[Bug target/65780] [5 Regression] Uninitialized common handling in executables

["jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65780

--- Comment #48 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Stupachenko Evgeny from comment #47)
> The patch caused significant regressions (see below) on spec2000 INT
> benchmarks compiled with options “-fPIE -pie -O2 -ffast-math -mfpmath=sse
> -m32 -march=corei7-avx” or “-fPIE -pie -O2 -ffast-math -mfpmath=sse -m32
> -march=slm”.
> 
> Sandybridge:
> 164.gzip    1635.0000  1602.0000 -2.01% 
> 197.parser  2159.0000  2117.0000 -1.94% 
> 254.gap     2909.0000  2886.0000 -0.79% 
> 256.bzip2   2232.0000  2154.0000 -3.49%
> 
> Silvermont:
> 164.gzip     964.0000   945.0000 -1.97% 
> 197.parser   951.0000   940.0000 -1.15% 
> 254.gap     1328.0000  1296.0000 -2.40% 
> 256.bzip2    952.0000   898.0000 -5.67%

That is the price to pay for correctness.  If you want to avoid that penalty,
I'd say change ld.bfd as well as ld.gold on i?86 to use COPY relocations for
PIEs like x86_64 has been changed some time ago, then when configured against
improved linker and with small patch to gcc you can recover not just that cost,
but some more on top of that.
>From gcc-bugs-return-484185-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Tue Apr 21 14:40:30 2015
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Subject: [Bug target/65780] [5 Regression] Uninitialized common handling in executables
Date: Tue, 21 Apr 2015 14:40:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65780

--- Comment #49 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Stupachenko Evgeny from comment #47)
> The patch caused significant regressions (see below) on spec2000 INT
> benchmarks compiled with options “-fPIE -pie -O2 -ffast-math -mfpmath=sse
> -m32 -march=corei7-avx” or “-fPIE -pie -O2 -ffast-math -mfpmath=sse -m32
> -march=slm”.
> 
> Sandybridge:
> 164.gzip    1635.0000  1602.0000 -2.01% 
> 197.parser  2159.0000  2117.0000 -1.94% 
> 254.gap     2909.0000  2886.0000 -0.79% 
> 256.bzip2   2232.0000  2154.0000 -3.49%
> 
> Silvermont:
> 164.gzip     964.0000   945.0000 -1.97% 
> 197.parser   951.0000   940.0000 -1.15% 
> 254.gap     1328.0000  1296.0000 -2.40% 
> 256.bzip2    952.0000   898.0000 -5.67%

As Jakub pointed out, this commit is for correctness.  Please open
a new bug report to optimize undefined/common symbol access in PIE
if linker supports copy reloc in PIE:

https://sourceware.org/bugzilla/show_bug.cgi?id=18289
>From gcc-bugs-return-484186-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Tue Apr 21 15:20:11 2015
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From: "manu at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug preprocessor/65834] New: give error for #if with no expression at the previous location
Date: Tue, 21 Apr 2015 15:20:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65834

            Bug ID: 65834
           Summary: give error for #if with no expression at the previous
                    location
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: preprocessor
          Assignee: unassigned at gcc dot gnu.org
          Reporter: manu at gcc dot gnu.org

Distilled from:
http://www.linuxquestions.org/questions/linux-from-scratch-13/replace-gcc-with-clang-4175491981/#post5108443

extern void foo(void);
#define TEST

int bar(void)
{
#if TEST
  foo();
#endif
  return 0;
}

Currently:

test.c:6:9: error: #if with no expression
 #if TEST
         ^

Expected something like:

test.c:6:9: error: #if with no expression
 #if TEST
     ^
test.c:2:14: note: in expansion of macro ‘TEST’

I think this could be possible by giving the error at the location of TEST
(which should be the previously encoded source_location) rather that at the
current one.

 #define TEST 
              ^
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From: "vries at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/65823] [6 Regression] ICE in gcc.c-torture/execute/stdarg-2.c -O0/-O1 for arm
Date: Tue, 21 Apr 2015 15:27:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?ide823

--- Comment #6 from vries at gcc dot gnu.org ---
(In reply to vries from comment #5)
> The nop introduced during gimplification is not meant to be there. This
> patch gets rid of it:

I've build an arm compiler with the patch, and tested execute.exp=stdarg-2.c.
Indeed the failure is gone, and the execution succeeds.