[Bug c/15464] New: ICE: unable to find a register to spill in class `DREG'

["coyote at coyotegulch dot com" <gcc-bugzilla at gcc dot gnu dot org>]

When compiling the attached program with

gcc -c -std=gnu99 -O1 -march=pentium4 -fschedule-insns -funit-at-a-time
-fno-inline bug_reg_spill.c

GCC mainline (3.5.0 20040514) expresses an ICE:

bug_reg_spill.c: In function `decode':
bug_reg_spill.c:135: error: unable to find a register to spill in class `DREG'
bug_reg_spill.c:135: error: this is the insn:
(insn 52 51 53 14 (parallel [
            (set (reg:SI 0 ax [95])
                (udiv:SI (reg:SI 0 ax [93])
                    (reg/v:SI 4 si [orig:70 range ] [70])))
            (set (reg:SI 96)
                (umod:SI (reg:SI 0 ax [93])
                    (reg/v:SI 4 si [orig:70 range ] [70])))
            (clobber (reg:CC 17 flags))
        ]) 190 {udivmodsi4} (insn_list 51 (insn_list 42 (nil)))
    (expr_list:REG_DEAD (reg:SI 0 ax [93])
        (expr_list:REG_UNUSED (reg:CC 17 flags)
            (expr_list:REG_UNUSED (reg:SI 96)
                (nil)))))
bug_reg_spill.c:135: confused by earlier errors, bailing out


I believe this is different from bug 15318, but the causes might be similar. 

This ICE does not occur on my X86_64 system, or if the -march=pentium4 flag is
removed from the compile command.

-- 
           Summary: ICE: unable to find a register to spill in class `DREG'
           Product: gcc
           Version: 3.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: coyote at coyotegulch dot com
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux
  GCC host triplet: i686-pc-linux
GCC target triplet: i686-pc-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15464