Re: [PATCH v2][PR libgfortran/78314] Fix ieee_support_halting

[Szabolcs Nagy]

On 21/11/16 14:16, FX wrote:
> Can you XFAIL the test on your platform, open a PR and assign it to me?

OK. Committed.

ARM and AArch64 may not support trapping so runtime and
compile time check can differ.

gcc/testsuite/
2016-11-22  Szabolcs Nagy  

PR libgfortran/78449
* gfortran.dg/ieee/ieee_8.f90 (aarch64*gnu, arm*gnu*): Mark xfail.

diff --git a/gcc/testsuite/gfortran.dg/ieee/ieee_8.f90 b/gcc/testsuite/gfortran.dg/ieee/ieee_8.f90
index 9806bcf..7d0cdfd 100644
--- a/gcc/testsuite/gfortran.dg/ieee/ieee_8.f90
+++ b/gcc/testsuite/gfortran.dg/ieee/ieee_8.f90
@@ -1,4 +1,5 @@
-! { dg-do run }
+! { dg-do run { xfail aarch64*-*-gnu arm*-*-gnueabi arm*-*-gnueabihf } }
+! XFAIL because of PR libfortran/78449.
 
 module foo
   use :: ieee_exceptions

Re: [PATCH v2][PR libgfortran/78314] Fix ieee_support_halting

[Szabolcs Nagy]

On 21/11/16 14:16, FX wrote:
>> it seems this broke ieee_8.f90 which tests compile time vs runtime value of 
>> ieee_support_halting
>> if fortran needs this, then support_halting should be always false on arm 
>> and aarch64.
>> but i'm not familiar enough with fortran to tell if there is some better 
>> workaround.
> 
> Can you XFAIL the test on your platform, open a PR and assign it to me?
> This is a corner of the Fortran standard that is not entirely clear, and 
> there have been some corrigenda on the topic, so I need to review it.
> 

i opened PR 78449

will do the xfail later.

Re: [PATCH v2][PR libgfortran/78314] Fix ieee_support_halting

[FX]

Dear Nagy,

> it seems this broke ieee_8.f90 which tests compile time vs runtime value of 
> ieee_support_halting
> if fortran needs this, then support_halting should be always false on arm and 
> aarch64.
> but i'm not familiar enough with fortran to tell if there is some better 
> workaround.

Can you XFAIL the test on your platform, open a PR and assign it to me?
This is a corner of the Fortran standard that is not entirely clear, and there 
have been some corrigenda on the topic, so I need to review it.

Thanks,
FX

Re: [PATCH v2][PR libgfortran/78314] Fix ieee_support_halting

[Szabolcs Nagy]

On 16/11/16 16:53, Szabolcs Nagy wrote:
> ieee_support_halting only checked the availability of status
> flags, not trapping support.  On some targets the later can
> only be checked at runtime: feenableexcept reports if
> enabling traps failed.
> 
> So check trapping support by enabling/disabling it.
> 
> Updated the test that enabled trapping to check if it is
> supported.
> 
> Tested on aarch64-linux-gnu and x86_64-linux-gnu.
> 
> gcc/testsuite/
> 2016-11-16  Szabolcs Nagy  
> 
>   PR libgfortran/78314
>   * gfortran.dg/ieee/ieee_6.f90: Use ieee_support_halting.
> 
> libgfortran/
> 2016-11-16  Szabolcs Nagy  
> 
>   PR libgfortran/78314
>   * config/fpu-glibc.h (support_fpu_trap): Use feenableexcept.
> 

it seems this broke ieee_8.f90 which tests compile time
vs runtime value of ieee_support_halting

if fortran needs this, then support_halting should be
always false on arm and aarch64.

but i'm not familiar enough with fortran to tell if
there is some better workaround.

Re: [PATCH v2][PR libgfortran/78314] Fix ieee_support_halting

[FX]

> gcc/testsuite/
> 2016-11-16  Szabolcs Nagy  
> 
>   PR libgfortran/78314
>   * gfortran.dg/ieee/ieee_6.f90: Use ieee_support_halting.
> 
> libgfortran/
> 2016-11-16  Szabolcs Nagy  
> 
>   PR libgfortran/78314
>   * config/fpu-glibc.h (support_fpu_trap): Use feenableexcept.

OK to commit.

FX

[PATCH v2][PR libgfortran/78314] Fix ieee_support_halting

[Szabolcs Nagy]

ieee_support_halting only checked the availability of status
flags, not trapping support.  On some targets the later can
only be checked at runtime: feenableexcept reports if
enabling traps failed.

So check trapping support by enabling/disabling it.

Updated the test that enabled trapping to check if it is
supported.

Tested on aarch64-linux-gnu and x86_64-linux-gnu.

gcc/testsuite/
2016-11-16  Szabolcs Nagy  

PR libgfortran/78314
* gfortran.dg/ieee/ieee_6.f90: Use ieee_support_halting.

libgfortran/
2016-11-16  Szabolcs Nagy  

PR libgfortran/78314
* config/fpu-glibc.h (support_fpu_trap): Use feenableexcept.

diff --git a/gcc/testsuite/gfortran.dg/ieee/ieee_6.f90 b/gcc/testsuite/gfortran.dg/ieee/ieee_6.f90
index 8fb4f6f..43aa3bf 100644
--- a/gcc/testsuite/gfortran.dg/ieee/ieee_6.f90
+++ b/gcc/testsuite/gfortran.dg/ieee/ieee_6.f90
@@ -9,7 +9,7 @@
   implicit none
 
   type(ieee_status_type) :: s1, s2
-  logical :: flags(5), halt(5)
+  logical :: flags(5), halt(5), haltworks
   type(ieee_round_type) :: mode
   real :: x
 
@@ -18,6 +18,7 @@
   call ieee_set_flag(ieee_all, .false.)
   call ieee_set_rounding_mode(ieee_down)
   call ieee_set_halting_mode(ieee_all, .false.)
+  haltworks = ieee_support_halting(ieee_overflow)
 
   call ieee_get_status(s1)
   call ieee_set_status(s1)
@@ -46,7 +47,7 @@
   call ieee_get_rounding_mode(mode)
   if (mode /= ieee_to_zero) call abort
   call ieee_get_halting_mode(ieee_all, halt)
-  if ((.not. halt(1)) .or. any(halt(2:))) call abort
+  if ((haltworks .and. .not. halt(1)) .or. any(halt(2:))) call abort
 
   call ieee_set_status(s2)
 
@@ -58,7 +59,7 @@
   call ieee_get_rounding_mode(mode)
   if (mode /= ieee_to_zero) call abort
   call ieee_get_halting_mode(ieee_all, halt)
-  if ((.not. halt(1)) .or. any(halt(2:))) call abort
+  if ((haltworks .and. .not. halt(1)) .or. any(halt(2:))) call abort
 
   call ieee_set_status(s1)
 
@@ -79,6 +80,6 @@
   call ieee_get_rounding_mode(mode)
   if (mode /= ieee_to_zero) call abort
   call ieee_get_halting_mode(ieee_all, halt)
-  if ((.not. halt(1)) .or. any(halt(2:))) call abort
+  if ((haltworks .and. .not. halt(1)) .or. any(halt(2:))) call abort
 
 end
diff --git a/libgfortran/config/fpu-glibc.h b/libgfortran/config/fpu-glibc.h
index 6e505da..8b29a76 100644
--- a/libgfortran/config/fpu-glibc.h
+++ b/libgfortran/config/fpu-glibc.h
@@ -121,7 +121,41 @@ get_fpu_trap_exceptions (void)
 int
 support_fpu_trap (int flag)
 {
-  return support_fpu_flag (flag);
+  int exceptions = 0;
+  int old;
+
+  if (!support_fpu_flag (flag))
+return 0;
+
+#ifdef FE_INVALID
+  if (flag & GFC_FPE_INVALID) exceptions |= FE_INVALID;
+#endif
+
+#ifdef FE_DIVBYZERO
+  if (flag & GFC_FPE_ZERO) exceptions |= FE_DIVBYZERO;
+#endif
+
+#ifdef FE_OVERFLOW
+  if (flag & GFC_FPE_OVERFLOW) exceptions |= FE_OVERFLOW;
+#endif
+
+#ifdef FE_UNDERFLOW
+  if (flag & GFC_FPE_UNDERFLOW) exceptions |= FE_UNDERFLOW;
+#endif
+
+#ifdef FE_DENORMAL
+  if (flag & GFC_FPE_DENORMAL) exceptions |= FE_DENORMAL;
+#endif
+
+#ifdef FE_INEXACT
+  if (flag & GFC_FPE_INEXACT) exceptions |= FE_INEXACT;
+#endif
+
+  old = feenableexcept (exceptions);
+  if (old == -1)
+return 0;
+  fedisableexcept (exceptions & ~old);
+  return 1;
 }