RE: [ARM] Enable FP16 vector arithmetic operations.

[Tamar Christina <Tamar.Christina@arm.com>]

Hi Christoph,

> > Thanks, bootstrapped and regtested now on arm-none-linux-gnueabihf
> and no issues.
> > I'll go ahead and commit then.
> >
> 
> One of the new tests fails on arm-none-linux-gnueabi (non-hf) targets:
> FAIL:    gcc.target/arm/armv8_2-fp16-neon-2.c scan-assembler-times
> vceq\\.f16\\td[0-9]+, d[0-0]+, #0 1
> 
> For instance when configured --with-cpu=cortex-a9.
> 

Thanks, I'm making a non-hf build now to fix it.

Tamar

> Christophe
> 
> 
> > Regards,
> > Tamar
> >
> >>
> >> Thanks,
> >> Kyrill
> >>
> >> > Tamar
> >> > ________________________________________
> >> > From: gcc-patches-owner@gcc.gnu.org <gcc-patches-
> owner@gcc.gnu.org>
> >> on
> >> > behalf of Matthew Wahab <matthew.wahab@foss.arm.com>
> >> > Sent: Friday, September 23, 2016 4:02 PM
> >> > To: gcc-patches
> >> > Subject: [ARM] Enable FP16 vector arithmetic operations.
> >> >
> >> > Hello,
> >> >
> >> > Support for the ARMv8.2-A FP16 NEON arithmetic instructions was
> >> > added using non-standard names for the instruction patterns. This
> >> > was needed because the NEON floating point semantics meant that
> >> > their use by the compiler for HFmode arithmetic operations needed to
> be restricted.
> >> > This follows the implementation for 32-bit NEON intructions.
> >> >
> >> > As with the 32-bit instructions, the restriction on the HFmode
> >> > operation can be lifted when -funsafe-math-optimizations is enabled.
> >> > This patch does that, defining the standard pattern names addhf3,
> >> > subhf3, mulhf3 and fmahf3.
> >> >
> >> > This patch also updates the NEON intrinsics to use the arithmetic
> >> > operations when -ffast-math is enabled. This is to make keep the
> >> > 16-bit support consistent with the 32-bit supportd. It is needed so
> >> > that code using the f16 intrinsics are subject to the same
> >> > optimizations as code using the f32 intrinsics would be.
> >> >
> >> > Tested for arm-none-linux-gnueabihf with native bootstrap and make
> >> > check on ARMv8-A and for arm-none-eabi and armeb-none-eabi with
> >> > cross-compiled make check on an ARMv8.2-A emulator.
> >> >
> >> > Ok for trunk?
> >> > Matthew
> >> >
> >> > gcc/
> >> > 2016-09-23  Matthew Wahab  <matthew.wahab@arm.com>
> >> >
> >> >         * config/arm/arm_neon.h (vadd_f16): Use standard arithmetic
> >> >         operations in fast-math mode.
> >> >         (vaddq_f16): Likewise.
> >> >         (vmul_f16): Likewise.
> >> >         (vmulq_f16): Likewise.
> >> >         (vsub_f16): Likewise.
> >> >         (vsubq_f16): Likewise.
> >> >         * config/arm/neon.md (add<mode>3): New.
> >> >         (sub<mode>3): New.
> >> >         (fma:<VH:mode>3): New.  Also remove outdated comment.
> >> >         (mul<mode>3): New.
> >> >
> >> > testsuite/
> >> > 2016-09-23  Matthew Wahab  <matthew.wahab@arm.com>
> >> >
> >> >         * gcc.target/arm/armv8_2-fp16-arith-1.c: Expand comment.
> Update
> >> >         expected output of vadd, vsub and vmul instructions.
> >> >         * gcc.target/arm/armv8_2-fp16-arith-2.c: New.
> >> >         * gcc.target/arm/armv8_2-fp16-neon-2.c: New.
> >> >         * gcc.target/arm/armv8_2-fp16-neon-3.c: New.
> >