powerpc64: Fix calls when r2 is not used [BZ #26173]

Teach the linker that __mcount_internal, __sigjmp_save_symbol,
__syscall_error and __GI_exit do not use r2, so that it does not need to
recover r2 after the call.

Test at configure time if the assembler supports @notoc and define
USE_PPC64_NOTOC.

1 files changed, 28 insertions, 0 deletions

diff --git a/sysdeps/powerpc/powerpc64/configure b/sysdeps/powerpc/powerpc64/configure
index 7632a7be04..5ce77af631 100644
--- a/sysdeps/powerpc/powerpc64/configure
+++ b/sysdeps/powerpc/powerpc64/configure
@@ -31,3 +31,31 @@ if test x$libc_cv_overlapping_opd = xyes; then
   $as_echo "#define USE_PPC64_OVERLAPPING_OPD 1" >>confdefs.h
 
 fi
+
+# @notoc started to be supported in GNU Binutils 2.31.
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking if the assembler supports @notoc" >&5
+$as_echo_n "checking if the assembler supports @notoc... " >&6; }
+if ${libc_cv_ppc64_notoc+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+	       cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+void foo (void) {asm("b foo@notoc");}
+
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  libc_cv_ppc64_notoc=yes
+else
+  libc_cv_ppc64_notoc=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_ppc64_notoc" >&5
+$as_echo "$libc_cv_ppc64_notoc" >&6; }
+if test x$libc_cv_ppc64_notoc = xyes; then :
+  $as_echo "#define USE_PPC64_NOTOC 1" >>confdefs.h
+
+fi