[Bug rtl-optimization/40086] New: [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[Bug rtl-optimization/40086] New: [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

With revision 147269 this test passed.
>From revision 147274 and on, this test has failed as follows:

Running /tmp/rforall_1b/gcc/gcc/testsuite/gfortran.dg/dg.exp ...
...
FAIL: gfortran.dg/forall_1.f90  -O1  execution test

With the message in the logfile being:
Executing on host: /tmp/rforall_1b/gccobj/gcc/testsuite/gfortran/../../gfortran
-B/tmp/rforall_1b/gccobj/gcc/testsuite/gfortran/../../
/tmp/rforall_1b/gcc/gcc/testsuite/gfortran.dg/forall_1.f90   -O1  
-pedantic-errors   -isystem
/tmp/rforall_1b/gccobj/cris-elf/./newlib/targ-include -isystem
/tmp/rforall_1b/gcc/newlib/libc/include
-B/tmp/rforall_1b/gccobj/cris-elf/./libgloss/cris/
-L/tmp/rforall_1b/gccobj/cris-elf/./libgloss/cris
-L/tmp/rforall_1b/gcc/libgloss/cris 
-B/tmp/rforall_1b/gccobj/cris-elf/./newlib/
-L/tmp/rforall_1b/gccobj/cris-elf/./newlib -sim3 
-B/tmp/rforall_1b/gccobj/cris-elf/./libgfortran/.libs
-L/tmp/rforall_1b/gccobj/cris-elf/./libgfortran/.libs
-L/tmp/rforall_1b/gccobj/cris-elf/./libiberty  -lm   -o ./forall_1.exe   
(timeout = 300)
PASS: gfortran.dg/forall_1.f90  -O1  (test for excess errors)
program stopped with signal 6.

FAIL: gfortran.dg/forall_1.f90  -O1  execution test

(that is, abort is called)

Author of patches in suspect revision range CC:ed.


-- 
           Summary: [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90  -O1
                    execution
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: hp at gcc dot gnu dot org
  GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: cris-axis-elf


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

------- Comment #1 from hp at gcc dot gnu dot org  2009-05-10 00:04 -------
Created an attachment (id=17839)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17839&action=view)
slightly reduced test-case

It's the second abort call that's executed, but removing the first causes the
test to pass.  Here's a slightly reduced case, removing the parts after the
abort call.  Tell me if you need further assistance.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[bonzini at gnu dot org]

------- Comment #2 from bonzini at gnu dot org  2009-05-10 17:22 -------
Well, if only -O1 fails now, it is almost definitely my patch.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

------- Comment #3 from hp at gcc dot gnu dot org  2009-05-10 19:26 -------
(In reply to comment #2)
> Well, if only -O1 fails now, it is almost definitely my patch.

It definitely is, there are no other authors in that revision range! :)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[bonzini at gnu dot org]

------- Comment #4 from bonzini at gnu dot org  2009-05-11 10:15 -------
I meant my fwprop patch. :-)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[bonzini at gnu dot org]

------- Comment #5 from bonzini at gnu dot org  2009-05-11 12:28 -------
It's a latent bug somewhere, possibly in delayed branch scheduling?  fwprop1
does a single copy propagation which is trivially valid.

Analyzing -O1 -fno-delayed-branch vs. -O1 -fno-delayed-branch
-fno-forward-propagate, I'm pretty sure that every change remains valid up to
the dbr pass.  In particular, as i said, the effect of fwprop is trivial:

 L154:
   155 NOTE_INSN_BASIC_BLOCK
   156 r94:SI=r97:SI+0x1
-  157 r92:SI=r94:SI
   158 r126:SI=r8:SI-0xa
   159 cc0=[r126:SI+r97:SI]
   160 pc={(cc0==0x0)?L165:pc}
@@ -913,7 +906,7 @@
   161 NOTE_INSN_BASIC_BLOCK
   162 r127:SI=r8:SI-0x41
   163 r128:SI=r97:SI<<0x2
-  164 [r127:SI+r128:SI]=r92:SI
+  164 [r127:SI+r128:SI]=r94:SI
 L165:
   166 NOTE_INSN_BASIC_BLOCK
   168 cc0=cmp(r94:SI,0xa)

Also after register allocation there is no major difference, except that
without fwprop r92 is allocated to the (special?) register $srp, giving:

 L154:
   155 NOTE_INSN_BASIC_BLOCK
-  265 r9:SI=r13:SI
-  156 r9:SI=r9:SI+0x1
-  157 srp:SI=r9:SI
+  265 r13:SI=r9:SI
+  156 r13:SI=r13:SI+0x1
   266 r12:SI=r8:SI
   158 r12:SI=r12:SI-0xa
       REG_EQUIV: r8:SI-0xa
-  159 cc0=[r12:SI+r13:SI]
+  159 cc0=[r12:SI+r9:SI]
   160 pc={(cc0==0x0)?L165:pc}
       REG_BR_PROB: 0x1388
   161 NOTE_INSN_BASIC_BLOCK
@@ -1025,14 +1009,14 @@
   267 r12:SI=r8:SI
   243 r12:SI=r12:SI-0x41
       REG_EQUIV: r8:SI-0x41
-  164 [r13:SI*0x4+r12:SI]=srp:SI
+  164 [r9:SI*0x4+r12:SI]=r13:SI
 L165:
   166 NOTE_INSN_BASIC_BLOCK
-  168 cc0=cmp(r9:SI,0xa)
+  168 cc0=cmp(r13:SI,0xa)
   169 pc={(cc0==0x0)?L167:pc}
       REG_BR_PROB: 0x38d
   172 NOTE_INSN_BASIC_BLOCK
-   55 r13:SI=r9:SI
+   55 r9:SI=r13:SI
   237 pc=L154


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

------- Comment #6 from hp at gcc dot gnu dot org  2009-05-11 19:40 -------
(In reply to comment #4)
> I meant my fwprop patch. :-)

That's the patch in that revision range, yes... (FWIW, $SRP is the subroutine
return pointer, valid to use as data storage if saved.)

It's a bit unclear whether L154 is fall-through && R9 live and holding "r97"
before your second dump snippet, and the first diff (both reversed, I believe?)
doesn't tell whether *all* uses of r92 have been replaced.

I'll have a look myself.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

------- Comment #7 from hp at gcc dot gnu dot org  2009-05-11 20:47 -------
(In reply to comment #5)
> It's a latent bug somewhere, possibly in delayed branch scheduling?

With vs. without -fno-delayed-branch at 147274 seems to justify this blame.
Ugh.
I'll see if I can nail it.  But, for the record, having said that, still your
exposure, your bug. ;)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

------- Comment #8 from hp at gcc dot gnu dot org  2009-05-11 21:14 -------
I see at least one invalid dbr transformation.  Assuming you can read m68k
assembler, I'm sure you'll have no problem gripping the important parts of:

        subq 25,$r13
        test.b [$r13+$r9.b]
-       beq .L6
-       nop
+       beq .L33
+       addq 1,$r9
+
        subu.b 100,$r13
        clear.d [$r13+$r9.d]
-.L6:
        addq 1,$r9
+.L33:

That's right, dbr moves an increment of $r9 *over a use* (the "clear.d
[$r13+$r9.d]" is like "[r9:SI*0x4+r13:SI]=0").  Bah.  Over to gdb...


-- 

hp at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2009-05-11 21:14:13
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

------- Comment #9 from hp at gcc dot gnu dot org  2009-05-11 21:19 -------
(In reply to comment #8)
> dbr moves an increment of $r9 *over a use*

Actually, "copies", not "moves", which is even worse (sort of; like "how could
it be worse").  I'll take it.


-- 

hp at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |hp at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2009-05-11 21:14:13         |2009-05-11 21:19:04
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[bonzini at gnu dot org]

------- Comment #10 from bonzini at gnu dot org  2009-05-12 05:58 -------
Thanks H-P.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

------- Comment #11 from hp at gcc dot gnu dot org  2009-05-13 00:09 -------
Two insns above the assembly sequence for the delay-slot fill quoted above,
there used to be a "clear.d $r9".  That insn is moved into a delay-slot in the
first reorg_pass_number round by fill_simple_delay_slots (0).  As a dataflow
marker, the insn is replaced by a USE:
(insn 308 204 94 (use (insn/s 52 286 310 (set (reg:SI 9 r9 [orig:95 ivtmp.101 ]
[95])
                (const_int 0 [0x0])) 38 {*movsi_internal} (expr_list:REG_EQUAL
(const_int 0 [0x0])
                (nil)))) -1 (nil))

The bug seems to be that at the next relax_delay_slots (first) call, the USE
placeholder is removed for some reason.  The df live-regs info is then
incorrect and at the next (the last) round, when fill_eager_delay_slots () is
called, it does the invalid delay-slot filling quoted above.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

------- Comment #12 from hp at gcc dot gnu dot org  2009-05-13 13:09 -------
The relax_delay_slots (first) call finds that there's a branch to a redundant
insn that it can eliminate.  It does this by redirecting the branch to a new or
existing label and deleting the insn, or rather move it and make it a USE-mark
at the "new" label.  When doing this, the old USE-mark quoted above (not
related to the new USE-mark by other means being before it in the execution
path) is now deemed unreachable and removed by jump.c:delete_related_insns. 
So, it seems a solution will include propagating existing USE-marks when
redirecting branch labels, perhaps in reorg_redirect_jump or update_block.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

------- Comment #13 from hp at gcc dot gnu dot org  2009-05-14 00:12 -------
By chance I stumbled upon an old fix I did some years ago in which I changed a
use of next_active_insn to next_real insn (to avoid skipping USE insns).  You
can see it in comments referring to a now-deleted "main" use (the references
gone stale).  This PR is just the same bug in another place! I think I'll be
going for the same solution; it will reduce the number of filled delay-slots or
redirected jumps and removed redundant insns, but presumably safer as it will
not include moving or duplicating the USE insns.  It would also be solved by a
reorg rewrite, in which USE insns wouldn't be sprinkled into the insn stream,
sometimes ignored, sometimes incorrectly...


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

------- Comment #14 from hp at gcc dot gnu dot org  2009-05-14 01:18 -------
Created an attachment (id=17861)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17861&action=view)
patch for just the bug at hand.

This patch just changes the next_active_insn for the exposure in this PR.
I think most uses of next_active_insn in reorg.c and resource.c should be
changed to next_real_insn.  Or reorg.c rewritten, at least to not use in-stream
liveness markers like those USE insns.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

------- Comment #15 from hp at gcc dot gnu dot org  2009-05-14 11:17 -------
patch posted after testing


-- 

hp at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                URL|                            |http://gcc.gnu.org/ml/gcc-
                   |                            |patches/2009-
                   |                            |05/msg00811.html
           Keywords|                            |patch, wrong-code


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[rguenth at gcc dot gnu dot org]

-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.5.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[rguenth at gcc dot gnu dot org]

-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[bonzini at gnu dot org]

------- Comment #16 from bonzini at gnu dot org  2009-05-24 08:04 -------
Subject: Re:  [4.5 Regression]: cris-elf 
        gfortran.dg/forall_1.f90 -O1 execution

I'll note that, even though the bug is very rare and no testcase is
known in general, it affects every target with delay slots -- so it
should be P2 IMO.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

------- Comment #17 from hp at gcc dot gnu dot org  2009-08-16 00:31 -------
For the record, the gfortran.dg/forall_1.f90 regression has been covered since
r150588.  (And I'm still on the hook to address the concerns with the posted
patch.)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

------- Comment #18 from hp at gcc dot gnu dot org  2009-11-30 07:13 -------
Subject: Bug 40086

Author: hp
Date: Mon Nov 30 07:13:21 2009
New Revision: 154751

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=154751
Log:
        PR rtl-optimization/40086
        * reorg.c (relax_delay_slots): When looking for redundant insn at
        the branch target, use next_real_insn, not next_active_insn.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/reorg.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[hp at gcc dot gnu dot org]

------- Comment #19 from hp at gcc dot gnu dot org  2009-11-30 07:19 -------
a comment


-- 

hp at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[danglin at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

--- Comment #21 from John David Anglin <danglin at gcc dot gnu.org> 2011-05-24 18:44:38 UTC ---
Author: danglin
Date: Tue May 24 18:44:35 2011
New Revision: 174132

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=174132
Log:
    PR rtl-optimization/49007
    Backport from mainline:
    2009-11-30  Hans-Peter Nilsson  <hp@axis.com>

    PR rtl-optimization/40086
    * reorg.c (relax_delay_slots): When looking for redundant insn at
    the branch target, use next_real_insn, not next_active_insn.


Modified:
    branches/gcc-4_3-branch/gcc/ChangeLog
    branches/gcc-4_3-branch/gcc/reorg.c

[Bug rtl-optimization/40086] [4.5 Regression]: cris-elf gfortran.dg/forall_1.f90 -O1 execution

[danglin at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40086

--- Comment #20 from John David Anglin <danglin at gcc dot gnu.org> 2011-05-23 22:31:59 UTC ---
Author: danglin
Date: Mon May 23 22:31:55 2011
New Revision: 174090

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=174090
Log:
    PR rtl-optimization/49007
    Backport from mainline:
    2009-11-30  Hans-Peter Nilsson  <hp@axis.com>

    PR rtl-optimization/40086
    * reorg.c (relax_delay_slots): When looking for redundant insn at
    the branch target, use next_real_insn, not next_active_insn.


Modified:
    branches/gcc-4_4-branch/gcc/ChangeLog
    branches/gcc-4_4-branch/gcc/reorg.c