optabs.c (expand_binop): Sign-extend xop0 and xop1 from the widest mode in…

optabs.c (expand_binop): Sign-extend xop0 and xop1 from the widest mode in narrowing and widening operations.

* optabs.c (expand_binop): Sign-extend xop0 and xop1 from the
widest mode in narrowing and widening operations.

From-SVN: r41885

gcc/ChangeLog

 2001-05-06  Alexandre Oliva  <aoliva@redhat.com>
 
+	* optabs.c (expand_binop): Sign-extend xop0 and xop1 from the
+	widest mode in narrowing and widening operations.
+
 	* config/mips/mips.md: Sign extend CONST_INTs.
 
 2001-05-06  Andreas Jaeger  <aj@suse.de>

gcc/optabs.c

@@ -725,13 +725,20 @@ expand_binop (mode, binoptab, op0, op1, target, unsignedp, methods)
       /* In case the insn wants input operands in modes different from
 	 the result, convert the operands.  It would seem that we
 	 don't need to convert CONST_INTs, but we do, so that they're
-	 a properly sign-extended for their modes.  */
+	 a properly sign-extended for their modes; we choose the
+	 widest mode between mode and mode[01], so that, in a widening
+	 operation, we call convert_modes with different FROM and TO
+	 modes, which ensures the value is sign-extended.  Shift
+	 operations are an exception, because the second operand needs
+	 not be extended to the mode of the result.  */
 
       if (GET_MODE (op0) != mode0
 	  && mode0 != VOIDmode)
 	xop0 = convert_modes (mode0,
 			      GET_MODE (op0) != VOIDmode
 			      ? GET_MODE (op0)
+			      : GET_MODE_SIZE (mode) > GET_MODE_SIZE (mode0)
+			      ? mode
 			      : mode0,
 			      xop0, unsignedp);
 
@@ -740,6 +747,9 @@ expand_binop (mode, binoptab, op0, op1, target, unsignedp, methods)
 	xop1 = convert_modes (mode1,
 			      GET_MODE (op1) != VOIDmode
 			      ? GET_MODE (op1)
+			      : (GET_MODE_SIZE (mode) > GET_MODE_SIZE (mode1)
+				 && ! shift_op)
+			      ? mode
 			      : mode1,
 			      xop1, unsignedp);