* optabs.c (expand_binop): Sign-extend xop0 and xop1 from the

widest mode in narrowing and widening operations.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@41885 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 11 insertions, 1 deletions

diff --git a/gcc/optabs.c b/gcc/optabs.c
index 4068fa863db..c6da81592fd 100644
--- a/gcc/optabs.c
+++ b/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);