# commit 0b2c2ace3601d5d59cf89130b16840e7f132f7a6
# Author: Alan Modra <amodra@gmail.com>
# Date:   Sat Aug 17 18:36:45 2013 +0930
# 
#     PowerPC makecontext
#     http://sourceware.org/ml/libc-alpha/2013-08/msg00092.html
#     
#     Use conditional form of branch and link to avoid destroying the cpu
#     link stack used to predict blr return addresses.
#     
#         * sysdeps/unix/sysv/linux/powerpc/powerpc32/makecontext.S: Use
#         conditional form of branch and link when obtaining pc.
#         * sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S: Likewise.
# 
---
# sysdeps/unix/sysv/linux/powerpc/powerpc32/makecontext.S |    8 ++++++--
# sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S |    6 ++++--
# 2 files changed, 10 insertions(+), 4 deletions(-)
#
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/makecontext.S
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/makecontext.S
@@ -47,7 +47,9 @@
 #ifdef PIC
 	mflr	r0
 	cfi_register(lr,r0)
-	bl	1f
+	/* Use this conditional form of branch and link to avoid destroying
+	   the cpu link stack used to predict blr return addresses.  */
+	bcl	20,31,1f
 1:	mflr	r6
 	addi	r6,r6,L(exitcode)-1b
 	mtlr	r0
@@ -136,7 +138,9 @@
 #ifdef PIC
 	mflr	r0
 	cfi_register(lr,r0)
-	bl	1f
+	/* Use this conditional form of branch and link to avoid destroying
+	   the cpu link stack used to predict blr return addresses.  */
+	bcl	20,31,1f
 1:	mflr	r6
 	addi	r6,r6,L(novec_exitcode)-1b
 	mtlr	r0
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S
@@ -124,8 +124,10 @@
 
   /* If the target function returns we need to do some cleanup.  We use a
      code trick to get the address of our cleanup function into the link
-     register.  Do not add any code between here and L(exitcode).  */
-  bl  L(gotexitcodeaddr);
+     register.  Do not add any code between here and L(exitcode).
+     Use this conditional form of branch and link to avoid destroying
+     the cpu link stack used to predict blr return addresses.  */
+  bcl	20,31,L(gotexitcodeaddr);
 
 	/* This is the helper code which gets called if a function which
 	   is registered with 'makecontext' returns.  In this case we
