[Bug target/101737] SH4 -Os causes internal compiler error when building pixman

[pietro.gcc at sociotechnical dot xyz via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101737

pietro <pietro.gcc at sociotechnical dot xyz> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pietro.gcc at sociotechnical 
dot x
                   |                            |yz

--- Comment #4 from pietro <pietro.gcc at sociotechnical dot xyz> ---
Using the sh4-linux cross compiler from debian unstable:

$ sh4-linux-gnu-gcc-14 -v
Using built-in specs.
COLLECT_GCC=sh4-linux-gnu-gcc-14
COLLECT_LTO_WRAPPER=/usr/libexec/gcc-cross/sh4-linux-gnu/14/lto-wrapper
Target: sh4-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 14-20240201-3'
--with-bugurl=file:///usr/share/doc/gcc-14/README.Bugs
--enable-languages=c,ada,c++,fortran,objc,obj-c++,rust --prefix=/usr
--with-gcc-major-version-only --program-suffix=-14 --enable-shared
--enable-linker-build-id --libexecdir=/usr/libexec --without-included-gettext
--enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/
--enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-libstdcxx-backtrace
--enable-gnu-unique-object --disable-libsanitizer --disable-libquadmath
--disable-libquadmath-support --enable-plugin --with-system-zlib
--enable-multiarch --disable-werror --with-cpu=sh4
--with-multilib-list=m4,m4-nofpu --enable-checking=yes
--build=aarch64-linux-gnu --host=aarch64-linux-gnu --target=sh4-linux-gnu
--program-prefix=sh4-linux-gnu- --includedir=/usr/sh4-linux-gnu/include
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 14.0.1 20240131 (experimental) [master r14-8680-g2f14c0dbb78]
(Debian 14-20240201-3)

I'm able to reproduce the issue with the attached test source file:

# sh4-linux-gnu-gcc-14 -c -Os test.c
during RTL pass: split1
pixman-fast-path.c: In function
'fast_composite_scaled_nearest_8888_565_cover_OVER':
pixman-fast-path.c:1201: internal compiler error: Segmentation fault
0xde6a7b crash_signal
        ../../src/gcc/toplev.cc:317
0x11ed95c sh_is_nott_insn(rtx_insn const*)
        ../../src/gcc/config/sh/sh.cc:11770
0x16f82df gen_split_13(rtx_insn*, rtx_def**)
        ../../src/gcc/config/sh/sh.md:951
0x946e5b try_split(rtx_def*, rtx_insn*, int)
        ../../src/gcc/emit-rtl.cc:3941
0xd3223f split_insn
        ../../src/gcc/recog.cc:3405
0xd37a97 split_all_insns()
        ../../src/gcc/recog.cc:3509
0xd37b8b execute
        ../../src/gcc/recog.cc:4433

But I'm not able to reproduce using the code from comment #2. I used creduce to
get a simple test case:

$ cat test2.c
int a;
void b() {
  int c;
  short *d = (short *)b;
  while (--c) {
    int e = a, f, g;
    while ((e -= 4) >= 0) {
      f += g;
      d++;
    }
    if (e & 2)
      f += g;
    if (e & 1)
      *d = f;
  }
}

$ sh4-linux-gnu-gcc-14 -c -Os test2.c
during RTL pass: split1
test2.c: In function 'b':
test2.c:16:1: internal compiler error: Segmentation fault
   16 | }
      | ^
0xde6a7b crash_signal
        ../../src/gcc/toplev.cc:317
0x11ed95c sh_is_nott_insn(rtx_insn const*)
        ../../src/gcc/config/sh/sh.cc:11770
0x16f82df gen_split_13(rtx_insn*, rtx_def**)
        ../../src/gcc/config/sh/sh.md:951
0x946e5b try_split(rtx_def*, rtx_insn*, int)
        ../../src/gcc/emit-rtl.cc:3941
0xd3223f split_insn
        ../../src/gcc/recog.cc:3405
0xd37a97 split_all_insns()
        ../../src/gcc/recog.cc:3509
0xd37b8b execute
        ../../src/gcc/recog.cc:4433