From: Richard Kenner <kenner@vlsi1.ultra.nyu.edu>
Date: Tue, 31 Aug 2004 22:28:44 +0000 (+0000)
Subject: tree-cfg.c (cfg_remove_useless_stmts_bb): Also invalidate if VAL gets modified.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=631b67ce1f819a4122eaf8b46f725dc5ff5ebd1d;p=gcc.git

tree-cfg.c (cfg_remove_useless_stmts_bb): Also invalidate if VAL gets modified.

	* tree-cfg.c (cfg_remove_useless_stmts_bb): Also invalidate if VAL
	gets modified.

Co-Authored-By: Jeff Law <law@redhat.com>

From-SVN: r86847
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index af60798b7c6..1cddc302288 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2004-08-31  Richard Kenner  <kenner@vlsi1.ultra.nyu.edu>
+	    Jeff Law  <law@redhat.com>
+
+	* tree-cfg.c (cfg_remove_useless_stmts_bb): Also invalidate if VAL
+	gets modified.
+
 2004-08-31  Mark Mitchell  <mark@codesourcery.com>
 
 	* hooks.c (hook_bool_void_true): New function.
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index dab912550d6..ae9521e0d0d 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -1738,10 +1738,14 @@ cfg_remove_useless_stmts_bb (basic_block bb)
 	  continue;
 	}
 
-      /* Invalidate the var if we encounter something that could modify it.  */
+      /* Invalidate the var if we encounter something that could modify it.
+	 Likewise for the value it was previously set to.  Note that we only
+	 consider values that are either a VAR_DECL or PARM_DECL so we
+	 can test for conflict very simply.  */
       if (TREE_CODE (stmt) == ASM_EXPR
 	  || (TREE_CODE (stmt) == MODIFY_EXPR
-	      && TREE_OPERAND (stmt, 0) == var))
+	      && (TREE_OPERAND (stmt, 0) == var
+		  || TREE_OPERAND (stmt, 0) == val)))
 	return;
   
       bsi_next (&bsi);