it);
 337   │     .loc 1 287 4
 338   │         callp   .s2 (consume_seq), B3   ;#
 339   │ .LVL15:
 340   │     ||  add .l1x    12, B15, A4 ;#,,
 341   │ .L14:
 342   │ .LBE66:
 343   │     .loc 1 274 35 is_stmt 1 discriminator 2
 344   │ .LVL16:
 345   │         b   .s1 .L12    ;#
 346   │     ||  add .d1 A10, 1, A10 ;# i,, i
 347   │         nop 5   ;#
 348   │     ;; jump to .L12 occurs  ;#
 349   │ .LVL17:
 350   │ .L13:
 351   │ .LBB67:
 352   │     .loc 1 292 4
 353   │ ;#
/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/src/gcc/libgcc/hardcfr.c:292:    if
(!check_seq (visited, &cfg_it))
 354   │     .loc 1 292 9 is_stmt 0
 355   │         callp   .s2 (check_seq), B3 ;#
 356   │ .LVL18:
 357   │     ||  add .l2 12, B15, B4 ;#,,
 358   │     ||  mv  .d1 A15, A4 ;# visited,
 359   │ ;#
/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/src/gcc/libgcc/hardcfr.c:292:    if
(!check_seq (visited, &cfg_it))
 360   │     .loc 1 292 7 discriminator 1
 361   │         extu    .s1 A4, 24, 24, A0  ;# tmp129, _1
 362   │     [A0]    b   .s1 .L15    ;#
 363   │         nop 5   ;#
 364   │     ;; condjump to .L15 occurs  ;#
 365   │ .LVL19:
 366   │ .L16:
 367   │     .loc 1 293 6 is_stmt 1
 368   │ .LBB64:
 369   │ .LBB65:
 370   │     .loc 1 262 3
 371   │         callp   .s2 (abort), B3 ;#
 372   │ .LVL20:
 373   │ .L15:
 374   │ .LBE65:
 375   │ .LBE64:
 376   │     .loc 1 296 4
 377   │ ;#
/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/src/gcc/libgcc/hardcfr.c:296:    if
(!check_seq (visited, &cfg_it))
 378   │     .loc 1 296 9 is_stmt 0
 379   │         callp   .s2 (check_seq), B3 ;#
 380   │ .LVL21:
 381   │     ||  add .l2 12, B15, B4 ;#,,
 382   │     ||  mv  .d1 A15, A4 ;# visited,
 383   │ ;#
/mnt/dkm/git/crosstool-ng/.build/tic6x-elf/src/gcc/libgcc/hardcfr.c:296:    if
(!check_seq (visited, &cfg_it))

[Bug target/114910] can't build a c6x cross compiler

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114910

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The only thing hardcfr.c uses special is __builtin_return_address and
__builtin_trap otherwise it is just normal C code ...

[Bug target/114910] can't build a c6x cross compiler

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114910

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
C6x Linux support was removed in 2021:
https://lore.kernel.org/linux-arm-kernel/20210120124812.2800027-1-arnd@kernel.org/T/

So maybe it is time to remove it from GCC too.

[Bug target/114910] can't build a c6x cross compiler

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114910

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
LVL labels comes from the debugging info when it comes to variable tracking.

This looks like it has always been broken ...

[Bug target/114910] can't build a c6x cross compiler

[dkm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114910

--- Comment #4 from Marc Poulhiès <dkm at gcc dot gnu.org> ---
Oh, so maybe I could use `-fno-var-tracking` to workaround the failure... I'll
try that, thanks.

[Bug target/114910] can't build a c6x cross compiler

[mikpelinux at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114910

--- Comment #5 from Mikael Pettersson <mikpelinux at gmail dot com> ---
I don't use crosstool-ng, but I have no problems building a cross to
c6x-unknown-elf with binutils-2.42, gcc-14.1.0-RC-20240430, and
newlib-4.4.0.20231231. (A cross to c6x-unknown-uclibc with uclibc-ng-1.0.47
experiences some problems not seen with gcc-13.2.0, but those are
compiler-warnings-that-now-are-errors rather than the assembler errors you
cited.)

[Bug target/114910] can't build a c6x cross compiler

[dkm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114910

--- Comment #6 from Marc Poulhiès <dkm at gcc dot gnu.org> ---
It fails with -Os.
It works with -O0, -O1, -O2, -O3 and -Os -fno-var-tracking.

Mikael, is it possible that you're not using -Os for target libs?

[Bug target/114910] can't build a c6x cross compiler

[mikpelinux at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114910

Mikael Pettersson <mikpelinux at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mikpelinux at gmail dot com

--- Comment #7 from Mikael Pettersson <mikpelinux at gmail dot com> ---
(In reply to Marc Poulhiès from comment #6)
> It fails with -Os.
> It works with -O0, -O1, -O2, -O3 and -Os -fno-var-tracking.
> 
> Mikael, is it possible that you're not using -Os for target libs?

I'm not adding -Os anywhere, just taking defaults.
Confirmed that adding --enable-target-optspace triggers the assembler error.

[Bug target/114910] can't build a c6x cross compiler

[mikpelinux at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114910

--- Comment #8 from Mikael Pettersson <mikpelinux at gmail dot com> ---
According to my git bisect, the assembler error started with

551935d11817dd5b139d66c36f62c0f0eba0db06 is the first new commit
commit 551935d11817dd5b139d66c36f62c0f0eba0db06
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Fri Oct 20 07:50:33 2023 -0300

    Control flow redundancy hardening

[Bug target/114910] can't build a c6x cross compiler

[dkm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114910

--- Comment #9 from Marc Poulhiès <dkm at gcc dot gnu.org> ---
Yes, sorry I should have added that in my original message (I did mention the
commit on IRC). This is the commit that introduces the hardcfr.c file that is
miscompiled. The error may be latent and bisecting should probably run the
above command with a copy of a preprocessed hardcfr.c ?