[PATCH] Avoid IA-64 prologue insns being deleted (was Re: Bug? flow_find_cross_jump deletes USE insns ...)

[Jakub Jelinek <jakub at redhat dot com>]

On Wed, Jan 16, 2002 at 10:30:32AM -0800, Richard Henderson wrote:
> On Wed, Jan 16, 2002 at 11:41:03AM +0100, Jakub Jelinek wrote:
> > What is the preferred way here?
> > Use some dummy unspec insn which will contain all the USEs, or use some
> > unspec insn in the sets (like
> > (set (reg:DI 33 r35) (unspec:DI[(reg:DI 320 b0)]  FOO))
> > ), or something else?
> 
> Another way is to leave the existing insn as-is and have
> 
>  (unspec:DI [(reg:DI r35)] FOO)
> 
> and make it type ignore.  That creates a generic "use"
> for the two or three places in the prologue that need this.

Like this?

2002-01-16  Jakub Jelinek  <jakub@redhat.com>

	* config/ia64/ia64.md (prologue_use): New.
	* config/ia64/ia64.c (ia64_expand_prologue): Use
	gen_prologue_use instead of gen_rtx_USE.
	(group_barrier_needed_p): Handle CODE_FOR_prologue_use the same way
	as CODE_FOR_pred_rel_mutex.
	(ia64_sched_reorder2): Likewise.

	* gcc.c-torture/compile/20020116-1.c: New test.

--- gcc/config/ia64/ia64.md.jj	Mon Dec 10 19:13:48 2001
+++ gcc/config/ia64/ia64.md	Wed Jan 16 21:36:57 2002
@@ -67,6 +67,7 @@
 ;;	22      bundle selector
 ;;	23      cycle display
 ;;      24      addp4
+;;	25	prologue_use
 ;;
 ;; unspec_volatile:
 ;;	0	alloc
@@ -5302,3 +5303,12 @@
   "addp4 %0 = 0,%1"
   [(set_attr "itanium_class" "ialu")])
 
+;;
+;; As USE insns aren't meaningful after reload, this is used instead
+;; to prevent deleting instructions setting registers for EH handling
+(define_insn "prologue_use"
+  [(unspec:DI [(match_operand:DI 0 "register_operand" "")] 25)]
+  ""
+  "// %0 needed for EH"
+  [(set_attr "itanium_class" "ignore")
+   (set_attr "predicable" "no")])
--- gcc/config/ia64/ia64.c.jj	Fri Jan  4 13:41:06 2002
+++ gcc/config/ia64/ia64.c	Wed Jan 16 21:39:26 2002
@@ -2137,7 +2137,7 @@ ia64_expand_prologue ()
       /* Even if we're not going to generate an epilogue, we still
 	 need to save the register so that EH works.  */
       if (! epilogue_p && current_frame_info.reg_save_ar_unat)
-	emit_insn (gen_rtx_USE (VOIDmode, ar_unat_save_reg));
+	emit_insn (gen_prologue_use (ar_unat_save_reg));
     }
   else
     ar_unat_save_reg = NULL_RTX;
@@ -2178,7 +2178,7 @@ ia64_expand_prologue ()
 	  /* Even if we're not going to generate an epilogue, we still
 	     need to save the register so that EH works.  */
 	  if (! epilogue_p)
-	    emit_insn (gen_rtx_USE (VOIDmode, alt_reg));
+	    emit_insn (gen_prologue_use (alt_reg));
 	}
       else
 	{
@@ -2222,7 +2222,7 @@ ia64_expand_prologue ()
 	  /* Even if we're not going to generate an epilogue, we still
 	     need to save the register so that EH works.  */
 	  if (! epilogue_p)
-	    emit_insn (gen_rtx_USE (VOIDmode, alt_reg));
+	    emit_insn (gen_prologue_use (alt_reg));
 	}
       else
 	{
@@ -2262,7 +2262,7 @@ ia64_expand_prologue ()
 	  /* Even if we're not going to generate an epilogue, we still
 	     need to save the register so that EH works.  */
 	  if (! epilogue_p)
-	    emit_insn (gen_rtx_USE (VOIDmode, alt_reg));
+	    emit_insn (gen_prologue_use (alt_reg));
 	}
       else
 	{
@@ -4776,6 +4776,7 @@ group_barrier_needed_p (insn)
 
 	  /* Doesn't generate code.  */
 	case CODE_FOR_pred_rel_mutex:
+	case CODE_FOR_prologue_use:
 	  return 0;
 
 	default:
@@ -6393,7 +6394,8 @@ ia64_sched_reorder2 (dump, sched_verbose
 
 	  /* Ignore cycle displays and .pred.rel.mutex.  */
 	  if (insn_code == CODE_FOR_cycle_display
-	      || insn_code == CODE_FOR_pred_rel_mutex)
+	      || insn_code == CODE_FOR_pred_rel_mutex
+	      || insn_code == CODE_FOR_prologue_use)
 	    continue;
 
 	  if (insn_code == CODE_FOR_insn_group_barrier)
--- gcc/testsuite/gcc.c-torture/compile/20020116-1.c.jj	Wed Jan 16 21:46:21 2002
+++ gcc/testsuite/gcc.c-torture/compile/20020116-1.c	Wed Jan 16 21:47:04 2002
@@ -0,0 +1,28 @@
+void noret (void) __attribute__ ((noreturn));
+int foo (int, char **);
+char *a, *b;
+int d;
+
+int
+main (int argc, char **argv)
+{
+  register int c;
+
+  d = 1;
+  while ((c = foo (argc, argv)) != -1)
+    switch (c) {
+    case 's':
+    case 'c':
+    case 'f':
+      a = b;
+      break;
+    case 'v':
+      d = 1;
+      break;
+    case 'V':
+      d = 0;
+      break;
+    }
+  noret ();
+  return 0;
+}


	Jakub