Implement Softmax

[cognaiger9]

• Add Softmax operation with forward and backward kernels.
• Add driver and gtest for kernels.

Average improvement over ROCm

type	fwd	bwd
float16	1.23	1.34
float	1.42	1.7
bfloat16	1.36	1.4

Detail Benchmark

float16

op_name	dtype	size	dim	direction	ROCm	MIOpen	Improvement
softmax	float16	[40 12 512 512]	0	fwd	2387296	2068530	1.15
softmax	float16	[40 12 512 512]	3	bwd	1621787	1258830	1.29
softmax	float16	[16 21 512 512]	3	bwd	1140924	882061	1.29
softmax	float16	[24 21 512 512]	2	fwd	2461811	2095470	1.17
softmax	float16	[24 21 512 512]	2	bwd	2809512	2517230	1.12
softmax	float16	[24 21 512 512]	3	bwd	1664764	1308200	1.27
softmax	float16	[64 21 254 333]	1	fwd	2262283	1630830	1.39
softmax	float16	[64 21 254 333]	1	bwd	2415334	1312320	1.84
softmax	float16	[64 21 274 275]	0	fwd	1874841	1521130	1.23
softmax	float16	[64 21 274 275]	0	bwd	2286461	1916420	1.19
softmax	float16	[16 12 512 512]	2	fwd	1093984	857349	1.28
softmax	float16	[16 12 512 512]	2	bwd	1345465	1014480	1.33
softmax	float16	[16 12 512 512]	3	bwd	698140	514815	1.36
softmax	float16	[16 12 1024 1024]	0	fwd	3340209	3115000	1.07
softmax	float16	[16 12 1024 1024]	3	bwd	2690629	1914170	1.41
softmax	float16	[64 21 273 322]	1	fwd	2308081	1705720	1.35

float32

op_name	dtype	size	dim	direction	ROCm	MIOpen	Improvement
softmax	float32	[40 12 512 512]	0	bwd	3387696	2342360	1.45
softmax	float32	[40 12 512 512]	3	bwd	2746646	1366120	2.01
softmax	float32	[16 21 512 512]	0	bwd	2182362	1269290	1.72
softmax	float32	[16 21 512 512]	3	bwd	1845381	962271	1.92
softmax	float32	[24 21 512 512]	2	fwd	2377126	2025380	1.17
softmax	float32	[24 21 512 512]	2	bwd	3644878	2351230	1.55
softmax	float32	[24 21 512 512]	3	bwd	2748875	1362150	2.02
softmax	float32	[64 21 254 333]	1	fwd	3117586	1786060	1.75
softmax	float32	[64 21 254 333]	1	bwd	3821724	2345770	1.63
softmax	float32	[64 21 254 333]	3	bwd	2558036	1624640	1.57
softmax	float32	[64 21 274 275]	0	fwd	2797934	1945240	1.44
softmax	float32	[64 21 274 275]	0	bwd	3651317	2577740	1.42
softmax	float32	[64 21 274 275]	3	bwd	2365995	1516970	1.56
softmax	float32	[16 12 512 512]	2	fwd	1007843	777760	1.30
softmax	float32	[16 12 512 512]	2	bwd	1470582	890450	1.65
softmax	float32	[16 12 512 512]	3	bwd	1099249	560503	1.96

bfloat16

op_name	dtype	size	dim	direction	ROCm	MIOpen	Improvement
softmax	bfloat16	[40 12 512 512]	0	fwd	2389249	2089470	1.14
softmax	bfloat16	[40 12 512 512]	3	fwd	2938001	1847650	1.59
softmax	bfloat16	[40 12 512 512]	3	bwd	1615068	1284590	1.26
softmax	bfloat16	[16 21 512 512]	3	bwd	1098381	899471	1.22
softmax	bfloat16	[24 21 512 512]	2	fwd	2492450	2133930	1.17
softmax	bfloat16	[24 21 512 512]	3	bwd	1625726	1334160	1.22
softmax	bfloat16	[64 21 254 333]	1	fwd	2264252	1673840	1.35
softmax	bfloat16	[64 21 254 333]	1	bwd	2526948	1325550	1.91
softmax	bfloat16	[64 21 274 275]	0	fwd	1870393	1531300	1.22
softmax	bfloat16	[64 21 274 275]	0	bwd	2306828	1920690	1.20
softmax	bfloat16	[16 12 512 512]	2	fwd	1102672	877420	1.26
softmax	bfloat16	[16 12 512 512]	2	bwd	1302154	1014289	1.28
softmax	bfloat16	[16 12 512 512]	3	bwd	701804	525358	1.34
softmax	bfloat16	[16 12 1024 1024]	3	bwd	2645928	1967850	1.34
softmax	bfloat16	[64 21 273 322]	1	fwd	2311698	1748050	1.32
softmax	bfloat16	[64 21 273 322]	1	bwd	2661480	1470710	1.81