re PR target/39254 (gcc.c-torture/execute/va-arg-trap-1.c ICEs on powerpc-apple-darwin9)

        PR target/39254
        * config/rs6000/rs6000.c (rs6000_emit_move): Don't emit a USE
        for the symbol ref of a constant that is the source of a move
        - nor for any other not-obvious-label-ref constants.

Co-Authored-By: Janis Johnson <janis187@us.ibm.com>

From-SVN: r148568

gcc/ChangeLog

+2009-06-16  J"orn Rennecke  <joern.rennecke@arc.com>
+	    Janis Johnson  <janis187@us.ibm.com>
+
+	PR target/39254
+	* config/rs6000/rs6000.c (rs6000_emit_move): Don't emit a USE
+	for the symbol ref of a constant that is the source of a move
+	- nor for any other not-obvious-label-ref constants.
+
 2009-06-16  Olatunji Ruwase  <tjruwase@google.com>
 
 	* plugin.c(position_pass): Skip newly inserted pass during list

gcc/config/rs6000/rs6000.c

@@ -5204,14 +5204,6 @@ rs6000_emit_move (rtx dest, rtx source, enum machine_mode mode)
 	       && ! legitimate_constant_pool_address_p (operands[1])
 	       && ! toc_relative_expr_p (operands[1]))
 	{
-	  /* Emit a USE operation so that the constant isn't deleted if
-	     expensive optimizations are turned on because nobody
-	     references it.  This should only be done for operands that
-	     contain SYMBOL_REFs with CONSTANT_POOL_ADDRESS_P set.
-	     This should not be done for operands that contain LABEL_REFs.
-	     For now, we just handle the obvious case.  */
-	  if (GET_CODE (operands[1]) != LABEL_REF)
-	    emit_use (operands[1]);
 
 #if TARGET_MACHO
 	  /* Darwin uses a special PIC legitimizer.  */