Fix PR67974 for Darwin by adding an asm shim for AVX.

The PR is about a set of tests that were not executed because of
missing asm support.  

However, the assembler can handle the insns now, so the tests are
attempted (but with a missing asm shim they fail).

This adds the shim.

In principle (bugs notwithstanding) Darwin’s x86_64 ABI is supposed
to follow the sysv psABI so we can have essentially a copy of the
Linux one.

2018-12-24  Iain Sandoe  <iain@sandoe.co.uk>

	PR testsuite/67974
	* gcc.target/x86_64/abi/avx/asm-support-darwin.s: New.

From-SVN: r267395

gcc/testsuite/ChangeLog

 2018-12-24  Iain Sandoe  <iain@sandoe.co.uk>
 
+	PR testsuite/67974
+	* gcc.target/x86_64/abi/avx/asm-support-darwin.s: New.
+
+2018-12-24  Iain Sandoe  <iain@sandoe.co.uk>
+
 	* c-c++-common/ident-0a.c: Skip for powerpc-darwin.
 	* c-c++-common/ident-0b.c: Likewise.
 	* c-c++-common/ident-1a.c: Likewise.

gcc/testsuite/gcc.target/x86_64/abi/avx/asm-support-darwin.s

+	.file	"asm-support-darwin.s"
+	.text
+	.p2align 4,,15
+	.globl _snapshot
+_snapshot:
+LFB3:
+	movq	%rax, _rax(%rip)
+	movq	%rbx, _rbx(%rip)
+	movq	%rcx, _rcx(%rip)
+	movq	%rdx, _rdx(%rip)
+	movq	%rdi, _rdi(%rip)
+	movq	%rsi, _rsi(%rip)
+	movq	%rbp, _rbp(%rip)
+	movq	%rsp, _rsp(%rip)
+	movq	%r8, _r8(%rip)
+	movq	%r9, _r9(%rip)
+	movq	%r10, _r10(%rip)
+	movq	%r11, _r11(%rip)
+	movq	%r12, _r12(%rip)
+	movq	%r13, _r13(%rip)
+	movq	%r14, _r14(%rip)
+	movq	%r15, _r15(%rip)
+	vmovdqu	%ymm0, _ymm_regs+0(%rip)
+	vmovdqu	%ymm1, _ymm_regs+32(%rip)
+	vmovdqu	%ymm2, _ymm_regs+64(%rip)
+	vmovdqu	%ymm3, _ymm_regs+96(%rip)
+	vmovdqu	%ymm4, _ymm_regs+128(%rip)
+	vmovdqu	%ymm5, _ymm_regs+160(%rip)
+	vmovdqu	%ymm6, _ymm_regs+192(%rip)
+	vmovdqu	%ymm7, _ymm_regs+224(%rip)
+	vmovdqu	%ymm8, _ymm_regs+256(%rip)
+	vmovdqu	%ymm9, _ymm_regs+288(%rip)
+	vmovdqu	%ymm10, _ymm_regs+320(%rip)
+	vmovdqu	%ymm11, _ymm_regs+352(%rip)
+	vmovdqu	%ymm12, _ymm_regs+384(%rip)
+	vmovdqu	%ymm13, _ymm_regs+416(%rip)
+	vmovdqu	%ymm14, _ymm_regs+448(%rip)
+	vmovdqu	%ymm15, _ymm_regs+480(%rip)
+	jmp	*_callthis(%rip)
+LFE3:
+	.p2align 4,,15
+	.globl _snapshot_ret
+_snapshot_ret:
+	movq	%rdi, _rdi(%rip)
+	subq	$8, %rsp
+	call	*_callthis(%rip)
+	addq	$8, %rsp
+	movq	%rax, _rax(%rip)
+	movq	%rdx, _rdx(%rip)
+	vmovdqu	%ymm0, _ymm_regs+0(%rip)
+	vmovdqu	%ymm1, _ymm_regs+32(%rip)
+	fstpt	_x87_regs(%rip)
+	fstpt	_x87_regs+16(%rip)
+	fldt	_x87_regs+16(%rip)
+	fldt	_x87_regs(%rip)
+	ret
+
+	.comm	_callthis,8,3
+	.comm	_rax,8,3
+	.comm	_rbx,8,3
+	.comm	_rcx,8,3
+	.comm	_rdx,8,3
+	.comm	_rsi,8,3
+	.comm	_rdi,8,3
+	.comm	_rsp,8,3
+	.comm	_rbp,8,3
+	.comm	_r8,8,3
+	.comm	_r9,8,3
+	.comm	_r10,8,3
+	.comm	_r11,8,3
+	.comm	_r12,8,3
+	.comm	_r13,8,3
+	.comm	_r14,8,3
+	.comm	_r15,8,3
+	.comm	_ymm_regs,512,5
+	.comm	_x87_regs,128,5
+	.comm   _volatile_var,8,3