[Bug rtl-optimization/64081] [5/6/7 Regression] r217827 prevents RTL loop unroll

[aldyh at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64081

--- Comment #31 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
(In reply to David Edelsohn from comment #30)
> .../src/src/configure --disable-werror --with-gmp=/opt/cfarm
> --with-libiconv-prefix=/opt/cfarm --disable-libstdcxx-pch
> --with-included-gettext
> 
> By the way, it's a lot faster if the src and build directories are in
> /scratch.  It's a ramdisk for transient, temporary files, so don't leave
> things there permanently.

Helps a little, but I now get the following during link:

/scratch/aldyh/bld/bisect/./prev-gcc/xg++ ... ...

c-family/c-ada-spec.o c-family/c-cilkplus.o c-family/array-notation-common.o
c-family/cilk.o c-family/c-ubsan.o default-c.o rs6000-c.o cc1plus-checksum.o
libbackend.a main.o tree-browser.o libcommon-target.a libcommon.a
../libcpp/libcpp.a ../libdecnumber/libdecnumber.a libcommon.a
../libcpp/libcpp.a ./../intl/libintl.a /opt/cfarm/lib/libiconv.a 
../libbacktrace/.libs/libbacktrace.a ../libiberty/libiberty.a
../libdecnumber/libdecnumber.a   -L/opt/cfarm/lib -lmpc -lmpfr -lgmp  
-L../zlib -lz
ld: 0711-380 STABSTRING ERROR: Symbol table entry 1152, object file c/c-lang.o
        Length of stabstring in .debug section is invalid.
        The stabstring is being deleted.
ld: 0711-380 STABSTRING ERROR: Symbol table entry 848, object file
c-family/stub-objc.o 
        Length of stabstring in .debug section is invalid.
        The stabstring is being deleted.
ld: 0711-380 STABSTRING ERROR: Symbol table entry 1172, object file attribs.o
        Length of stabstring in .debug section is invalid.
        The stabstring is being deleted.
ld: 0711-380 STABSTRING ERROR: Symbol table entry 870, object file c/c-errors.o
        Length of stabstring in .debug section is invalid.
        The stabstring is being deleted.
ld: 0711-380 STABSTRING ERROR: Symbol table entry 5636, object file c/c-decl.o
        Length of stabstring in .debug section is invalid.
        The stabstring is being deleted.

etc etc etc.