Original patch from: gentoo/src/patchsets/glibc/2.9/6018_all_glibc-ptr-mangling.patch

-= BEGIN original header =-
http://bugs.gentoo.org/201910

For every arch, PTR_MANGLE and PTR_DEMANGLE defines are in
sysdeps/unix/sysv/linux/<arch>/sysdep.h. But for alpha this is not true. The
defines are in sysdeps/unix/alpha/sysdep.h and unix/sysv/linux/alpha/sysdep.h
includes the first.

This is a patch that fixes the issue and let alpha build, at the expense of
disabling MANGLING in the non PIC case, but googling showed that the issue is
known, and that nobody really cares about it. 

Info from: http://sourceware.org/bugzilla/show_bug.cgi?id=5216

-= END original header =-

diff -durN glibc-2_9.orig/sysdeps/unix/alpha/sysdep.h glibc-2_9/sysdeps/unix/alpha/sysdep.h
--- glibc-2_9.orig/sysdeps/unix/alpha/sysdep.h	2006-03-03 12:21:28.000000000 +0100
+++ glibc-2_9/sysdeps/unix/alpha/sysdep.h	2009-02-02 22:01:39.000000000 +0100
@@ -397,42 +397,4 @@
 	_sc_ret = _sc_0, _sc_err = _sc_19;			\
 }
 
-/* Pointer mangling support.  Note that tls access is slow enough that
-   we don't deoptimize things by placing the pointer check value there.  */
-
-#include <stdint.h>
-
-#if defined NOT_IN_libc && defined IS_IN_rtld
-# ifdef __ASSEMBLER__
-#  define PTR_MANGLE(dst, src, tmp)				\
-	ldah	tmp, __pointer_chk_guard_local($29) !gprelhigh;	\
-	ldq	tmp, __pointer_chk_guard_local(tmp) !gprellow;	\
-	xor	src, tmp, dst
-#  define PTR_MANGLE2(dst, src, tmp)				\
-	xor	src, tmp, dst
-#  define PTR_DEMANGLE(dst, tmp)   PTR_MANGLE(dst, dst, tmp)
-#  define PTR_DEMANGLE2(dst, tmp)  PTR_MANGLE2(dst, dst, tmp)
-# else
-extern uintptr_t __pointer_chk_guard_local attribute_relro attribute_hidden;
-#  define PTR_MANGLE(var)	\
-  (var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard_local)
-#  define PTR_DEMANGLE(var)  PTR_MANGLE(var)
-# endif
-#elif defined PIC
-# ifdef __ASSEMBLER__
-#  define PTR_MANGLE(dst, src, tmp)		\
-	ldq	tmp, __pointer_chk_guard;	\
-	xor	src, tmp, dst
-#  define PTR_MANGLE2(dst, src, tmp)		\
-	xor	src, tmp, dst
-#  define PTR_DEMANGLE(dst, tmp)   PTR_MANGLE(dst, dst, tmp)
-#  define PTR_DEMANGLE2(dst, tmp)  PTR_MANGLE2(dst, dst, tmp)
-# else
-extern uintptr_t __pointer_chk_guard attribute_relro;
-#  define PTR_MANGLE(var)	\
-	(var) = (void *) ((uintptr_t) (var) ^ __pointer_chk_guard)
-#  define PTR_DEMANGLE(var)  PTR_MANGLE(var)
-# endif
-#endif
-
 #endif /* ASSEMBLER */
diff -durN glibc-2_9.orig/sysdeps/unix/sysv/linux/alpha/sysdep.h glibc-2_9/sysdeps/unix/sysv/linux/alpha/sysdep.h
--- glibc-2_9.orig/sysdeps/unix/sysv/linux/alpha/sysdep.h	2007-08-21 10:07:28.000000000 +0200
+++ glibc-2_9/sysdeps/unix/sysv/linux/alpha/sysdep.h	2009-02-02 22:01:39.000000000 +0100
@@ -98,4 +98,46 @@
 	INTERNAL_SYSCALL1(name, err_out, nr, args);			\
 })
 
+/* Pointer mangling support.  Note that tls access is slow enough that
+   we don't deoptimize things by placing the pointer check value there.  */
+
+#if defined NOT_IN_libc && defined IS_IN_rtld
+# ifdef __ASSEMBLER__
+#  define PTR_MANGLE(dst, src, tmp)                            \
+       ldah    tmp, __pointer_chk_guard_local($29) !gprelhigh; \
+       ldq     tmp, __pointer_chk_guard_local(tmp) !gprellow;  \
+       xor     src, tmp, dst
+#  define PTR_MANGLE2(dst, src, tmp)                           \
+       xor     src, tmp, dst
+#  define PTR_DEMANGLE(dst, tmp)   PTR_MANGLE(dst, dst, tmp)
+#  define PTR_DEMANGLE2(dst, tmp)  PTR_MANGLE2(dst, dst, tmp)
+# else
+extern uintptr_t __pointer_chk_guard_local attribute_relro attribute_hidden;
+#  define PTR_MANGLE(var)      \
+  (var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard_local)
+#  define PTR_DEMANGLE(var)  PTR_MANGLE(var)
+# endif
+#elif defined PIC
+# ifdef __ASSEMBLER__
+#  define PTR_MANGLE(dst, src, tmp)            \
+       ldq     tmp, __pointer_chk_guard;       \
+       xor     src, tmp, dst
+#  define PTR_MANGLE2(dst, src, tmp)           \
+       xor     src, tmp, dst
+#  define PTR_DEMANGLE(dst, tmp)   PTR_MANGLE(dst, dst, tmp)
+#  define PTR_DEMANGLE2(dst, tmp)  PTR_MANGLE2(dst, dst, tmp)
+# else
+extern uintptr_t __pointer_chk_guard attribute_relro;
+#  define PTR_MANGLE(var)      \
+       (var) = (void *) ((uintptr_t) (var) ^ __pointer_chk_guard)
+#  define PTR_DEMANGLE(var)  PTR_MANGLE(var)
+# endif
+#else
+/* Pointer mangling is not yet supported for static libc on alpha.  */
+# ifndef __ASSEMBLER__
+#  define PTR_MANGLE(var)   (void) (var)
+#  define PTR_DEMANGLE(var) (void) (var)
+# endif
+#endif
+
 #endif /* _LINUX_ALPHA_SYSDEP_H */