RE: [PATCH] [ARM] ] Add support for fenv_private on ARM

["Wilco" <wdijkstr at arm dot com>]

On Wed, 19 Mar 2014, Joseph Myers wrote:
>> +#include <arm-features.h>
>
> Now you're using __SOFTFP__, I don't think you need this #include any 
> more.
>
> OK with that removed (subject to testing in a hard-float configuration 
> that there are no exceptions-related or rounding-mode-related failures; 
> there might be ulps that postdate the last ulps regeneration).

I've removed the include. All math tests pass - the latest version
only shows one ULP error in test-{i}double.out.

Since I don't have write permissions, maybe Marcus can check this in?

Wilco

---
 sysdeps/arm/fenv_private.h |  249 ++++++++++++++++++++++++++++++++++++++++++++
 sysdeps/arm/fpu_control.h  |    7 +-
 sysdeps/arm/math_private.h |    6 ++
 3 files changed, 261 insertions(+), 1 deletion(-)
 create mode 100644 sysdeps/arm/fenv_private.h
 create mode 100644 sysdeps/arm/math_private.h

diff --git a/sysdeps/arm/fenv_private.h b/sysdeps/arm/fenv_private.h
new file mode 100644
index 0000000..e246fb5
--- /dev/null
+++ b/sysdeps/arm/fenv_private.h
@@ -0,0 +1,249 @@
+/* Private floating point rounding and exceptions handling.  ARM VFP version.
+   Copyright (C) 2014 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef FENV_PRIVATE_H
+#define FENV_PRIVATE_H 1
+
+#include <fenv.h>
+#include <fpu_control.h>
+
+#ifndef __SOFTFP__
+
+static __always_inline void
+libc_feholdexcept_vfp (fenv_t *envp)
+{
+  fpu_control_t fpscr;
+
+  _FPU_GETCW (fpscr);
+  envp->__cw = fpscr;
+
+  /* Clear exception flags and set all exceptions to non-stop.  */
+  fpscr &= ~_FPU_MASK_EXCEPT;
+  _FPU_SETCW (fpscr);
+}
+
+static __always_inline void
+libc_fesetround_vfp (int round)
+{
+  fpu_control_t fpscr;
+
+  _FPU_GETCW (fpscr);
+
+  /* Set new rounding mode if different.  */
+  if (__glibc_unlikely ((fpscr & FE_TOWARDZERO) != round))
+    _FPU_SETCW ((fpscr & ~FE_TOWARDZERO) | round);
+}
+
+static __always_inline void
+libc_feholdexcept_setround_vfp (fenv_t *envp, int round)
+{
+  fpu_control_t fpscr;
+
+  _FPU_GETCW (fpscr);
+  envp->__cw = fpscr;
+
+  /* Clear exception flags, set all exceptions to non-stop,
+     and set new rounding mode.  */
+  fpscr &= ~(_FPU_MASK_EXCEPT | FE_TOWARDZERO);
+  _FPU_SETCW (fpscr | round);
+}
+
+static __always_inline void
+libc_feholdsetround_vfp (fenv_t *envp, int round)
+{
+  fpu_control_t fpscr;
+
+  _FPU_GETCW (fpscr);
+  envp->__cw = fpscr;
+
+  /* Set new rounding mode if different.  */
+  if (__glibc_unlikely ((fpscr & FE_TOWARDZERO) != round))
+    _FPU_SETCW ((fpscr & ~FE_TOWARDZERO) | round);
+}
+
+static __always_inline void
+libc_feresetround_vfp (fenv_t *envp)
+{
+  fpu_control_t fpscr, round;
+
+  _FPU_GETCW (fpscr);
+
+  /* Check whether rounding modes are different.  */
+  round = (envp->__cw ^ fpscr) & FE_TOWARDZERO;
+
+  /* Restore the rounding mode if it was changed.  */
+  if (__glibc_unlikely (round != 0))
+    _FPU_SETCW (fpscr ^ round);
+}
+
+static __always_inline int
+libc_fetestexcept_vfp (int ex)
+{
+  fpu_control_t fpscr;
+
+  _FPU_GETCW (fpscr);
+  return fpscr & ex & FE_ALL_EXCEPT;
+}
+
+static __always_inline void
+libc_fesetenv_vfp (const fenv_t *envp)
+{
+  fpu_control_t fpscr, new_fpscr;
+
+  _FPU_GETCW (fpscr);
+  new_fpscr = envp->__cw;
+
+  /* Write new FPSCR if different (ignoring NZCV flags).  */
+  if (__glibc_unlikely (((fpscr ^ new_fpscr) & ~_FPU_MASK_NZCV) != 0))
+    _FPU_SETCW (new_fpscr);
+}
+
+static __always_inline int
+libc_feupdateenv_test_vfp (const fenv_t *envp, int ex)
+{
+  fpu_control_t fpscr, new_fpscr;
+  int excepts;
+
+  _FPU_GETCW (fpscr);
+
+  /* Merge current exception flags with the saved fenv.  */
+  excepts = fpscr & FE_ALL_EXCEPT;
+  new_fpscr = envp->__cw | excepts;
+
+  /* Write new FPSCR if different (ignoring NZCV flags).  */
+  if (__glibc_unlikely (((fpscr ^ new_fpscr) & ~_FPU_MASK_NZCV) != 0))
+    _FPU_SETCW (new_fpscr);
+
+  /* Raise the exceptions if enabled in the new FP state.  */
+  if (__glibc_unlikely (excepts & (new_fpscr >> FE_EXCEPT_SHIFT)))
+    feraiseexcept (excepts);
+
+  return excepts & ex;
+}
+
+static __always_inline void
+libc_feupdateenv_vfp (const fenv_t *envp)
+{
+  libc_feupdateenv_test_vfp (envp, 0);
+}
+
+#define libc_feholdexcept  libc_feholdexcept_vfp
+#define libc_feholdexceptf libc_feholdexcept_vfp
+#define libc_feholdexceptl libc_feholdexcept_vfp
+
+#define libc_fesetround  libc_fesetround_vfp
+#define libc_fesetroundf libc_fesetround_vfp
+#define libc_fesetroundl libc_fesetround_vfp
+
+#define libc_feresetround  libc_feresetround_vfp
+#define libc_feresetroundf libc_feresetround_vfp
+#define libc_feresetroundl libc_feresetround_vfp
+
+#define libc_feresetround_noex  libc_fesetenv_vfp
+#define libc_feresetround_noexf libc_fesetenv_vfp
+#define libc_feresetround_noexl libc_fesetenv_vfp
+
+#define libc_feholdexcept_setround  libc_feholdexcept_setround_vfp
+#define libc_feholdexcept_setroundf libc_feholdexcept_setround_vfp
+#define libc_feholdexcept_setroundl libc_feholdexcept_setround_vfp
+
+#define libc_feholdsetround  libc_feholdsetround_vfp
+#define libc_feholdsetroundf libc_feholdsetround_vfp
+#define libc_feholdsetroundl libc_feholdsetround_vfp
+
+#define libc_fetestexcept  libc_fetestexcept_vfp
+#define libc_fetestexceptf libc_fetestexcept_vfp
+#define libc_fetestexceptl libc_fetestexcept_vfp
+
+#define libc_fesetenv  libc_fesetenv_vfp
+#define libc_fesetenvf libc_fesetenv_vfp
+#define libc_fesetenvl libc_fesetenv_vfp
+
+#define libc_feupdateenv  libc_feupdateenv_vfp
+#define libc_feupdateenvf libc_feupdateenv_vfp
+#define libc_feupdateenvl libc_feupdateenv_vfp
+
+#define libc_feupdateenv_test  libc_feupdateenv_test_vfp
+#define libc_feupdateenv_testf libc_feupdateenv_test_vfp
+#define libc_feupdateenv_testl libc_feupdateenv_test_vfp
+
+/* We have support for rounding mode context.  */
+#define HAVE_RM_CTX 1
+
+static __always_inline void
+libc_feholdsetround_vfp_ctx (struct rm_ctx *ctx, int r)
+{
+  fpu_control_t fpscr, round;
+
+  _FPU_GETCW (fpscr);
+  ctx->updated_status = false;
+  ctx->env.__cw = fpscr;
+
+  /* Check whether rounding modes are different.  */
+  round = (fpscr ^ r) & FE_TOWARDZERO;
+
+  /* Set the rounding mode if changed.  */
+  if (__glibc_unlikely (round != 0))
+    {
+      ctx->updated_status = true;
+      _FPU_SETCW (fpscr ^ round);
+    }
+}
+
+static __always_inline void
+libc_feresetround_vfp_ctx (struct rm_ctx *ctx)
+{
+  /* Restore the rounding mode if updated.  */
+  if (__glibc_unlikely (ctx->updated_status))
+    {
+      fpu_control_t fpscr;
+
+      _FPU_GETCW (fpscr);
+      fpscr = (fpscr & ~FE_TOWARDZERO) | (ctx->env.__cw & FE_TOWARDZERO);
+      _FPU_SETCW (fpscr);
+    }
+}
+
+static __always_inline void
+libc_fesetenv_vfp_ctx (struct rm_ctx *ctx)
+{
+  fpu_control_t fpscr, new_fpscr;
+
+  _FPU_GETCW (fpscr);
+  new_fpscr = ctx->env.__cw;
+
+  /* Write new FPSCR if different (ignoring NZCV flags).  */
+  if (__glibc_unlikely (((fpscr ^ new_fpscr) & ~_FPU_MASK_NZCV) != 0))
+    _FPU_SETCW (new_fpscr);
+}
+
+#define libc_feholdsetround_ctx		libc_feholdsetround_vfp_ctx
+#define libc_feresetround_ctx		libc_feresetround_vfp_ctx
+#define libc_feresetround_noex_ctx	libc_fesetenv_vfp_ctx
+
+#define libc_feholdsetroundf_ctx	libc_feholdsetround_vfp_ctx
+#define libc_feresetroundf_ctx		libc_feresetround_vfp_ctx
+#define libc_feresetround_noexf_ctx	libc_fesetenv_vfp_ctx
+
+#define libc_feholdsetroundl_ctx	libc_feholdsetround_vfp_ctx
+#define libc_feresetroundl_ctx		libc_feresetround_vfp_ctx
+#define libc_feresetround_noexl_ctx	libc_fesetenv_vfp_ctx
+
+#endif
+
+#endif /* FENV_PRIVATE_H */
diff --git a/sysdeps/arm/fpu_control.h b/sysdeps/arm/fpu_control.h
index 6d54b9b..0377697 100644
--- a/sysdeps/arm/fpu_control.h
+++ b/sysdeps/arm/fpu_control.h
@@ -37,11 +37,16 @@ extern fpu_control_t __fpu_control;
 #define _FPU_MASK_UM	0x00000800	/* underflow */
 #define _FPU_MASK_PM	0x00001000	/* inexact */
 
+#define _FPU_MASK_NZCV	0xF0000000	/* NZCV flags */
+
+#define _FPU_MASK_EXCEPT 0x00001f1f	/* all exception flags */
+
 /* Some bits in the FPSCR are not yet defined.  They must be preserved when
    modifying the contents.  */
 #define _FPU_RESERVED	0x00086060
 #define _FPU_DEFAULT    0x00000000
-/* Default + exceptions enabled. */
+
+/* Default + exceptions enabled.  */
 #define _FPU_IEEE	(_FPU_DEFAULT | 0x00001f00)
 
 /* Type of the control word.  */
diff --git a/sysdeps/arm/math_private.h b/sysdeps/arm/math_private.h
new file mode 100644
index 0000000..541a7f8
--- /dev/null
+++ b/sysdeps/arm/math_private.h
@@ -0,0 +1,6 @@
+#ifndef _MATH_PRIVATE_H
+
+#include "fenv_private.h"
+#include_next <math_private.h>
+
+#endif
-- 
1.7.9.5