Cleanup and move gather-bench to util folder

util/gather-bench/src/avx512/gather.S

@@ -0,0 +1,62 @@
+.intel_syntax noprefix
+.data
+.align 64
+SCALAR:
+.double 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
+
+# rdi -> a
+# rsi -> idx
+# rdx -> N
+# rcx -> t
+.text
+.globl gather
+.type gather, @function
+gather :
+push rbp
+mov rbp, rsp
+push rbx
+push r12
+push r13
+push r14
+push r15
+
+xor   rax, rax
+.align 16
+1:
+vpcmpeqb k1, xmm0, xmm0
+vpcmpeqb k2, xmm0, xmm0
+vpcmpeqb k3, xmm0, xmm0
+vpcmpeqb k4, xmm0, xmm0
+vmovdqu ymm0, [rsi + rax * 4]
+vmovdqu ymm1, [rsi + rax * 4 + 32]
+vmovdqu ymm2, [rsi + rax * 4 + 64]
+vmovdqu ymm3, [rsi + rax * 4 + 96]
+vpxord zmm4, zmm4, zmm4
+vpxord zmm5, zmm5, zmm5
+vpxord zmm6, zmm6, zmm6
+vpxord zmm7, zmm7, zmm7
+vgatherdpd zmm4{k1}, [rdi + ymm0 * 8]
+vgatherdpd zmm5{k2}, [rdi + ymm1 * 8]
+vgatherdpd zmm6{k3}, [rdi + ymm2 * 8]
+vgatherdpd zmm7{k4}, [rdi + ymm3 * 8]
+
+#ifdef TEST
+vmovapd [rcx + rax * 8],       zmm4
+vmovapd [rcx + rax * 8 + 64],  zmm5
+vmovapd [rcx + rax * 8 + 128], zmm6
+vmovapd [rcx + rax * 8 + 192], zmm7
+#endif
+
+addq rax, 32
+cmpq rax, rdx
+jl 1b
+
+pop r15
+pop r14
+pop r13
+pop r12
+pop rbx
+mov  rsp, rbp
+pop rbp
+ret
+.size gather, .-gather