[Bug middle-end/18420] New: ICE compiling mesa at -O2

[Bug middle-end/18420] New: ICE compiling mesa at -O2

[jgrimm2 at us dot ibm dot com]

I'll add more details as they unfold, but wanted to get this posted into
bugzilla.  The autotester has been pretty flaky lately that I don't have a good
idea when this broke, but looks to have broken somewhere between Oct 29 and Nov
4.  I don't have data between those dates, but Nov 4. build did not compile
mesa.  SegFault doesn't happen at -O1.  

SegFault Building mesa. 

/opt/gcc-nightly/gcc/libexec/gcc/powerpc64-linux/4.0.0/cc1 -O2 context.c

context.c: In function gl_create_visual:
context.c:1082: internal compiler error: Segmentation fault
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://gcc.gnu.org/bugs.html> for instructions.

Watching in GDB shows. 

Analyzing compilation unit
Performing intraprocedural optimizations
Assembling functions:
 free_shared_state
 init_material
 gl_create_visual

Program received signal SIGSEGV, Segmentation fault.
note_stores (x=0x403d62f0, fun=0x10325090 <forget_old_reloads_1>, data=0x0)
    at /home/gccbuild/gcc_mline_anoncvs/gcc/gcc/rtlanal.c:1405
1405    /home/gccbuild/gcc_mline_anoncvs/gcc/gcc/rtlanal.c: No such file or
directory.
        in /home/gccbuild/gcc_mline_anoncvs/gcc/gcc/rtlanal.c

-- 
           Summary: ICE compiling mesa at -O2
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jgrimm2 at us dot ibm dot com
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug middle-end/18420] ICE compiling mesa at -O2

[jgrimm2 at us dot ibm dot com]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
 GCC target triplet|                            |powerpc64-linux
            Summary|ICE compiling mesa at -O2   |ICE compiling mesa at -O2
            Version|unknown                     |4.0.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|middle-end                  |rtl-optimization
           Keywords|                            |ice-on-valid-code
            Summary|ICE compiling mesa at -O2   |[4.0 Regression] ICE
                   |                            |compiling mesa at -O2
   Target Milestone|---                         |4.0.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[jgrimm2 at us dot ibm dot com]

------- Additional Comments From jgrimm2 at us dot ibm dot com  2004-11-10 22:50 -------
Testcase reduced from the mesa context.c file.

Compiling this with -O2 segfaults on linux-powerpc64 segfaults.


typedef unsigned int size_t;
extern void *malloc (size_t __size) __attribute__ ((__malloc__));
extern void abort(void);

struct _abc {
  int ebc;
};

void xxx ( float rscale,
           float gscale,
           float bscale,
           float ascale)
{
   struct _abc *vis;

   if (rscale > 255.0) abort();
   if (gscale > 255.0) abort();
   if (bscale > 255.0) abort();
   if (ascale > 255.0) abort();

   vis = (struct _abc *) malloc(sizeof(struct _abc) );

   if (rscale==255.0F && gscale==255.0F
     && bscale==255.0F && ascale==255.0F) {
     vis->ebc = 1;
   }

}


 



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-10 22:57 -------
Confirmed, also happens on powerpc-darwin with -O2 -fPIC.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
 GCC target triplet|powerpc64-linux             |powerpc64-linux, powerpc-
                   |                            |darwin
   Last reconfirmed|0000-00-00 00:00:00         |2004-11-10 22:57:11
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-10 23:04 -------
Hmm, someone did an emit_rtx and did not end_sequence as the insn looks like:
(insn 143 0 0 (set (nil)
        (reg:CC 75 cr7)) -1 (nil)
    (nil))



-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pinskia at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-10 23:45 -------
I was wrong in the sense that is the right RTL except that nill is wrong and is being overwritten.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-10 23:49 -------
in gen_reload, we do:
    emit_insn (gen_rtx_SET (VOIDmode, out, in));

but somehow the set gets changed for the out to be nil.  Note out and in are correct here.
After this we don't get the correct insn in the sequence at all.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-10 23:58 -------
Never mind my comment about "emit_insn (gen_rtx_SET " because we are not calling that but
7530        emit_insn (gen_move_insn (out, in));


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-11 00:04 -------
The bug is in emit_move_insn_1, we set the out side to null for some reason.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-11 00:30 -------
We used to change the mode to CC from CCFP but now we don't.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-11 00:31 -------
This is the rtl we used to produce:
(insn 144 69 75 8 (set (reg:CC 75 cr7)
        (reg:CC 30 r30 [125])) 336 {*movcc_internal1} (nil)
    (nil))  <-- this the insn which we are messing up now.

(jump_insn:HI 75 144 80 8 (set (pc)
        (if_then_else (ne (reg:CCFP 75 cr7)
                (const_int 0 [0x0]))
            (label_ref 115)
            (pc))) 527 {*rs6000.md:13676} (insn_list:REG_DEP_ANTI 67 (insn_list:REG_DEP_ANTI 69 
(insn_list:REG_DEP_ANTI 68 (nil))))
    (expr_list:REG_BR_PROB (

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-11 00:34 -------
Found the patch which caused the problem:
        * simplify-rtx.c (simplify_gen_subreg): Fail if simplify_subreg
        has failed when passed a hard register.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |uweigand at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-11 00:47 -------
This patch fixes it:
Index: simplify-rtx.c
===============================================================
====
RCS file: /cvs/gcc/gcc/gcc/simplify-rtx.c,v
retrieving revision 1.207
diff -u -p -r1.207 simplify-rtx.c
--- simplify-rtx.c	28 Oct 2004 12:47:21 -0000	1.207
+++ simplify-rtx.c	11 Nov 2004 00:47:26 -0000
@@ -3790,7 +3790,8 @@ simplify_gen_subreg (enum machine_mode o
     return newx;
 
   if (GET_CODE (op) == SUBREG || GET_MODE (op) == VOIDmode
-      || (REG_P (op) && REGNO (op) < FIRST_PSEUDO_REGISTER))
+      || (REG_P (op) && REGNO (op) < FIRST_PSEUDO_REGISTER
+          && GET_MODE_SIZE (innermode) != GET_MODE_SIZE (innermode)))
     return NULL_RTX;
 
   return gen_rtx_SUBREG (outermode, op, byte);


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-11 01:04 -------
Even though this patch fixes it, it is not the right fix as simplify_subreg should just return a change in 
the mode rather than return null.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-11 01:49 -------
The problem is that the register is r30 (which is the FRAME_POINTER_REGNUM) and reload is not 
complete at this point, maybe this is not the correct check.

((reload_completed && !frame_pointer_needed)
	  || (REGNO (op) != FRAME_POINTER_REGNUM
#if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
	      && REGNO (op) != HARD_FRAME_POINTER_REGNUM
#endif
	     ))

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-11 02:04 -------
Jan you added that code to simplify_subreg but I could not figure out why it was really added except 
that it effected x86_64 (when bootstrapped with -fomit-frame-pointer).  Note in this case the mode the 
modes are the same size which is unlike the case you found.

Reference: 
http://gcc.gnu.org/ml/gcc-patches/2001-05/msg01737.html
http://gcc.gnu.org/ml/gcc-patches/2001-05/msg01729.html

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hubicka at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-11 02:10 -------
The reason why we are not using r31 at least on darwin is because that is the PIC register.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[wilson at gcc dot gnu dot org]

------- Additional Comments From wilson at gcc dot gnu dot org  2004-11-11 05:19 -------
This looks like the same problem as 18294 which is an ia64-hpux bootstrap
failure.  In that PR, I suggested that simplify_gen_subreg should just create
the subreg for a hard register when simplify_subreg does not, but I haven't
looked at this very closely.  This problem occurs early, during virtual register
instantiation.

The patch in comment #11 is flawed.  It has
+          && GET_MODE_SIZE (innermode) != GET_MODE_SIZE (innermode)))
which will always be false.  Probably one of these was meant to be outermode.

If we are trying to prevent reload from creating subregs, then maybe the
reload_completed check could instead be !reload_in_progress.  This is just a
random guess though.  I haven't tried looking at Ulrich Weigand's patch yet.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[uweigand at gcc dot gnu dot org]

------- Additional Comments From uweigand at gcc dot gnu dot org  2004-11-25 18:33 -------
Now that RTH's validate_subreg patch is in, I guess the right fix for
this problem might be to always return a SUBREG in simplify_gen_subreg
unless that SUBREG is actually invalid.

What do you think of this patch:

Index: simplify-rtx.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/simplify-rtx.c,v
retrieving revision 1.211
diff -c -p -r1.211 simplify-rtx.c
*** simplify-rtx.c      24 Nov 2004 00:09:03 -0000      1.211
--- simplify-rtx.c      25 Nov 2004 18:29:38 -0000
*************** simplify_gen_subreg (enum machine_mode o
*** 3782,3792 ****
    if (newx)
      return newx;

!   if (GET_CODE (op) == SUBREG || GET_MODE (op) == VOIDmode
!       || (REG_P (op) && REGNO (op) < FIRST_PSEUDO_REGISTER))
!     return NULL_RTX;
!
!   if (validate_subreg (outermode, innermode, op, byte))
      return gen_rtx_SUBREG (outermode, op, byte);

    return NULL_RTX;
--- 3782,3788 ----
    if (newx)
      return newx;

!   if (REG_P (op) && validate_subreg (outermode, innermode, op, byte))
      return gen_rtx_SUBREG (outermode, op, byte);

    return NULL_RTX;


(B.t.w. shouldn't validate_subreg reject non-REG inputs itself?)

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2004-11-28 13:03 -------
Subject: Bug 18420

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	uweigand@gcc.gnu.org	2004-11-28 13:02:53

Modified files:
	gcc            : ChangeLog simplify-rtx.c 

Log message:
	PR rtl-optimization/18420
	* simplify-rtx.c (simplify_gen_subreg): Revert 2004-10-28 change.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.6599&r2=2.6600
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/simplify-rtx.c.diff?cvsroot=gcc&r1=1.211&r2=1.212



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-28 15:40 -------
Fixed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[jgrimm2 at us dot ibm dot com]

------- Additional Comments From jgrimm2 at us dot ibm dot com  2004-11-30 14:49 -------
Verified this fixed mesa too. 

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |VERIFIED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

[Bug rtl-optimization/18420] [4.0 Regression] ICE compiling mesa at -O2

[seurer at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=18420

seurer at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|VERIFIED                    |CLOSED
                 CC|                            |seurer at gcc dot gnu.org

--- Comment #21 from seurer at gcc dot gnu.org ---
This was fixed long ago.  Closing.