aclocal.m4 (AC_FUNC_MMAP_ZERO): New macro.

* aclocal.m4 (AC_FUNC_MMAP_ZERO): New macro.
* configure.in (AC_FUNC_MMAP_ZERO): Use instead of AC_FUNC_MMAP.
* ggc-page.c: Replace HAVE_MMAP with HAVE_MMAP_ZERO.
* configure, config.in: Rebuilt.

From-SVN: r31444

gcc/ChangeLog

@@ -1,3 +1,10 @@
+2000-01-16  Alexandre Oliva  <oliva@lsd.ic.unicamp.br>
+
+	* aclocal.m4 (AC_FUNC_MMAP_ZERO): New macro.
+	* configure.in (AC_FUNC_MMAP_ZERO): Use instead of AC_FUNC_MMAP.
+	* ggc-page.c: Replace HAVE_MMAP with HAVE_MMAP_ZERO.
+	* configure, config.in: Rebuilt.
+
 2000-01-16  Zack Weinberg  <zack@wolery.cumb.org>
 
 	* config/i386/i386.md: Add peephole to merge successive stack

gcc/aclocal.m4

@@ -680,3 +680,85 @@ else
 fi
 AC_SUBST($1)dnl
 ])
+
+# Check whether mmap can map an arbitrary page from /dev/zero, without
+# MAP_FIXED.
+AC_DEFUN([AC_FUNC_MMAP_ANYWHERE],
+[AC_CHECK_HEADERS(unistd.h)
+AC_CHECK_FUNCS(getpagesize)
+AC_CACHE_CHECK(for working mmap from /dev/zero, ac_cv_func_mmap_zero,
+[AC_TRY_RUN([
+/* Test by Richard Henderson and Alexandre Oliva.
+   Check whether mmap from /dev/zero works. */
+#include <sys/types.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+
+/* This mess was copied from the GNU getpagesize.h.  */
+#ifndef HAVE_GETPAGESIZE
+# ifdef HAVE_UNISTD_H
+#  include <unistd.h>
+# endif
+
+/* Assume that all systems that can run configure have sys/param.h.  */
+# ifndef HAVE_SYS_PARAM_H
+#  define HAVE_SYS_PARAM_H 1
+# endif
+
+# ifdef _SC_PAGESIZE
+#  define getpagesize() sysconf(_SC_PAGESIZE)
+# else /* no _SC_PAGESIZE */
+#  ifdef HAVE_SYS_PARAM_H
+#   include <sys/param.h>
+#   ifdef EXEC_PAGESIZE
+#    define getpagesize() EXEC_PAGESIZE
+#   else /* no EXEC_PAGESIZE */
+#    ifdef NBPG
+#     define getpagesize() NBPG * CLSIZE
+#     ifndef CLSIZE
+#      define CLSIZE 1
+#     endif /* no CLSIZE */
+#    else /* no NBPG */
+#     ifdef NBPC
+#      define getpagesize() NBPC
+#     else /* no NBPC */
+#      ifdef PAGESIZE
+#       define getpagesize() PAGESIZE
+#      endif /* PAGESIZE */
+#     endif /* no NBPC */
+#    endif /* no NBPG */
+#   endif /* no EXEC_PAGESIZE */
+#  else /* no HAVE_SYS_PARAM_H */
+#   define getpagesize() 8192	/* punt totally */
+#  endif /* no HAVE_SYS_PARAM_H */
+# endif /* no _SC_PAGESIZE */
+
+#endif /* no HAVE_GETPAGESIZE */
+
+int main()
+{
+  char *x;
+  int fd, pg;
+
+  fd = open("/dev/zero", O_RDWR);
+  if (fd < 0)
+    exit(1);
+
+  pg = getpagesize();
+  x = (char*)mmap(0, pg, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
+  if (x == (char *) -1)
+    exit(2);
+
+  *(int *)x += 1;
+
+  if (munmap(x, pg) < 0)
+    exit(3);
+
+  exit(0);
+}], ac_cv_func_mmap_anywhere=yes, ac_cv_func_mmap_anywhere=no,
+ac_cv_func_mmap_anywhere=no)])
+if test $ac_cv_func_mmap_anywhere = yes; then
+  AC_DEFINE(HAVE_MMAP_ANYWHERE, 1,
+	    [Define if mmap can get us zeroed pages from /dev/zero.])
+fi
+])

gcc/config.in

@@ -415,3 +415,7 @@
 
 /* Define if you have the i library (-li).  */
 #undef HAVE_LIBI
+
+/* Define if mmap can get us zeroed pages from /dev/zero. */
+#undef HAVE_MMAP_ANYWHERE
+

gcc/configure.in

@@ -405,7 +405,7 @@ case "${host}" in
   ;;
 esac
 AC_FUNC_VFORK
-AC_FUNC_MMAP
+AC_FUNC_MMAP_ANYWHERE
 
 GCC_NEED_DECLARATIONS(bcopy bzero bcmp \
 	index rindex getenv atol sbrk abort atof strerror getcwd getwd \
@@ -4578,9 +4578,8 @@ AC_ARG_WITH(gc,
     AC_MSG_ERROR([$withval is an invalid option to --with-gc])
     ;;
 esac],
-[if test $ac_cv_func_mmap_fixed_mapped = yes; then
-  GGC=ggc-page
-elif test $ac_cv_func_valloc = yes; then
+[if test $ac_cv_func_mmap_anywhere = yes \
+    || test $ac_cv_func_valloc = yes; then
   GGC=ggc-page
 else
   GGC=ggc-simple

gcc/ggc-page.c

@@ -1,5 +1,5 @@
 /* "Bag-of-pages" garbage collector for the GNU compiler.
-   Copyright (C) 1999 Free Software Foundation, Inc.
+   Copyright (C) 1999, 2000 Free Software Foundation, Inc.
 
    This file is part of GNU CC.
 
@@ -27,7 +27,7 @@
 #include "flags.h"
 #include "ggc.h"
 
-#ifdef HAVE_MMAP
+#ifdef HAVE_MMAP_ANYWHERE
 #include <sys/mman.h>
 #endif
 
@@ -229,7 +229,7 @@ static struct globals
   unsigned char context_depth;
 
   /* A file descriptor open to /dev/zero for reading.  */
-#if defined (HAVE_MMAP) && !defined(MAP_ANONYMOUS)
+#if defined (HAVE_MMAP_ANYWHERE) && !defined(MAP_ANONYMOUS)
   int dev_zero_fd;
 #endif
 
@@ -408,7 +408,7 @@ alloc_anon (pref, size)
 {
   char *page;
 
-#ifdef HAVE_MMAP
+#ifdef HAVE_MMAP_ANYWHERE
 #ifdef MAP_ANONYMOUS
   page = (char *) mmap (pref, size, PROT_READ | PROT_WRITE,
 			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
@@ -430,7 +430,7 @@ alloc_anon (pref, size)
       exit(1);
     }
 #endif /* HAVE_VALLOC */
-#endif /* HAVE_MMAP */
+#endif /* HAVE_MMAP_ANYWHERE */
 
   /* Remember that we allocated this memory.  */
   G.bytes_mapped += size;
@@ -533,7 +533,7 @@ free_page (entry)
 static void
 release_pages ()
 {
-#ifdef HAVE_MMAP
+#ifdef HAVE_MMAP_ANYWHERE
   page_entry *p, *next;
   char *start;
   size_t len;
@@ -579,7 +579,7 @@ release_pages ()
       free (p);
     }
 #endif /* HAVE_VALLOC */
-#endif /* HAVE_MMAP */
+#endif /* HAVE_MMAP_ANYWHERE */
 
   G.free_pages = NULL;
 }
@@ -794,7 +794,7 @@ init_ggc ()
   G.pagesize = getpagesize();
   G.lg_pagesize = exact_log2 (G.pagesize);
 
-#if defined (HAVE_MMAP) && !defined(MAP_ANONYMOUS)
+#if defined (HAVE_MMAP_ANYWHERE) && !defined(MAP_ANONYMOUS)
   G.dev_zero_fd = open ("/dev/zero", O_RDONLY);
   if (G.dev_zero_fd == -1)
     abort ();
@@ -808,7 +808,7 @@ init_ggc ()
 
   G.allocated_last_gc = GGC_MIN_LAST_ALLOCATED;
 
-#ifdef HAVE_MMAP
+#ifdef HAVE_MMAP_ANYWHERE
   /* StunOS has an amazing off-by-one error for the first mmap allocation
      after fiddling with RLIMIT_STACK.  The result, as hard as it is to
      believe, is an unaligned page allocation, which would cause us to