[Bug middle-end/30807] New: sh postreload bug (might be generic in trunk)

[Bug middle-end/30807] New: sh postreload bug (might be generic in trunk)

[christian dot bruel at st dot com]

I can only reproduce this problem on the sh target with a gcc version 3.4.3.
However my analysis makes me believe the problem still exists on the trunk.

After greg I have the following sequence :

(insn:HI 11 10 12 0 (set (reg/v/f:SI 2 r2 [orig:160 PrivateData_p ] [160])
        (const_int 128 [0x80])) 122 {movsi_i} (nil)
    (nil))

(insn:HI 12 11 134 0 (set (reg/v/f:SI 2 r2 [orig:160 PrivateData_p ] [160])
        (plus:SI (reg/v/f:SI 2 r2 [orig:160 PrivateData_p ] [160])
            (reg:SI 3 r3 [orig:162 Device_p ] [162]))) 23 {*addsi3_compact}
(insn_list 10 (insn_list 11 (nil)))
    (expr_list:REG_EQUAL (plus:SI (reg:SI 3 r3 [orig:162 Device_p ] [162])
            (const_int 128 [0x80]))
        (nil)))

...

(insn:HI 16 135 17 0 (set (reg:SI 1 r1 [166])
        (const_int 188 [0xbc])) 122 {movsi_i} (nil)
    (nil))

(insn:HI 17 16 18 0 (set (reg:SI 1 r1 [166])
        (plus:SI (reg:SI 1 r1 [166])
            (reg/v/f:SI 2 r2 [orig:160 PrivateData_p ] [160]))) 23
{*addsi3_compact} (insn_list 16 (nil))
    (expr_list:REG_EQUAL (plus:SI (reg:SI 3 r3 [orig:162 Device_p ] [162])
            (const_int 316 [0x13c]))
        (nil)))

'reload_combine' decides to optimize insns 16/17. After the optimisation, there
is a 'continue' and reload_combines tries other pattern.

The problem is that with this 'continue' reg_state[regno] was is updated with
the other uses (here r2).

later on insn 11/12 are optimized away, believing that r2 is dead because not
makrked in the reg_state use list, leaving it undefined.

The problem is very difficult to isolate (didn't succeed on trunk with i686)
but by reading the postreload code the bug seems latent.


-- 
           Summary: sh postreload bug (might be generic in trunk)
           Product: gcc
           Version: 3.4.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: christian dot bruel at st dot com
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnugcc
GCC target triplet: sh-superh-elf-gcc


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30807

[Bug middle-end/30807] sh postreload bug (might be generic in trunk)

[christian dot bruel at st dot com]

------- Comment #1 from christian dot bruel at st dot com  2007-02-15 15:37 -------
The bug might be clearer to explain like this

we have
16: (set reg:r1) (const_int 188)
17: (set reg:r1) (plus (reg:r1 reg:r2)
18: (set reg:r1) (mem (plus (reg:r1) (const_int 4))

is transformed into
16: (set reg:r0) (const_int 192)
18: (set reg:r1) (mem (plus (reg:r0) (reg:r2))

since insn 18 is not reg_state[2].reg_use[i].insn, r2 might be seen as dead by 
another similar combine transformation on previous insns


-- 

christian dot bruel at st dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |christian dot bruel at st
                   |                            |dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30807

[Bug middle-end/30807] sh postreload bug (might be generic in trunk)

[christian dot bruel at st dot com]

------- Comment #2 from christian dot bruel at st dot com  2007-02-15 15:55 -------
Created an attachment (id=13052)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13052&action=view)
Proposed fix for postreload combine

the following patch fixes the problem in the sh 3.4.3 compiler.

Since I didn't see a similar fix in the trunk, I suspect it is also needed
(even if I was not able an isns similar sequence to reproduce the problem). 

-c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30807

[Bug middle-end/30807] sh postreload bug (might be generic in trunk)

[christian dot bruel at st dot com]

------- Comment #3 from christian dot bruel at st dot com  2007-02-16 07:04 -------
Created an attachment (id=13053)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13053&action=view)
Add testcase.

compile with sh-superh-elf-gcc (3.4.3) -O2 sh_postreload_bug.c -S -da
at line 28 of sh_postreload_bug.s mov.l @(r0,r2),r1 uses an unitialized r2.

in sh_postreload_bug.c.26.postreload line 47 r1 was replaced by r2 by
postreload_combine. 

is it generic and not target specific ?

see patch and other attachements for proposed analysis and fix.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30807

[Bug middle-end/30807] sh postreload bug (might be generic in trunk)

[christian dot bruel at st dot com]

------- Comment #4 from christian dot bruel at st dot com  2007-02-16 07:42 -------
looks like a similar analysis for a bigger case was proposed in

http://gcc.gnu.org/ml/gcc-patches/2006-01/msg01395.html


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30807

[Bug middle-end/30807] sh postreload bug (might be generic in trunk)

[kkojima at gcc dot gnu dot org]

------- Comment #5 from kkojima at gcc dot gnu dot org  2009-05-30 22:56 -------
*** Bug 40301 has been marked as a duplicate of this bug. ***


-- 

kkojima at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sugioka at itonet dot co dot
                   |                            |jp


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30807

[Bug rtl-optimization/30807] postreload bug (might be generic in trunk)

[kkojima at gcc dot gnu dot org]

------- Comment #6 from kkojima at gcc dot gnu dot org  2009-05-30 23:02 -------
Reported against 4.3 with another big test case.


-- 

kkojima at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kkojima at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
          Component|middle-end                  |rtl-optimization
     Ever Confirmed|0                           |1
      Known to fail|                            |4.3.2
           Priority|P3                          |P4
   Last reconfirmed|0000-00-00 00:00:00         |2009-05-30 23:02:47
               date|                            |
            Summary|sh postreload bug (might be |postreload bug (might be
                   |generic in trunk)           |generic in trunk)


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30807

[Bug rtl-optimization/30807] postreload bug (might be generic in trunk)

[kkojima at gcc dot gnu dot org]

------- Comment #7 from kkojima at gcc dot gnu dot org  2009-06-07 22:58 -------
Created an attachment (id=17961)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17961&action=view)
test case for 4.3

A reduced test case for 4.3 -O2 -fpic on sh4-unknown-linux-gnu.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30807

[Bug rtl-optimization/30807] postreload bug (might be generic in trunk)

[kkojima at gcc dot gnu dot org]

------- Comment #8 from kkojima at gcc dot gnu dot org  2009-07-06 13:28 -------
Subject: Bug 30807

Author: kkojima
Date: Mon Jul  6 13:28:22 2009
New Revision: 149282

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=149282
Log:
        PR rtl-optimization/30807
        * postreload.c (reload_combine): For every new use of REG_SUM,
        record the use of BASE.


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


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30807

[Bug rtl-optimization/30807] postreload bug (might be generic in trunk)

[sezeroz at gmail dot com]

------- Comment #9 from sezeroz at gmail dot com  2009-07-08 11:37 -------
Will there be a backport of this to the branches 4.3 and 4.4?


-- 

sezeroz at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sezeroz at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30807

[Bug rtl-optimization/30807] postreload bug (might be generic in trunk)

[kkojima at gcc dot gnu dot org]

------- Comment #10 from kkojima at gcc dot gnu dot org  2009-07-08 11:54 -------
I don't think this is a regression, unfortunately.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30807

[Bug rtl-optimization/30807] postreload bug (might be generic in trunk)

[olegendo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30807

Oleg Endo <olegendo at gcc dot gnu.org> changed:

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

--- Comment #14 from Oleg Endo <olegendo at gcc dot gnu.org> ---
Test case added to 4.9.  Closed.

[Bug rtl-optimization/30807] postreload bug (might be generic in trunk)

[olegendo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30807

--- Comment #13 from Oleg Endo <olegendo at gcc dot gnu.org> ---
Author: olegendo
Date: Wed Nov  6 20:26:35 2013
New Revision: 204473

URL: http://gcc.gnu.org/viewcvs?rev=204473&root=gcc&view=rev
Log:
    PR target/30807
    * gcc.target/sh/torture/pr30807.c: New.


Added:
    trunk/gcc/testsuite/gcc.target/sh/torture/pr30807.c
Modified:
    trunk/gcc/testsuite/ChangeLog

[Bug rtl-optimization/30807] postreload bug (might be generic in trunk)

[kkojima at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30807

--- Comment #12 from Kazumoto Kojima <kkojima at gcc dot gnu.org> ---
(In reply to Oleg Endo from comment #11)
> Would it be OK to add this test case to gcc.target/sh/torture and close this
> PR?

Please go ahead.

[Bug rtl-optimization/30807] postreload bug (might be generic in trunk)

[olegendo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30807

Oleg Endo <olegendo at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |olegendo at gcc dot gnu.org

--- Comment #11 from Oleg Endo <olegendo at gcc dot gnu.org> ---
(In reply to Kazumoto Kojima from comment #7)
> Created attachment 17961 [details]
> test case for 4.3
> 
> A reduced test case for 4.3 -O2 -fpic on sh4-unknown-linux-gnu.

Would it be OK to add this test case to gcc.target/sh/torture and close this
PR?