The fallback implementation of fesetexceptflag currently fails if any
exceptions are specified. It should always succeed, because the
exception state is always that all exceptions (if any are defined in
<fenv.h> but not supported in this configuration) are always clear,
just as fallback fetestexcept always succeeds and fallback fesetenv
always succeeds unless asked to set FE_NOMASK_ENV.
This patch fixes it accordingly. Together with the patch to
test-fexcept.c to allow feraiseexcept to fail in another place, this
stops that test from failing for MIPS soft-float.
Tested for mips64 soft-float.
[BZ #21028]
* math/fsetexcptflg.c (__fesetexceptflag): Always return 0.
* math/test-fexcept.c (test_set): Allow failure of feraiseexcept
if EXCEPTION_TESTS returns false.
ISO C allows feraiseexcept to raise "inexact", in addition to the
requested exceptions, when requested to raise "overflow" or
"underflow". Testing on ARM and PowerPC e500 (where glibc's
feraiseexcept has this property) showed that the new test-fexcept test
failed to allow for this; this patch fixes it, by wrapping
feraiseexcept to clear FE_INEXACT if implicitly raised and not raised
before the call. (It would also be possible to do this with
fesetexcept, which always affects exactly the requested flags, but
this patch avoids making this fix depend on the fesetexcept changes.)
Tested for x86_64, x86, arm and e500.
* math/test-fexcept.c (feraiseexcept_exact): New function.
(test_set): Call feraiseexcept_exact instead of feraiseexcept.
(test_except): Likewise.
I noticed that there was no meaningful test coverage for
fegetexceptflag and fesetexceptflag (one test ensures that calls to
them compile and link, but nothing to verify they work correctly).
This patch adds tests for these functions.
fesetexceptflag is meant to set the relevant exception flag bits to
the saved state without causing enabled traps to be taken. On some
architectures, it is not possible to set exception flag bits without
causing enabled traps to occur. Such architectures need to define
EXCEPTION_SET_FORCES_TRAP to 1 in their math-tests.h, as is done in
this patch for powerpc. x86 avoids needing to define this because the
traps resulting from setting exception bits don't occur until the next
floating-point operation or fwait instruction.
Tested for x86_64, x86 and powerpc. Note that test-fexcept fails for
powerpc because of a pre-existing bug in fesetexceptflag for powerpc,
which I'll fix separately.
* math/test-fexcept-traps.c: New file.
* math/test-fexcept.c: Likewise.
* math/Makefile (tests): Add test-fexcept and test-fexcept-traps.
* sysdeps/generic/math-tests.h (EXCEPTION_SET_FORCES_TRAP): New
macro.
* sysdeps/powerpc/math-tests.h [!__NO_FPRS__]
(EXCEPTION_SET_FORCES_TRAP): Likewise.
Joseph Myers