gdb and binutils branch master updated. 1642b4b33783d70979dca379d57a0ce02559daec

[tmsriram at sourceware dot org]

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https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=1642b4b33783d70979dca379d57a0ce02559daec

commit 1642b4b33783d70979dca379d57a0ce02559daec
Author: Sriraman Tallam <tmsriram@google.com>
Date:   Tue May 13 10:33:59 2014 -0700

    Optimizing accesses to Globals with -fpie -pie:
    
    With -pie and x86, the linker complains if it sees a PC-relative relocation
    to access a global as it expects a GOTPCREL relocation.  This is really not
    necessary as the linker could use a copy relocation to get around it.  This
    patch enables copy relocations with pie.
    
    Context:
    This is useful because currently the GCC compiler with option -fpie makes
    every extern global access go through the GOT. That is because the compiler
    cannot tell if a global will end up being defined in the executable or not
    and is conservative. This ends up hurting performance when the binary is linked
    as mostly static where most of the globals do end up being defined in the
    executable.  By allowing copy relocs with fPIE, the compiler need not generate
    a GOTPCREL(GOT access) for any global access.  It can safely assume that all
    globals will be defined in the executable and generate a PC-relative access
    instead.  Gold can then create a copy reloc for only the undefined globals.

-----------------------------------------------------------------------

Summary of changes:
 gold/testsuite/pie_copyrelocs_shared_test.cc |   26 +++++++++++++++++++++
 gold/testsuite/pie_copyrelocs_test.cc        |   31 ++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 0 deletions(-)
 create mode 100644 gold/testsuite/pie_copyrelocs_shared_test.cc
 create mode 100644 gold/testsuite/pie_copyrelocs_test.cc


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