[PATCH] Fix high handling in wi::mul_internal (PR tree-optimization/61682)

[Jakub Jelinek]

Hi!

Several places in wi::mul_internal didn't handle high parameter
and would return the low bits instead of high bits.

Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?

2014-07-03  Jakub Jelinek  <ja...@redhat.com>

        PR tree-optimization/61682
        * wide-int.cc (wi::mul_internal): Handle high correctly
        for umul_ppmm using cases and when one of the operands is
        equal to 1.

        * gcc.c-torture/execute/pr61682.c: New test.

--- gcc/wide-int.cc.jj  2014-05-30 10:51:11.000000000 +0200
+++ gcc/wide-int.cc     2014-07-03 09:35:11.084228924 +0200
@@ -1,5 +1,5 @@
 /* Operations with very long integers.
-   Copyright (C) 2012-2013 Free Software Foundation, Inc.
+   Copyright (C) 2012-2014 Free Software Foundation, Inc.
    Contributed by Kenneth Zadeck <zad...@naturalbridge.com>
 
 This file is part of GCC.
@@ -1282,6 +1282,12 @@ wi::mul_internal (HOST_WIDE_INT *val, co
          && wi::fits_uhwi_p (op1)
          && wi::fits_uhwi_p (op2))
        {
+         /* This case never overflows.  */
+         if (high)
+           {
+             val[0] = 0;
+             return 1;
+           }
          umul_ppmm (val[1], val[0], op1.ulow (), op2.ulow ());
          return 1 + (val[1] != 0 || val[0] < 0);
        }
@@ -1294,6 +1300,8 @@ wi::mul_internal (HOST_WIDE_INT *val, co
          umul_ppmm (upper, val[0], op1.ulow (), op2.ulow ());
          if (needs_overflow)
            *overflow = (upper != 0);
+         if (high)
+           val[0] = upper;
          return 1;
        }
     }
@@ -1302,12 +1310,28 @@ wi::mul_internal (HOST_WIDE_INT *val, co
   /* Handle multiplications by 1.  */
   if (op1 == 1)
     {
+      if (high)
+       {
+         if (sgn == SIGNED && wi::neg_p (op2))
+           val[0] = -1;
+         else
+           val[0] = 0;
+         return 1;
+       }
       for (i = 0; i < op2len; i++)
        val[i] = op2val[i];
       return op2len;
     }
   if (op2 == 1)
     {
+      if (high)
+       {
+         if (sgn == SIGNED && wi::neg_p (op1))
+           val[0] = -1;
+         else
+           val[0] = 0;
+         return 1;
+       }
       for (i = 0; i < op1len; i++)
        val[i] = op1val[i];
       return op1len;
--- gcc/testsuite/gcc.c-torture/execute/pr61682.c.jj    2014-03-19 
15:57:57.735114622 +0100
+++ gcc/testsuite/gcc.c-torture/execute/pr61682.c       2014-07-03 
09:40:26.215520476 +0200
@@ -0,0 +1,17 @@
+/* PR tree-optimization/61682 */
+
+int a, b;
+static int *c = &b;
+
+int
+main ()
+{
+  int *d = &a;
+  for (a = 0; a < 12; a++)
+    *c |= *d / 9;
+
+  if (b != 1)
+    __builtin_abort ();
+
+  return 0;
+}

        Jakub