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authorJoseph Myers <joseph@codesourcery.com>2016-03-10 23:48:46 +0000
committerJoseph Myers <joseph@codesourcery.com>2016-03-10 23:48:46 +0000
commitb55b28e6574c215689e4656628b911788870de31 (patch)
tree1c518f634bf77f45f52d642309da0afa5b8fc3d3
parent6aa3e97e2530f9917f504eb4146af119a3f27229 (diff)
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Allow spurious underflow / inexact for ldbl-128ibm.
A large number of the test-ldouble failures seen for ldbl-128ibm are spurious "underflow" and "inexact" exceptions. These arise from such exceptions in the underlying arithmetic; unlike other spurious exceptions from that arithmetic, they do not in general relate to cases where the returned result is also substantially inaccurate, are not so readily avoidable by appropriately conditional libgcc patches, and are widespread enough to be hard to handle through individual XFAILing of the affected tests. Thus, this patch documents relaxed accuracy goals for libm functions for IBM long double and makes libm-test.inc reflect these spurious exceptions in ldbl-128ibm arithmetic and always allow them in ldbl-128ibm testing (while still not allowing these exceptions to be missing where required to be present). Tested for powerpc. * manual/math.texi (Errors in Math Functions): Document relaxed accuracy goals for IBM long double. * math/libm-test.inc (test_exceptions): Always allow spurious "underflow" and "inexact" exceptions for IBM long double.
-rw-r--r--ChangeLog7
-rw-r--r--manual/math.texi10
-rw-r--r--math/libm-test.inc11
3 files changed, 26 insertions, 2 deletions
diff --git a/ChangeLog b/ChangeLog
index 9cd1d70..23487d7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2016-03-10 Joseph Myers <joseph@codesourcery.com>
+
+ * manual/math.texi (Errors in Math Functions): Document relaxed
+ accuracy goals for IBM long double.
+ * math/libm-test.inc (test_exceptions): Always allow spurious
+ "underflow" and "inexact" exceptions for IBM long double.
+
2016-03-10 H.J. Lu <hongjiu.lu@intel.com>
[BZ #19762]
diff --git a/manual/math.texi b/manual/math.texi
index 72f3fda..5c9f7b9 100644
--- a/manual/math.texi
+++ b/manual/math.texi
@@ -1327,6 +1327,16 @@ necessarily the exact value actually passed with discontiguous
mantissa bits.
@item
+For the IBM @code{long double} format, functions whose results are
+fully specified by reference to corresponding IEEE 754 floating-point
+operations have the same accuracy goals as other functions, but with
+the error bound being the same as that for division (3ulp).
+Furthermore, ``inexact'' and ``underflow'' exceptions may be raised
+for all functions for any inputs, even where such exceptions are
+inconsistent with the returned value, since the underlying
+floating-point arithmetic has that property.
+
+@item
Functions behave as if the infinite-precision result computed is zero,
infinity or NaN if and only if that is the mathematically correct
infinite-precision result. They behave as if the infinite-precision
diff --git a/math/libm-test.inc b/math/libm-test.inc
index c9925fd..f1ba7dd 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -672,13 +672,20 @@ test_exceptions (const char *test_name, int exception)
test_single_exception (test_name, exception, OVERFLOW_EXCEPTION,
FE_OVERFLOW, "Overflow");
#endif
+ /* Spurious "underflow" and "inexact" exceptions are always
+ allowed for IBM long double, in line with the underlying
+ arithmetic. */
#ifdef FE_UNDERFLOW
- if ((exception & UNDERFLOW_EXCEPTION_OK) == 0)
+ if ((exception & UNDERFLOW_EXCEPTION_OK) == 0
+ && !(TEST_COND_ldbl_128ibm
+ && (exception & UNDERFLOW_EXCEPTION) == 0))
test_single_exception (test_name, exception, UNDERFLOW_EXCEPTION,
FE_UNDERFLOW, "Underflow");
#endif
#ifdef FE_INEXACT
- if ((exception & (INEXACT_EXCEPTION | NO_INEXACT_EXCEPTION)) != 0)
+ if ((exception & (INEXACT_EXCEPTION | NO_INEXACT_EXCEPTION)) != 0
+ && !(TEST_COND_ldbl_128ibm
+ && (exception & NO_INEXACT_EXCEPTION) != 0))
test_single_exception (test_name, exception, INEXACT_EXCEPTION,
FE_INEXACT, "Inexact");
#endif