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authorH.J. Lu <hjl.tools@gmail.com>2016-05-24 08:44:10 -0700
committerH.J. Lu <hjl.tools@gmail.com>2016-05-24 08:44:23 -0700
commit6901def689b5c77465d34f07822989ec67e80c1e (patch)
tree2efde72294545c6b0129133d43d1f7335182fa61 /configure
parent4c011268960c6f24650672597deed756f21ad363 (diff)
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Avoid an extra branch to PLT for -z now
When --enable-bind-now is used to configure glibc build, we can avoid
an extra branch to the PLT entry by using indirect branch via the GOT
slot instead, which is similar to the first instructuon in the PLT
entry.  Changes in the shared library sizes in text sections:

Shared library    Before (bytes)   After (bytes)
libm.so             1060813          1060797
libmvec.so           160881           160805
libpthread.so         94992            94984
librt.so              25064            25048

	* config.h.in (BIND_NOW): New.
	* configure.ac (BIND_NOW): New.  Defined for --enable-bind-now.
	* configure: Regenerated.
	* sysdeps/x86_64/sysdep.h (JUMPTARGET)[BIND_NOW]: Defined to
	indirect branch via the GOT slot.
Diffstat (limited to 'configure')
-rwxr-xr-xconfigure4
1 files changed, 4 insertions, 0 deletions
diff --git a/configure b/configure
index 8fe59377ea..19a4829466 100755
--- a/configure
+++ b/configure
@@ -3416,6 +3416,10 @@ else
 fi
 
 
+if test "x$bindnow" = xyes; then
+  $as_echo "#define BIND_NOW 1" >>confdefs.h
+
+fi
 
 # Check whether --enable-static-nss was given.
 if test "${enable_static_nss+set}" = set; then :