[Bug rtl-optimization/37514] New: [4.4 Regression] Wrong code generated for 20021120-1.c with -O3 -fomit-frame-pointer on sh4

[Bug rtl-optimization/37514] New: [4.4 Regression] Wrong code generated for 20021120-1.c with -O3 -fomit-frame-pointer on sh4

[kkojima at gcc dot gnu dot org]

gcc.c-torture/execute/20021120-1.c execution fails with -m4 -ml -O3
-fomit-frame-pointer on sh-elf.  gf[0] is wrongly set to 1.0
by foo.  It started to fail after the IRA merge.


-- 
           Summary: [4.4  Regression] Wrong code generated for 20021120-1.c
                    with -O3 -fomit-frame-pointer on sh4
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kkojima at gcc dot gnu dot org
GCC target triplet: sh-elf


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37514

[Bug rtl-optimization/37514] [4.4 Regression] Wrong code generated for 20021120-1.c with -O3 -fomit-frame-pointer on sh4

[kkojima at gcc dot gnu dot org]

------- Comment #1 from kkojima at gcc dot gnu dot org  2008-09-14 00:38 -------
Created an attachment (id=16315)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=16315&action=view)
a test case

I've attached a slightly reduced testcase.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37514

[Bug rtl-optimization/37514] [4.4 Regression] Wrong code generated for 20021120-1.c with -O3 -fomit-frame-pointer on sh4

[kkojima at gcc dot gnu dot org]

------- Comment #2 from kkojima at gcc dot gnu dot org  2008-09-14 00:38 -------
Here is the problematic part of the generated code:

        mov.w   .L240,r7
        add     #4,r1
        mov.w   .L241,r6
        add     #4,r3
        add     r15,r7
        fmov.s  @r7,fr14
        add     r15,r6
        add     #4,r14
        mov.l   .L242,r7
        fmov.s  fr14,@r2
        add     #4,r13
        fmov.s  @r6,fr14
        add     #4,r12
        add     #4,r11
        mov.l   .L243,r6
        fmov.s  fr14,@r2
        ...
.L240:
        .short  368
.L241:
        .short  364

where r2 is set to &gf[0].   Thus the float value in [r15+368]
is written to gf[0] and then the float value in [r15+364] is
stored to gf[0] again.  The corresponding rtl dump in .sched1
is:

(insn:HI 828 826 832 6 xxx.c:42 (parallel [
            (set (mem/s/v:SF (reg/f:SI 434) [3 gf+0 S4 A32])
                (reg/v:SF 289 [ f00 ]))
            (use (reg/v:PSI 151 ))
            (clobber (scratch:SI))
        ]) 205 {movsf_ie} (expr_list:REG_DEAD (reg/f:SI 434)
        (expr_list:REG_DEAD (reg/v:SF 289 [ f00 ])
            (nil))))

(insn:HI 832 828 836 6 xxx.c:42 (parallel [
            (set (mem/s/v:SF (reg/f:SI 551) [3 gf+4 S4 A32])
                (reg/v:SF 288 [ f10 ]))
            (use (reg/v:PSI 151 ))
            (clobber (scratch:SI))
        ]) 205 {movsf_ie} (expr_list:REG_DEAD (reg/f:SI 551)
        (expr_list:REG_DEAD (reg/v:SF 288 [ f10 ])
            (nil))))

which looks to be right.  OTOH that in .ira is:

(insn 2024 826 2025 5 xxx.c:42 (set (reg:SI 7 r7)
        (const_int 368 [0x170])) 175 {movsi_ie} (nil))

(insn 2025 2024 2026 5 xxx.c:42 (set (reg:SI 7 r7)
        (plus:SI (reg:SI 7 r7)
            (reg/f:SI 15 r15))) 35 {*addsi3_compact} (expr_list:REG_EQUIV
(plus:SI (reg/f:SI 15 r15)
            (const_int 368 [0x170]))
        (nil)))

(insn 2026 2025 828 5 xxx.c:42 (parallel [
            (set (reg:SF 78 fr14)
                (mem/c:SF (reg:SI 7 r7) [7 f00+0 S4 A32]))
            (use (reg/v:PSI 151 ))
            (clobber (scratch:SI))
        ]) 205 {movsf_ie} (nil))

(insn:HI 828 2026 2028 5 xxx.c:42 (parallel [
            (set (mem/s/v:SF (reg/f:SI 2 r2 [434]) [3 gf+0 S4 A32])
                (reg:SF 78 fr14))
            (use (reg/v:PSI 151 ))
            (clobber (scratch:SI))
        ]) 205 {movsf_ie} (nil))

(insn 2028 828 2029 5 xxx.c:42 (set (reg:SI 6 r6)
        (const_int 364 [0x16c])) 175 {movsi_ie} (nil))

(insn 2029 2028 2030 5 xxx.c:42 (set (reg:SI 6 r6)
        (plus:SI (reg:SI 6 r6)
            (reg/f:SI 15 r15))) 35 {*addsi3_compact} (expr_list:REG_EQUIV
(plus:SI (reg/f:SI 15 r15)
            (const_int 364 [0x16c]))
        (nil)))

(insn 2030 2029 832 5 xxx.c:42 (parallel [
            (set (reg:SF 78 fr14)
                (mem/c:SF (reg:SI 6 r6) [8 f10+0 S4 A32]))
            (use (reg/v:PSI 151 ))
            (clobber (scratch:SI))
        ]) 205 {movsf_ie} (nil))

(insn:HI 832 2030 2033 5 xxx.c:42 (parallel [
            (set (mem/s/v:SF (reg/f:SI 2 r2 [434]) [3 gf+4 S4 A32])
                (reg:SF 78 fr14))
            (use (reg/v:PSI 151 ))
            (clobber (scratch:SI))
        ]) 205 {movsf_ie} (nil))

which shows that IRA uses r434 both for gf+0 and gf+4.
I've confirmed that the error goes away with -fno-ira-share-spill-slots.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37514

[Bug rtl-optimization/37514] [4.4 Regression] Wrong code generated for 20021120-1.c with -O3 -fomit-frame-pointer on sh4

[kkojima at gcc dot gnu dot org]

------- Comment #3 from kkojima at gcc dot gnu dot org  2008-09-14 00:51 -------
I'd like to add Vlad to the CC list.


-- 

kkojima at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vmakarov at redhat dot com
            Summary|[4.4  Regression] Wrong code|[4.4 Regression] Wrong code
                   |generated for 20021120-1.c  |generated for 20021120-1.c
                   |with -O3 -fomit-frame-      |with -O3 -fomit-frame-
                   |pointer on sh4              |pointer on sh4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37514

[Bug rtl-optimization/37514] [4.4 Regression] Wrong code generated for 20021120-1.c with -O3 -fomit-frame-pointer on sh4

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ra
   Target Milestone|---                         |4.4.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37514

[Bug rtl-optimization/37514] [4.4 Regression] Wrong code generated for 20021120-1.c with -O3 -fomit-frame-pointer on sh4

[jakub at gcc dot gnu dot org]

-- 

jakub at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37514

[Bug rtl-optimization/37514] [4.4 Regression] Wrong code generated for 20021120-1.c with -O3 -fomit-frame-pointer on sh4

[kkojima at gcc dot gnu dot org]

------- Comment #4 from kkojima at gcc dot gnu dot org  2008-11-10 23:11 -------
Subject: Bug 37514

Author: kkojima
Date: Mon Nov 10 23:10:10 2008
New Revision: 141752

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=141752
Log:
        PR rtl-optimization/37514
        * config/sh/sh.h (OPTIMIZATION_OPTIONS): Set
        flag_ira_share_spill_slots to 2 if it's already non-zero.
        (OVERRIDE_OPTIONS): Clear flag_ira_share_spill_slots if
        flag_ira_share_spill_slots is 2.
        * gcc.target/sh/pr37514.c: New test.


Added:
    trunk/gcc/testsuite/gcc.target/sh/pr37514.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/sh/sh.h
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37514

[Bug rtl-optimization/37514] [4.4 Regression] Wrong code generated for 20021120-1.c with -O3 -fomit-frame-pointer on sh4

[kkojima at gcc dot gnu dot org]

------- Comment #5 from kkojima at gcc dot gnu dot org  2008-11-10 23:25 -------
Currently worked around with the patch in #4.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37514

[Bug rtl-optimization/37514] [4.4 Regression] Wrong code generated for 20021120-1.c with -O3 -fomit-frame-pointer on sh4

[vmakarov at redhat dot com]

------- Comment #6 from vmakarov at redhat dot com  2008-11-11 15:22 -------
  Sorry, Kaz.  I missed this PR.  I've just found it after Bernd's email.

  I don't think it is a right solution or stable workaround.  In fact all
pseudos (551, 289, 288) involved in 2 wrong insns got different stack slots. 
It might be IRA triggered some latent bug in reload inheritence. Reload decided
that r2 contains value of 551 (gf+4) but it contains gf+0 (pseudo 434 which
died in prev insn 828).

  I'll look at this problem but taking reload complexity into account it will
take a few days.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37514

[Bug rtl-optimization/37514] [4.4 Regression] Wrong code generated for 20021120-1.c with -O3 -fomit-frame-pointer on sh4

[vmakarov at redhat dot com]

------- Comment #7 from vmakarov at redhat dot com  2008-11-24 22:26 -------
This is a latent bug in reload inheritance which IRA triggered.  Here
is the important info.  r434 was assigned to hard register 2 and r551
was assigned to memory.  After insn #1164, r434 and r551 are
synchronized and as a consequence the value of r551 is in hard register 2
(see reload1.c::reg_last_reload_reg).  After insn 179, the
pseudo-registers should be not synchronized (because of increment of r551) but
reload does not invalidate reg_last_reload_reg[551].  For this case it is done
in inc_for_reload by the following code

  /* No hard register is equivalent to this register after
     inc/dec operation.  If REG_LAST_RELOAD_REG were nonzero,
     we could inc/dec that register as well (maybe even using it for
     the source), but I'm not sure it's worth worrying about.  */
  if (REG_P (incloc))
    reg_last_reload_reg[REGNO (incloc)] = 0;

It is not done because incloc is memory assigned to pseudo-register
r551.  So after insn #179 reg_last_reload_reg[551] is still hard
register 2.  This results in that hard register #2 is used for reload #1
in in insn 831 which is wrong

I'll sent a patch solving the problem soon.

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

(insn:HI 1161 25 27 5 a.i:30 (set (reg/f:SI 434)
        (symbol_ref:SI ("gf") <var_decl 0x7f9a1cc6f500 gf>)) 175 {movsi_ie}
(nil))

...


(insn:HI 1164 177 179 6 a.i:15 (set (reg/f:SI 551)
        (reg/f:SI 434)) 175 {movsi_ie} (nil))


(insn:HI 179 1164 183 6 a.i:15 (parallel [
            (set (reg/v:SF 289 [ f00 ])
                (mem/s/v:SF (post_inc:SI (reg/f:SI 551)) [2 gf+0 S4 A32]))
            (use (reg/v:PSI 151 ))
            (clobber (scratch:SI))
        ]) 205 {movsf_ie} (expr_list:REG_INC (reg/f:SI 551)
        (expr_list:REG_EQUAL (mem/s/v:SF (symbol_ref:SI ("gf") <var_decl
0x7f9a1cc6f500 gf>) [2 gf+0 S4 A32])
            (nil))))

...

(insn:HI 827 825 831 6 a.i:19 (parallel [
            (set (mem/s/v:SF (reg/f:SI 434) [2 gf+0 S4 A32])
                (reg/v:SF 289 [ f00 ]))
            (use (reg/v:PSI 151 ))
            (clobber (scratch:SI))
        ]) 205 {movsf_ie} (expr_list:REG_DEAD (reg/f:SI 434)
        (expr_list:REG_DEAD (reg/v:SF 289 [ f00 ])
            (nil))))

(insn:HI 831 827 835 6 a.i:19 (parallel [
            (set (mem/s/v:SF (reg/f:SI 551) [2 gf+4 S4 A32])
                (reg/v:SF 288 [ f10 ]))
            (use (reg/v:PSI 151 ))
            (clobber (scratch:SI))
        ]) 205 {movsf_ie} (expr_list:REG_DEAD (reg/f:SI 551)
        (expr_list:REG_DEAD (reg/v:SF 288 [ f10 ])
            (nil))))


Spilling for insn 827.
Using reg 7 for reload 0
Using reg 78 for reload 2
Spilling for insn 831.
Using reg 2 for reload 0
Using reg 2 for reload 1
Using reg 2 for reload 2
Using reg 78 for reload 4

Reloads for insn # 827
...
Reload 1: reload_out (SF) = (mem/s/v:SF (reg/f:SI 2 r2 [434]) [2 gf+0 S4 A32])
        NO_REGS, RELOAD_FOR_OUTPUT (opnum = 0), optional
        reload_out_reg: (mem/s/v:SF (reg/f:SI 2 r2 [434]) [2 gf+0 S4 A32])
...

Reloads for insn # 831
...
Reload 1: reload_in (SI) = (mem/c:SI (plus:SI (plus:SI (reg/f:SI 15 r15)
                                                            (const_int 764
[0x2fc]))
                                                        (const_int 52 [0x34]))
[5 %sfp+-196 S4 A32])
        GENERAL_REGS, RELOAD_FOR_OPERAND_ADDRESS (opnum = 0), can't combine
        reload_in_reg: (reg/f:SI 551)
        reload_reg_rtx: (reg/f:SI 2 r2 [434])
...


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37514

[Bug rtl-optimization/37514] [4.4 Regression] Wrong code generated for 20021120-1.c with -O3 -fomit-frame-pointer on sh4

[kkojima at gcc dot gnu dot org]

------- Comment #8 from kkojima at gcc dot gnu dot org  2008-11-26 00:03 -------
Vlad, thanks for taking the time to look into this!  Your comments
in #7 and http://gcc.gnu.org/ml/gcc-patches/2008-11/msg01323.html
give a very clear picture of the problem.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37514

[Bug rtl-optimization/37514] [4.4 Regression] Wrong code generated for 20021120-1.c with -O3 -fomit-frame-pointer on sh4

[hjl at gcc dot gnu dot org]

------- Comment #9 from hjl at gcc dot gnu dot org  2008-12-01 17:04 -------
Subject: Bug 37514

Author: hjl
Date: Mon Dec  1 17:03:13 2008
New Revision: 142324

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=142324
Log:
2008-12-01  Vladimir Makarov  <vmakarov@redhat.com>

        PR rtl-optimization/37514
        * reload1.c (reload_as_needed): Invalidate reg_last_reload
        from previous insns.

Modified:
    branches/ira-merge/gcc/ChangeLog.ira
    branches/ira-merge/gcc/reload1.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37514

[Bug rtl-optimization/37514] [4.4 Regression] Wrong code generated for 20021120-1.c with -O3 -fomit-frame-pointer on sh4

[vmakarov at gcc dot gnu dot org]

------- Comment #10 from vmakarov at gcc dot gnu dot org  2008-12-01 19:33 -------
Subject: Bug 37514

Author: vmakarov
Date: Mon Dec  1 19:31:41 2008
New Revision: 142328

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=142328
Log:
2008-12-01  Vladimir Makarov  <vmakarov@redhat.com>

        PR rtl-optimization/37514
        * reload1.c (reload_as_needed): Invalidate reg_last_reload
        from previous insns.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/reload1.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37514

[Bug rtl-optimization/37514] [4.4 Regression] Wrong code generated for 20021120-1.c with -O3 -fomit-frame-pointer on sh4

[kkojima at gcc dot gnu dot org]

------- Comment #11 from kkojima at gcc dot gnu dot org  2008-12-02 08:36 -------
Fixed.


-- 

kkojima at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37514