C gcc 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 gcc #6	2.14	8.44	2,712	1582	2.68
* 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 gcc #4	14.05	14.06	2,351	1190	2.31
C gcc #5	7.28	28.32—28.45	2,949	917	2.17
C clang #5	8.10	32.01—32.15	4,792	917	5.61
* 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
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
C gcc #3	36.84	36.84—36.89	2,343	574	2.19
C gcc #8	39.34	39.52—40.22	2,343	483	2.20
C gcc	39.65	39.64—40.07	2,343	514	2.12
* C gcc #2	10.18	39.98—40.15	2,695	1563	2.51
n-body
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
* C gcc #9	2.10	2.10	2,482	1639	2.99
* C clang #9	2.20	2.20	2,494	1639	6.10
* C gcc #4	4.06	4.06	2,499	1398	2.98
* C clang #5	4.86	4.86	2,417	1436	5.03
C gcc #6	4.98	4.99	2,482	1186	2.33
C clang #6	5.17	5.17	2,970	1186	5.19
C gcc #2	5.20	5.20	2,490	1270	2.43
C gcc	5.23	5.23	2,486	1179	2.58
C gcc #3	5.24	5.24	2,482	1214	2.42
C clang	5.38	5.40	2,974	1179	5.35
C clang #2	5.43	5.44	2,982	1270	5.30
* C gcc #5	5.44	5.44	2,494	1436	2.31
C gcc #8	5.54	5.54	2,486	1195	2.52
* 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
C clang #3	6.13	6.13	2,978	1214	5.65
C clang #7	6.78	6.79	2,974	1250	5.16
C gcc #7	6.89	6.90	2,490	1250	2.32
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 gcc #6	0.40	1.60	3,199	1203	3.38
* C gcc #5	0.72	2.86	3,858	576	2.52
* C clang #5	0.73	2.87	5,206	576	5.85
* C gcc #7	0.72	2.86	4,067	906	3.21
* C gcc #4	0.72	2.86	3,719	1145	2.49
* 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
C gcc #8	5.41	5.41	3,219	389	2.42
C clang #8	5.41	5.42	3,211	389	5.20
C gcc #3	1.43	5.71	4,080	470	2.42
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
* C gcc #2		Empty
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
* C gcc #6	1.29	5.11	35,578	1147	2.64
C clang #5	1.54	6.10	36,893	788	5.17
C gcc #5	1.64	6.32	35,582	788	2.38
* C clang #4	3.49	13.85—13.93	36,458	805	5.13
* C gcc #4	3.50	13.91	35,197	805	2.16
* C gcc #7	3.51	13.94	35,447	1000	2.60
* C gcc	3.50	13.94	35,017	828	2.23
* C clang	3.50	13.95	35,627	828	5.30
* C clang #7	3.53	14.02	36,758	1000	5.70
* C gcc #3	3.55	14.12	34,873	769	2.26
* C clang #3	3.56	14.16—14.22	35,484	769	5.23
C gcc #9	4.07	15.72	35,394	700	2.47
C gcc #8	25.17	25.18	2,355	412	2.29
C clang #8	25.48	25.50—25.55	2,359	412	5.04
* C clang #6		Empty
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 gcc #3	0.79	0.79	2,236	1469	2.26
C clang #5	1.20	1.20	2,208	1286	5.41
C gcc #5	1.24	1.25	2,154	1286	2.42
C clang #2	2.44	2.44	2,200	1299	5.46
C gcc #2	2.77	2.77	2,204	1299	2.25
C gcc #6	0.95	2.77—2.81	3,748	1936	2.44
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 gcc #7	0.83	3.28	4,514	2276	2.39
C clang	3.47	3.47	2,396	1213	5.07
C gcc	3.71	3.71	2,421	1213	2.25
C clang #8	8.09	8.19—8.30	2,200	839	4.95
C gcc #8	8.27	8.31—8.37	2,195	839	2.20
C gcc #4		Empty
C clang #4		Empty
k-nucleotide
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
C gcc	3.58	12.06—12.40	135,234	1512	2.82
C clang	6.34	13.99—14.10	134,189	1512	5.85
reverse-complement
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
* C gcc #7	0.44	0.62	514,208	1899	3.13
* 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 gcc #9	0.49	0.78	514,159	1551	2.20
C gcc #6	0.97	1.37	693,969	828	2.26
C gcc #5	1.54	1.54	1,020,662	654	2.05
C gcc #2	1.07	1.59	1,021,755	757	2.15
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
* C gcc #4	3.70	3.71	514,077	716	2.22
* 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 gcc #2	1.56	4.30—4.45	174,780	816	3.21
C gcc #3	1.96	4.79—4.93	138,711	842	2.94
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 gcc	21.21	21.39—21.70	272,065	660	2.37
C gcc #5	8.71	31.85—32.27	361,587	914	2.34
C clang #5	9.24	33.44—33.54	361,550	914	5.00
pidigits [ Contentious. Different libraries. ]
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
C gcc #2	0.74	0.74	4,006	422	2.25
C clang #2	0.74	0.74	3,990	422	5.46
C gcc	0.75	0.75	3,727	459	2.30
C clang	0.75	0.75	3,719	459	5.06
regex-redux [ Contentious. Different libraries. ]
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
C gcc #5	0.81	2.05	157,463	1403	2.47
C clang #5	0.84	2.84	159,756	1403	5.28
C gcc #2	3.22	3.22	106,713	1121	2.14
C clang #2	3.23	3.23	106,799	1121	5.07
C gcc #4	0.97	3.30	157,417	1237	2.18
C gcc #3	1.73	3.32	107,401	1273	2.27
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
C gcc	gcc (Ubuntu 14.2.0-4ubuntu2) 14.2.0
C clang	Ubuntu clang version 19.1.1 (1ubuntu1)