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Steven Munroe wrote: > Jakub Jelinek wrote: > >> Hi! >> >> feholdexcept is supposed to clear the sticky exception bits: >> "The feholdexcept function saves the current floating-point environment in the object >> pointed to by envp, clears the floating-point status flags, and then installs a non-stop >> (continue on floating-point exceptions) mode, if available, for all floating-point >> exceptions." >> and >> "A floating-point status flag is a system variable whose value is set >> (but never cleared) when a floating-point exception is raised, which occurs as a side effect >> of exceptional floating-point arithmetic to provide auxiliary information." >> >> Several feholdexcept implementations didn't handle this right. >> Also, e.g. feupdateenv was a stub on x86_64 eventhough it is IMHO easily >> implementable and other arches had bugs in it too (e.g. ia64 would rise >> wrong exceptions and always return a failure). >> I added a new testcase for feholdexcept/feupdateenv (hopefully I haven't >> misinterpreted the standard) and I believe other arches (ppc*, s390*, ...) >> will need some care too. >> >> > > powerpc32 and powerpc64 both show two failures with the new test-fenv: > > Test: feholdexcept_tests FE_DIVBYZERO|FE_INVALID test > Fail: Exception "DIVBYZERO" is not set > Pass: Exception "INVALID" is set > Pass: Exception "INEXACT" is not set > Pass: Exception "UNDERFLOW" is not set > Pass: Exception "OVERFLOW" is not set > > and > > Test: feholdexcept_tests FE_INEXACT|FE_INVALID test > Pass: Exception "DIVBYZERO" is not set > Fail: Exception "INVALID" is not set > Pass: Exception "INEXACT" is set > Pass: Exception "UNDERFLOW" is not set > Pass: Exception "OVERFLOW" is not set > > We will look into this. > feupdateenv was not merging pending and current exceptions correctly and caused 2 failures with the new feholdexcept tests. The attached patch fixes feupdateenv for ppc32/ppc64.
2007-03-26 Steven Munroe <sjmunroe@us.ibm.com> * sysdeps/powerpc/fpu/feupdateenv.c: Change mask to merge exceptions from env. diff -urN libc25-cvstip-20070320/sysdeps/powerpc/fpu/feupdateenv.c libc25/sysdeps/powerpc/fpu/feupdateenv.c --- libc25-cvstip-20070320/sysdeps/powerpc/fpu/feupdateenv.c 2001-07-05 23:56:02.000000000 -0500 +++ libc25/sysdeps/powerpc/fpu/feupdateenv.c 2007-03-27 09:13:54.875363776 -0500 @@ -1,5 +1,5 @@ /* Install given floating-point environment and raise exceptions. - Copyright (C) 1997,99,2000,01 Free Software Foundation, Inc. + Copyright (C) 1997,99,2000,01,07 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997. @@ -30,8 +30,10 @@ new.fenv = *envp; old.fenv = fegetenv_register (); - /* Copy the set exceptions from `old' to `new'. */ - new.l[1] = (new.l[1] & 0xE00000FF) | (old.l[1] & 0x1FFFFF00); + /* Restore rounding mode and exception enable from *envp and merge + exceptions. Leave fraction rounded/inexact and FP result/CC bits + unchanged. */ + new.l[1] = (old.l[1] & 0x1FFFFF00) | (new.l[1] & 0x1FF80FFF); /* Atomically enable and raise (if appropriate) exceptions set in `new'. */ fesetenv_register (new.fenv);
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