1 files changed, 50 insertions, 0 deletions
diff --git a/gcc/config/rs6000/host-darwin.c b/gcc/config/rs6000/host-darwin.c
index 7ef7c9aefdc..7e8055690e4 100644
--- a/gcc/config/rs6000/host-darwin.c
+++ b/gcc/config/rs6000/host-darwin.c
@@ -23,6 +23,7 @@
 #include "coretypes.h"
 #include <signal.h>
 #include <sys/ucontext.h>
+#include <sys/mman.h>
 #include "hosthooks.h"
 #include "hosthooks-def.h"
 #include "toplev.h"
@@ -135,5 +136,54 @@ darwin_rs6000_extra_signals (void)
   if (sigaction (SIGSEGV, &sact, 0) < 0) 
     fatal_error ("While setting up signal handler: %m");
 }
+
+static void * darwin_rs6000_gt_pch_get_address (size_t);
+static bool darwin_rs6000_gt_pch_use_address (void *, size_t);
+
+#undef HOST_HOOKS_GT_PCH_GET_ADDRESS
+#define HOST_HOOKS_GT_PCH_GET_ADDRESS darwin_rs6000_gt_pch_get_address
+#undef HOST_HOOKS_GT_PCH_USE_ADDRESS
+#define HOST_HOOKS_GT_PCH_USE_ADDRESS darwin_rs6000_gt_pch_use_address
+
+
+/* Yes, this is really supposed to work.  */
+static char pch_address_space[1024*1024*1024] __attribute__((aligned (4096)));
+
+/* Return the address of the PCH address space, if the PCH will fit in it.  */
+
+static void *
+darwin_rs6000_gt_pch_get_address (size_t sz)
+{
+  if (sz <= sizeof (pch_address_space))
+    return pch_address_space;
+  else
+    return NULL;
+}
+
+/* Check ADDR and SZ for validity, and deallocate (using munmap) that part of
+   pch_address_space beyond SZ.  */
+
+static bool
+darwin_rs6000_gt_pch_use_address (void *addr, size_t sz)
+{
+  const size_t pagesize = getpagesize();
+  bool result;
+
+  if ((size_t)pch_address_space % pagesize != 0
+      || sizeof (pch_address_space) % pagesize != 0)
+    abort ();
+  
+  result = (addr == pch_address_space && sz <= sizeof (pch_address_space));
+  if (! result)
+    sz = 0;
+
+  /* Round the size to a whole page size.  Normally this is a no-op.  */
+  sz = (sz + pagesize - 1) / pagesize * pagesize;
+
+  if (munmap (pch_address_space + sz, sizeof (pch_address_space) - sz) != 0)
+    fatal_error ("couldn't unmap pch_address_space: %m\n");
+
+  return result;
+}
 
 const struct host_hooks host_hooks = HOST_HOOKS_INITIALIZER;