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	2,941	1582	5.47
* C clang #4	13.38	13.39	2,351	1190	5.22
* 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	8.13	32.00—32.15	4,764	917	5.37
C clang #3	34.18	34.19—34.26	2,355	574	5.02
* C clang #2	8.70	34.15—34.33	2,945	1563	5.27
C clang #8	36.36	36.44—36.51	2,347	483	5.13
C clang	36.52	36.54—36.63	2,347	514	5.35
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	2,417	1639	6.15
* C gcc #4	4.06	4.06	2,499	1398	2.98
* C clang #5	4.86	4.86	2,470	1436	5.17
C gcc #6	4.98	4.99	2,482	1186	2.33
C clang #6	5.17	5.17	2,970	1186	5.42
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	5.39	2,978	1179	5.06
C clang #2	5.43	5.43	2,966	1270	5.25
* 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	2,953	1398	6.30
C clang #8	5.70	5.56—6.19	2,961	1195	5.27
C clang #3	6.13	6.13	2,966	1214	5.26
C clang #7	6.78	6.80	2,966	1250	5.05
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	1.55	4,686	1203	6.45
* 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 gcc #7	0.72	2.86	4,067	906	3.21
* C clang #4	0.73	2.87	5,382	1145	5.66
* C clang #5	0.73	2.87—2.91	5,403	576	5.55
* C gcc #4	0.72	2.86	3,719	1145	2.49
* C clang #2	0.74	4.30—7.09	5,288	941	6.43
C gcc #8	5.41	5.41	3,219	389	2.42
C clang #8	5.41	5.42	3,211	389	5.15
C gcc #3	1.43	5.71	4,080	470	2.42
C clang #3	1.45	5.75—5.79	5,423	470	5.58
* C clang #7	1.84	8.98—10.12	5,439	906	6.66
* C gcc #2		Empty
mandelbrot
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
C clang #9	1.24	4.92	36,811	700	5.32
* C gcc #6	1.29	5.11	35,578	1147	2.64
C clang #5	1.54	6.10	37,044	788	5.35
C gcc #5	1.64	6.32	35,582	788	2.38
* C clang #4	3.49	13.89—13.95	36,102	805	5.26
* 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	3.51	13.95	35,643	828	5.65
* C clang #7	3.54	14.02—14.06	36,491	1000	5.49
* C gcc #3	3.55	14.12	34,873	769	2.26
* C clang #3	3.56	14.16—14.20	35,418	769	5.06
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	25.51	25.52	2,359	412	5.22
* C clang #6		Empty
fasta
	elapsed	Mean or 95% CI
source	secs	cpu secs	mem	gz	make
C clang #3	0.79	0.79	2,273	1469	4.57
C gcc #3	0.79	0.79	2,236	1469	2.26
C clang #5	1.20	1.20	2,204	1286	5.64
C gcc #5	1.24	1.25	2,154	1286	2.42
C clang #2	2.44	2.44	2,163	1299	5.14
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	1.04	3.05	5,272	1936	5.40
C clang #7	0.83	3.28—3.32	5,861	2276	5.29
C gcc #7	0.83	3.28	4,514	2276	2.39
C clang	3.47	3.47	2,392	1213	5.28
C gcc	3.71	3.71	2,421	1213	2.25
C clang #8	8.08	8.14—8.25	2,200	839	5.08
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	6.27	13.93—14.23	134,038	1512	6.01
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	0.45	0.61—0.67	514,220	1899	6.22
C clang #9	0.47	0.72	514,216	1551	5.13
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	1.17	1.70	1,021,891	757	5.17
C clang #5	1.97	2.03—2.09	1,020,813	654	5.16
* C gcc #4	3.70	3.71	514,077	716	2.22
* C clang #4	3.77	3.78	514,023	716	4.93
C clang #6	1.05	4.15—4.20	714,764	828	5.90
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	1.66	5.23—6.05	176,116	816	5.77
C clang #3	1.91	5.90	138,719	842	5.90
C clang	17.72	17.78—18.29	271,938	660	5.20
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	9.25	33.42—33.59	361,689	914	4.96
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	5.19
C gcc	0.75	0.75	3,727	459	2.30
C clang	0.75	0.75	3,731	459	5.35
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	0.83	2.82	159,736	1403	5.40
C gcc #2	3.22	3.22	106,713	1121	2.14
C clang #2	3.22	3.22	106,783	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	0.99	3.82—3.86	159,539	1237	5.11
C clang #3	1.76	4.34	109,867	1273	5.08
C gcc	gcc (Ubuntu 14.2.0-4ubuntu2) 14.2.0
C clang	Ubuntu clang version 18.1.8 (11)