2002-05-23 David S. Miller <davem@redhat.com>

	* basic-block.h (CLEANUP_NO_INSN_DEL): Define it.
	* cfgcleanup.c (cleanup_cfg): If it is set do not
	attempt to delete trivially dead insns.
	* except.c (finish_eh_generation): Pass it to cleanup_cfg.
	* toplev.c (rest_of_compilation): Document non-trivial aspect
	the RTL before optimize_save_area_alloca is run.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@53789 138bc75d-0d04-0410-961f-82ee72b054a4

5 files changed, 21 insertions, 5 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9da36a96634..d7334a9cb7a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2002-05-23  David S. Miller  <davem@redhat.com>
+
+	* basic-block.h (CLEANUP_NO_INSN_DEL): Define it.
+	* cfgcleanup.c (cleanup_cfg): If it is set do not
+	attempt to delete trivially dead insns.
+	* except.c (finish_eh_generation): Pass it to cleanup_cfg.
+	* toplev.c (rest_of_compilation): Document non-trivial aspect
+	the RTL before optimize_save_area_alloca is run.
+
 2002-05-23  Neil Booth  <neil@daikokuya.demon.co.uk>
 
 	* c-lex.c (indent_level): Remove.
diff --git a/gcc/basic-block.h b/gcc/basic-block.h
index cf0d13ad2d5..69ec1224b4e 100644
--- a/gcc/basic-block.h
+++ b/gcc/basic-block.h
@@ -595,6 +595,8 @@ enum update_life_extent
 					   notes.  */
 #define CLEANUP_UPDATE_LIFE	32	/* Keep life information up to date.  */
 #define CLEANUP_THREADING	64	/* Do jump threading.  */
+#define CLEANUP_NO_INSN_DEL	128	/* Do not try to delete trivially dead
+					   insns.  */
 /* Flags for loop discovery.  */
 
 #define LOOP_TREE		1	/* Build loop hierarchy tree.  */
diff --git a/gcc/cfgcleanup.c b/gcc/cfgcleanup.c
index d5f6de18555..1e4056a60f4 100644
--- a/gcc/cfgcleanup.c
+++ b/gcc/cfgcleanup.c
@@ -1800,7 +1800,8 @@ cleanup_cfg (mode)
       changed = true;
       /* We've possibly created trivially dead code.  Cleanup it right
 	 now to introduce more oppurtunities for try_optimize_cfg.  */
-      if (!(mode & (CLEANUP_UPDATE_LIFE | CLEANUP_PRE_SIBCALL))
+      if (!(mode & (CLEANUP_NO_INSN_DEL
+		    | CLEANUP_UPDATE_LIFE | CLEANUP_PRE_SIBCALL))
 	  && !reload_completed)
 	delete_trivially_dead_insns (get_insns(), max_reg_num ());
     }
@@ -1819,7 +1820,8 @@ cleanup_cfg (mode)
 						 | PROP_LOG_LINKS))
 	    break;
 	}
-      else if (!(mode & CLEANUP_PRE_SIBCALL) && !reload_completed)
+      else if (!(mode & (CLEANUP_NO_INSN_DEL | CLEANUP_PRE_SIBCALL))
+	       && !reload_completed)
 	{
 	  if (!delete_trivially_dead_insns (get_insns(), max_reg_num ()))
 	    break;
diff --git a/gcc/except.c b/gcc/except.c
index e1f32a56718..ee6ee9f023d 100644
--- a/gcc/except.c
+++ b/gcc/except.c
@@ -2501,7 +2501,7 @@ finish_eh_generation ()
 
   rebuild_jump_labels (get_insns ());
   find_basic_blocks (get_insns (), max_reg_num (), 0);
-  cleanup_cfg (CLEANUP_PRE_LOOP);
+  cleanup_cfg (CLEANUP_PRE_LOOP | CLEANUP_NO_INSN_DEL);
 
   /* These registers are used by the landing pads.  Make sure they
      have been generated.  */
@@ -2524,7 +2524,7 @@ finish_eh_generation ()
   find_exception_handler_labels ();
   rebuild_jump_labels (get_insns ());
   find_basic_blocks (get_insns (), max_reg_num (), 0);
-  cleanup_cfg (CLEANUP_PRE_LOOP);
+  cleanup_cfg (CLEANUP_PRE_LOOP | CLEANUP_NO_INSN_DEL);
 }
 
 static hashval_t
diff --git a/gcc/toplev.c b/gcc/toplev.c
index fc4f658c62b..bb6a4486d83 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -2573,7 +2573,10 @@ rest_of_compilation (decl)
   unshare_all_rtl (current_function_decl, insns);
 
 #ifdef SETJMP_VIA_SAVE_AREA
-  /* This must be performed before virtual register instantiation.  */
+  /* This must be performed before virtual register instantiation.
+     Please be aware the everything in the compiler that can look
+     at the RTL up to this point must understand that REG_SAVE_AREA
+     is just like a use of the REG contained inside.  */
   if (current_function_calls_alloca)
     optimize_save_area_alloca (insns);
 #endif