{"action":"created","issue":{"url":"https://api.github.com/repos/libjpeg-turbo/libjpeg-turbo/issues/97","repository_url":"https://api.github.com/repos/libjpeg-turbo/libjpeg-turbo","labels_url":"https://api.github.com/repos/libjpeg-turbo/libjpeg-turbo/issues/97/labels{/name}","comments_url":"https://api.github.com/repos/libjpeg-turbo/libjpeg-turbo/issues/97/comments","events_url":"https://api.github.com/repos/libjpeg-turbo/libjpeg-turbo/issues/97/events","html_url":"https://github.com/libjpeg-turbo/libjpeg-turbo/issues/97","id":176693529,"number":97,"title":"crash on aarch64 in simd optimisation","user":{"login":"nullr0ute","id":1917405,"avatar_url":"https://avatars.githubusercontent.com/u/1917405?v=3","gravatar_id":"","url":"https://api.github.com/users/nullr0ute","html_url":"https://github.com/nullr0ute","followers_url":"https://api.github.com/users/nullr0ute/followers","following_url":"https://api.github.com/users/nullr0ute/following{/other_user}","gists_url":"https://api.github.com/users/nullr0ute/gists{/gist_id}","starred_url":"https://api.github.com/users/nullr0ute/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/nullr0ute/subscriptions","organizations_url":"https://api.github.com/users/nullr0ute/orgs","repos_url":"https://api.github.com/users/nullr0ute/repos","events_url":"https://api.github.com/users/nullr0ute/events{/privacy}","received_events_url":"https://api.github.com/users/nullr0ute/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":5,"created_at":"2016-09-13T16:51:44Z","updated_at":"2016-09-16T15:24:10Z","closed_at":null,"body":"We're seeing the following crash with 1.5.0 on aarch64 (Fedora 25)\r\n\r\nFull details in this downstream bug: https://bugzilla.redhat.com/show_bug.cgi?id=1368569\r\n\r\nBacktrace:\r\nThread 1 \"Xvnc\" received signal SIGSEGV, Segmentation fault.\r\nencode_mcu_huff (cinfo=0x2aaee610850, MCU_data=<optimized out>) at jchuff.c:675\r\n675          state.cur.last_dc_val[ci] = MCU_data[blkn][0][0];\r\n(gdb) bt full\r\n#0  encode_mcu_huff (cinfo=0x2aaee610850, MCU_data=<optimized out>)\r\n    at jchuff.c:675\r\n        entropy = 0x2aaee9eda90\r\n        state = {next_output_byte = 0x2aaee748142 \"\\001\\377\",\r\n          free_in_buffer = 125054, cur = {put_buffer = 13396343463626488332,\r\n            put_bits = 16, last_dc_val = {210, -5, -1, 15132390}},\r\n          cinfo = 0x2aaee610850}\r\n        blkn = 3\r\n        ci = -1487503252\r\n        compptr = <optimized out>"},"comment":{"url":"https://api.github.com/repos/libjpeg-turbo/libjpeg-turbo/issues/comments/247629617","html_url":"https://github.com/libjpeg-turbo/libjpeg-turbo/issues/97#issuecomment-247629617","issue_url":"https://api.github.com/repos/libjpeg-turbo/libjpeg-turbo/issues/97","id":247629617,"user":{"login":"dcommander","id":651941,"avatar_url":"https://avatars.githubusercontent.com/u/651941?v=3","gravatar_id":"","url":"https://api.github.com/users/dcommander","html_url":"https://github.com/dcommander","followers_url":"https://api.github.com/users/dcommander/followers","following_url":"https://api.github.com/users/dcommander/following{/other_user}","gists_url":"https://api.github.com/users/dcommander/gists{/gist_id}","starred_url":"https://api.github.com/users/dcommander/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/dcommander/subscriptions","organizations_url":"https://api.github.com/users/dcommander/orgs","repos_url":"https://api.github.com/users/dcommander/repos","events_url":"https://api.github.com/users/dcommander/events{/privacy}","received_events_url":"https://api.github.com/users/dcommander/received_events","type":"User","site_admin":false},"created_at":"2016-09-16T15:24:10Z","updated_at":"2016-09-16T15:24:10Z","body":"Several things to try that will give me much-needed data points:\r\n\r\n* Try setting the environment variable `JSIMD_NOHUFFENC=1` to disable the SIMD-accelerated Huffman encoder at run time.  If the crash goes away, then that tells me that the problem is in the 64-bit NEON Huffman encoding algorithm, which is new in libjpeg-turbo 1.5.\r\n\r\n* Try setting the environment variable `JSIMD_FORCENONE=1` to disable all of the SIMD code in libjpeg-turbo at run time.  If the crash goes away, then that tells me that the problem is in some other 64-bit NEON algorithm.\r\n\r\n* Try building TigerVNC against plain libjpeg.  If the crash goes away, then that tells me that the problem is in one of the libjpeg-turbo C algorithms (I somewhat doubt that this is the case, but I've been surprised before.)\r\n\r\nI unfortunately don't have access to a machine on which I could install Fedora 25 aarch64.  My only aarch64 test platforms are a jailbroken iPhone 5S and a Google Nexus 5X"}}
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