Re: [PATCH], Add support for __builtin_{sqrt,fma}f128 on PowerPC ISA 3.0

[Michael Meissner <meissner at linux dot vnet dot ibm dot com>]

On Thu, Sep 14, 2017 at 09:54:14AM -0500, Segher Boessenkool wrote:
> On Wed, Sep 13, 2017 at 05:46:00PM -0400, Michael Meissner wrote:
> > This patch adds support on PowerPC ISA 3.0 for the built-in function
> > __builtin_sqrtf128 generating the XSSQRTQP hardware square root instruction and
> > the built-in function __builtin_fmaf128 generating XSMADDQP, XSMSUBQP,
> > XSNMADDQP, and XSNMSUBQP fused multiply-add instructions.
> > 
> > While I was at it, I changed the documentation so that it no longer documents
> > the 'q' built-in functions (to mirror libquadmath) but instead just documented
> > the 'f128' functions that matches glibc 2.26 and the technical report that
> > added the _FloatF128 date.
> > 
> > I changed the tests that used __fabsq to use __fabsf128 instead.
> > 
> > I also added && lp64 to float128-5.c so that it doesn't cause errors when doing
> > the test for a 32-bit target.  This is due to the fact that if you enable
> > hardware IEEE 128-bit floating point, you eventually will need TImode
> > supported, and that is not supported on 32-bit targets.
> > 
> > I did a bootstrap and make check with subversion id 252033 on a little endian
> > power8 system.  The subversion id 252033 is one of the last svn ids that
> > bootstrap without additional patches on the PowerPC.  There were no regressions
> > in this patch, and I verified the 4 new tests were run.  Can I check this patch
> > into the trunk?
> 
> Yes please.  A few trivial things:
> 
> > 	* doc/extend.texi (RS/6000 built-in functions): Document the
> > 	'f128' IEEE 128-bit floating point built-in functions.  Don't
> > 	document the older 'q' versions of the functions. Document the
> > 	built-in IEEE 128-bit floating point square root and fused
> > 	multiply-add built-ins.
> 
> Dot space space.
> 
> > +/* 1 argument IEEE 128-bit floating point functions that require ISA 3.0
> > +   hardware.  We define both a 'q' version for libquadmath compatibility, and a
> > +   'f128' for glibc 2.26.  We didn't need this for FABS/COPYSIGN, since the
> > +   machine independent built-in support already defines the F128 versions,  */
> 
> Dot instead of comma?
> 
> > --- gcc/testsuite/gcc.target/powerpc/float128-5.c	(revision 252730)
> > +++ gcc/testsuite/gcc.target/powerpc/float128-5.c	(working copy)
> > @@ -1,4 +1,4 @@
> > -/* { dg-do compile { target { powerpc*-*-linux* } } } */
> > +/* { dg-do compile { target { powerpc*-*-linux* && lp64 } } } */
> 
> Maybe add a comment why this is -m64 only?

I removed the changes to the documentation that didn't pertain to the functions
I was adding (we can clean that up some other time), and added a -m64 comment.

I checked this into the trunk:

[gcc]
2017-09-14  Michael Meissner  <meissner@linux.vnet.ibm.com>

	* config/rs6000/rs6000-builtin.def (BU_FLOAT128_1_HW): New macros
	to support float128 built-in functions that require the ISA 3.0
	hardware.
	(BU_FLOAT128_3_HW): Likewise.
	(SQRTF128): Add support for the IEEE 128-bit square root and fma
	built-in functions.
	(FMAF128): Likewise.
	(FMAQ): Likewise.
	* config/rs6000/rs6000.c (rs6000_builtin_mask_calculate): Add
	support for built-in functions that need the ISA 3.0 IEEE 128-bit
	floating point instructions.
	(rs6000_invalid_builtin): Likewise.
	(rs6000_builtin_mask_names): Likewise.
	* config/rs6000/rs6000.h (MASK_FLOAT128_HW): Likewise.
	(RS6000_BTM_FLOAT128_HW): Likewise.
	(RS6000_BTM_COMMON): Likewise.
	* config/rs6000/rs6000.md (fma<mode>4_hw): Add a generator
	function.
	* doc/extend.texi (RS/6000 built-in functions): Document the
	'f128' IEEE 128-bit floating point built-in functions. Don't
	document the older 'q' versions of the functions. Document the
	built-in IEEE 128-bit floating point square root and fused
	multiply-add built-ins.

[gcc/testsuite]
2017-09-14  Michael Meissner  <meissner@linux.vnet.ibm.com>

	* gcc.target/powerpc/abs128-1.c: Use __builtin_fabsf128 instead of
	__builtin_fabsq.
	* gcc.target/powerpc/float128-5.c: Use __builtin_fabsf128 instead
	of __builtin_fabsq.  Prevent the test from running on 32-bit.
	* gcc.target/powerpc/float128-fma1.c: New test.
	* gcc.target/powerpc/float128-fma2.c: Likewise.
	* gcc.target/powerpc/float128-sqrt1.c: Likewise.
	* gcc.target/powerpc/float128-sqrt2.c: Likewise.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.vnet.ibm.com, phone: +1 (978) 899-4797

Attachment: ieee128-patch31b
Description: Text document