[Bug lto/64025] New: Several testsuite execution failures with -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects

[Bug lto/64025] New: Several testsuite execution failures with -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64025

            Bug ID: 64025
           Summary: Several testsuite execution failures with -O2 -flto
                    -fuse-linker-plugin -fno-fat-lto-objects
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ubizjak at gmail dot com

This problem was unearthed on i686-linux-gnu with -fpic (see [1]):

FAIL: gcc.c-torture/execute/builtins/memmove-chk.c execution,  -O2 -flto
-fuse-linker-plugin -fno-fat-lto-objects 
FAIL: gcc.c-torture/execute/builtins/mempcpy-2.c execution,  -O2 -flto
-fuse-linker-plugin -fno-fat-lto-objects 
FAIL: gcc.c-torture/execute/builtins/strcpy.c execution,  -O2 -flto
-fuse-linker-plugin -fno-fat-lto-objects 

FAIL: gcc.c-torture/execute/pr17252.c   -O2 -flto -fuse-linker-plugin
-fno-fat-lto-objects  execution test
FAIL: gcc.dg/torture/pr47365.c   -O2 -flto -fuse-linker-plugin
-fno-fat-lto-objects  execution test

[1] https://gcc.gnu.org/ml/gcc-testresults/2014-11/msg02442.html

[Bug lto/64025] [5 Regression] Several testsuite execution failures with -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64025

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
           Priority|P3                          |P1
                 CC|                            |hubicka at gcc dot gnu.org
   Target Milestone|---                         |5.0
            Summary|Several testsuite execution |[5 Regression] Several
                   |failures with -O2 -flto     |testsuite execution
                   |-fuse-linker-plugin         |failures with -O2 -flto
                   |-fno-fat-lto-objects        |-fuse-linker-plugin
                   |                            |-fno-fat-lto-objects

[Bug lto/64025] [5 Regression] Several testsuite execution failures with -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64025

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-11-24
                 CC|                            |enkovich.gnu at gmail dot com,
                   |                            |jakub at redhat dot com
     Ever confirmed|0                           |1

--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> ---
It was caused by r216540.

[Bug lto/64025] [5 Regression] Several testsuite execution failures with -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64025

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |uros at gcc dot gnu.org

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
This breaks because find_base_term is confused by what ix86_find_base_term
(which calls ix86_delegitimize_address) returns, namely the
(something - symbol_ref ("_GLOBAL_OFFSET_TABLE_")) + (const ((symbol_ref ("p")
+ const_int))
as find_base_term considers only one symbol for its purposes.
So, either we change ix86_find_base_term, so that it hides the (something -
symbol_ref ("_GLOBAL_OFFSET_TABLE_")) part - often it stands for 0,
as something is often just VALUE of the pic register or say pic register plus
some variable offset and just returns the other part, or
swap the order of the PLUS operands, so that the (const ...) part comes first
and thus find_base_term first recurses on that, or move
ix86_delegitimize_address to ix86_delegitimize_address_1, call it from
ix86_delegitimize_address with some bool flag allowing what it does now, and
from ix86_find_base_term disallowing that.  Or change find_base_term, so that
for PLUS/MINUS it always recurses into both arguments, and if both provide
different bases, returns NULL (though, this change might be too expensive).
Preferences?

[Bug lto/64025] [5 Regression] Several testsuite execution failures with -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64025

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Just to explain more why the strcpy.c testcase breaks.

During postreload cse, we have:
(insn 63 61 70 5 (set (mem/c:QI (plus:SI (reg:SI 5 di [87])
                (const:SI (plus:SI (unspec:SI [
                                (symbol_ref:SI ("p") [flags 0x2]  <var_decl
0x7f4bb4427990 p>)
                            ] UNSPEC_GOTOFF)
                        (const_int 1 [0x1])))) [0 MEM[(void *)&p + 1B]+0 S1
A8])
        (const_int 0 [0]))
/usr/src/gcc/gcc/testsuite/gcc.c-torture/execute/builtins/strcpy.c:22 93
{*movqi_internal}
     (nil))
...
(insn 111 109 113 7 (set (mem/c:SI (plus:SI (reg:SI 5 di [87])
                (const:SI (unspec:SI [
                            (symbol_ref:SI ("p") [flags 0x2]  <var_decl
0x7f4bb4427990 p>)
                        ] UNSPEC_GOTOFF))) [0 MEM[(void *)&p]+0 S4 A8])
        (const_int 1145258561 [0x44434241]))
/usr/src/gcc/gcc/testsuite/gcc.c-torture/execute/builtins/strcpy.c:26 90
{*movsi_internal}
     (nil))

and when trying to invalidate memories because of the insn 111 store, we call
find_base_term on:

(plus:SI (value:SI 23:23 @0x2068db0/0x205e3f0)
    (const:SI (plus:SI (unspec:SI [
                    (symbol_ref:SI ("p") [flags 0x2] <var_decl 0x7ffff1865990
p>)
                ] UNSPEC_GOTOFF)
            (const_int 1 [0x1]))))

(from the 63 instruction, stored in cselib stuff), and
ix86_delegitimize_address returns

(plus:SI (minus:SI (value:SI 23:23 @0x2068db0/0x205e3f0)
        (symbol_ref:SI ("_GLOBAL_OFFSET_TABLE_")))
    (const:SI (plus:SI (symbol_ref:SI ("p") [flags 0x2] <var_decl
0x7ffff1865990 p>)
            (const_int 1 [0x1]))))

and finally find_base_term returns
(symbol_ref "_GLOBAL_OFFSET_TABLE_") (incorrectly), and then call
find_base_term on:
(plus:SI (reg:SI 5 di [87])
    (const:SI (unspec:SI [
                (symbol_ref:SI ("p") [flags 0x2] <var_decl 0x7ffff1865990 p>)
            ] UNSPEC_GOTOFF)))
(directly from the insn, so no VALUEs yet), and as ORIGINAL_REGNO of di is 87 -
the pic reg pseudo, we delegitimize that to
(symbol_ref:SI ("p") [flags 0x2] <var_decl 0x7ffff1865990 p>)
and find_base_term on that is that symbol, and thus we think those two memory
stores don't overlap.

[Bug lto/64025] [5 Regression] Several testsuite execution failures with -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64025

--- Comment #4 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Jakub Jelinek from comment #2)
> This breaks because find_base_term is confused by what ix86_find_base_term
> (which calls ix86_delegitimize_address) returns, namely the
> (something - symbol_ref ("_GLOBAL_OFFSET_TABLE_")) + (const ((symbol_ref
> ("p") + const_int))
> as find_base_term considers only one symbol for its purposes.
> So, either we change ix86_find_base_term, so that it hides the (something -
> symbol_ref ("_GLOBAL_OFFSET_TABLE_")) part - often it stands for 0,
> as something is often just VALUE of the pic register or say pic register
> plus some variable offset and just returns the other part, or
> swap the order of the PLUS operands, so that the (const ...) part comes
> first and thus find_base_term first recurses on that, or move
> ix86_delegitimize_address to ix86_delegitimize_address_1, call it from
> ix86_delegitimize_address with some bool flag allowing what it does now, and
> from ix86_find_base_term disallowing that.  Or change find_base_term, so
> that for PLUS/MINUS it always recurses into both arguments, and if both
> provide different bases, returns NULL (though, this change might be too
> expensive).
> Preferences?

I think that we should just swap the order of the PLUS operands and add some
comment on the expected form of the RTX.
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Subject: [Bug target/63965] [5 Regression] ICE: in extract_constrain_insn, at recog.c:2230 on ppc64
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idc965

Michael Meissner <meissner at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |ASSIGNED

--- Comment #12 from Michael Meissner <meissner at gcc dot gnu.org> ---
Whoops, I committed the wrong changes. I committed a change that I was working
on (but I had not gotten it to work yet), instead of the fix that was approved.
 I have backed out those changes (subversion id 218027), and I will shortly
submit the correct patch.

[Bug lto/64025] [5 Regression] Several testsuite execution failures with -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64025

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Author: jakub
Date: Thu Nov 27 11:02:02 2014
New Revision: 218119

URL: https://gcc.gnu.org/viewcvs?rev=218119&root=gcc&view=rev
Log:
    PR lto/64025
    * alias.c (find_base_term): Use std::swap.  Prefer tmp2
    if it is CONSTANT_P other than CONST_INT.

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