arm: Add movmisalign patterns for MVE (PR target/97875)

arm: Add movmisalign patterns for MVE (PR target/97875)

This patch adds new movmisalign<mode>_mve_load and store patterns for
MVE to help vectorization. They are very similar to their Neon
counterparts, but use different iterators and instructions.

Indeed MVE supports less vectors modes than Neon, so we use the
MVE_VLD_ST iterator where Neon uses VQX.

Since the supported modes are different from the ones valid for
arithmetic operators, we introduce two new sets of macros:

ARM_HAVE_NEON_<MODE>_LDST
  true if Neon has vector load/store instructions for <MODE>

ARM_HAVE_<MODE>_LDST
  true if any vector extension has vector load/store instructions for <MODE>

We move the movmisalign<mode> expander from neon.md to vec-commond.md, and
replace the TARGET_NEON enabler with ARM_HAVE_<MODE>_LDST.

The patch also updates the mve-vneg.c test to scan for the better code
generation when loading and storing the vectors involved: it checks
that no 'orr' instruction is generated to cope with misalignment at
runtime.
This test was chosen among the other mve tests, but any other should
be OK. Using a plain vector copy loop (dest[i] = a[i]) is not a good
test because the compiler chooses to use memcpy.

For instance we now generate:
test_vneg_s32x4:
	vldrw.32       q3, [r1]
	vneg.s32  q3, q3
	vstrw.32       q3, [r0]
	bx      lr

instead of:
test_vneg_s32x4:
	orr     r3, r1, r0
	lsls    r3, r3, #28
	bne     .L15
	vldrw.32	q3, [r1]
	vneg.s32  q3, q3
	vstrw.32	q3, [r0]
	bx      lr
	.L15:
	push    {r4, r5}
	ldrd    r2, r3, [r1, #8]
	ldrd    r5, r4, [r1]
	rsbs    r2, r2, #0
	rsbs    r5, r5, #0
	rsbs    r4, r4, #0
	rsbs    r3, r3, #0
	strd    r5, r4, [r0]
	pop     {r4, r5}
	strd    r2, r3, [r0, #8]
	bx      lr

2021-01-12  Christophe Lyon  <christophe.lyon@linaro.org>

	PR target/97875
	gcc/
	* config/arm/arm.h (ARM_HAVE_NEON_V8QI_LDST): New macro.
	(ARM_HAVE_NEON_V16QI_LDST, ARM_HAVE_NEON_V4HI_LDST): Likewise.
	(ARM_HAVE_NEON_V8HI_LDST, ARM_HAVE_NEON_V2SI_LDST): Likewise.
	(ARM_HAVE_NEON_V4SI_LDST, ARM_HAVE_NEON_V4HF_LDST): Likewise.
	(ARM_HAVE_NEON_V8HF_LDST, ARM_HAVE_NEON_V4BF_LDST): Likewise.
	(ARM_HAVE_NEON_V8BF_LDST, ARM_HAVE_NEON_V2SF_LDST): Likewise.
	(ARM_HAVE_NEON_V4SF_LDST, ARM_HAVE_NEON_DI_LDST): Likewise.
	(ARM_HAVE_NEON_V2DI_LDST): Likewise.
	(ARM_HAVE_V8QI_LDST, ARM_HAVE_V16QI_LDST): Likewise.
	(ARM_HAVE_V4HI_LDST, ARM_HAVE_V8HI_LDST): Likewise.
	(ARM_HAVE_V2SI_LDST, ARM_HAVE_V4SI_LDST, ARM_HAVE_V4HF_LDST): Likewise.
	(ARM_HAVE_V8HF_LDST, ARM_HAVE_V4BF_LDST, ARM_HAVE_V8BF_LDST): Likewise.
	(ARM_HAVE_V2SF_LDST, ARM_HAVE_V4SF_LDST, ARM_HAVE_DI_LDST): Likewise.
	(ARM_HAVE_V2DI_LDST): Likewise.
	* config/arm/mve.md (*movmisalign<mode>_mve_store): New pattern.
	(*movmisalign<mode>_mve_load): New pattern.
	* config/arm/neon.md (movmisalign<mode>): Move to ...
	* config/arm/vec-common.md: ... here.

	PR target/97875
	gcc/testsuite/
	* gcc.target/arm/simd/mve-vneg.c: Update test.