[Bug rtl-optimization/71150] New: ICE on valid code at -O1 and above in 64-bit mode on x86_64-linux-gnu in lra_eliminate_reg_if_possible, at lra-eliminations.c:1402

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71150

            Bug ID: 71150
           Summary: ICE on valid code at -O1 and above in 64-bit mode on
                    x86_64-linux-gnu in lra_eliminate_reg_if_possible, at
                    lra-eliminations.c:1402
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu
  Target Milestone: ---

The following code causes an ICE when compiled with the current gcc trunk at
-O1 and above on x86_64-linux-gnu in the 64-bit mode.


$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto
--prefix=/usr/local/gcc-trunk --disable-bootstrap
Thread model: posix
gcc version 7.0.0 20160516 (experimental) [trunk revision 236272] (GCC)
$
$ gcc-trunk -O0 -c small.c
$
$ gcc-trunk -O1 -c small.c
small.c: In function ‘fn2’:
small.c:11:1: internal compiler error: in lra_eliminate_reg_if_possible, at
lra-eliminations.c:1402
 }
 ^
0xa5d0fe lra_eliminate_reg_if_possible(rtx_def**)
        ../../gcc-source-trunk/gcc/lra-eliminations.c:1402
0xa4d9ee in_class_p
        ../../gcc-source-trunk/gcc/lra-constraints.c:266
0xa51031 process_addr_reg
        ../../gcc-source-trunk/gcc/lra-constraints.c:1320
0xa54b11 process_address_1
        ../../gcc-source-trunk/gcc/lra-constraints.c:2983
0xa55ce9 process_address
        ../../gcc-source-trunk/gcc/lra-constraints.c:3233
0xa55ce9 curr_insn_transform
        ../../gcc-source-trunk/gcc/lra-constraints.c:3534
0xa5a736 lra_constraints(bool)
        ../../gcc-source-trunk/gcc/lra-constraints.c:4530
0xa46484 lra(_IO_FILE*)
        ../../gcc-source-trunk/gcc/lra.c:2290
0x9fd839 do_reload
        ../../gcc-source-trunk/gcc/ira.c:5381
0x9fd839 execute
        ../../gcc-source-trunk/gcc/ira.c:5565
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
$


--------------------------------------


long a;

void fn1 () {}

void
fn2 ()
{ 
  unsigned b = (unsigned long) fn1;
  if (a ^ b)
    a--;
}