Swift versus C clang

How the programs are written matters! Always look at the source code.

If the fastest programs are flagged * possible hand-written vector instructions or "unsafe" or naked ffi, does the host language matter? You might be more interested in the less optimised programs — more seconds, less gz source code.

fannkuch-redux
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
* C clang #6	2.25	8.88	2,933	1582	5.56
* C clang #4	13.39	13.39	2,343	1190	5.32
C clang #5	8.10	32.01—32.15	4,792	917	5.61
* Swift #3	8.20	32.45—32.61	13,722	1103	12.93
* C clang #2	8.68	34.14—34.46	2,703	1563	5.59
C clang #3	34.14	34.19—34.26	2,351	574	5.16
Swift #8	34.68	34.68—34.74	13,484	470	12.33
C clang #8	36.35	36.38—36.47	2,347	483	5.08
C clang	36.52	36.54—36.63	2,347	514	5.39
n-body
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
* C clang #9	2.20	2.20	2,494	1639	6.10
* C clang #5	4.86	4.86	2,417	1436	5.03
C clang #6	5.17	5.17	2,970	1186	5.19
C clang	5.38	5.40	2,974	1179	5.35
C clang #2	5.43	5.44	2,982	1270	5.30
* Swift #3	5.45	5.44—5.48	24,928	1688	14.75
* Swift #4	5.48	5.49	24,846	1361	13.94
* Swift #5	5.52	5.50—5.55	24,928	1372	12.83
* Swift #7	5.53	5.52	24,932	1333	13.80
* C clang #4	5.60	5.61	2,941	1398	6.20
C clang #8	5.70	5.70—5.75	2,941	1195	5.20
Swift #6	5.82	5.81	12,956	1213	12.42
C clang #3	6.13	6.13	2,978	1214	5.65
Swift #8	6.66	6.56—6.95	12,804	1285	12.85
C clang #7	6.78	6.79	2,974	1250	5.16
Swift	7.89	7.88	12,812	1210	12.10
Swift #9	287.37	287.38—288.05	24,793	1532	13.91
spectral-norm
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
* C clang #6	0.39	1.52—1.56	4,706	1203	6.40
* C clang #5	0.73	2.87	5,206	576	5.85
* C clang #4	0.73	2.88—2.92	5,366	1145	5.86
* C clang #2	0.73	4.15—6.50	5,411	941	6.35
Swift #8	5.36	5.35	24,859	411	14.09
C clang #8	5.41	5.42	3,211	389	5.20
Swift #3	1.45	5.71	13,689	607	12.54
C clang #3	1.45	5.74	5,390	470	5.53
* C clang #7	1.85	8.31—9.99	5,399	906	6.27
mandelbrot
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
C clang #9	1.23	4.91	36,614	700	5.36
* Swift #7	1.35	5.29	57,836	1147	14.15
* Swift #6	1.48	5.80	60,985	1147	14.36
C clang #5	1.54	6.10	36,893	788	5.17
* C clang #4	3.49	13.85—13.93	36,458	805	5.13
* C clang	3.50	13.95	35,627	828	5.30
* C clang #7	3.53	14.02	36,758	1000	5.70
* C clang #3	3.56	14.16—14.22	35,484	769	5.23
C clang #8	25.48	25.50—25.55	2,359	412	5.04
Swift #8	25.62	25.60—25.64	12,784	426	11.26
Swift	26.55	26.54	12,780	400	12.99
Swift #5	7.27	27.13	49,312	665	13.83
* C clang #6		Empty
* Swift #3		Bad Output
fasta
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
C clang #3	0.78	0.78	2,257	1469	5.10
C clang #5	1.20	1.20	2,208	1286	5.41
C clang #2	2.44	2.44	2,200	1299	5.46
C clang #6	1.05	3.05	5,104	1936	5.36
C clang #7	0.83	3.28—3.32	5,947	2276	5.40
C clang	3.47	3.47	2,396	1213	5.07
* Swift	5.37	5.38	12,546	1533	13.34
* Swift #3	2.20	5.37	39,002	2097	14.73
* Swift #2	3.15	5.63—5.96	13,726	1952	14.91
C clang #8	8.09	8.19—8.30	2,200	839	4.95
Swift #8	18.19	18.18—18.35	12,829	828	11.99
C clang #4		Empty
k-nucleotide
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
C clang	6.34	13.99—14.10	134,189	1512	5.85
* Swift #2	14.45	54.24—57.70	273,949	1373	15.39
Swift #8	166.95	168.68—173.38	650,023	658	14.46
Swift #7	223.40	226.91—248.09	650,023	607	13.04
Swift		Empty
reverse-complement
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
* C clang #7	0.46	0.65	514,040	1899	6.27
C clang #9	0.48	0.72	514,277	1551	5.42
C clang #2	1.19	1.72	1,021,899	757	5.27
C clang #5	2.01	2.07—2.12	1,020,629	654	5.18
* Swift	2.05	2.48	825,635	1293	14.28
* C clang #4	3.79	3.80	514,073	716	5.07
C clang #6	1.08	4.26—4.30	699,249	828	5.14
binary-trees [ Contentious. Different approaches. ]
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
C clang #2	1.68	5.26—6.08	176,222	816	2.58
C clang #3	1.92	5.90	138,723	842	5.80
C clang	17.86	17.75—18.31	271,938	660	5.22
C clang #5	9.24	33.44—33.54	361,550	914	5.00
Swift	18.21	54.03—54.29	763,523	720	13.97
Swift #4	17.62	54.69—59.64	733,094	772	13.31
Swift #5	18.90	56.44—56.88	764,391	813	14.89
Swift #3	18.26	58.41—58.87	733,180	868	18.46
Swift #2	18.24	58.41—58.84	732,828	822	14.89
* Swift #9		Empty
pidigits [ Contentious. Different libraries. ]
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
C clang #2	0.74	0.74	3,990	422	5.46
C clang	0.75	0.75	3,719	459	5.06
* Swift #2	0.76	0.75	14,459	606	12.50
regex-redux [ Contentious. Different libraries. ]
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
C clang #5	0.84	2.84	159,756	1403	5.28
C clang #2	3.23	3.23	106,799	1121	5.07
C clang #4	1.00	3.84—3.89	159,789	1237	5.30
C clang #3	1.76	4.33—4.37	109,871	1273	5.44
Swift #2	39.33	39.34—39.45	710,697	678	13.66
Swift	23.92	40.23—40.37	922,243	721	13.56
Swift #4	18.21	41.75—42.40	1,102,254	751	13.30
Swift	Swift version 6.0.3 (swift-6.0.3-RELEASE) Target: x86_64-unknown-linux-gnu
C clang	Ubuntu clang version 19.1.1 (1ubuntu1)