It breaks a lot of debugging and profiling tools.
Looks like -fomit-frame-pointer is worth 0.8% - 2.1%, depending on how you measure: Benchmark report for SunSpider, V8, and Kraken on garen (MacPro5,1). VMs tested: "BASELINE" at /Volumes/Big/ggaren/baseline-webkit/WebKitBuild/Release/jsc (r104476) "PATCH" at /Volumes/Big/ggaren/webkit/WebKitBuild/Release/jsc (r106297) Collected 12 samples per benchmark/VM, with 4 VM invocations per benchmark. Emitted a call to gc() between sample measurements. Used 1 benchmark iteration per VM invocation for warm-up. Used the jsc-specific preciseTime() function to get microsecond-level timing. Reporting benchmark execution times with 95% confidence intervals in milliseconds. BASELINE PATCH SunSpider: 3d-cube 6.2832+-0.0705 ? 6.3624+-0.0529 ? might be 1.0126x slower 3d-morph 10.3329+-0.0833 ! 11.1263+-0.0962 ! definitely 1.0768x slower 3d-raytrace 9.0501+-0.1140 ? 9.0610+-0.0583 ? access-binary-trees 1.9275+-0.0565 ? 1.9422+-0.0469 ? access-fannkuch 8.5806+-0.0615 ? 8.6193+-0.0574 ? access-nbody 4.6266+-0.0129 ? 4.6468+-0.0199 ? access-nsieve 4.0076+-0.0359 ? 4.0448+-0.0666 ? bitops-3bit-bits-in-byte 1.4710+-0.0128 ? 1.4991+-0.0242 ? might be 1.0191x slower bitops-bits-in-byte 6.0283+-0.0315 6.0206+-0.0241 bitops-bitwise-and 3.7821+-0.0031 ? 3.8177+-0.0489 ? bitops-nsieve-bits 6.5326+-0.0398 ? 6.5447+-0.0434 ? controlflow-recursive 2.6963+-0.0090 ? 2.7020+-0.0099 ? crypto-aes 8.6589+-0.1152 ? 8.7653+-0.1248 ? might be 1.0123x slower crypto-md5 2.9537+-0.0415 ? 2.9915+-0.0300 ? might be 1.0128x slower crypto-sha1 2.6467+-0.0271 ? 2.6827+-0.0248 ? might be 1.0136x slower date-format-tofte 12.3344+-0.2090 ? 12.3843+-0.1693 ? date-format-xparb 11.7982+-0.1534 11.4550+-0.2289 might be 1.0300x faster math-cordic 8.4270+-0.0401 ! 8.5359+-0.0531 ! definitely 1.0129x slower math-partial-sums 12.7962+-0.8647 12.1591+-0.0395 might be 1.0524x faster math-spectral-norm 3.0514+-0.0086 ? 3.0685+-0.0093 ? regexp-dna 10.2264+-0.0879 10.1472+-0.0854 string-base64 5.0800+-0.0954 ? 5.1075+-0.0649 ? string-fasta 8.1116+-0.0443 ! 8.3843+-0.1035 ! definitely 1.0336x slower string-tagcloud 14.6432+-0.1840 ? 14.9873+-0.1952 ? might be 1.0235x slower string-unpack-code 23.7459+-0.2290 ! 24.2807+-0.2670 ! definitely 1.0225x slower string-validate-input 6.4673+-0.0989 ? 6.5887+-0.0723 ? might be 1.0188x slower <arithmetic> * 7.5484+-0.0423 ? 7.6125+-0.0350 ? might be 1.0085x slower <geometric> 6.1501+-0.0246 ! 6.2034+-0.0256 ! definitely 1.0087x slower <harmonic> 4.8972+-0.0219 ! 4.9447+-0.0248 ! definitely 1.0097x slower BASELINE PATCH V8: crypto 90.5244+-0.3369 ? 90.7639+-0.2440 ? deltablue 180.7002+-0.7885 ! 183.3483+-0.9451 ! definitely 1.0147x slower earley-boyer 110.6346+-2.9285 ? 112.9138+-3.2482 ? might be 1.0206x slower raytrace 59.2737+-0.3940 59.2274+-0.3765 regexp 110.8469+-0.2226 ! 113.0236+-0.4022 ! definitely 1.0196x slower richards 161.4071+-0.2963 ? 162.0047+-0.9780 ? splay 82.6837+-0.4739 ! 84.4847+-0.5265 ! definitely 1.0218x slower <arithmetic> 113.7244+-0.4768 ! 115.1095+-0.5764 ! definitely 1.0122x slower <geometric> * 106.8071+-0.4643 ! 108.0556+-0.5450 ! definitely 1.0117x slower <harmonic> 100.2623+-0.4211 ! 101.3228+-0.4775 ! definitely 1.0106x slower BASELINE PATCH Kraken: ai-astar 946.2446+-1.3266 ? 946.4154+-1.0022 ? audio-beat-detection 224.2164+-0.9900 223.7855+-0.9974 audio-dft 329.3049+-1.0115 ? 330.1559+-0.8097 ? audio-fft 139.4842+-0.1170 139.2279+-0.1638 audio-oscillator 350.5775+-1.8833 ^ 345.8721+-1.1269 ^ definitely 1.0136x faster imaging-darkroom 346.7210+-7.7570 ? 350.4888+-10.6823 ? might be 1.0109x slower imaging-desaturate 273.0441+-0.2344 ? 273.6385+-0.8707 ? imaging-gaussian-blur 598.4207+-0.3361 ? 599.2143+-0.5656 ? json-parse-financial 71.9035+-0.3480 ! 73.3239+-0.0855 ! definitely 1.0198x slower json-stringify-tinderbox 84.4003+-0.3435 ! 89.4044+-0.5517 ! definitely 1.0593x slower stanford-crypto-aes 119.5915+-0.4886 ! 121.0547+-0.3671 ! definitely 1.0122x slower stanford-crypto-ccm 119.4735+-0.8816 ! 121.6546+-0.9818 ! definitely 1.0183x slower stanford-crypto-pbkdf2 227.7467+-2.5952 ! 235.7733+-3.6152 ! definitely 1.0352x slower stanford-crypto-sha256-iterative 105.6350+-0.7371 ? 105.9827+-0.1620 ? <arithmetic> * 281.1974+-0.6981 ? 282.5709+-0.8601 ? might be 1.0049x slower <geometric> 213.2957+-0.5630 ! 215.5104+-0.6586 ! definitely 1.0104x slower <harmonic> 168.3795+-0.3955 ! 171.1594+-0.4382 ! definitely 1.0165x slower BASELINE PATCH All benchmarks: <arithmetic> 104.8743+-0.2795 ! 105.5252+-0.3439 ! definitely 1.0062x slower <geometric> 27.0565+-0.0833 ! 27.3170+-0.0960 ! definitely 1.0096x slower <harmonic> 8.6048+-0.0379 ! 8.6892+-0.0427 ! definitely 1.0098x slower BASELINE PATCH Geomean of preferred means: <scaled-result> 60.9751+-0.2058 ! 61.4844+-0.2342 ! definitely 1.0084x slower Benchmark report for SunSpider, V8, and Kraken on garen (MacPro5,1). VMs tested: "BASELINE" at /Volumes/Big/ggaren/baseline-webkit/WebKitBuild/Release/DumpRenderTree (r104476) "PATCH" at /Volumes/Big/ggaren/webkit/WebKitBuild/Release/DumpRenderTree (r106297) Collected 12 samples per benchmark/VM, with 4 VM invocations per benchmark. Emitted a call to gc() between sample measurements. Used 1 benchmark iteration per VM invocation for warm-up. Used the portable Date.now() method to get millisecond-level timing. Reporting benchmark execution times with 95% confidence intervals in milliseconds. BASELINE PATCH SunSpider: 3d-cube 7.5000+-0.8779 ? 7.9167+-0.7879 ? might be 1.0556x slower 3d-morph 10.6667+-0.4138 ? 11.1667+-0.2473 ? might be 1.0469x slower 3d-raytrace 9.6667+-0.6818 ? 10.0833+-0.7399 ? might be 1.0431x slower access-binary-trees 2.5000+-0.5069 2.5000+-0.5069 access-fannkuch 8.3333+-0.3128 ? 8.8333+-0.2473 ? might be 1.0600x slower access-nbody 4.8333+-0.2473 ? 4.9167+-0.1834 ? might be 1.0172x slower access-nsieve 4.1667+-0.2473 4.1667+-0.2473 bitops-3bit-bits-in-byte 1.5833+-0.3272 ? 1.6667+-0.3128 ? might be 1.0526x slower bitops-bits-in-byte 6.3333+-0.3128 ? 6.4167+-0.3272 ? might be 1.0132x slower bitops-bitwise-and 4.0000+-0.0000 3.9167+-0.1834 might be 1.0213x faster bitops-nsieve-bits 6.5000+-0.3318 ? 6.5833+-0.3272 ? might be 1.0128x slower controlflow-recursive 2.7500+-0.2874 ? 3.0000+-0.0000 ? might be 1.0909x slower crypto-aes 9.5833+-0.8332 9.5000+-0.9954 crypto-md5 2.8333+-0.2473 ? 3.2500+-0.2874 ? might be 1.1471x slower crypto-sha1 2.8333+-0.2473 ? 3.0000+-0.0000 ? might be 1.0588x slower date-format-tofte 14.8333+-1.4034 ? 14.9167+-1.4704 ? date-format-xparb 13.3333+-1.0609 13.3333+-1.1600 math-cordic 8.8333+-0.2473 8.5833+-0.3272 might be 1.0291x faster math-partial-sums 12.0833+-0.1834 ? 12.1667+-0.2473 ? math-spectral-norm 3.0833+-0.1834 ? 3.2500+-0.2874 ? might be 1.0541x slower regexp-dna 11.0833+-0.5038 10.9167+-0.5720 might be 1.0153x faster string-base64 6.1667+-0.8917 ? 6.5000+-0.9954 ? might be 1.0541x slower string-fasta 9.0833+-0.7399 ? 9.2500+-0.6705 ? might be 1.0183x slower string-tagcloud 15.0000+-0.5418 ? 15.5000+-0.6354 ? might be 1.0333x slower string-unpack-code 26.1667+-1.2366 ? 26.8333+-1.2065 ? might be 1.0255x slower string-validate-input 7.8333+-1.0434 ? 7.9167+-0.9939 ? might be 1.0106x slower <arithmetic> * 8.1378+-0.4007 ? 8.3109+-0.4184 ? might be 1.0213x slower <geometric> 6.5749+-0.3078 ? 6.7648+-0.3349 ? might be 1.0289x slower <harmonic> 5.1409+-0.2714 ? 5.3669+-0.3144 ? might be 1.0440x slower BASELINE PATCH V8: crypto 90.0000+-0.5418 ? 90.4167+-0.7879 ? deltablue 187.2500+-4.8776 ? 188.1667+-3.2717 ? earley-boyer 109.6667+-4.1561 ? 111.6667+-3.9104 ? might be 1.0182x slower raytrace 59.9167+-0.5720 ? 60.4167+-0.6330 ? regexp 110.0833+-0.5038 ! 112.8333+-0.5956 ! definitely 1.0250x slower richards 161.3333+-1.1912 ? 163.0833+-0.5720 ? might be 1.0108x slower splay 108.6667+-23.3062 ? 109.4167+-23.5133 ? <arithmetic> 118.1310+-4.5113 ? 119.4286+-4.3491 ? might be 1.0110x slower <geometric> * 110.8475+-4.2694 ? 112.0893+-4.1895 ? might be 1.0112x slower <harmonic> 103.7819+-3.7482 ? 104.9206+-3.7311 ? might be 1.0110x slower BASELINE PATCH Kraken: ai-astar 950.0833+-3.0826 ? 950.8333+-2.1646 ? audio-beat-detection 229.6667+-2.1217 ? 230.9167+-1.2550 ? audio-dft 337.3333+-3.1517 335.7500+-2.2197 audio-fft 142.1667+-0.5304 ? 142.5000+-0.3318 ? audio-oscillator 355.8333+-2.4657 ? 358.5000+-3.0711 ? imaging-darkroom 358.5833+-2.0714 357.4167+-1.3399 imaging-desaturate 272.6667+-0.3128 272.5833+-0.3272 imaging-gaussian-blur 579.5000+-0.3318 578.7500+-0.5502 json-parse-financial 74.7500+-0.3949 ! 75.5000+-0.3318 ! definitely 1.0100x slower json-stringify-tinderbox 95.8333+-0.4560 ! 100.3333+-0.6257 ! definitely 1.0470x slower stanford-crypto-aes 126.4167+-1.8466 ? 126.5000+-0.8350 ? stanford-crypto-ccm 137.8333+-0.8496 ! 140.4167+-0.8332 ! definitely 1.0187x slower stanford-crypto-pbkdf2 234.5833+-0.7399 ! 241.1667+-1.2946 ! definitely 1.0281x slower stanford-crypto-sha256-iterative 111.6667+-1.3636 ? 113.5000+-1.3133 ? might be 1.0164x slower <arithmetic> * 286.2083+-0.4001 ! 287.4762+-0.3627 ! definitely 1.0044x slower <geometric> 221.6157+-0.4041 ! 223.6166+-0.4556 ! definitely 1.0090x slower <harmonic> 178.1092+-0.4351 ! 180.4984+-0.5459 ! definitely 1.0134x slower BASELINE PATCH All benchmarks: <arithmetic> 107.3493+-0.9550 ? 108.0160+-0.9514 ? might be 1.0062x slower <geometric> 28.5407+-0.9017 ? 29.1188+-0.9623 ? might be 1.0203x slower <harmonic> 9.0311+-0.4662 ? 9.4197+-0.5393 ? might be 1.0430x slower BASELINE PATCH Geomean of preferred means: <scaled-result> 63.6443+-1.8583 ? 64.4252+-1.8821 ? might be 1.0123x slower TEST COMPARISON FROM TO DETAILS ============================================================================= ** TOTAL **: *1.021x as slow* 191.2ms +/- 0.2% 195.3ms +/- 0.2% significant ============================================================================= 3d: *1.055x as slow* 27.5ms +/- 0.6% 29.0ms +/- 0.2% significant cube: *1.064x as slow* 8.5ms +/- 1.7% 9.0ms +/- 0.0% significant morph: *1.098x as slow* 10.0ms +/- 0.4% 11.0ms +/- 0.5% significant raytrace: - 9.0ms +/- 0.4% 9.0ms +/- 0.0% access: ?? 16.6ms +/- 0.8% 16.7ms +/- 0.8% not conclusive: might be *1.005x as slow* binary-trees: - 1.0ms +/- 0.0% 1.0ms +/- 0.0% fannkuch: - 8.0ms +/- 0.0% 8.0ms +/- 0.0% nbody: - 4.0ms +/- 0.0% 4.0ms +/- 0.0% nsieve: ?? 3.6ms +/- 3.9% 3.7ms +/- 3.6% not conclusive: might be *1.022x as slow* bitops: ?? 15.8ms +/- 0.8% 15.8ms +/- 0.7% not conclusive: might be *1.003x as slow* 3bit-bits-in-byte: - 1.0ms +/- 0.0% 1.0ms +/- 0.0% bits-in-byte: ?? 5.8ms +/- 2.1% 5.8ms +/- 2.0% not conclusive: might be *1.007x as slow* bitwise-and: - 3.0ms +/- 0.0% 3.0ms +/- 0.0% nsieve-bits: - 6.0ms +/- 0.0% 6.0ms +/- 0.0% controlflow: - 2.0ms +/- 0.0% 2.0ms +/- 0.0% recursive: - 2.0ms +/- 0.0% 2.0ms +/- 0.0% crypto: *1.088x as slow* 12.1ms +/- 0.6% 13.1ms +/- 1.5% significant aes: *1.087x as slow* 8.1ms +/- 0.8% 8.8ms +/- 1.4% significant md5: *1.180x as slow* 2.0ms +/- 0.0% 2.4ms +/- 5.8% significant sha1: - 2.0ms +/- 0.0% 2.0ms +/- 0.0% date: *1.011x as slow* 26.2ms +/- 0.5% 26.5ms +/- 0.7% significant format-tofte: *1.034x as slow* 14.2ms +/- 0.9% 14.7ms +/- 0.9% significant format-xparb: 1.017x as fast 12.0ms +/- 0.0% 11.8ms +/- 1.0% significant math: ?? 22.9ms +/- 0.4% 23.0ms +/- 0.3% not conclusive: might be *1.005x as slow* cordic: - 8.0ms +/- 0.0% 8.0ms +/- 0.0% partial-sums: ?? 11.9ms +/- 0.6% 12.0ms +/- 0.7% not conclusive: might be *1.008x as slow* spectral-norm: ?? 3.0ms +/- 1.3% 3.0ms +/- 0.0% not conclusive: might be *1.007x as slow* regexp: ?? 12.0ms +/- 0.3% 12.0ms +/- 0.6% not conclusive: might be *1.003x as slow* dna: ?? 12.0ms +/- 0.3% 12.0ms +/- 0.6% not conclusive: might be *1.003x as slow* string: *1.017x as slow* 56.1ms +/- 0.2% 57.1ms +/- 0.2% significant base64: - 5.0ms +/- 0.0% 5.0ms +/- 0.0% fasta: - 8.0ms +/- 0.0% 8.0ms +/- 0.0% tagcloud: ?? 14.0ms +/- 0.3% 14.0ms +/- 0.4% not conclusive: might be *1.001x as slow* unpack-code: *1.040x as slow* 23.1ms +/- 0.4% 24.0ms +/- 0.2% significant validate-input: - 6.0ms +/- 0.0% 6.0ms +/- 0.0%
Created attachment 124669 [details] Patch
You didn't say anything about -funwind-tables?
(In reply to comment #3) > You didn't say anything about -funwind-tables? -funwind-tables was only there to ensure that unwind information was generated. Some tools would fall back to that information when attempting to generate a backtrace in code that lacked frame pointers.
Comment on attachment 124669 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=124669&action=review > Source/JavaScriptCore/Configurations/JavaScriptCore.xcconfig:52 > OTHER_CFLAGS = $(OTHER_CFLAGS_$(CONFIGURATION)_$(CURRENT_VARIANT)); This appears to be unnecessary.
Committed r106429: <http://trac.webkit.org/changeset/106429>
Thanks for putting the motivation and data in this bug!