gcc/

	PR middle-end/66311
	* wide-int.cc (wi::from_mpz): Make sure that absolute mpz value
	is zero- rather than sign-extended.

gcc/testsuite/
2015-08-05  Francois-Xavier Coudert  <fxcoudert@gcc.gnu.org>

	PR middle-end/66311
	* gfortran.dg/pr66311.f90: New file.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@226632 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 10 insertions, 3 deletions

diff --git a/gcc/wide-int.cc b/gcc/wide-int.cc
index 13ba10c866f..9a93660defc 100644
--- a/gcc/wide-int.cc
+++ b/gcc/wide-int.cc
@@ -252,13 +252,15 @@ wi::from_mpz (const_tree type, mpz_t x, bool wrap)
     }
 
   /* Determine the number of unsigned HOST_WIDE_INTs that are required
-     for representing the value.  The code to calculate count is
+     for representing the absolute value.  The code to calculate count is
      extracted from the GMP manual, section "Integer Import and Export":
      http://gmplib.org/manual/Integer-Import-and-Export.html  */
   numb = CHAR_BIT * sizeof (HOST_WIDE_INT);
   count = (mpz_sizeinbase (x, 2) + numb - 1) / numb;
   HOST_WIDE_INT *val = res.write_val ();
-  /* Write directly to the wide_int storage if possible, otherwise leave
+  /* Read the absolute value.
+
+     Write directly to the wide_int storage if possible, otherwise leave
      GMP to allocate the memory for us.  It might be slightly more efficient
      to use mpz_tdiv_r_2exp for the latter case, but the situation is
      pathological and it seems safer to operate on the original mpz value
@@ -276,7 +278,12 @@ wi::from_mpz (const_tree type, mpz_t x, bool wrap)
       memcpy (val, valres, count * sizeof (HOST_WIDE_INT));
       free (valres);
     }
-  res.set_len (canonize (val, count, prec));
+  /* Zero-extend the absolute value to PREC bits.  */
+  if (count < BLOCKS_NEEDED (prec) && val[count - 1] < 0)
+    val[count++] = 0;
+  else
+    count = canonize (val, count, prec);
+  res.set_len (count);
 
   if (mpz_sgn (x) < 0)
     res = -res;