[Bug target/25919] New: Bootstrap failure with ICE in expand_compound_operation

["kkojima at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>]

The mainline compiler for sh4-*-linux-gnu fails during libgcc build:

/exp/ldroot/dodes/xsh-gcc-orig/./gcc/xgcc
-B/exp/ldroot/dodes/xsh-gcc-orig/./gcc/ -B/usr/local/sh4-unknown-linux-gnu/bin/
-B/usr/local/sh4-unknown-linux-gnu/lib/ -isystem
/usr/local/sh4-unknown-linux-gnu/include -isystem
/usr/local/sh4-unknown-linux-gnu/sys-include -O2  -O2 -g -O2  -DIN_GCC
-DCROSS_COMPILE   -W -Wall -Wwrite-strings -Wstrict-prototypes
-Wmissing-prototypes -Wold-style-definition -isystem ./include  -fpic
-DNO_FPSCR_VALUES -g -DHAVE_GTHR_DEFAULT -DIN_LIBGCC2 -D__GCC_FLOAT_NOT_NEEDED 
-I. -I. -I../../ORIG/trunk/gcc -I../../ORIG/trunk/gcc/.
-I../../ORIG/trunk/gcc/../include -I../../ORIG/trunk/gcc/../libcpp/include 
-I../../ORIG/trunk/gcc/../libdecnumber -I../libdecnumber -DL_negvsi2
-fvisibility=hidden -DHIDE_EXPORTS -c ../../ORIG/trunk/gcc/libgcc2.c -o
libgcc/./_negvsi2.o
../../ORIG/trunk/gcc/libgcc2.c: In function '__negvsi2':
../../ORIG/trunk/gcc/libgcc2.c:174: internal compiler error: in
expand_compound_operation, at combine.c:5644

A reduced testcase is:

void foo (int a)
{
  int w = -a;
  if (a >= 0 ? w > 0 : w < 0)
    bar ();
}

which fails to compile with -O.  This ICEs also on sh-elf with -O -m4.

Binary search shows that it starts to fail after the patch:

r109961 | bonzini | 2006-01-19 23:54:57 +0900 (Thu, 19 Jan 2006) | 13 lines

2006-01-19  Paolo Bonzini  <bonzini@gnu.org>

        * combine.c (try_combine): Do not worry about MEMs wrapped by USEs.
        (expand_compound_operation, expand_field_assignment): Fail if the
        bit lengths of an extract operation are out of range.
        (make_extraction): Compute wanted_inner_mode based on the position
        and length of the extraction.  Make it extraction_mode for non-constant
        positions, and do not modify offset in that case.  When generating a
        new MEM, use a mode that can hold the extraction while keeping correct
        alignment.  Remove code that supported MEMs wrapped by USEs.
        (simplify_shift_const_1, force_to_mode) <case USE>: Remove.


-- 
           Summary: Bootstrap failure with ICE in expand_compound_operation
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code, build, ice-checking
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kkojima at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: sh4-*-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25919