[Bug rtl-optimization/126635] [17 regression] Miscompiled compiler in LTO build [r17-2301-gf7a75a1506d91f]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126635

--- Comment #6 from Andreas Schwab <[email protected]> ---
Using this compiler to build gcc (for any target) results in this crash:

g++ -c   -O2 -funwind-tables -fasynchronous-unwind-tables
-fstack-clash-protection -Werror=return-type -g     -DIN_GCC
-DCROSS_DIRECTORY_STRUCTURE   -fno-exceptions -fno-rtti
-fasynchronous-unwind-tables -W -Wall -Wno-error=narrowing -Wwrite-strings
-Wcast-qual -Wmissing-format-attribute -Wconditionally-supported
-Woverloaded-virtual -pedantic -Wno-long-long -Wno-variadic-macros
-Wno-overlength-strings  -DHAVE_CONFIG_H  -DGENERATOR_FILE -I. -Ibuild
-I../../gcc -I../../gcc/build -I../../gcc/../include 
-I../../gcc/../libcpp/include  \
        -o build/read-md.o ../../gcc/read-md.cc
during GIMPLE pass: store-merging
../../gcc/read-md.cc: In member function ‘file_location
md_reader::get_current_location() const’:
../../gcc/read-md.cc:1191:1: internal compiler error: Segmentation fault
 1191 | md_reader::get_current_location () const
      | ^~~~~~~~~
0x12c562cb diagnostics::context::diagnostic_impl(rich_location*,
diagnostics::metadata const*, diagnostics::option_id, char const*, char**,
diagnostics::kind)
        ???:0
0x12c32293 internal_error(char const*, ...)
        ???:0
0x10ced0f4 gsi_insert_seq_after(gimple_stmt_iterator*, gimple*,
gsi_iterator_update)
        ???:0
/usr/lib64/gcc/powerpc64le-suse-linux/17/cc1plus -quiet -I . -I build -I
../../gcc -I ../../gcc/build -I ../../gcc/../include -I
../../gcc/../libcpp/include -D_GNU_SOURCE -D IN_GCC -D
CROSS_DIRECTORY_STRUCTURE -D HAVE_CONFIG_H -D GENERATOR_FILE
../../gcc/read-md.cc -msecure-plt -quiet -dumpdir build/ -dumpbase read-md.cc
-dumpbase-ext .cc -mtune=power9 -mcpu=power8 -g -O2 -Werror=return-type -Wextra
-Wall -Wno-error=narrowing -Wwrite-strings -Wcast-qual
-Wsuggest-attribute=format -Wconditionally-supported -Woverloaded-virtual=2
-Wpedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings
-funwind-tables -fstack-clash-protection -fno-exceptions -fno-rtti
-fasynchronous-unwind-tables -o /tmp/ccBh66MG.s