[Bug middle-end/59327] New: warning in expand_used_vars

[Bug middle-end/59327] New: warning in expand_used_vars

[amylaar at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59327

            Bug ID: 59327
           Summary: warning in expand_used_vars
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Keywords: build
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: amylaar at gcc dot gnu.org
                CC: jakub at redhat dot com

Code added this morning to cfgexpand.c:expand_used_vars causes a warning:

g++ -c   -g  -DIN_GCC  -DCROSS_DIRECTORY_STRUCTURE  -fno-exceptions -fno-rtti
-fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings
-Wcast-qual -Wmissing-format-attribute -pedantic -Wno-long-long
-Wno-variadic-macros -Wno-overlength-strings -Werror -fno-common 
-DHAVE_CONFIG_H -I. -I. -I../../gcc/gcc -I../../gcc/gcc/.
-I../../gcc/gcc/../include -I../../gcc/gcc/../libcpp/include 
-I../../gcc/gcc/../libdecnumber -I../../gcc/gcc/../libdecnumber/dpd
-I../libdecnumber -I../../gcc/gcc/../libbacktrace    -o cfgexpand.o -MT
cfgexpand.o -MMD -MP -MF ./.deps/cfgexpand.TPo ../../gcc/gcc/cfgexpand.c
../../gcc/gcc/cfgexpand.c: In function ‘rtx_def* expand_used_vars()’:
../../gcc/gcc/cfgexpand.c:1836:35: error: comparison between signed and
unsigned integer expressions [-Werror=sign-compare]
        && sz + ASAN_RED_ZONE_SIZE >= data.asan_alignb)
                                   ^
cc1plus: all warnings being treated as errors
make: *** [cfgexpand.o] Error 1


Seen for target arc-elf.
[amylaar@rowan gcc]$ g++ --version
g++ (GCC) 4.9.0 20131126 (experimental)
Copyright (C) 2013 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[amylaar@rowan gcc]$ uname -a
Linux rowan 3.11.7-200.fc19.i686.PAE #1 SMP Mon Nov 4 14:22:33 UTC 2013 i686
i686 i386 GNU/Linux
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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug debug/59323] [4.9 Regression] Int. comp. error: in add_AT_specification, at dwarf2out.c:4026
Date: Thu, 28 Nov 2013 10:00:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idY323

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-11-28
   Target Milestone|---                         |4.9.0
     Ever confirmed|0                           |1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.  Nested functions.  There seems to be a declaration coming in
from BLOCK_VARS

#5  0x000000000074b91a in decls_for_scope (stmt=<block 0x7ffff6e4f190>,
    context_die=0x7ffff6e4f050, depth=2)
    at /space/rguenther/src/svn/trunk/gcc/dwarf2out.c:19971

but the decl itself has non-BLOCK scope (its DECL_CONTEXT is the main fn).

There are two BLOCKs which contain the exact same BLOCK_VARs ...

So it seems we duplicate BLOCKs either bogously during streaming (maybe only
in the context of nested functions) or they are duplicate also in the
compile phase.

It seems that one BLOCK is BLOCK_SUPERCONTEXT of the other which cannot
really be a streaming artifact.

It's a tree merging artifact - we merge the TYPE_DECLs for

    enum { X };

which end up being written to the global section despite their
DECL_CONTEXT being a FUNCTION_DECL (bah).  Such merging happens
without considering DECL_CHAIN as we assume they are not in BLOCK
context.  They end up there because the nested function decl 'foo'
is in that same block (I think) and thus they form a tree SCC
via BLOCK_VARS.

Ah no - it's ultimately the CONST_DECL for X that pulls the enum
type and its type decl global.  Ick...

I have a fix.

[Bug middle-end/59327] warning in expand_used_vars

[amylaar at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59327

--- Comment #2 from Jorn Wolfgang Rennecke <amylaar at gcc dot gnu.org> ---
sz is HOST_WIDE_INT, ASAN_RED_ZONE_SIZE is an int literal, and data.asan_alignb
is an unsigned int.

With 32 bit int and HOST_WIDE_INT, this results in a 32 bit signed/unsigned
comparison.

When building a target with need_64bit_hwint (according to config.gcc),
on a host with 32 bit int, the right hand side of the comparison gets
sign extended to HOST_WIDE_INT, thus the warning will not show up when
testing such a combination / bootstrapping such a host/target.

[Bug middle-end/59327] [4.9 Regression] warning in expand_used_vars

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59327

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |jakub at gcc dot gnu.org

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 31318
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31318&action=edit
gcc49-pr59327.patch

Untested fix.

[Bug middle-end/59327] [4.9 Regression] warning in expand_used_vars

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59327

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Author: jakub
Date: Thu Nov 28 22:52:40 2013
New Revision: 205499

URL: http://gcc.gnu.org/viewcvs?rev=205499&root=gcc&view=rev
Log:
    PR middle-end/59327
    * cfgexpand.c (expand_used_vars): Avoid warning on 32-bit
    HWI hosts.

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

[Bug middle-end/59327] [4.9 Regression] warning in expand_used_vars

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59327

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

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

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed.