Fix missing overflow exceptions from pow (bug 13873).

diff --git a/ChangeLog b/ChangeLog
index 6c4bd0732af2638f758bf1bbb761fbd43a4a5e31..75a5ca813764164c8b38f16d2f245b90dba31ffa 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
 2012-04-09  Joseph Myers  <joseph@codesourcery.com>
 
+       [BZ #13873]
+       * sysdeps/ieee754/dbl-64/e_pow.c (huge, tiny): New variables.
+       (__ieee754_pow): Generate overflow and underflow using huge*huge
+       and tiny*tiny rather than just returning constant infinity or zero
+       for large exponents.
+       * math/libm-test.inc (pow_test): Require overflow exceptions for
+       applicable cases of large exponents.
+
        [BZ #706]
        * sysdeps/i386/fpu/e_pow.S (p10): New object.
        (__ieee754_pow): Use iterative multiplication algorithm only for

diff --git a/NEWS b/NEWS
index 5bd167709ba8fd8b001a5e0a408189e56a7107a9..a17f611ff3731ac3b1df59a90fd2c42b8693ff22 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -18,9 +18,9 @@ Version 2.16
   13533, 13547, 13551, 13552, 13553, 13555, 13559, 13566, 13583, 13592,
   13618, 13637, 13656, 13658, 13673, 13691, 13695, 13704, 13705, 13706,
   13726, 13738, 13760, 13761, 13786, 13792, 13806, 13824, 13840, 13841,
-  13844, 13846, 13851, 13852, 13854, 13871, 13879, 13883, 13892, 13895,
-  13908, 13910, 13911, 13912, 13913, 13915, 13916, 13917, 13918, 13919,
-  13920, 13921, 13926, 13928, 13938
+  13844, 13846, 13851, 13852, 13854, 13871, 13873, 13879, 13883, 13892,
+  13895, 13908, 13910, 13911, 13912, 13913, 13915, 13916, 13917, 13918,
+  13919, 13920, 13921, 13926, 13928, 13938
 
 * ISO C11 support:
 

diff --git a/math/libm-test.inc b/math/libm-test.inc
index b9ff9f3ad28a9546ad2e3334dc500fea74675c66..05334837492a597f128d626c1930c2f7ae5a7f0c 100644 (file)
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -5621,8 +5621,7 @@ pow_test (void)
 
   TEST_ff_f (pow, 0x1p72L, 0x1p72L, plus_infty, OVERFLOW_EXCEPTION);
   TEST_ff_f (pow, 10, -0x1p72L, 0);
-  /* Bug 13873: OVERFLOW exception may be missing.  */
-  TEST_ff_f (pow, max_value, max_value, plus_infty, OVERFLOW_EXCEPTION_OK);
+  TEST_ff_f (pow, max_value, max_value, plus_infty, OVERFLOW_EXCEPTION);
   /* Bug 13872: spurious OVERFLOW exception may be present.  */
   TEST_ff_f (pow, 10, -max_value, 0, OVERFLOW_EXCEPTION_OK);
 
@@ -5908,8 +5907,7 @@ pow_test (void)
   TEST_ff_f (pow, -2.0, 0x1.ffffffffffffffffffffffffffffp+113L, plus_infty, OVERFLOW_EXCEPTION);
 # endif
 #endif
-  /* Bug 13873: OVERFLOW exception may be missing.  */
-  TEST_ff_f (pow, -2.0, max_value, plus_infty, OVERFLOW_EXCEPTION_OK);
+  TEST_ff_f (pow, -2.0, max_value, plus_infty, OVERFLOW_EXCEPTION);
 
   TEST_ff_f (pow, -max_value, 0.5, nan_value, INVALID_EXCEPTION);
   TEST_ff_f (pow, -max_value, 1.5, nan_value, INVALID_EXCEPTION);
@@ -5962,8 +5960,7 @@ pow_test (void)
   TEST_ff_f (pow, -max_value, 0x1.ffffffffffffffffffffffffffffp+113L, plus_infty, OVERFLOW_EXCEPTION);
 # endif
 #endif
-  /* Bug 13873: OVERFLOW exception may be missing.  */
-  TEST_ff_f (pow, -max_value, max_value, plus_infty, OVERFLOW_EXCEPTION_OK);
+  TEST_ff_f (pow, -max_value, max_value, plus_infty, OVERFLOW_EXCEPTION);
 
   TEST_ff_f (pow, -0.5, 126, 0x1p-126);
   TEST_ff_f (pow, -0.5, 127, -0x1p-127);
@@ -5990,8 +5987,7 @@ pow_test (void)
   TEST_ff_f (pow, -0.5, -0x1.ffffffffffffffffffffffffffffp+113L, plus_infty, OVERFLOW_EXCEPTION);
 # endif
 #endif
-  /* Bug 13873: OVERFLOW exception may be missing.  */
-  TEST_ff_f (pow, -0.5, -max_value, plus_infty, OVERFLOW_EXCEPTION_OK);
+  TEST_ff_f (pow, -0.5, -max_value, plus_infty, OVERFLOW_EXCEPTION);
 
   TEST_ff_f (pow, -0.5, 0xffffff, minus_zero);
   TEST_ff_f (pow, -0.5, 0x1fffffe, plus_zero);
@@ -6044,8 +6040,7 @@ pow_test (void)
   TEST_ff_f (pow, -min_value, -0x1.ffffffffffffffffffffffffffffp+113L, plus_infty, OVERFLOW_EXCEPTION);
 # endif
 #endif
-  /* Bug 13873: OVERFLOW exception may be missing.  */
-  TEST_ff_f (pow, -min_value, -max_value, plus_infty, OVERFLOW_EXCEPTION_OK);
+  TEST_ff_f (pow, -min_value, -max_value, plus_infty, OVERFLOW_EXCEPTION);
 
   TEST_ff_f (pow, -min_value, 0xffffff, minus_zero);
   TEST_ff_f (pow, -min_value, 0x1fffffe, plus_zero);

diff --git a/sysdeps/ieee754/dbl-64/e_pow.c b/sysdeps/ieee754/dbl-64/e_pow.c
index 26ffaaddc6601ace3994d1b1deeceedc729508ce..6c41af93ba4b732ea9951ebcf4b89178d534e135 100644 (file)
--- a/sysdeps/ieee754/dbl-64/e_pow.c
+++ b/sysdeps/ieee754/dbl-64/e_pow.c
@@ -47,6 +47,7 @@
 # define SECTION
 #endif
 
+static const double huge = 1.0e300, tiny = 1.0e-300;
 
 double __exp1(double x, double xx, double error);
 static double log1(double x, double *delta, double *error);
@@ -156,8 +157,8 @@ __ieee754_pow(double x, double y) {
 
   if (qy > 0x45f00000 && qy < 0x7ff00000) {
     if (x == 1.0) return 1.0;
-    if (y>0) return (x>1.0)?INF.x:0;
-    if (y<0) return (x<1.0)?INF.x:0;
+    if (y>0) return (x>1.0)?huge*huge:tiny*tiny;
+    if (y<0) return (x<1.0)?huge*huge:tiny*tiny;
   }
 
   if (x == 1.0) return 1.0;