randall77
commented
4 years ago Strange.
I get the same behavior from C.
main.c:
void foo();
int main(int argc, char *argv[]) {
foo();
}main.s:
.globl _foo
_foo:
vpopcntw %zmm1, %zmm0
retThis program also hangs. Compile with gcc main.c main.s, run with ./a.out.
So I think this is an OSX bug, not a Go bug.
Nothing obvious when run under a debugger. The debugger runs it forever, and every time I interrupt it it is at the vpopcntw instruction.
vsivsi
What version of Go are you using (
go version)?Does this issue reproduce with the latest release?
Yes
What operating system and processor architecture are you using (
go env)?MacOS 10.15.7
go envOutputWhat did you do?
Attempt to use Intel AVX-512
VPOPCNTfamily AVX-512 instructions in go assembler.What did you expect to see?
Assembly code using these instruction should run properly on processors supporting them, and should generate a UD fault (SIGILL) and terminate when invoked on a CPU without support.
What did you see instead?
Go runtime hangs forever with 100% CPU utilization upon executing a VPOPCNT(B/W/D/Q) instruction on hardware that doesn't support it. Tested running on a MacPro (2019) with 2.7 GHz 24-Core Intel Xeon W CPU (Xeon W-3265M)
Note, this processor does not include AVX512_BITALG or AVX512_VPOPCNTDQ, which are required for VPOPCNT(B/W) and VPOPCNT(D/Q) respectively. For a summary of the VPOPCNT support matrix, see: https://github.com/HJLebbink/asm-dude/wiki/VPOPCNT
The Intel processor documentation says that attempting to run such AVX512 instructions when the supporting feature CPUID flags are not set should result in raising a #UD exception. As expected, directly executing the amd64
UD2instruction causes the go runtime to abort withSIGILL: illegal instruction. But when unsupported, these AVX512 instructions cause the runtime to hang in a tight loop of some kind, which doesn't seem to be consistent or correct behavior.Here is a dump from a process sample of the hung go runtime process resulting from the repro below.
/usr/bin/sampleOutputSampling process 40325 for 3 seconds with 1 millisecond of run time between samples Sampling completed, processing symbols... Analysis of sampling vpopcntw (pid 40325) every 1 millisecond Process: vpopcntw [40325] Path: /Users/USER/*/vpopcntw Load Address: 0x1000000 Identifier: vpopcntw Version: ??? Code Type: X86-64 Parent Process: zsh [37987] Date/Time: 2020-11-16 15:50:45.036 -0800 Launch Time: 2020-11-16 15:50:29.269 -0800 OS Version: Mac OS X 10.15.7 (19H15) Report Version: 7 Analysis Tool: /usr/bin/sample Physical footprint: 1732K Physical footprint (peak): 1732K ---- Call graph: 2819 Thread_355890 DispatchQueue_1: com.apple.main-thread (serial) + 2816 ??? (in) [0xc00009e7d0]
+ ! 2816 main.popcnt (in vpopcntw) + 0 [0x105c8e0]
+ 3 runtime.main (in vpopcntw) + 521 [0x102ee69]
+ 3 0x0
+ 2 _sigtramp (in libsystem_platform.dylib) + 0 [0x7fff685985e0]
+ 1 _sigtramp (in libsystem_platform.dylib) + 29 [0x7fff685985fd]
+ 1 runtime.sigtramp (in vpopcntw) + 51 [0x105aeb3]
+ 1 ??? (in ) [0xc000000480]
+ 1 runtime.setg (in vpopcntw) + 5 [0x1059405]
2819 Thread_355892
+ 2819 thread_start (in libsystem_pthread.dylib) + 15 [0x7fff6859fb8b]
+ 2819 runtime.mstart_stub (in vpopcntw) + 46 [0x105b14e]
+ 2819 runtime.mstart (in vpopcntw) + 102 [0x10316a6]
+ 2819 runtime.mstart1 (in vpopcntw) + 200 [0x1031788]
+ 2818 runtime.sysmon (in vpopcntw) + 173 [0x10399ed]
+ ! 2818 runtime.usleep (in vpopcntw) + 49 [0x1047dd1]
+ ! 2818 runtime.asmcgocall (in vpopcntw) + 173 [0x10593ed]
+ ! 2818 runtime.usleep_trampoline (in vpopcntw) + 11 [0x105b02b]
+ ! 2818 usleep (in libsystem_c.dylib) + 53 [0x7fff68466de4]
+ ! 2818 nanosleep (in libsystem_c.dylib) + 196 [0x7fff68466eea]
+ ! 2816 __semwait_signal (in libsystem_kernel.dylib) + 10 [0x7fff684e3756]
+ ! 1 cerror (in libsystem_kernel.dylib) + 20 [0x7fff684e2241]
+ ! : 1 cerror_nocancel (in libsystem_kernel.dylib) + 0 [0x7fff684e1629]
+ ! 1 cerror (in libsystem_kernel.dylib) + 0 [0x7fff684e222d]
+ 1 runtime.sysmon (in vpopcntw) + 433 [0x1039af1]
+ 1 runtime.retake (in vpopcntw) + 518 [0x103a0e6]
+ 1 runtime.preemptone (in vpopcntw) + 165 [0x103a2a5]
+ 1 runtime.preemptM (in vpopcntw) + 135 [0x103f307]
+ 1 runtime.pthread_kill (in vpopcntw) + 49 [0x1047b11]
+ 1 runtime.asmcgocall (in vpopcntw) + 173 [0x10593ed]
+ 1 runtime.pthread_kill_trampoline (in vpopcntw) + 16 [0x105b330]
+ 1 pthread_kill (in libsystem_pthread.dylib) + 179 [0x7fff685a3d65]
2819 Thread_355893
+ 2819 runtime.mcall (in vpopcntw) + 91 [0x105799b]
+ 2819 runtime.park_m (in vpopcntw) + 157 [0x103571d]
+ 2819 runtime.schedule (in vpopcntw) + 110 [0x1034f0e]
+ 2819 runtime.startlockedm (in vpopcntw) + 133 [0x1033785]
+ 2819 runtime.stopm (in vpopcntw) + 197 [0x1032d25]
+ 2819 runtime.notesleep (in vpopcntw) + 231 [0x1009387]
+ 2819 runtime.semasleep (in vpopcntw) + 141 [0x102972d]
+ 2819 runtime.pthread_cond_wait (in vpopcntw) + 57 [0x1048459]
+ 2819 runtime.asmcgocall (in vpopcntw) + 173 [0x10593ed]
+ 2819 runtime.pthread_cond_wait_trampoline (in vpopcntw) + 16 [0x105b2b0]
+ 2819 _pthread_cond_wait (in libsystem_pthread.dylib) + 698 [0x7fff685a4425]
+ 2819 __psynch_cvwait (in libsystem_kernel.dylib) + 10 [0x7fff684e3882]
2819 Thread_355894
+ 2819 runtime.mcall (in vpopcntw) + 91 [0x105799b]
+ 2819 runtime.park_m (in vpopcntw) + 157 [0x103571d]
+ 2819 runtime.schedule (in vpopcntw) + 110 [0x1034f0e]
+ 2819 runtime.startlockedm (in vpopcntw) + 133 [0x1033785]
+ 2819 runtime.stopm (in vpopcntw) + 197 [0x1032d25]
+ 2819 runtime.notesleep (in vpopcntw) + 231 [0x1009387]
+ 2819 runtime.semasleep (in vpopcntw) + 141 [0x102972d]
+ 2819 runtime.pthread_cond_wait (in vpopcntw) + 57 [0x1048459]
+ 2819 runtime.asmcgocall (in vpopcntw) + 173 [0x10593ed]
+ 2819 runtime.pthread_cond_wait_trampoline (in vpopcntw) + 16 [0x105b2b0]
+ 2819 _pthread_cond_wait (in libsystem_pthread.dylib) + 698 [0x7fff685a4425]
+ 2819 __psynch_cvwait (in libsystem_kernel.dylib) + 10 [0x7fff684e3882]
2819 Thread_355895
2819 thread_start (in libsystem_pthread.dylib) + 15 [0x7fff6859fb8b]
2819 runtime.mstart_stub (in vpopcntw) + 46 [0x105b14e]
2819 runtime.mstart (in vpopcntw) + 102 [0x10316a6]
2819 runtime.mstart1 (in vpopcntw) + 147 [0x1031753]
2819 runtime.schedule (in vpopcntw) + 727 [0x1035177]
2819 runtime.findrunnable (in vpopcntw) + 2687 [0x10344ff]
2819 runtime.stopm (in vpopcntw) + 197 [0x1032d25]
2819 runtime.notesleep (in vpopcntw) + 231 [0x1009387]
2819 runtime.semasleep (in vpopcntw) + 141 [0x102972d]
2819 runtime.pthread_cond_wait (in vpopcntw) + 57 [0x1048459]
2819 runtime.asmcgocall (in vpopcntw) + 173 [0x10593ed]
2819 runtime.pthread_cond_wait_trampoline (in vpopcntw) + 16 [0x105b2b0]
2819 _pthread_cond_wait (in libsystem_pthread.dylib) + 698 [0x7fff685a4425]
2819 __psynch_cvwait (in libsystem_kernel.dylib) + 10 [0x7fff684e3882]
Total number in stack (recursive counted multiple, when >=5):
5 runtime.asmcgocall (in vpopcntw) + 173 [0x10593ed]
Sort by top of stack, same collapsed (when >= 5):
__psynch_cvwait (in libsystem_kernel.dylib) 8457
__semwait_signal (in libsystem_kernel.dylib) 2816
main.popcnt (in vpopcntw) 2816
Binary Images:
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0x7fff6614d000 - 0x7fff66152fff libgermantok.dylib (24) /usr/lib/libgermantok.dylib
0x7fff6615d000 - 0x7fff6624dfff libiconv.2.dylib (59) <18311A67-E4EF-3CC7-95B3-C0EDEE3A282F> /usr/lib/libiconv.2.dylib
0x7fff6624e000 - 0x7fff664a5fff libicucore.A.dylib (64260.0.1) <8AC2CB07-E7E0-340D-A849-186FA1F27251> /usr/lib/libicucore.A.dylib
0x7fff664bf000 - 0x7fff664c0fff liblangid.dylib (133) <30CFC08C-EF36-3CF5-8AEA-C1CB070306B7> /usr/lib/liblangid.dylib
0x7fff664c1000 - 0x7fff664d9ff3 liblzma.5.dylib (16) /usr/lib/liblzma.5.dylib
0x7fff664f1000 - 0x7fff66598ff7 libmecab.dylib (883.11) <0D5BFD01-D4A7-3C8D-AA69-C329C1A69792> /usr/lib/libmecab.dylib
0x7fff66599000 - 0x7fff667fbff1 libmecabra.dylib (883.11) /usr/lib/libmecabra.dylib
0x7fff66cc7000 - 0x7fff67143ff5 libnetwork.dylib (1880.120.4) /usr/lib/libnetwork.dylib
0x7fff671e4000 - 0x7fff67217fde libobjc.A.dylib (787.1) <6DF81160-5E7F-3E31-AA1E-C875E3B98AF6> /usr/lib/libobjc.A.dylib
0x7fff6722a000 - 0x7fff6722efff libpam.2.dylib (25.100.1) <0502F395-8EE6-3D2A-9239-06FD5622E19E> /usr/lib/libpam.2.dylib
0x7fff67231000 - 0x7fff67267ff7 libpcap.A.dylib (89.120.1) /usr/lib/libpcap.A.dylib
0x7fff6735f000 - 0x7fff67549ff7 libsqlite3.dylib (308.5) <35A2BD9F-4E33-30DE-A994-4AB585AC3AFE> /usr/lib/libsqlite3.dylib
0x7fff6779a000 - 0x7fff6779dffb libutil.dylib (57) /usr/lib/libutil.dylib
0x7fff6779e000 - 0x7fff677abff7 libxar.1.dylib (425.2) /usr/lib/libxar.1.dylib
0x7fff677b1000 - 0x7fff67893fff libxml2.2.dylib (33.5) /usr/lib/libxml2.2.dylib
0x7fff67897000 - 0x7fff678bffff libxslt.1.dylib (16.9) <34A45627-DA5B-37D2-9609-65B425E0010A> /usr/lib/libxslt.1.dylib
0x7fff678c0000 - 0x7fff678d2ff3 libz.1.dylib (76) <793D9643-CD83-3AAC-8B96-88D548FAB620> /usr/lib/libz.1.dylib
0x7fff68181000 - 0x7fff68186ff3 libcache.dylib (83) /usr/lib/system/libcache.dylib
0x7fff68187000 - 0x7fff68192fff libcommonCrypto.dylib (60165.120.1) /usr/lib/system/libcommonCrypto.dylib
0x7fff68193000 - 0x7fff6819afff libcompiler_rt.dylib (101.2) <49B8F644-5705-3F16-BBE0-6FFF9B17C36E> /usr/lib/system/libcompiler_rt.dylib
0x7fff6819b000 - 0x7fff681a4ff7 libcopyfile.dylib (166.40.1) <3C481225-21E7-370A-A30E-0CCFDD64A92C> /usr/lib/system/libcopyfile.dylib
0x7fff681a5000 - 0x7fff68237fdb libcorecrypto.dylib (866.140.1) <60567BF8-80FA-359A-B2F3-A3BAEFB288FD> /usr/lib/system/libcorecrypto.dylib
0x7fff68344000 - 0x7fff68384ff0 libdispatch.dylib (1173.100.2) /usr/lib/system/libdispatch.dylib
0x7fff68385000 - 0x7fff683bbfff libdyld.dylib (750.6) <789A18C2-8AC7-3C88-813D-CD674376585D> /usr/lib/system/libdyld.dylib
0x7fff683bc000 - 0x7fff683bcffb libkeymgr.dylib (30) /usr/lib/system/libkeymgr.dylib
0x7fff683bd000 - 0x7fff683c9ff3 libkxld.dylib (6153.141.2.2) <30AACC57-2314-3863-94B2-64AB3E002B35> /usr/lib/system/libkxld.dylib
0x7fff683ca000 - 0x7fff683caff7 liblaunch.dylib (1738.140.1) /usr/lib/system/liblaunch.dylib
0x7fff683cb000 - 0x7fff683d0ff7 libmacho.dylib (959.0.1) /usr/lib/system/libmacho.dylib
0x7fff683d1000 - 0x7fff683d3ff3 libquarantine.dylib (110.40.3) /usr/lib/system/libquarantine.dylib
0x7fff683d4000 - 0x7fff683d5ff7 libremovefile.dylib (48) <7C7EFC79-BD24-33EF-B073-06AED234593E> /usr/lib/system/libremovefile.dylib
0x7fff683d6000 - 0x7fff683edff3 libsystem_asl.dylib (377.60.2) <1563EE02-0657-3B78-99BE-A947C24122EF> /usr/lib/system/libsystem_asl.dylib
0x7fff683ee000 - 0x7fff683eeff7 libsystem_blocks.dylib (74) <0D53847E-AF5F-3ACF-B51F-A15DEA4DEC58> /usr/lib/system/libsystem_blocks.dylib
0x7fff683ef000 - 0x7fff68476fff libsystem_c.dylib (1353.100.2) /usr/lib/system/libsystem_c.dylib
0x7fff68477000 - 0x7fff6847affb libsystem_configuration.dylib (1061.141.1) <0EE84C33-64FD-372B-974A-AF7A136F2068> /usr/lib/system/libsystem_configuration.dylib
0x7fff6847b000 - 0x7fff6847efff libsystem_coreservices.dylib (114) /usr/lib/system/libsystem_coreservices.dylib
0x7fff6847f000 - 0x7fff68487fff libsystem_darwin.dylib (1353.100.2) <5B12B5DB-3F30-37C1-8ECC-49A66B1F2864> /usr/lib/system/libsystem_darwin.dylib
0x7fff68488000 - 0x7fff6848ffff libsystem_dnssd.dylib (1096.100.3) /usr/lib/system/libsystem_dnssd.dylib
0x7fff68490000 - 0x7fff68491ffb libsystem_featureflags.dylib (17) <29FD922A-EC2C-3F25-BCCC-B58D716E60EC> /usr/lib/system/libsystem_featureflags.dylib
0x7fff68492000 - 0x7fff684dfff7 libsystem_info.dylib (538) <8A321605-5480-330B-AF9E-64E65DE61747> /usr/lib/system/libsystem_info.dylib
0x7fff684e0000 - 0x7fff6850cff7 libsystem_kernel.dylib (6153.141.2.2) <5CDBBC06-6CA6-3432-9FDA-681047866F3E> /usr/lib/system/libsystem_kernel.dylib
0x7fff6850d000 - 0x7fff68554fff libsystem_m.dylib (3178) <00F331F1-0D09-39B3-8736-1FE90E64E903> /usr/lib/system/libsystem_m.dylib
0x7fff68555000 - 0x7fff6857cfff libsystem_malloc.dylib (283.100.6) <8549294E-4C53-36EB-99F3-584A7393D8D5> /usr/lib/system/libsystem_malloc.dylib
0x7fff6857d000 - 0x7fff6858affb libsystem_networkextension.dylib (1095.140.2) /usr/lib/system/libsystem_networkextension.dylib
0x7fff6858b000 - 0x7fff68594ff7 libsystem_notify.dylib (241.100.2) /usr/lib/system/libsystem_notify.dylib
0x7fff68595000 - 0x7fff6859dfef libsystem_platform.dylib (220.100.1) <009A7C1F-313A-318E-B9F2-30F4C06FEA5C> /usr/lib/system/libsystem_platform.dylib
0x7fff6859e000 - 0x7fff685a8fff libsystem_pthread.dylib (416.100.3) <62CB1A98-0B8F-31E7-A02B-A1139927F61D> /usr/lib/system/libsystem_pthread.dylib
0x7fff685a9000 - 0x7fff685adff3 libsystem_sandbox.dylib (1217.141.2) <051C4018-4345-3034-AC98-6DE42FB8273B> /usr/lib/system/libsystem_sandbox.dylib
0x7fff685ae000 - 0x7fff685b0fff libsystem_secinit.dylib (62.100.2) /usr/lib/system/libsystem_secinit.dylib
0x7fff685b1000 - 0x7fff685b8ffb libsystem_symptoms.dylib (1238.120.1) <5820A2AF-CE72-3AB3-ABCC-273A3419FB55> /usr/lib/system/libsystem_symptoms.dylib
0x7fff685b9000 - 0x7fff685cfff2 libsystem_trace.dylib (1147.120) <04B47629-847B-3D74-8ABE-C05EF9DEEFE4> /usr/lib/system/libsystem_trace.dylib
0x7fff685d1000 - 0x7fff685d6ff7 libunwind.dylib (35.4) <42B7B509-BAFE-365B-893A-72414C92F5BF> /usr/lib/system/libunwind.dylib
0x7fff685d7000 - 0x7fff6860cffe libxpc.dylib (1738.140.1) <3E243A41-030F-38E3-9FD2-7B38C66C35B1> /usr/lib/system/libxpc.dylib
Sample analysis of process 40325 written to file /dev/stdout
Minimal Reproduction
The code below when compiled with
go buildand then executed, should immediately hang with 100% processor utilization on a single process thread, when run on a CPU missing either AVX512_BITALG or AVX512_VPOPCNTDQ CPUID feature flags (which I believe at the time of this writing is all Apple Macs Edited to Add: except the top of the line 10th Gen Core (Ice Lake) powered 13" Macbook Pros).main.go
popcnt_amd64.s