x86: Add a new option -mdaz-ftz to enable FTZ and DAZ flags in MXCSR.
Checks
Commit Message
> The quoted patch shows -shared in context and you didn't post a
> backport version
> to look at. But yes, we shouldn't change -shared behavior on a
> branch, even less so make it
> inconsistent between targets.
Here's the patch.
Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
Ok for GCC 11/12 backport?
if (mdaz-ftz)
link crtfastmath.o
else if ((Ofast || ffast-math || funsafe-math-optimizations)
&& !mno-daz-ftz)
link crtfastmath.o
else
Don't link crtfastmath.o
gcc/ChangeLog:
* config/i386/cygwin.h (ENDFILE_SPEC): Link crtfastmath.o
whenever -mdaz-ftz is specified. Don't link crtfastmath.o
when -mno-daz-ftz is specified.
* config/i386/darwin.h (ENDFILE_SPEC): Ditto.
* config/i386/gnu-user-common.h
(GNU_USER_TARGET_MATHFILE_SPEC): Ditto.
* config/i386/mingw32.h (ENDFILE_SPEC): Ditto.
* config/i386/i386.opt (mdaz-ftz): New option.
* doc/invoke.texi (x86 options): Document mftz-daz.
---
gcc/config/i386/cygwin.h | 2 +-
gcc/config/i386/darwin.h | 4 ++--
gcc/config/i386/gnu-user-common.h | 2 +-
gcc/config/i386/i386.opt | 4 ++++
gcc/config/i386/mingw32.h | 2 +-
gcc/doc/invoke.texi | 11 ++++++++++-
6 files changed, 19 insertions(+), 6 deletions(-)
Comments
On Wed, May 10, 2023 at 5:10 PM liuhongt <hongtao.liu@intel.com> wrote:
>
> > The quoted patch shows -shared in context and you didn't post a
> > backport version
> > to look at. But yes, we shouldn't change -shared behavior on a
> > branch, even less so make it
> > inconsistent between targets.
> Here's the patch.
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> Ok for GCC 11/12 backport?
I'm going to push the patch next week if there's no objection.
>
> if (mdaz-ftz)
> link crtfastmath.o
> else if ((Ofast || ffast-math || funsafe-math-optimizations)
> && !mno-daz-ftz)
> link crtfastmath.o
> else
> Don't link crtfastmath.o
>
> gcc/ChangeLog:
>
> * config/i386/cygwin.h (ENDFILE_SPEC): Link crtfastmath.o
> whenever -mdaz-ftz is specified. Don't link crtfastmath.o
> when -mno-daz-ftz is specified.
> * config/i386/darwin.h (ENDFILE_SPEC): Ditto.
> * config/i386/gnu-user-common.h
> (GNU_USER_TARGET_MATHFILE_SPEC): Ditto.
> * config/i386/mingw32.h (ENDFILE_SPEC): Ditto.
> * config/i386/i386.opt (mdaz-ftz): New option.
> * doc/invoke.texi (x86 options): Document mftz-daz.
> ---
> gcc/config/i386/cygwin.h | 2 +-
> gcc/config/i386/darwin.h | 4 ++--
> gcc/config/i386/gnu-user-common.h | 2 +-
> gcc/config/i386/i386.opt | 4 ++++
> gcc/config/i386/mingw32.h | 2 +-
> gcc/doc/invoke.texi | 11 ++++++++++-
> 6 files changed, 19 insertions(+), 6 deletions(-)
>
> diff --git a/gcc/config/i386/cygwin.h b/gcc/config/i386/cygwin.h
> index d06eda369cf..5412c5d4479 100644
> --- a/gcc/config/i386/cygwin.h
> +++ b/gcc/config/i386/cygwin.h
> @@ -57,7 +57,7 @@ along with GCC; see the file COPYING3. If not see
>
> #undef ENDFILE_SPEC
> #define ENDFILE_SPEC \
> - "%{Ofast|ffast-math|funsafe-math-optimizations:crtfastmath.o%s}\
> + "%{mdaz-ftz:crtfastmath.o%s;Ofast|ffast-math|funsafe-math-optimizations:%{!mno-daz-ftz:crtfastmath.o%s}} \
> %{!shared:%:if-exists(default-manifest.o%s)}\
> %{fvtable-verify=none:%s; \
> fvtable-verify=preinit:vtv_end.o%s; \
> diff --git a/gcc/config/i386/darwin.h b/gcc/config/i386/darwin.h
> index a55f6b2b874..2f773924d6e 100644
> --- a/gcc/config/i386/darwin.h
> +++ b/gcc/config/i386/darwin.h
> @@ -109,8 +109,8 @@ along with GCC; see the file COPYING3. If not see
> "%{!force_cpusubtype_ALL:-force_cpusubtype_ALL} "
>
> #undef ENDFILE_SPEC
> -#define ENDFILE_SPEC \
> - "%{Ofast|ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
> +#define ENDFILE_SPEC
> +\ "%{mdaz-ftz:crtfastmath.o%s;Ofast|ffast-math|funsafe-math-optimizations:%{!mno-daz-ftz:crtfastmath.o%s}} \
> %{mpc32:crtprec32.o%s} \
> %{mpc64:crtprec64.o%s} \
> %{mpc80:crtprec80.o%s}" TM_DESTRUCTOR
> diff --git a/gcc/config/i386/gnu-user-common.h b/gcc/config/i386/gnu-user-common.h
> index 23b54c5be52..3d2a33f1714 100644
> --- a/gcc/config/i386/gnu-user-common.h
> +++ b/gcc/config/i386/gnu-user-common.h
> @@ -47,7 +47,7 @@ along with GCC; see the file COPYING3. If not see
>
> /* Similar to standard GNU userspace, but adding -ffast-math support. */
> #define GNU_USER_TARGET_MATHFILE_SPEC \
> - "%{Ofast|ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
> + "%{mdaz-ftz:crtfastmath.o%s;Ofast|ffast-math|funsafe-math-optimizations:%{!mno-daz-ftz:crtfastmath.o%s}} \
> %{mpc32:crtprec32.o%s} \
> %{mpc64:crtprec64.o%s} \
> %{mpc80:crtprec80.o%s}"
> diff --git a/gcc/config/i386/i386.opt b/gcc/config/i386/i386.opt
> index a3675e515bc..5cfb7cdcbc2 100644
> --- a/gcc/config/i386/i386.opt
> +++ b/gcc/config/i386/i386.opt
> @@ -420,6 +420,10 @@ mpc80
> Target RejectNegative
> Set 80387 floating-point precision to 80-bit.
>
> +mdaz-ftz
> +Target
> +Set the FTZ and DAZ Flags.
> +
> mpreferred-stack-boundary=
> Target RejectNegative Joined UInteger Var(ix86_preferred_stack_boundary_arg)
> Attempt to keep stack aligned to this power of 2.
> diff --git a/gcc/config/i386/mingw32.h b/gcc/config/i386/mingw32.h
> index d3ca0cd0279..ddbe6a4054b 100644
> --- a/gcc/config/i386/mingw32.h
> +++ b/gcc/config/i386/mingw32.h
> @@ -197,7 +197,7 @@ along with GCC; see the file COPYING3. If not see
>
> #undef ENDFILE_SPEC
> #define ENDFILE_SPEC \
> - "%{Ofast|ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
> + "%{mdaz-ftz:crtfastmath.o%s;Ofast|ffast-math|funsafe-math-optimizations:%{!mno-daz-ftz:crtfastmath.o%s}} \
> %{!shared:%:if-exists(default-manifest.o%s)}\
> %{fvtable-verify=none:%s; \
> fvtable-verify=preinit:vtv_end.o%s; \
> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> index cb83dd8a1cc..87eedfffa6c 100644
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -1434,7 +1434,7 @@ See RS/6000 and PowerPC Options.
> -m96bit-long-double -mlong-double-64 -mlong-double-80 -mlong-double-128 @gol
> -mregparm=@var{num} -msseregparm @gol
> -mveclibabi=@var{type} -mvect8-ret-in-mem @gol
> --mpc32 -mpc64 -mpc80 -mstackrealign @gol
> +-mpc32 -mpc64 -mpc80 -mdaz-ftz -mstackrealign @gol
> -momit-leaf-frame-pointer -mno-red-zone -mno-tls-direct-seg-refs @gol
> -mcmodel=@var{code-model} -mabi=@var{name} -maddress-mode=@var{mode} @gol
> -m32 -m64 -mx32 -m16 -miamcu -mlarge-data-threshold=@var{num} @gol
> @@ -32078,6 +32078,15 @@ are enabled by default; routines in such libraries could suffer significant
> loss of accuracy, typically through so-called ``catastrophic cancellation'',
> when this option is used to set the precision to less than extended precision.
>
> +@item -mdaz-ftz
> +@opindex mdaz-ftz
> +
> +The flush-to-zero (FTZ) and denormals-are-zero (DAZ) flags in the MXCSR register
> +are used to control floating-point calculations.SSE and AVX instructions
> +including scalar and vector instructions could benefit from enabling the FTZ
> +and DAZ flags when @option{-mdaz-ftz} is specified. Don't set FTZ/DAZ flags
> +when @option{-mno-daz-ftz} is specified.
> +
> @item -mstackrealign
> @opindex mstackrealign
> Realign the stack at entry. On the x86, the @option{-mstackrealign}
> --
> 2.39.1.388.g2fc9e9ca3c
>
On Fri, May 12, 2023 at 1:43 PM Hongtao Liu <crazylht@gmail.com> wrote:
>
> On Wed, May 10, 2023 at 5:10 PM liuhongt <hongtao.liu@intel.com> wrote:
> >
> > > The quoted patch shows -shared in context and you didn't post a
> > > backport version
> > > to look at. But yes, we shouldn't change -shared behavior on a
> > > branch, even less so make it
> > > inconsistent between targets.
> > Here's the patch.
> >
> > Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> > Ok for GCC 11/12 backport?
> I'm going to push the patch next week if there's no objection.
pushed to gcc-11/gcc-12 branch.
> >
> > if (mdaz-ftz)
> > link crtfastmath.o
> > else if ((Ofast || ffast-math || funsafe-math-optimizations)
> > && !mno-daz-ftz)
> > link crtfastmath.o
> > else
> > Don't link crtfastmath.o
> >
> > gcc/ChangeLog:
> >
> > * config/i386/cygwin.h (ENDFILE_SPEC): Link crtfastmath.o
> > whenever -mdaz-ftz is specified. Don't link crtfastmath.o
> > when -mno-daz-ftz is specified.
> > * config/i386/darwin.h (ENDFILE_SPEC): Ditto.
> > * config/i386/gnu-user-common.h
> > (GNU_USER_TARGET_MATHFILE_SPEC): Ditto.
> > * config/i386/mingw32.h (ENDFILE_SPEC): Ditto.
> > * config/i386/i386.opt (mdaz-ftz): New option.
> > * doc/invoke.texi (x86 options): Document mftz-daz.
> > ---
> > gcc/config/i386/cygwin.h | 2 +-
> > gcc/config/i386/darwin.h | 4 ++--
> > gcc/config/i386/gnu-user-common.h | 2 +-
> > gcc/config/i386/i386.opt | 4 ++++
> > gcc/config/i386/mingw32.h | 2 +-
> > gcc/doc/invoke.texi | 11 ++++++++++-
> > 6 files changed, 19 insertions(+), 6 deletions(-)
> >
> > diff --git a/gcc/config/i386/cygwin.h b/gcc/config/i386/cygwin.h
> > index d06eda369cf..5412c5d4479 100644
> > --- a/gcc/config/i386/cygwin.h
> > +++ b/gcc/config/i386/cygwin.h
> > @@ -57,7 +57,7 @@ along with GCC; see the file COPYING3. If not see
> >
> > #undef ENDFILE_SPEC
> > #define ENDFILE_SPEC \
> > - "%{Ofast|ffast-math|funsafe-math-optimizations:crtfastmath.o%s}\
> > + "%{mdaz-ftz:crtfastmath.o%s;Ofast|ffast-math|funsafe-math-optimizations:%{!mno-daz-ftz:crtfastmath.o%s}} \
> > %{!shared:%:if-exists(default-manifest.o%s)}\
> > %{fvtable-verify=none:%s; \
> > fvtable-verify=preinit:vtv_end.o%s; \
> > diff --git a/gcc/config/i386/darwin.h b/gcc/config/i386/darwin.h
> > index a55f6b2b874..2f773924d6e 100644
> > --- a/gcc/config/i386/darwin.h
> > +++ b/gcc/config/i386/darwin.h
> > @@ -109,8 +109,8 @@ along with GCC; see the file COPYING3. If not see
> > "%{!force_cpusubtype_ALL:-force_cpusubtype_ALL} "
> >
> > #undef ENDFILE_SPEC
> > -#define ENDFILE_SPEC \
> > - "%{Ofast|ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
> > +#define ENDFILE_SPEC
> > +\ "%{mdaz-ftz:crtfastmath.o%s;Ofast|ffast-math|funsafe-math-optimizations:%{!mno-daz-ftz:crtfastmath.o%s}} \
> > %{mpc32:crtprec32.o%s} \
> > %{mpc64:crtprec64.o%s} \
> > %{mpc80:crtprec80.o%s}" TM_DESTRUCTOR
> > diff --git a/gcc/config/i386/gnu-user-common.h b/gcc/config/i386/gnu-user-common.h
> > index 23b54c5be52..3d2a33f1714 100644
> > --- a/gcc/config/i386/gnu-user-common.h
> > +++ b/gcc/config/i386/gnu-user-common.h
> > @@ -47,7 +47,7 @@ along with GCC; see the file COPYING3. If not see
> >
> > /* Similar to standard GNU userspace, but adding -ffast-math support. */
> > #define GNU_USER_TARGET_MATHFILE_SPEC \
> > - "%{Ofast|ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
> > + "%{mdaz-ftz:crtfastmath.o%s;Ofast|ffast-math|funsafe-math-optimizations:%{!mno-daz-ftz:crtfastmath.o%s}} \
> > %{mpc32:crtprec32.o%s} \
> > %{mpc64:crtprec64.o%s} \
> > %{mpc80:crtprec80.o%s}"
> > diff --git a/gcc/config/i386/i386.opt b/gcc/config/i386/i386.opt
> > index a3675e515bc..5cfb7cdcbc2 100644
> > --- a/gcc/config/i386/i386.opt
> > +++ b/gcc/config/i386/i386.opt
> > @@ -420,6 +420,10 @@ mpc80
> > Target RejectNegative
> > Set 80387 floating-point precision to 80-bit.
> >
> > +mdaz-ftz
> > +Target
> > +Set the FTZ and DAZ Flags.
> > +
> > mpreferred-stack-boundary=
> > Target RejectNegative Joined UInteger Var(ix86_preferred_stack_boundary_arg)
> > Attempt to keep stack aligned to this power of 2.
> > diff --git a/gcc/config/i386/mingw32.h b/gcc/config/i386/mingw32.h
> > index d3ca0cd0279..ddbe6a4054b 100644
> > --- a/gcc/config/i386/mingw32.h
> > +++ b/gcc/config/i386/mingw32.h
> > @@ -197,7 +197,7 @@ along with GCC; see the file COPYING3. If not see
> >
> > #undef ENDFILE_SPEC
> > #define ENDFILE_SPEC \
> > - "%{Ofast|ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
> > + "%{mdaz-ftz:crtfastmath.o%s;Ofast|ffast-math|funsafe-math-optimizations:%{!mno-daz-ftz:crtfastmath.o%s}} \
> > %{!shared:%:if-exists(default-manifest.o%s)}\
> > %{fvtable-verify=none:%s; \
> > fvtable-verify=preinit:vtv_end.o%s; \
> > diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> > index cb83dd8a1cc..87eedfffa6c 100644
> > --- a/gcc/doc/invoke.texi
> > +++ b/gcc/doc/invoke.texi
> > @@ -1434,7 +1434,7 @@ See RS/6000 and PowerPC Options.
> > -m96bit-long-double -mlong-double-64 -mlong-double-80 -mlong-double-128 @gol
> > -mregparm=@var{num} -msseregparm @gol
> > -mveclibabi=@var{type} -mvect8-ret-in-mem @gol
> > --mpc32 -mpc64 -mpc80 -mstackrealign @gol
> > +-mpc32 -mpc64 -mpc80 -mdaz-ftz -mstackrealign @gol
> > -momit-leaf-frame-pointer -mno-red-zone -mno-tls-direct-seg-refs @gol
> > -mcmodel=@var{code-model} -mabi=@var{name} -maddress-mode=@var{mode} @gol
> > -m32 -m64 -mx32 -m16 -miamcu -mlarge-data-threshold=@var{num} @gol
> > @@ -32078,6 +32078,15 @@ are enabled by default; routines in such libraries could suffer significant
> > loss of accuracy, typically through so-called ``catastrophic cancellation'',
> > when this option is used to set the precision to less than extended precision.
> >
> > +@item -mdaz-ftz
> > +@opindex mdaz-ftz
> > +
> > +The flush-to-zero (FTZ) and denormals-are-zero (DAZ) flags in the MXCSR register
> > +are used to control floating-point calculations.SSE and AVX instructions
> > +including scalar and vector instructions could benefit from enabling the FTZ
> > +and DAZ flags when @option{-mdaz-ftz} is specified. Don't set FTZ/DAZ flags
> > +when @option{-mno-daz-ftz} is specified.
> > +
> > @item -mstackrealign
> > @opindex mstackrealign
> > Realign the stack at entry. On the x86, the @option{-mstackrealign}
> > --
> > 2.39.1.388.g2fc9e9ca3c
> >
>
>
> --
> BR,
> Hongtao
@@ -57,7 +57,7 @@ along with GCC; see the file COPYING3. If not see
#undef ENDFILE_SPEC
#define ENDFILE_SPEC \
- "%{Ofast|ffast-math|funsafe-math-optimizations:crtfastmath.o%s}\
+ "%{mdaz-ftz:crtfastmath.o%s;Ofast|ffast-math|funsafe-math-optimizations:%{!mno-daz-ftz:crtfastmath.o%s}} \
%{!shared:%:if-exists(default-manifest.o%s)}\
%{fvtable-verify=none:%s; \
fvtable-verify=preinit:vtv_end.o%s; \
@@ -109,8 +109,8 @@ along with GCC; see the file COPYING3. If not see
"%{!force_cpusubtype_ALL:-force_cpusubtype_ALL} "
#undef ENDFILE_SPEC
-#define ENDFILE_SPEC \
- "%{Ofast|ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
+#define ENDFILE_SPEC
+\ "%{mdaz-ftz:crtfastmath.o%s;Ofast|ffast-math|funsafe-math-optimizations:%{!mno-daz-ftz:crtfastmath.o%s}} \
%{mpc32:crtprec32.o%s} \
%{mpc64:crtprec64.o%s} \
%{mpc80:crtprec80.o%s}" TM_DESTRUCTOR
@@ -47,7 +47,7 @@ along with GCC; see the file COPYING3. If not see
/* Similar to standard GNU userspace, but adding -ffast-math support. */
#define GNU_USER_TARGET_MATHFILE_SPEC \
- "%{Ofast|ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
+ "%{mdaz-ftz:crtfastmath.o%s;Ofast|ffast-math|funsafe-math-optimizations:%{!mno-daz-ftz:crtfastmath.o%s}} \
%{mpc32:crtprec32.o%s} \
%{mpc64:crtprec64.o%s} \
%{mpc80:crtprec80.o%s}"
@@ -420,6 +420,10 @@ mpc80
Target RejectNegative
Set 80387 floating-point precision to 80-bit.
+mdaz-ftz
+Target
+Set the FTZ and DAZ Flags.
+
mpreferred-stack-boundary=
Target RejectNegative Joined UInteger Var(ix86_preferred_stack_boundary_arg)
Attempt to keep stack aligned to this power of 2.
@@ -197,7 +197,7 @@ along with GCC; see the file COPYING3. If not see
#undef ENDFILE_SPEC
#define ENDFILE_SPEC \
- "%{Ofast|ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
+ "%{mdaz-ftz:crtfastmath.o%s;Ofast|ffast-math|funsafe-math-optimizations:%{!mno-daz-ftz:crtfastmath.o%s}} \
%{!shared:%:if-exists(default-manifest.o%s)}\
%{fvtable-verify=none:%s; \
fvtable-verify=preinit:vtv_end.o%s; \
@@ -1434,7 +1434,7 @@ See RS/6000 and PowerPC Options.
-m96bit-long-double -mlong-double-64 -mlong-double-80 -mlong-double-128 @gol
-mregparm=@var{num} -msseregparm @gol
-mveclibabi=@var{type} -mvect8-ret-in-mem @gol
--mpc32 -mpc64 -mpc80 -mstackrealign @gol
+-mpc32 -mpc64 -mpc80 -mdaz-ftz -mstackrealign @gol
-momit-leaf-frame-pointer -mno-red-zone -mno-tls-direct-seg-refs @gol
-mcmodel=@var{code-model} -mabi=@var{name} -maddress-mode=@var{mode} @gol
-m32 -m64 -mx32 -m16 -miamcu -mlarge-data-threshold=@var{num} @gol
@@ -32078,6 +32078,15 @@ are enabled by default; routines in such libraries could suffer significant
loss of accuracy, typically through so-called ``catastrophic cancellation'',
when this option is used to set the precision to less than extended precision.
+@item -mdaz-ftz
+@opindex mdaz-ftz
+
+The flush-to-zero (FTZ) and denormals-are-zero (DAZ) flags in the MXCSR register
+are used to control floating-point calculations.SSE and AVX instructions
+including scalar and vector instructions could benefit from enabling the FTZ
+and DAZ flags when @option{-mdaz-ftz} is specified. Don't set FTZ/DAZ flags
+when @option{-mno-daz-ftz} is specified.
+
@item -mstackrealign
@opindex mstackrealign
Realign the stack at entry. On the x86, the @option{-mstackrealign}