[Bug target/124701] New: ICE: in replace_regs, at config/aarch64/aarch64-early-ra.cc:3238 with -fnon-call-exceptions -fharden-control-flow-redundancy -mearly-ra=all and _Decimal64

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124701

            Bug ID: 124701
           Summary: ICE: in replace_regs, at
                    config/aarch64/aarch64-early-ra.cc:3238 with
                    -fnon-call-exceptions -fharden-control-flow-redundancy
                    -mearly-ra=all and _Decimal64
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
            Target: aarch64-unknown-linux-gnu

Created attachment 64084
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=64084&action=edit
reduced testcase

Compiler output:
$ aarch64-unknown-linux-gnu-gcc -fnon-call-exceptions
-fharden-control-flow-redundancy -mearly-ra=all testcase.c 
during RTL pass: early_ra
testcase.c: In function 'foo':
testcase.c:2:26: internal compiler error: in replace_regs, at
config/aarch64/aarch64-early-ra.cc:3238
    2 | void foo() { d += d / 2; }
      |                          ^
0x289316d internal_error(char const*, ...)
        /repo/gcc-trunk/gcc/diagnostic-global-context.cc:787
0xc9d41f fancy_abort(char const*, int, char const*)
        /repo/gcc-trunk/gcc/diagnostics/context.cc:1813
0xa00298 replace_regs
        /repo/gcc-trunk/gcc/config/aarch64/aarch64-early-ra.cc:3238
0x1a7ea06 apply_allocation
        /repo/gcc-trunk/gcc/config/aarch64/aarch64-early-ra.cc:3480
0x1a7ea06 process_region
        /repo/gcc-trunk/gcc/config/aarch64/aarch64-early-ra.cc:3535
0x1a82ffe process_blocks
        /repo/gcc-trunk/gcc/config/aarch64/aarch64-early-ra.cc:3891
0x1a82ffe execute
        /repo/gcc-trunk/gcc/config/aarch64/aarch64-early-ra.cc:3910
0x1a82ffe execute
        /repo/gcc-trunk/gcc/config/aarch64/aarch64-early-ra.cc:3946
/repo/gcc-trunk/binary-trunk-20260330021621-r16-8325-g59c407c71a6648-checking-yes-rtl-df-extra-aarch64/bin/../libexec/gcc/aarch64-unknown-linux-gnu/16.0.1/cc1
-quiet -iprefix
/repo/gcc-trunk/binary-trunk-20260330021621-r16-8325-g59c407c71a6648-checking-yes-rtl-df-extra-aarch64/bin/../lib/gcc/aarch64-unknown-linux-gnu/16.0.1/
testcase.c -quiet -dumpdir a- -dumpbase testcase.c -dumpbase-ext .c
-mearly-ra=all -mlittle-endian -mabi=lp64 -fnon-call-exceptions
-fharden-control-flow-redundancy -o /tmp/ccPkl4kD.s
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

$ aarch64-unknown-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-aarch64/bin/aarch64-unknown-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-20260330021621-r16-8325-g59c407c71a6648-checking-yes-rtl-df-extra-aarch64/bin/../libexec/gcc/aarch64-unknown-linux-gnu/16.0.1/lto-wrapper
Target: aarch64-unknown-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--with-sysroot=/usr/aarch64-unknown-linux-gnu --build=x86_64-pc-linux-gnu
--host=x86_64-pc-linux-gnu --target=aarch64-unknown-linux-gnu
--with-ld=/usr/bin/aarch64-unknown-linux-gnu-ld
--with-as=/usr/bin/aarch64-unknown-linux-gnu-as --enable-libsanitizer
--disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-20260330021621-r16-8325-g59c407c71a6648-checking-yes-rtl-df-extra-aarch64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 16.0.1 20260330 (experimental) (GCC)