re PR rtl-optimization/6233 (simple loop miscompilation)

	PR optimization/6233
	* rtlanal.c (pure_call_p): New function.
	* rtl.h (pure_call_p): Declare.
	* loop.c (prescan_loop): Use it to set has_nonconst_call.
	* gcse.c (store_killed_in_insn): Use pure_call_p here too.

From-SVN: r52110

gcc/ChangeLog

+2002-04-10  Alan Modra  <amodra@bigpond.net.au>
+
+	PR optimization/6233
+	* rtlanal.c (pure_call_p): New function.
+	* rtl.h (pure_call_p): Declare.
+	* loop.c (prescan_loop): Use it to set has_nonconst_call.
+	* gcse.c (store_killed_in_insn): Use pure_call_p here too.
+
 2002-04-09  Eric Christopher  <echristo@redhat.com>
 
 	* config/mips/mips.h (ASM_OUTPUT_ALIGNED_DECL_COMMON): Add additional

gcc/gcse.c

@@ -6528,21 +6528,7 @@ store_killed_in_insn (x, insn)
     {
       /* A normal or pure call might read from pattern,
 	 but a const call will not.  */
-      if (CONST_OR_PURE_CALL_P (insn))
-	{
-	  rtx link;
-
-	  for (link = CALL_INSN_FUNCTION_USAGE (insn);
-	       link;
-	       link = XEXP (link, 1))
-	    if (GET_CODE (XEXP (link, 0)) == USE
-		&& GET_CODE (XEXP (XEXP (link, 0), 0)) == MEM
-		&& GET_CODE (XEXP (XEXP (XEXP (link, 0), 0), 0)) == SCRATCH)
-	      return 1;
-	  return 0;
-	}
-      else
-	return 1;
+      return ! CONST_OR_PURE_CALL_P (insn) || pure_call_p (insn);
     }
   
   if (GET_CODE (PATTERN (insn)) == SET)

gcc/loop.c

@@ -2494,6 +2494,8 @@ prescan_loop (loop)
 	      loop_info->unknown_address_altered = 1;
 	      loop_info->has_nonconst_call = 1;
 	    }
+	  else if (pure_call_p (insn))
+	    loop_info->has_nonconst_call = 1;
 	  loop_info->has_call = 1;
 	  if (can_throw_internal (insn))
 	    loop_info->has_multiple_exit_targets = 1;

gcc/rtl.h

@@ -1502,6 +1502,7 @@ extern rtx find_reg_equal_equiv_note	PARAMS ((rtx));
 extern int find_reg_fusage		PARAMS ((rtx, enum rtx_code, rtx));
 extern int find_regno_fusage		PARAMS ((rtx, enum rtx_code,
 						 unsigned int));
+extern int pure_call_p			PARAMS ((rtx));
 extern void remove_note			PARAMS ((rtx, rtx));
 extern int side_effects_p		PARAMS ((rtx));
 extern int volatile_refs_p		PARAMS ((rtx));

gcc/rtlanal.c

@@ -2011,6 +2011,31 @@ find_regno_fusage (insn, code, regno)
 
   return 0;
 }
+
+/* Return true if INSN is a call to a pure function.  */
+
+int
+pure_call_p (insn)
+     rtx insn;
+{
+  rtx link;
+
+  if (GET_CODE (insn) != CALL_INSN || ! CONST_OR_PURE_CALL_P (insn))
+    return 0;
+
+  /* Look for the note that differentiates const and pure functions.  */
+  for (link = CALL_INSN_FUNCTION_USAGE (insn); link; link = XEXP (link, 1))
+    {
+      rtx u, m;
+
+      if (GET_CODE (u = XEXP (link, 0)) == USE
+	  && GET_CODE (m = XEXP (u, 0)) == MEM && GET_MODE (m) == BLKmode
+	  && GET_CODE (XEXP (m, 0)) == SCRATCH)
+	return 1;
+    }
+
+  return 0;
+}
 
 /* Remove register note NOTE from the REG_NOTES of INSN.  */