Re: New math test failures on Fedora/33

[Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org>]

On 11/01/2021 13:00, H.J. Lu via Libc-alpha wrote:
> On Fedora 33, I got these new math test failures:
> 
> FAIL: math/test-double-cosh
> FAIL: math/test-float32x-cosh
> FAIL: math/test-float64-cosh
> 
> for i686 glibc like
> 
> Failure: cosh_upward (-0x2.c5d374p+12): Exception "Overflow" not set
> Failure: cosh_upward (-0x2.c5d37700c6bb2p+12): Exception "Overflow" not set
> Failure: cosh_upward (-0x2.c5d37700c6bbp+12): Exception "Overflow" not set
> Failure: cosh_upward (-0x2.c5d378p+12): Exception "Overflow" not set
> Failure: cosh_upward (-0x2.c679d1f73f0fcp+8): Exception "Overflow" not set
> Failure: cosh_upward (-0x2.c679d4p+8): Exception "Overflow" not set
> Failure: cosh_upward (-0xf.ffffffffffff8p+1020): Exception "Overflow" not set
> Failure: cosh_upward (-0xf.fffffp+124): Exception "Overflow" not set
> Failure: cosh_upward (0x2.c5d374p+12): Exception "Overflow" not set
> Failure: cosh_upward (0x2.c5d37700c6bb2p+12): Exception "Overflow" not set
> Failure: cosh_upward (0x2.c5d37700c6bbp+12): Exception "Overflow" not set
> Failure: cosh_upward (0x2.c5d378p+12): Exception "Overflow" not set
> Failure: cosh_upward (0x2.c679d1f73f0fcp+8): Exception "Overflow" not set
> Failure: cosh_upward (0x2.c679d4p+8): Exception "Overflow" not set
> Failure: cosh_upward (0xf.ffffffffffff8p+1020): Exception "Overflow" not set
> Failure: cosh_upward (0xf.fffffp+124): Exception "Overflow" not set

This is a regression of BZ#18980 caused by 9e97f239eae1f2b1.  The original
issue was fixed by c8235dda728c445, but the patch did not add the fix for
wordsize64 version because it does not require back then (since it seems
to happen on 32-bit, at least I am seeing on i686).

This seems to fix it:

diff --git a/sysdeps/ieee754/dbl-64/e_cosh.c b/sysdeps/ieee754/dbl-64/e_cosh.c
index 4f41ca2c92..81de5ae6bd 100644
--- a/sysdeps/ieee754/dbl-64/e_cosh.c
+++ b/sysdeps/ieee754/dbl-64/e_cosh.c
@@ -33,6 +33,7 @@
 
 #include <math.h>
 #include <math_private.h>
+#include <math-narrow-eval.h>
 #include <libm-alias-finite.h>
 
 static const double one = 1.0, half=0.5, huge = 1.0e300;
@@ -80,6 +81,6 @@ __ieee754_cosh (double x)
        if(ix>=0x7ff00000) return x*x;
 
     /* |x| > overflowthresold, cosh(x) overflow */
-       return huge*huge;
+       return math_narrow_eval (huge * huge);
 }
 libm_alias_finite (__ieee754_cosh, __cosh)