libiberty, gcc: Add memrchr to libiberty and use it [PR119283].

This adds an implementation of memrchr to libiberty and arranges
to configure gcc to use it, if the host does not have it.

	PR cobol/119283

gcc/ChangeLog:

	* config.in: Regenerate.
	* configure: Regenerate.
	* configure.ac: Check for host memrchr.

include/ChangeLog:

	* libiberty.h (memrchr): New.

libiberty/ChangeLog:

	* Makefile.in: Add memrchr build rules.
	* config.in: Regenerate.
	* configure: Regenerate.
	* configure.ac: Check for memrchr.
	* functions.texi: Document memrchr.
	* memrchr.c: New file.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>

libiberty/Makefile.in

@@ -139,8 +139,8 @@ CFILES = alloca.c argv.c asprintf.c atexit.c				\
 	ldirname.c							\
 	lrealpath.c							\
 	make-relative-prefix.c						\
-	make-temp-file.c md5.c memchr.c memcmp.c memcpy.c memmem.c	\
-	 memmove.c mempcpy.c memset.c mkstemps.c			\
+	make-temp-file.c md5.c memchr.c memrchr.c memcmp.c memcpy.c     \
+	memmem.c memmove.c mempcpy.c memset.c mkstemps.c		\
 	objalloc.c obstack.c						\
 	partition.c pexecute.c						\
 	 pex-common.c pex-djgpp.c pex-msdos.c pex-one.c			\
@@ -213,8 +213,8 @@ CONFIGURED_OFILES = ./asprintf.$(objext) ./atexit.$(objext)		\
 	./getcwd.$(objext) ./getpagesize.$(objext)			\
 	 ./gettimeofday.$(objext)					\
 	./index.$(objext) ./insque.$(objext)				\
-	./memchr.$(objext) ./memcmp.$(objext) ./memcpy.$(objext) 	\
-	./memmem.$(objext) ./memmove.$(objext)				\
+	./memchr.$(objext) ./memrchr.$(objext) ./memcmp.$(objext) 	\
+	./memcpy.$(objext) ./memmem.$(objext) ./memmove.$(objext)	\
 	 ./mempcpy.$(objext) ./memset.$(objext) ./mkstemps.$(objext)	\
 	./pex-djgpp.$(objext) ./pex-msdos.$(objext)			\
 	 ./pex-unix.$(objext) ./pex-win32.$(objext)			\
@@ -1025,6 +1025,15 @@ $(CONFIGURED_OFILES): stamp-picdir stamp-noasandir
 	else true; fi
 	$(COMPILE.c) $(srcdir)/memchr.c $(OUTPUT_OPTION)
 
+./memrchr.$(objext): $(srcdir)/memrchr.c $(INCDIR)/ansidecl.h
+	if [ x"$(PICFLAG)" != x ]; then \
+	  $(COMPILE.c) $(PICFLAG) $(srcdir)/memrchr.c -o pic/$@; \
+	else true; fi
+	if [ x"$(NOASANFLAG)" != x ]; then \
+	  $(COMPILE.c) $(PICFLAG) $(NOASANFLAG) $(srcdir)/memrchr.c -o noasan/$@; \
+	else true; fi
+	$(COMPILE.c) $(srcdir)/memrchr.c $(OUTPUT_OPTION)
+
 ./memcmp.$(objext): $(srcdir)/memcmp.c $(INCDIR)/ansidecl.h
 	if [ x"$(PICFLAG)" != x ]; then \
 	  $(COMPILE.c) $(PICFLAG) $(srcdir)/memcmp.c -o pic/$@; \

libiberty/config.in

@@ -186,6 +186,9 @@
 /* Define to 1 if you have the <memory.h> header file. */
 #undef HAVE_MEMORY_H
 
+/* Define to 1 if you have the `memrchr' function. */
+#undef HAVE_MEMRCHR
+
 /* Define to 1 if you have the `memset' function. */
 #undef HAVE_MEMSET
 

libiberty/configure

@@ -6210,6 +6210,7 @@ funcs="$funcs gettimeofday"
 funcs="$funcs index"
 funcs="$funcs insque"
 funcs="$funcs memchr"
+funcs="$funcs memrchr"
 funcs="$funcs memcmp"
 funcs="$funcs memcpy"
 funcs="$funcs memmem"
@@ -6276,7 +6277,7 @@ if test "x" = "y"; then
     ffs __fsetlocking \
     getcwd getpagesize getrlimit getrusage getsysinfo gettimeofday \
     index insque \
-    memchr memcmp memcpy memmem memmove memset mkstemps \
+    memchr memrchr memcmp memcpy memmem memmove memset mkstemps \
     on_exit \
     pipe2 posix_spawn posix_spawnp psignal \
     pstat_getdynamic pstat_getstatic putenv \
@@ -6691,7 +6692,7 @@ esac
 
     for f in atexit basename bcmp bcopy bsearch bzero calloc clock ffs \
              getcwd getpagesize getrusage gettimeofday \
-             index insque memchr memcmp memcpy memmove memset psignal \
+             index insque memchr memrchr memcmp memcpy memmove memset psignal \
              putenv random rename rindex sbrk setenv stpcpy strcasecmp \
              strchr strdup strerror strncasecmp strrchr strstr strtod \
              strtol strtoul sysconf times tmpnam vfprintf vprintf \

libiberty/configure.ac

@@ -370,6 +370,7 @@ funcs="$funcs gettimeofday"
 funcs="$funcs index"
 funcs="$funcs insque"
 funcs="$funcs memchr"
+funcs="$funcs memrchr"
 funcs="$funcs memcmp"
 funcs="$funcs memcpy"
 funcs="$funcs memmem"
@@ -436,7 +437,7 @@ if test "x" = "y"; then
     ffs __fsetlocking \
     getcwd getpagesize getrlimit getrusage getsysinfo gettimeofday \
     index insque \
-    memchr memcmp memcpy memmem memmove memset mkstemps \
+    memchr memrchr memcmp memcpy memmem memmove memset mkstemps \
     on_exit \
     pipe2 posix_spawn posix_spawnp psignal \
     pstat_getdynamic pstat_getstatic putenv \
@@ -555,7 +556,7 @@ if test -n "${with_target_subdir}"; then
 
     for f in atexit basename bcmp bcopy bsearch bzero calloc clock ffs \
              getcwd getpagesize getrusage gettimeofday \
-             index insque memchr memcmp memcpy memmove memset psignal \
+             index insque memchr memrchr memcmp memcpy memmove memset psignal \
              putenv random rename rindex sbrk setenv stpcpy strcasecmp \
              strchr strdup strerror strncasecmp strrchr strstr strtod \
              strtol strtoul sysconf times tmpnam vfprintf vprintf \

libiberty/functions.texi

@@ -749,6 +749,20 @@ returned.
 
 @end deftypefn
 
+@c memrchr.c:3
+@deftypefn Supplemental void* memrchr (const void *@var{s}, int @var{c}, @
+  size_t @var{n})
+
+This function searches memory for the character @var{c} in reverse order,
+starting at @code{*@var{s}+@var{n}-1} .  The search only ends with
+the first occurrence of @var{c}, or when the start us reached; in particular,
+a null character does not terminate the search.  If the character @var{c} is
+found within @var{length} characters of @code{*@var{s}}, a pointer
+to the character is returned.  If @var{c} is not found, then @code{NULL} is
+returned.
+
+@end deftypefn
+
 @c memcmp.c:6
 @deftypefn Supplemental int memcmp (const void *@var{x}, const void *@var{y}, @
   size_t @var{count})

libiberty/memrchr.c

@@ -0,0 +1,33 @@
+/*
+
+@deftypefn Supplemental void* memrchr (const void *@var{s}, int @var{c}, @
+  size_t @var{n})
+
+This function searches memory for the character @var{c} in reverse order,
+starting at @code{*@var{s}+@var{n}-1} .  The search only ends with
+the first occurrence of @var{c}, or when the start us reached; in particular,
+a null character does not terminate the search.  If the character @var{c} is
+found within @var{length} characters of @code{*@var{s}}, a pointer
+to the character is returned.  If @var{c} is not found, then @code{NULL} is
+returned.
+
+@end deftypefn
+
+*/
+
+#include <ansidecl.h>
+#include <stddef.h>
+
+void *
+memrchr (const void *src_void, int c, size_t length)
+{
+  if (length == 0)
+    return NULL;
+
+  const unsigned char *p = (const unsigned char*)src_void;
+  p += length;
+  while (*--p != (unsigned char)c)
+    if (src_void == p)
+      return NULL;
+  return (void *)p;
+}