Fix dbl-64/wordsize-64 remquo (bug 17569).

The dbl-64/wordsize-64 remquo implementation follows similar logic to
various other implementations, but where that logic computes some
absolute values, it wrongly uses a previously computed bit-pattern for
the absolute value of the first argument, where actually it needs the
absolute value of the first argument mod 8 times the second.  This
patch fixes it to compute the correct absolute value.

The integer quotient result of remquo is only specified mod 8
(including its sign); architecture-specific versions may well vary in
what results they give for higher bits of that result (and indeed bug
17569 gives an example correct result from __builtin_remquo giving 9
for that result, where the particular glibc implementation used in
that bug report would give 1 after this fix).  Thus, this patch adapts
the tests of remquo to test that result only mod 8, to allow for such
variation when tests with higher quotient are included.

Tested for x86_64 and x86.

	[BZ #17569]
	* sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c (__remquo):
	Compute absolute value of x as modified by fmod, not original
	value of x.
	* math/libm-test.inc (RUN_TEST_ffI_f1): Rename to
	RUN_TEST_ffI_f1_mod8.  Check extra return value mod 8.
	(RUN_TEST_LOOP_ffI_f1): Rename to RUN_TEST_LOOP_ffI_f1_mod8.  Call
	RUN_TEST_ffI_f1_mod8.
	(remquo_test_data): Add more tests.

4 files changed, 34 insertions, 17 deletions

diff --git a/ChangeLog b/ChangeLog
index 4456bc90d6..74d1a1a48c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2015-02-13  Joseph Myers  <joseph@codesourcery.com>
+
+	[BZ #17569]
+	* sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c (__remquo):
+	Compute absolute value of x as modified by fmod, not original
+	value of x.
+	* math/libm-test.inc (RUN_TEST_ffI_f1): Rename to
+	RUN_TEST_ffI_f1_mod8.  Check extra return value mod 8.
+	(RUN_TEST_LOOP_ffI_f1): Rename to RUN_TEST_LOOP_ffI_f1_mod8.  Call
+	RUN_TEST_ffI_f1_mod8.
+	(remquo_test_data): Add more tests.
+
 2015-02-13  Roland McGrath  <roland@hack.frob.com>
 
 	* sysdeps/init_array/pt-crti.S: New file.
diff --git a/NEWS b/NEWS
index b95f5e6d25..89e48c868a 100644
--- a/NEWS
+++ b/NEWS
@@ -9,8 +9,8 @@ Version 2.22
 
 * The following bugs are resolved with this release:
 
-  4719, 15467, 15790, 16560, 17912, 17932, 17944, 17949, 17964, 17965,
-  17967, 17969.
+  4719, 15467, 15790, 16560, 17569, 17912, 17932, 17944, 17949, 17964,
+  17965, 17967, 17969.
 
 Version 2.21
 
diff --git a/math/libm-test.inc b/math/libm-test.inc
index aa7ba2b765..2f3902a445 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -1461,9 +1461,9 @@ struct test_fFF_11_data
 		      (ARRAY)[i].RM_##ROUNDING_MODE.extra_test,		\
 		      (ARRAY)[i].RM_##ROUNDING_MODE.extra_expected);	\
   ROUND_RESTORE_ ## ROUNDING_MODE
-#define RUN_TEST_ffI_f1(ARG_STR, FUNC_NAME, ARG1, ARG2, EXPECTED,	\
-			EXCEPTIONS, EXTRA_VAR, EXTRA_TEST,		\
-			EXTRA_EXPECTED)					\
+#define RUN_TEST_ffI_f1_mod8(ARG_STR, FUNC_NAME, ARG1, ARG2, EXPECTED,	\
+			     EXCEPTIONS, EXTRA_VAR, EXTRA_TEST,		\
+			     EXTRA_EXPECTED)				\
   do									\
     if (enable_test (EXCEPTIONS))					\
       {									\
@@ -1474,22 +1474,22 @@ struct test_fFF_11_data
 		     EXPECTED, EXCEPTIONS);				\
 	EXTRA_OUTPUT_TEST_SETUP (ARG_STR, 1);				\
 	if (EXTRA_TEST)							\
-	  check_int (extra1_name, EXTRA_VAR, EXTRA_EXPECTED, 0);	\
+	  check_int (extra1_name, (EXTRA_VAR) % 8, EXTRA_EXPECTED, 0);	\
 	EXTRA_OUTPUT_TEST_CLEANUP (1);					\
 	COMMON_TEST_CLEANUP;						\
       }									\
   while (0)
-#define RUN_TEST_LOOP_ffI_f1(FUNC_NAME, ARRAY, ROUNDING_MODE,		\
-			     EXTRA_VAR)					\
+#define RUN_TEST_LOOP_ffI_f1_mod8(FUNC_NAME, ARRAY, ROUNDING_MODE,	\
+				  EXTRA_VAR)				\
   IF_ROUND_INIT_ ## ROUNDING_MODE					\
     for (size_t i = 0; i < sizeof (ARRAY) / sizeof (ARRAY)[0]; i++)	\
-      RUN_TEST_ffI_f1 ((ARRAY)[i].arg_str, FUNC_NAME,			\
-		       (ARRAY)[i].arg1, (ARRAY)[i].arg2,		\
-		       (ARRAY)[i].RM_##ROUNDING_MODE.expected,		\
-		       (ARRAY)[i].RM_##ROUNDING_MODE.exceptions,	\
-		       EXTRA_VAR,					\
-		       (ARRAY)[i].RM_##ROUNDING_MODE.extra_test,	\
-		       (ARRAY)[i].RM_##ROUNDING_MODE.extra_expected);	\
+      RUN_TEST_ffI_f1_mod8 ((ARRAY)[i].arg_str, FUNC_NAME,		\
+			    (ARRAY)[i].arg1, (ARRAY)[i].arg2,		\
+			    (ARRAY)[i].RM_##ROUNDING_MODE.expected,	\
+			    (ARRAY)[i].RM_##ROUNDING_MODE.exceptions,	\
+			    EXTRA_VAR,					\
+			    (ARRAY)[i].RM_##ROUNDING_MODE.extra_test,	\
+			    (ARRAY)[i].RM_##ROUNDING_MODE.extra_expected); \
   ROUND_RESTORE_ ## ROUNDING_MODE
 #define RUN_TEST_c_c(ARG_STR, FUNC_NAME, ARGR, ARGC, EXPR, EXPC,	\
 		     EXCEPTIONS)					\
@@ -8759,6 +8759,11 @@ static const struct test_ffI_f1_data remquo_test_data[] =
 
     TEST_ffI_f1 (remquo, 5, 2, 1, 2, NO_INEXACT_EXCEPTION),
     TEST_ffI_f1 (remquo, 3, 2, -1, 2, NO_INEXACT_EXCEPTION),
+
+    TEST_ffI_f1 (remquo, 3419, 360, 179, 1, NO_INEXACT_EXCEPTION),
+    TEST_ffI_f1 (remquo, -3419, 360, -179, -1, NO_INEXACT_EXCEPTION),
+    TEST_ffI_f1 (remquo, 3419, -360, 179, -1, NO_INEXACT_EXCEPTION),
+    TEST_ffI_f1 (remquo, -3419, -360, -179, 1, NO_INEXACT_EXCEPTION),
   };
 
 static void
@@ -8766,7 +8771,7 @@ remquo_test (void)
 {
   int x;
 
-  ALL_RM_TEST (remquo, 1, remquo_test_data, RUN_TEST_LOOP_ffI_f1, END, x);
+  ALL_RM_TEST (remquo, 1, remquo_test_data, RUN_TEST_LOOP_ffI_f1_mod8, END, x);
 }
 
 static const struct test_f_f_data rint_test_data[] =
diff --git a/sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c b/sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c
index 36fc37c134..5b7142576a 100644
--- a/sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c
+++ b/sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c
@@ -55,7 +55,7 @@ __remquo (double x, double y, int *quo)
       return zero * x;
     }
 
-  INSERT_WORDS64 (x, hx);
+  x = fabs (x);
   INSERT_WORDS64 (y, hy);
   cquo = 0;