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[Bug libc/15648] Support building glibc with -flto.
- From: "carlos at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sourceware dot org
- Date: Thu, 20 Jun 2013 03:32:01 +0000
- Subject: [Bug libc/15648] Support building glibc with -flto.
- Auto-submitted: auto-generated
- References: <bug-15648-131 at http dot sourceware dot org/bugzilla/>
http://sourceware.org/bugzilla/show_bug.cgi?id=15648
Carlos O'Donell <carlos at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|WAITING |NEW
Summary|multiple definition of |Support building glibc with
|`__lll_lock_wait_private' |-flto.
Severity|normal |enhancement
--- Comment #4 from Carlos O'Donell <carlos at redhat dot com> ---
This doesn't work at all for me for entirely different reasons.
I expect that you haven't actually tried to use -flto.
glibc master is currently unbuildable with -flto because of:
http://sourceware.org/bugzilla/show_bug.cgi?id=15648
You should always see:
checking for .preinit_array/.init_array/.fini_array support... no
configure: error: Need linker with .init_array/.fini_array support.
This is because -flto throws out the .init_array support.
A potential fix is:
diff --git a/configure.in b/configure.in
index 8b11081..415e777 100644
--- a/configure.in
+++ b/configure.in
@@ -1383,7 +1383,7 @@ AC_CACHE_CHECK(for .preinit_array/.init_array/.fini_array
support,
libc_cv_initfini_array, [dnl
LIBC_TRY_LINK_STATIC([
int foo (void) { return 1; }
-int (*fp) (void) __attribute__ ((section (".init_array"))) = foo;
+int (*fp) (void) __attribute__ ((section (".init_array"), used)) = foo;
],
[if $READELF -S conftest | fgrep INIT_ARRAY > /dev/null; then
libc_cv_initfini_array=yes
~~~
However, given that nobody has built with -flto it's going to require
considerable work to make it happen.
I'm retitling and marking as enhancement.
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