simplify-rtx.c (simplifi_binary_operation): If DIV has narrower mode than op0,…

simplify-rtx.c (simplifi_binary_operation): If DIV has narrower mode than op0, only return the bits in DIV's mode.

	* simplify-rtx.c (simplifi_binary_operation) [DIV]: If DIV has
	narrower mode than op0, only return the bits in DIV's mode.

	* gcc.c-torture/compile/20011219-2.c: New test.

From-SVN: r48199

gcc/ChangeLog

 2001-12-20  Jakub Jelinek  <jakub@redhat.com>
 
+	* simplify-rtx.c (simplifi_binary_operation) [DIV]: If DIV has
+	narrower mode than op0, only return the bits in DIV's mode.
+
+2001-12-20  Jakub Jelinek  <jakub@redhat.com>
+
 	* combine.c (distribute_notes): Avoid adding REG_LABEL notes
 	to JUMP_INSNs with JUMP_LABEL.
 

gcc/simplify-rtx.c

@@ -1412,7 +1412,10 @@ simplify_binary_operation (code, mode, op0, op1)
 
 	case DIV:
 	  if (trueop1 == CONST1_RTX (mode))
-	    return op0;
+	    {
+	      rtx x = gen_lowpart_common (mode, op0);
+	      return x ? x : op0;
+	    }
 
 	  /* In IEEE floating point, 0/x is not always 0.  */
 	  if ((TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT

gcc/testsuite/ChangeLog

 2001-12-20  Jakub Jelinek  <jakub@redhat.com>
 
+	* gcc.c-torture/compile/20011219-2.c: New test.
+
 	* gcc.c-torture/execute/20011219-1.c: New test.
 
 2001-12-19  David Billinghurst <David.Billinghurst@riotinto.com>

gcc/testsuite/gcc.c-torture/compile/20011219-2.c

+/* This testcase failed on Alpha at -O2 when simplifying conditional
+   expressions.  */
+
+struct S {
+  unsigned long a;
+  double b, c;
+};
+
+extern double bar (double, double);
+
+int
+foo (unsigned long x, unsigned int y, struct S *z)
+{
+  unsigned int a = z->a;
+  int b = y / z->a > 1 ? y / z->a : 1;
+
+  a = y / b < z->a ? y / b : z->a;
+  z->c = z->b * bar ((double) a, (double) x);
+  return 0;
+}