[PATCH] add uClibc target hook (PR bootstrap/77819)

[Martin Sebor]

The attached patch adds a uclibc_printf_pointer_format target
hook equivalent to the linux glibc_printf_pointer_format hook.
I couldn't find a good uclibc-only file where to put the new
definition of the hook so I conditionally added it to
targethooks.c.

I tested the new hook by bootstrapping GCC for tic6x-uclinux
and bfin-uclinux targets on x86_64.

Martin

PR bootstrap/77819 - undefined reference to gnu_libc_printf_pointer_format with uClibc

gcc/ChangeLog:
2016-10-02  Martin Sebor  <mse...@redhat.com>

	PR bootstrap/77819
	* config/linux.h [DEFAULT_LIBC == LIBC_UCLIBC) && SINGLE_LIBC]
	(TARGET_PRINTF_POINTER_FORMAT): Define macro.
	* targhooks.c [DEFAULT_LIBC == LIBC_UCLIBC) && SINGLE_LIBC]
	(default_printf_pointer_format): Define function.
	* targhooks.h (default_printf_pointer_format): Declare.

diff --git a/gcc/config/linux.h b/gcc/config/linux.h
index 3ff005b..1649b01 100644
--- a/gcc/config/linux.h
+++ b/gcc/config/linux.h
@@ -200,6 +200,10 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 # undef TARGET_LIBC_HAS_FUNCTION
 # define TARGET_LIBC_HAS_FUNCTION no_c99_libc_has_function
 
+/* The format string to which "%p" corresponds.  */
+#  undef TARGET_PRINTF_POINTER_FORMAT
+#  define TARGET_PRINTF_POINTER_FORMAT uclibc_printf_pointer_format
+
 #else /* !uClinux, i.e., normal Linux */
 
 /* Determine what functions are present at the runtime;
@@ -207,8 +211,8 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 # undef TARGET_LIBC_HAS_FUNCTION
 # define TARGET_LIBC_HAS_FUNCTION linux_libc_has_function
 
-#endif
-
 /* The format string to which "%p" corresponds.  */
-#undef TARGET_PRINTF_POINTER_FORMAT
-#define TARGET_PRINTF_POINTER_FORMAT gnu_libc_printf_pointer_format
+#  undef TARGET_PRINTF_POINTER_FORMAT
+#  define TARGET_PRINTF_POINTER_FORMAT gnu_libc_printf_pointer_format
+
+#endif
diff --git a/gcc/targhooks.c b/gcc/targhooks.c
index d75650f..77b4a18 100644
--- a/gcc/targhooks.c
+++ b/gcc/targhooks.c
@@ -1523,6 +1523,26 @@ default_printf_pointer_format (tree, const char **flags)
   return "%zx";
 }
 
+#if (DEFAULT_LIBC == LIBC_UCLIBC) && defined (SINGLE_LIBC) /* uClinux */
+
+/* For *uclibc* targets only, define the hook here because otherwise
+   it would have to be duplicated in each target's .c file (such as
+   in bfin/bfin.c and c6x/c6x.c, etc.)
+   uClibc (and Glibc) format pointers as if by "%zx" except for the null
+   pointer which outputs "(nil)".  It ignores the pound ('#') format
+   flag but interprets the space and plus flags the same as in the integer
+   directive.  */
+
+const char*
+uclibc_printf_pointer_format (tree arg, const char **flags)
+{
+  *flags = " +";
+
+  return arg && integer_zerop (arg) ? "(nil)" : "%#zx";
+}
+
+#endif
+
 tree
 default_builtin_tm_load_store (tree ARG_UNUSED (type))
 {
diff --git a/gcc/targhooks.h b/gcc/targhooks.h
index 3356f0a..52d36e0 100644
--- a/gcc/targhooks.h
+++ b/gcc/targhooks.h
@@ -194,6 +194,7 @@ extern bool gnu_libc_has_function (enum function_class);
 extern const char* default_printf_pointer_format (tree, const char **);
 extern const char* gnu_libc_printf_pointer_format (tree, const char **);
 extern const char* solaris_printf_pointer_format (tree, const char **);
+extern const char* uclibc_printf_pointer_format (tree, const char **);
 
 extern tree default_builtin_tm_load_store (tree);