[tests/tpow_fr.c] added test case exposing reuse bug (I don't know how to enter

		  such a test in pow_fr.dat)
[src/pow.c] fixed corresponding bug


git-svn-id: svn://scm.gforge.inria.fr/svn/mpc/trunk@1088 211d60ee-9f03-0410-a15a-8952a2c7a4e4

3 files changed, 38 insertions, 5 deletions

diff --git a/src/pow.c b/src/pow.c
index 5627831..a05a928 100644
--- a/src/pow.c
+++ b/src/pow.c
@@ -164,6 +164,8 @@ fix_sign (mpc_t z, int sign_eps, int sign_a, mpfr_t y)
    should be called again with a larger value of maxprec).
 
    Assume one of Re(x) or Im(x) is non-zero, and y is non-zero (y is real).
+
+   Warning: z and x might be the same variable.
 */
 static int
 mpc_pow_exact (mpc_ptr z, mpc_srcptr x, mpfr_srcptr y, mpc_rnd_t rnd,
@@ -173,6 +175,9 @@ mpc_pow_exact (mpc_ptr z, mpc_srcptr x, mpfr_srcptr y, mpc_rnd_t rnd,
   mpz_t my, a, b, c, d, u;
   unsigned long int t;
   int ret = -2;
+  int sign_rex = mpfr_signbit (MPC_RE(x));
+  int sign_imx = mpfr_signbit (MPC_IM(x));
+  int x_imag = mpfr_zero_p (MPC_RE(x));
 
   mpz_init (my);
   mpz_init (a);
@@ -188,7 +193,7 @@ mpc_pow_exact (mpc_ptr z, mpc_srcptr x, mpfr_srcptr y, mpc_rnd_t rnd,
   mpz_tdiv_q_2exp (my, my, t);
   /* y = my*2^ey */
 
-  if (mpfr_zero_p (MPC_RE(x)))
+  if (x_imag)
     {
       mpz_set_ui (c, 0);
       ec = 0;
@@ -203,7 +208,7 @@ mpc_pow_exact (mpc_ptr z, mpc_srcptr x, mpfr_srcptr y, mpc_rnd_t rnd,
   else
     {
       ed = mpfr_get_z_exp (d, MPC_IM(x));
-      if (mpfr_zero_p (MPC_RE(x)))
+      if (x_imag)
         ec = ed;
     }
   /* x = c*2^ec + I * d*2^ed */
@@ -400,8 +405,8 @@ mpc_pow_exact (mpc_ptr z, mpc_srcptr x, mpfr_srcptr y, mpc_rnd_t rnd,
   mpz_clear (d);
   mpz_clear (u);
 
-  if (ret >= 0 && mpfr_zero_p (MPC_RE(x)))
-    fix_sign (z, mpfr_signbit (MPC_RE(x)), mpfr_signbit (MPC_IM(x)), y);
+  if (ret >= 0 && x_imag)
+    fix_sign (z, sign_rex, sign_imx, y);
 
   return ret;
 }
diff --git a/tests/tgeneric.c b/tests/tgeneric.c
index a0bde27..e276038 100644
--- a/tests/tgeneric.c
+++ b/tests/tgeneric.c
@@ -625,7 +625,7 @@ reuse_ccf (mpc_function* function, mpc_srcptr z, mpfr_srcptr x, mpc_ptr got,
   function->pointer.CCF (got, got, x, MPC_RNDNN);
   if (!same_mpc_value (got, expected, ks))
     {
-      printf ("Reuse error for %s(z, z, x) for\n", function->name);
+      printf ("Reuse error for %s(z, z, x, RNDNN) for\n", function->name);
       MPC_OUT (z);
       MPFR_OUT (x);
       MPC_OUT (expected);
diff --git a/tests/tpow_fr.c b/tests/tpow_fr.c
index bccc093..d9968a8 100644
--- a/tests/tpow_fr.c
+++ b/tests/tpow_fr.c
@@ -20,12 +20,40 @@ along with this program. If not, see http://www.gnu.org/licenses/ .
 
 #include "mpc-tests.h"
 
+static void
+test_reuse (void)
+{
+  mpc_t z;
+  mpfr_t y;
+  int inex;
+
+  mpfr_init2 (y, 2);
+  mpc_init2 (z, 2);
+  mpc_set_si_si (z, 0, -1, MPC_RNDNN);
+  mpfr_neg (mpc_realref (z), mpc_realref (z), GMP_RNDN);
+  mpc_div_2exp (z, z, 4, MPC_RNDNN);
+  mpfr_set_ui (y, 512, GMP_RNDN);
+  inex = mpc_pow_fr (z, z, y, MPC_RNDNN);
+  if (MPC_INEX_RE(inex) != 0 || MPC_INEX_IM(inex) != 0 ||
+      mpfr_cmp_ui_2exp (MPC_RE(z), 1, -2048) != 0 ||
+      mpfr_cmp_ui (MPC_IM(z), 0) != 0 || mpfr_signbit (MPC_IM(z)) == 0)
+    {
+      printf ("Error in test_reuse, wrong ternary value or output\n");
+      printf ("inex=(%d %d)\n", MPC_INEX_RE(inex), MPC_INEX_IM(inex));
+      printf ("z="); mpc_out_str (stdout, 2, 0, z, MPC_RNDNN); printf ("\n");
+      exit (1);
+    }
+  mpfr_clear (y);
+  mpc_clear (z);
+}
+
 int
 main (void)
 {
   DECL_FUNC (CCF, f, mpc_pow_fr);
   test_start ();
 
+  test_reuse ();
   data_check (f, "pow_fr.dat");
   tgeneric (f, 2, 1024, 7, 10);