[Bug c/114310] New: [aarch64] __sync_val_compare_and_swap fails on __int128_t with newval = 0

["p.nguyen at yahooinc dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114310

            Bug ID: 114310
           Summary: [aarch64] __sync_val_compare_and_swap fails on
                    __int128_t with newval = 0
           Product: gcc
           Version: 8.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: p.nguyen at yahooinc dot com
  Target Milestone: ---

I am encountering a compiler error when __sync_val_compare_and_swap is passed
__int128_t types and newval = 0. It does not occur when newval is not zero, or
a const volatile variable with the value of 0 is passed to it. This only fails
when using built-in aarch64 LSE instructions, enabled with -march=armv8.1-a or
greater. It does not have problems with -march=armv8-a. 

I have been able to replicate the issue on GCC 8.5.0, 10.3.1, 11.2.1, 11.4.0,
12.2.1 and 13.1.1 on linux-aarch64. 

I have attached a trivial test case, and also have a small result set on
godbolt: https://godbolt.org/z/ex9adPTPc

I am showing the output from Ubuntu 22.04.4 LTS with gcc 11.4.0

The command line options are: gcc -v -march=armv8.1-a -save-temps test.c

The complete compiler output is: 

Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/aarch64-linux-gnu/11/lto-wrapper
Target: aarch64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
11.4.0-1ubuntu1~22.04' --with-bugurl=file:///usr/share/doc/gcc-11/README.Bugs
--enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2 --prefix=/usr
--with-gcc-major-version-only --program-suffix=-11
--program-prefix=aarch64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-libquadmath --disable-libquadmath-support --enable-plugin
--enable-default-pie --with-system-zlib --enable-libphobos-checking=release
--with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch
--enable-fix-cortex-a53-843419 --disable-werror --enable-checking=release
--build=aarch64-linux-gnu --host=aarch64-linux-gnu --target=aarch64-linux-gnu
--with-build-config=bootstrap-lto-lean --enable-link-serialization=2
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.4.0 (Ubuntu 11.4.0-1ubuntu1~22.04) 
COLLECT_GCC_OPTIONS='-v' '-march=armv8.1-a' '-save-temps' '-mlittle-endian'
'-mabi=lp64' '-dumpdir' 'a-'
 /usr/lib/gcc/aarch64-linux-gnu/11/cc1 -E -quiet -v -imultiarch
aarch64-linux-gnu test.c -march=armv8.1-a -mlittle-endian -mabi=lp64
-fpch-preprocess -fasynchronous-unwind-tables -fstack-protector-strong -Wformat
-Wformat-security -fstack-clash-protection -o a-test.i
ignoring nonexistent directory "/usr/local/include/aarch64-linux-gnu"
ignoring nonexistent directory
"/usr/lib/gcc/aarch64-linux-gnu/11/include-fixed"
ignoring nonexistent directory
"/usr/lib/gcc/aarch64-linux-gnu/11/../../../../aarch64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/aarch64-linux-gnu/11/include
 /usr/local/include
 /usr/include/aarch64-linux-gnu
 /usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-march=armv8.1-a' '-save-temps' '-mlittle-endian'
'-mabi=lp64' '-dumpdir' 'a-'
 /usr/lib/gcc/aarch64-linux-gnu/11/cc1 -fpreprocessed a-test.i -quiet -dumpdir
a- -dumpbase test.c -dumpbase-ext .c -march=armv8.1-a -mlittle-endian
-mabi=lp64 -version -fasynchronous-unwind-tables -fstack-protector-strong
-Wformat -Wformat-security -fstack-clash-protection -o a-test.s
GNU C17 (Ubuntu 11.4.0-1ubuntu1~22.04) version 11.4.0 (aarch64-linux-gnu)
        compiled by GNU C version 11.4.0, GMP version 6.2.1, MPFR version
4.1.0, MPC version 1.2.1, isl version isl-0.24-GMP

GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C17 (Ubuntu 11.4.0-1ubuntu1~22.04) version 11.4.0 (aarch64-linux-gnu)
        compiled by GNU C version 11.4.0, GMP version 6.2.1, MPFR version
4.1.0, MPC version 1.2.1, isl version isl-0.24-GMP

GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 52ed857e9cd110e5efaa797811afcfbb
test.c: In function ‘main’:
test.c:6:1: error: unrecognizable insn:
    6 | }
      | ^
(insn 12 11 13 2 (parallel [
            (set (reg:TI 92 [ _1 ])
                (mem/v:TI (reg:DI 99) [-1  S16 A128]))
            (set (mem/v:TI (reg:DI 99) [-1  S16 A128])
                (unspec_volatile:TI [
                        (reg:TI 92 [ _1 ])
                        (const_int 0 [0])
                        (const_int 32773 [0x8005])
                    ] UNSPECV_ATOMIC_CMPSW))
        ]) "test.c":4:31 -1
     (nil))
during RTL pass: vregs
test.c:6:1: internal compiler error: in extract_insn, at recog.c:2770
0xaeb1c7 internal_error(char const*, ...)
        ???:0
0xae3d4b fancy_abort(char const*, int, char const*)
        ???:0
0x72c083 _fatal_insn(char const*, rtx_def const*, char const*, int, char
const*)
        ???:0
0x72c0b7 _fatal_insn_not_found(rtx_def const*, char const*, int, char const*)
        ???:0
0xef957b extract_insn(rtx_insn*)
        ???:0
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <file:///usr/share/doc/gcc-11/README.Bugs> for instructions.


The preprocessed file is as follows: 

# 0 "test.c"
# 0 "<built-in>"
# 0 "<command-line>"
# 1 "/usr/include/stdc-predef.h" 1 3 4
# 0 "<command-line>" 2
# 1 "test.c"
int main(void) {
      __int128_t src = 0;
      __int128_t dst = 0;
      *(__int128_t *)&(dst) = __sync_val_compare_and_swap((__int128_t *)&(src),
(__int128_t) 10, 0);
  return 0;
}