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

[hjl.tools at gmail dot com]

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