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

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

[coyote at coyotegulch dot com]

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

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

[coyote at coyotegulch dot com]

------- Additional Comments From coyote at coyotegulch dot com  2004-05-15 15:39 -------
Created an attachment (id=6302)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=6302&action=view)
Testcase that demonstrates the bug

I'll try to reduce this further later today.

-- 


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

[Bug rtl-optimization/15464] ICE: unable to find a register to spill in class `DREG'

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-05-15 16:17 -------
Confirmed, known problem in x86, -fschedule-insns schedule instructions before register allocation 
which is known to ICE on x86.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
  BugsThisDependsOn|                            |9085
             Status|UNCONFIRMED                 |NEW
          Component|c                           |rtl-optimization
     Ever Confirmed|                            |1
           Keywords|                            |ice-on-valid-code
   Last reconfirmed|0000-00-00 00:00:00         |2004-05-15 16:17:49
               date|                            |


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

[Bug rtl-optimization/15464] ICE: unable to find a register to spill in class `DREG'

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-08-15 03:12 -------
Fixed.
: Search converges between 2004-07-06-trunk (#480) and 2004-07-07-trunk (#481).

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |3.5.0


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