Gecko [ 167.86.127.34 ]

Name	Size	Permission
cgo	[ DIR ]	drwxr-xr-x
debug	[ DIR ]	drwxr-xr-x
internal	[ DIR ]	drwxr-xr-x
msan	[ DIR ]	drwxr-xr-x
pprof	[ DIR ]	drwxr-xr-x
race	[ DIR ]	drwxr-xr-x
testdata	[ DIR ]	drwxr-xr-x
trace	[ DIR ]	drwxr-xr-x
HACKING.md	13.07 KB	-rw-r--r--
Makefile	178 B	-rw-r--r--
alg.go	10.18 KB	-rw-r--r--
asm.s	1.16 KB	-rw-r--r--
asm_386.s	40.2 KB	-rw-r--r--
asm_amd64.s	45.78 KB	-rw-r--r--
asm_arm.s	30.89 KB	-rw-r--r--
asm_arm64.s	33.12 KB	-rw-r--r--
asm_mips64x.s	22.45 KB	-rw-r--r--
asm_mipsx.s	24.72 KB	-rw-r--r--
asm_ppc64x.h	1023 B	-rw-r--r--
asm_ppc64x.s	29.39 KB	-rw-r--r--
asm_riscv64.s	17.38 KB	-rw-r--r--
asm_s390x.s	26.35 KB	-rw-r--r--
asm_wasm.s	9.65 KB	-rw-r--r--
atomic_arm64.s	259 B	-rw-r--r--
atomic_mips64x.s	296 B	-rw-r--r--
atomic_mipsx.s	258 B	-rw-r--r--
atomic_pointer.go	2.62 KB	-rw-r--r--
atomic_ppc64x.s	433 B	-rw-r--r--
atomic_riscv64.s	307 B	-rw-r--r--
auxv_none.go	358 B	-rw-r--r--
callers_test.go	7.7 KB	-rw-r--r--
cgo.go	2.01 KB	-rw-r--r--
cgo_mmap.go	2.38 KB	-rw-r--r--
cgo_ppc64x.go	411 B	-rw-r--r--
cgo_sigaction.go	3.09 KB	-rw-r--r--
cgocall.go	21.38 KB	-rw-r--r--
cgocallback.go	317 B	-rw-r--r--
cgocheck.go	6.8 KB	-rw-r--r--
chan.go	19.71 KB	-rw-r--r--
chan_test.go	21.27 KB	-rw-r--r--
chanbarrier_test.go	1.4 KB	-rw-r--r--
checkptr.go	2.5 KB	-rw-r--r--
checkptr_test.go	1.27 KB	-rw-r--r--
closure_test.go	936 B	-rw-r--r--
compiler.go	413 B	-rw-r--r--
complex.go	1.59 KB	-rw-r--r--
complex_test.go	1.05 KB	-rw-r--r--
cpuflags.go	740 B	-rw-r--r--
cpuflags_amd64.go	533 B	-rw-r--r--
cpuprof.go	6.65 KB	-rw-r--r--
cputicks.go	478 B	-rw-r--r--
crash_cgo_test.go	13.71 KB	-rw-r--r--
crash_nonunix_test.go	385 B	-rw-r--r--
crash_test.go	20.24 KB	-rw-r--r--
crash_unix_test.go	8.89 KB	-rw-r--r--
debug.go	1.63 KB	-rw-r--r--
debug_test.go	6.16 KB	-rw-r--r--
debugcall.go	2.83 KB	-rw-r--r--
debuglog.go	17.08 KB	-rw-r--r--
debuglog_off.go	356 B	-rw-r--r--
debuglog_on.go	1.09 KB	-rw-r--r--
debuglog_test.go	4.56 KB	-rw-r--r--
defer_test.go	9.98 KB	-rw-r--r--
defs1_linux.go	844 B	-rw-r--r--
defs1_netbsd_386.go	2.84 KB	-rw-r--r--
defs1_netbsd_amd64.go	3.07 KB	-rw-r--r--
defs1_netbsd_arm.go	2.96 KB	-rw-r--r--
defs1_netbsd_arm64.go	3.18 KB	-rw-r--r--
defs1_solaris_amd64.go	4.02 KB	-rw-r--r--
defs2_linux.go	3.51 KB	-rw-r--r--
defs3_linux.go	1.09 KB	-rw-r--r--
defs_aix.go	4.16 KB	-rw-r--r--
defs_aix_ppc64.go	3.61 KB	-rw-r--r--
defs_arm_linux.go	2.67 KB	-rw-r--r--
defs_darwin.go	3.84 KB	-rw-r--r--
defs_darwin_386.go	5.98 KB	-rw-r--r--
defs_darwin_amd64.go	6.07 KB	-rw-r--r--
defs_darwin_arm.go	3.78 KB	-rw-r--r--
defs_darwin_arm64.go	3.84 KB	-rw-r--r--
defs_dragonfly.go	2.54 KB	-rw-r--r--
defs_dragonfly_amd64.go	3.25 KB	-rw-r--r--
defs_freebsd.go	3.84 KB	-rw-r--r--
defs_freebsd_386.go	4.35 KB	-rw-r--r--
defs_freebsd_amd64.go	4.62 KB	-rw-r--r--
defs_freebsd_arm.go	3.68 KB	-rw-r--r--
defs_freebsd_arm64.go	4 KB	-rw-r--r--
defs_illumos_amd64.go	285 B	-rw-r--r--
defs_linux.go	3.04 KB	-rw-r--r--
defs_linux_386.go	4.05 KB	-rw-r--r--
defs_linux_amd64.go	4.56 KB	-rw-r--r--
defs_linux_arm.go	3.31 KB	-rw-r--r--
defs_linux_arm64.go	3.23 KB	-rw-r--r--
defs_linux_mips64x.go	3.04 KB	-rw-r--r--
defs_linux_mipsx.go	3.18 KB	-rw-r--r--
defs_linux_ppc64.go	3.28 KB	-rw-r--r--
defs_linux_ppc64le.go	3.28 KB	-rw-r--r--
defs_linux_riscv64.go	3.27 KB	-rw-r--r--
defs_linux_s390x.go	2.76 KB	-rw-r--r--
defs_netbsd.go	2.74 KB	-rw-r--r--
defs_netbsd_386.go	854 B	-rw-r--r--
defs_netbsd_amd64.go	1.01 KB	-rw-r--r--
defs_netbsd_arm.go	763 B	-rw-r--r--
defs_openbsd.go	2.6 KB	-rw-r--r--
defs_openbsd_386.go	2.63 KB	-rw-r--r--
defs_openbsd_amd64.go	2.83 KB	-rw-r--r--
defs_openbsd_arm.go	2.74 KB	-rw-r--r--
defs_openbsd_arm64.go	2.34 KB	-rw-r--r--
defs_plan9_386.go	1.47 KB	-rw-r--r--
defs_plan9_amd64.go	1.66 KB	-rw-r--r--
defs_plan9_arm.go	1.73 KB	-rw-r--r--
defs_solaris.go	3.33 KB	-rw-r--r--
defs_solaris_amd64.go	1003 B	-rw-r--r--
defs_windows.go	2.07 KB	-rw-r--r--
defs_windows_386.go	3.75 KB	-rw-r--r--
defs_windows_amd64.go	4.51 KB	-rw-r--r--
defs_windows_arm.go	3.59 KB	-rw-r--r--
duff_386.s	8.24 KB	-rw-r--r--
duff_amd64.s	5.53 KB	-rw-r--r--
duff_arm.s	7.11 KB	-rw-r--r--
duff_arm64.s	5.25 KB	-rw-r--r--
duff_mips64x.s	11.28 KB	-rw-r--r--
duff_ppc64x.s	2.45 KB	-rw-r--r--
duff_s390x.s	507 B	-rw-r--r--
env_plan9.go	855 B	-rw-r--r--
env_posix.go	1.82 KB	-rw-r--r--
env_test.go	1.28 KB	-rw-r--r--
error.go	7.26 KB	-rw-r--r--
example_test.go	1.34 KB	-rw-r--r--
export_aix_test.go	204 B	-rw-r--r--
export_arm_test.go	226 B	-rw-r--r--
export_darwin_test.go	351 B	-rw-r--r--
export_debug_test.go	5.28 KB	-rw-r--r--
export_debuglog_test.go	1.27 KB	-rw-r--r--
export_futex_test.go	529 B	-rw-r--r--
export_linux_test.go	429 B	-rw-r--r--
export_mmap_test.go	481 B	-rw-r--r--
export_solaris_test.go	282 B	-rw-r--r--
export_test.go	23.58 KB	-rw-r--r--
export_unix_test.go	2.28 KB	-rw-r--r--
export_windows_test.go	652 B	-rw-r--r--
extern.go	11.6 KB	-rw-r--r--
fastlog2.go	1.22 KB	-rw-r--r--
fastlog2_test.go	784 B	-rw-r--r--
fastlog2table.go	904 B	-rw-r--r--
float.go	1.35 KB	-rw-r--r--
funcdata.h	2.44 KB	-rw-r--r--
futex_test.go	2.1 KB	-rw-r--r--
gc_test.go	13.22 KB	-rw-r--r--
gcinfo_test.go	6.18 KB	-rw-r--r--
go_tls.h	366 B	-rw-r--r--
hash32.go	2.51 KB	-rw-r--r--
hash64.go	2.6 KB	-rw-r--r--
hash_test.go	17.54 KB	-rw-r--r--
heapdump.go	17.1 KB	-rw-r--r--
iface.go	15.78 KB	-rw-r--r--
iface_test.go	6.81 KB	-rw-r--r--
lfstack.go	1.77 KB	-rw-r--r--
lfstack_32bit.go	522 B	-rw-r--r--
lfstack_64bit.go	2.15 KB	-rw-r--r--
lfstack_test.go	2.78 KB	-rw-r--r--
libfuzzer.go	2.58 KB	-rw-r--r--
libfuzzer_amd64.s	940 B	-rw-r--r--
libfuzzer_arm64.s	751 B	-rw-r--r--
lock_futex.go	5.06 KB	-rw-r--r--
lock_js.go	5.45 KB	-rw-r--r--
lock_sema.go	6.6 KB	-rw-r--r--
malloc.go	48.32 KB	-rw-r--r--
malloc_test.go	9.37 KB	-rw-r--r--
map.go	42.13 KB	-rw-r--r--
map_benchmark_test.go	10.16 KB	-rw-r--r--
map_fast32.go	12.18 KB	-rw-r--r--
map_fast64.go	12.37 KB	-rw-r--r--
map_faststr.go	13.82 KB	-rw-r--r--
map_test.go	27.11 KB	-rw-r--r--
mbarrier.go	12.14 KB	-rw-r--r--
mbitmap.go	67.53 KB	-rw-r--r--
mcache.go	5.61 KB	-rw-r--r--
mcentral.go	7.14 KB	-rw-r--r--
mem_aix.go	1.93 KB	-rw-r--r--
mem_bsd.go	2.05 KB	-rw-r--r--
mem_darwin.go	1.88 KB	-rw-r--r--
mem_js.go	2.32 KB	-rw-r--r--
mem_linux.go	5.58 KB	-rw-r--r--
mem_plan9.go	4.53 KB	-rw-r--r--
mem_windows.go	3.86 KB	-rw-r--r--
memclr_386.s	2.4 KB	-rw-r--r--
memclr_amd64.s	3.65 KB	-rw-r--r--
memclr_arm.s	2.44 KB	-rw-r--r--
memclr_arm64.s	3.48 KB	-rw-r--r--
memclr_mips64x.s	785 B	-rw-r--r--
memclr_mipsx.s	1.24 KB	-rw-r--r--
memclr_plan9_386.s	905 B	-rw-r--r--
memclr_plan9_amd64.s	433 B	-rw-r--r--
memclr_ppc64x.s	4.2 KB	-rw-r--r--
memclr_riscv64.s	848 B	-rwxr-xr-x
memclr_s390x.s	1.89 KB	-rw-r--r--
memclr_wasm.s	544 B	-rw-r--r--
memmove_386.s	4.45 KB	-rw-r--r--
memmove_amd64.s	12.33 KB	-rw-r--r--
memmove_arm.s	5.9 KB	-rw-r--r--
memmove_arm64.s	3.56 KB	-rw-r--r--
memmove_linux_amd64_test.go	1.61 KB	-rw-r--r--
memmove_mips64x.s	1.82 KB	-rw-r--r--
memmove_mipsx.s	4.39 KB	-rw-r--r--
memmove_plan9_386.s	3.06 KB	-rw-r--r--
memmove_plan9_amd64.s	3.04 KB	-rw-r--r--
memmove_ppc64x.s	3.33 KB	-rw-r--r--
memmove_riscv64.s	1.81 KB	-rwxr-xr-x
memmove_s390x.s	2.92 KB	-rw-r--r--
memmove_test.go	10.97 KB	-rw-r--r--
memmove_wasm.s	1.74 KB	-rw-r--r--
mfinal.go	14.8 KB	-rw-r--r--
mfinal_test.go	5.85 KB	-rw-r--r--
mfixalloc.go	2.72 KB	-rw-r--r--
mgc.go	74.87 KB	-rw-r--r--
mgcmark.go	46.5 KB	-rw-r--r--
mgcscavenge.go	30.95 KB	-rw-r--r--
mgcscavenge_test.go	12.34 KB	-rw-r--r--
mgcstack.go	10.55 KB	-rw-r--r--
mgcsweep.go	14.79 KB	-rw-r--r--
mgcsweepbuf.go	5.98 KB	-rw-r--r--
mgcwork.go	14.24 KB	-rw-r--r--
mheap.go	61.5 KB	-rw-r--r--
mkduff.go	6.23 KB	-rw-r--r--
mkfastlog2table.go	1.32 KB	-rw-r--r--
mkpreempt.go	13.33 KB	-rw-r--r--
mksizeclasses.go	8.62 KB	-rw-r--r--
mmap.go	847 B	-rw-r--r--
mpagealloc.go	35.25 KB	-rw-r--r--
mpagealloc_32bit.go	3.75 KB	-rw-r--r--
mpagealloc_64bit.go	6.51 KB	-rw-r--r--
mpagealloc_test.go	28.88 KB	-rw-r--r--
mpagecache.go	5.03 KB	-rw-r--r--
mpagecache_test.go	9.93 KB	-rw-r--r--
mpallocbits.go	10.69 KB	-rw-r--r--
mpallocbits_test.go	12.93 KB	-rw-r--r--
mprof.go	24.06 KB	-rw-r--r--
mranges.go	5.41 KB	-rw-r--r--
msan.go	1.39 KB	-rw-r--r--
msan0.go	647 B	-rw-r--r--
msan_amd64.s	2.03 KB	-rw-r--r--
msan_arm64.s	1.69 KB	-rw-r--r--
msize.go	785 B	-rw-r--r--
mstats.go	22.62 KB	-rw-r--r--
mwbbuf.go	10.07 KB	-rw-r--r--
nbpipe_fcntl_libc_test.go	463 B	-rw-r--r--
nbpipe_fcntl_unix_test.go	445 B	-rw-r--r--
nbpipe_pipe.go	411 B	-rw-r--r--
nbpipe_pipe2.go	509 B	-rw-r--r--
nbpipe_test.go	2.17 KB	-rw-r--r--
net_plan9.go	645 B	-rw-r--r--
netpoll.go	14.46 KB	-rw-r--r--
netpoll_aix.go	4.64 KB	-rw-r--r--
netpoll_epoll.go	4 KB	-rw-r--r--
netpoll_fake.go	648 B	-rw-r--r--
netpoll_kqueue.go	4.39 KB	-rw-r--r--
netpoll_solaris.go	10.56 KB	-rw-r--r--
netpoll_stub.go	1.3 KB	-rw-r--r--
netpoll_windows.go	4.51 KB	-rw-r--r--
norace_linux_test.go	888 B	-rw-r--r--
norace_test.go	979 B	-rw-r--r--
numcpu_freebsd_test.go	381 B	-rw-r--r--
os2_aix.go	20.67 KB	-rw-r--r--
os2_freebsd.go	302 B	-rw-r--r--
os2_openbsd.go	296 B	-rw-r--r--
os2_plan9.go	1.48 KB	-rw-r--r--
os2_solaris.go	320 B	-rw-r--r--
os3_plan9.go	3.99 KB	-rw-r--r--
os3_solaris.go	16.92 KB	-rw-r--r--
os_aix.go	8.29 KB	-rw-r--r--
os_android.go	463 B	-rw-r--r--
os_darwin.go	10.59 KB	-rw-r--r--
os_darwin_arm.go	749 B	-rw-r--r--
os_darwin_arm64.go	416 B	-rw-r--r--
os_dragonfly.go	6.2 KB	-rw-r--r--
os_freebsd.go	10.97 KB	-rw-r--r--
os_freebsd2.go	478 B	-rw-r--r--
os_freebsd_amd64.go	529 B	-rw-r--r--
os_freebsd_arm.go	1.32 KB	-rw-r--r--
os_freebsd_arm64.go	2.97 KB	-rw-r--r--
os_freebsd_noauxv.go	254 B	-rw-r--r--
os_illumos.go	3.93 KB	-rw-r--r--
os_js.go	2.93 KB	-rw-r--r--
os_linux.go	13.16 KB	-rw-r--r--
os_linux_arm.go	1.35 KB	-rw-r--r--
os_linux_arm64.go	1.02 KB	-rw-r--r--
os_linux_be64.go	816 B	-rw-r--r--
os_linux_generic.go	916 B	-rw-r--r--
os_linux_mips64x.go	999 B	-rw-r--r--
os_linux_mipsx.go	1.05 KB	-rw-r--r--
os_linux_noauxv.go	307 B	-rw-r--r--
os_linux_novdso.go	298 B	-rw-r--r--
os_linux_ppc64x.go	527 B	-rw-r--r--
os_linux_riscv64.go	198 B	-rw-r--r--
os_linux_s390x.go	455 B	-rw-r--r--
os_linux_x86.go	2.69 KB	-rw-r--r--
os_netbsd.go	8.49 KB	-rw-r--r--
os_netbsd_386.go	588 B	-rw-r--r--
os_netbsd_amd64.go	585 B	-rw-r--r--
os_netbsd_arm.go	1.13 KB	-rw-r--r--
os_netbsd_arm64.go	827 B	-rw-r--r--
os_nonopenbsd.go	436 B	-rw-r--r--
os_only_solaris.go	356 B	-rw-r--r--
os_openbsd.go	7.81 KB	-rw-r--r--
os_openbsd_arm.go	749 B	-rw-r--r--
os_openbsd_arm64.go	714 B	-rw-r--r--
os_plan9.go	9.3 KB	-rw-r--r--
os_plan9_arm.go	462 B	-rw-r--r--
os_solaris.go	6.49 KB	-rw-r--r--
os_windows.go	37.01 KB	-rw-r--r--
os_windows_arm.go	511 B	-rw-r--r--
panic.go	42.23 KB	-rw-r--r--
panic32.go	4.79 KB	-rw-r--r--
plugin.go	4.16 KB	-rw-r--r--
preempt.go	14.72 KB	-rw-r--r--
preempt_386.s	983 B	-rw-r--r--
preempt_amd64.s	1.62 KB	-rw-r--r--
preempt_arm.s	1.48 KB	-rw-r--r--
preempt_arm64.s	2.8 KB	-rw-r--r--
preempt_mips64x.s	2.71 KB	-rw-r--r--
preempt_mipsx.s	2.68 KB	-rw-r--r--
preempt_nonwindows.go	289 B	-rw-r--r--
preempt_ppc64x.s	2.71 KB	-rw-r--r--
preempt_riscv64.s	197 B	-rw-r--r--
preempt_s390x.s	1.01 KB	-rw-r--r--
preempt_wasm.s	176 B	-rw-r--r--
print.go	5.98 KB	-rw-r--r--
proc.go	149.75 KB	-rw-r--r--
proc_runtime_test.go	820 B	-rw-r--r--
proc_test.go	22.89 KB	-rw-r--r--
profbuf.go	18.26 KB	-rw-r--r--
profbuf_test.go	8.65 KB	-rw-r--r--
proflabel.go	1.52 KB	-rw-r--r--
race.go	18.11 KB	-rw-r--r--
race0.go	2.61 KB	-rw-r--r--
race_amd64.s	13.59 KB	-rw-r--r--
race_arm64.s	13.53 KB	-rw-r--r--
race_ppc64le.s	17.93 KB	-rw-r--r--
rand_test.go	783 B	-rw-r--r--
rdebug.go	553 B	-rw-r--r--
relax_stub.go	597 B	-rw-r--r--
rt0_aix_ppc64.s	4.33 KB	-rw-r--r--
rt0_android_386.s	822 B	-rw-r--r--
rt0_android_amd64.s	754 B	-rw-r--r--
rt0_android_arm.s	843 B	-rw-r--r--
rt0_android_arm64.s	941 B	-rw-r--r--
rt0_darwin_386.s	452 B	-rw-r--r--
rt0_darwin_amd64.s	399 B	-rw-r--r--
rt0_darwin_arm.s	290 B	-rw-r--r--
rt0_darwin_arm64.s	2.32 KB	-rw-r--r--
rt0_dragonfly_amd64.s	448 B	-rw-r--r--
rt0_freebsd_386.s	454 B	-rw-r--r--
rt0_freebsd_amd64.s	442 B	-rw-r--r--
rt0_freebsd_arm.s	298 B	-rw-r--r--
rt0_freebsd_arm64.s	2.46 KB	-rw-r--r--
rt0_illumos_amd64.s	311 B	-rw-r--r--
rt0_js_wasm.s	2.3 KB	-rw-r--r--
rt0_linux_386.s	450 B	-rw-r--r--
rt0_linux_amd64.s	307 B	-rw-r--r--
rt0_linux_arm.s	1007 B	-rw-r--r--
rt0_linux_arm64.s	2.39 KB	-rw-r--r--
rt0_linux_mips64x.s	1015 B	-rw-r--r--
rt0_linux_mipsx.s	798 B	-rw-r--r--
rt0_linux_ppc64.s	705 B	-rw-r--r--
rt0_linux_ppc64le.s	3.72 KB	-rw-r--r--
rt0_linux_riscv64.s	370 B	-rw-r--r--
rt0_linux_s390x.s	676 B	-rw-r--r--
rt0_netbsd_386.s	452 B	-rw-r--r--
rt0_netbsd_amd64.s	309 B	-rw-r--r--
rt0_netbsd_arm.s	296 B	-rw-r--r--
rt0_netbsd_arm64.s	2.39 KB	-rw-r--r--
rt0_openbsd_386.s	454 B	-rw-r--r--
rt0_openbsd_amd64.s	311 B	-rw-r--r--
rt0_openbsd_arm.s	298 B	-rw-r--r--
rt0_openbsd_arm64.s	2.42 KB	-rw-r--r--
rt0_plan9_386.s	523 B	-rw-r--r--
rt0_plan9_amd64.s	481 B	-rw-r--r--
rt0_plan9_arm.s	397 B	-rw-r--r--
rt0_solaris_amd64.s	311 B	-rw-r--r--
rt0_windows_386.s	1.28 KB	-rw-r--r--
rt0_windows_amd64.s	1.15 KB	-rw-r--r--
rt0_windows_arm.s	386 B	-rw-r--r--
runtime-gdb.py	14.83 KB	-rw-r--r--
runtime-gdb_test.go	16.85 KB	-rw-r--r--
runtime-lldb_test.go	5.09 KB	-rw-r--r--
runtime.go	1.42 KB	-rw-r--r--
runtime1.go	11.97 KB	-rw-r--r--
runtime2.go	37.85 KB	-rw-r--r--
runtime_linux_test.go	1.46 KB	-rw-r--r--
runtime_mmap_test.go	1.82 KB	-rw-r--r--
runtime_test.go	7.81 KB	-rw-r--r--
runtime_unix_test.go	1.2 KB	-rw-r--r--
rwmutex.go	3.4 KB	-rw-r--r--
rwmutex_test.go	4.03 KB	-rw-r--r--
select.go	13.24 KB	-rw-r--r--
sema.go	15.95 KB	-rw-r--r--
sema_test.go	2.41 KB	-rw-r--r--
semasleep_test.go	1.62 KB	-rw-r--r--
sigaction.go	460 B	-rw-r--r--
signal_386.go	2.14 KB	-rw-r--r--
signal_aix_ppc64.go	3.55 KB	-rw-r--r--
signal_amd64.go	2.56 KB	-rw-r--r--
signal_arm.go	2.63 KB	-rw-r--r--
signal_arm64.go	3.12 KB	-rw-r--r--
signal_darwin.go	2.13 KB	-rw-r--r--
signal_darwin_386.go	2.33 KB	-rw-r--r--
signal_darwin_amd64.go	3.85 KB	-rw-r--r--
signal_darwin_arm.go	2.71 KB	-rw-r--r--
signal_darwin_arm64.go	3.6 KB	-rw-r--r--
signal_dragonfly.go	2.17 KB	-rw-r--r--
signal_dragonfly_amd64.go	2.01 KB	-rw-r--r--
signal_freebsd.go	2.2 KB	-rw-r--r--
signal_freebsd_386.go	1.55 KB	-rw-r--r--
signal_freebsd_amd64.go	2.03 KB	-rw-r--r--
signal_freebsd_arm.go	2.18 KB	-rw-r--r--
signal_freebsd_arm64.go	3.23 KB	-rw-r--r--
signal_linux_386.go	1.59 KB	-rw-r--r--
signal_linux_amd64.go	2.05 KB	-rw-r--r--
signal_linux_arm.go	2.13 KB	-rw-r--r--
signal_linux_arm64.go	2.95 KB	-rw-r--r--
signal_linux_mips64x.go	3.35 KB	-rw-r--r--
signal_linux_mipsx.go	3.67 KB	-rw-r--r--
signal_linux_ppc64x.go	3.42 KB	-rw-r--r--
signal_linux_riscv64.go	2.92 KB	-rw-r--r--
signal_linux_s390x.go	4.45 KB	-rw-r--r--
signal_mips64x.go	3.16 KB	-rw-r--r--
signal_mipsx.go	3.05 KB	-rw-r--r--
signal_netbsd.go	2.18 KB	-rw-r--r--
signal_netbsd_386.go	1.76 KB	-rw-r--r--
signal_netbsd_amd64.go	2.33 KB	-rw-r--r--
signal_netbsd_arm.go	2.3 KB	-rw-r--r--
signal_netbsd_arm64.go	3.4 KB	-rw-r--r--
signal_openbsd.go	2.15 KB	-rw-r--r--
signal_openbsd_386.go	1.58 KB	-rw-r--r--
signal_openbsd_amd64.go	2.04 KB	-rw-r--r--
signal_openbsd_arm.go	2.12 KB	-rw-r--r--
signal_openbsd_arm64.go	3.38 KB	-rw-r--r--
signal_plan9.go	1.93 KB	-rw-r--r--
signal_ppc64x.go	3.61 KB	-rw-r--r--
signal_riscv64.go	2.45 KB	-rw-r--r--
signal_solaris.go	4.5 KB	-rw-r--r--
signal_solaris_amd64.go	2.47 KB	-rw-r--r--
signal_unix.go	35.95 KB	-rw-r--r--
signal_windows.go	8.54 KB	-rw-r--r--
signal_windows_test.go	1.6 KB	-rw-r--r--
sigqueue.go	7.69 KB	-rw-r--r--
sigqueue_note.go	654 B	-rw-r--r--
sigqueue_plan9.go	3.31 KB	-rw-r--r--
sigtab_aix.go	11.3 KB	-rw-r--r--
sigtab_linux_generic.go	3.49 KB	-rw-r--r--
sigtab_linux_mipsx.go	5.89 KB	-rw-r--r--
sizeclasses.go	7.9 KB	-rw-r--r--
sizeof_test.go	839 B	-rw-r--r--
slice.go	6.88 KB	-rw-r--r--
slice_test.go	8.78 KB	-rw-r--r--
softfloat64.go	10.7 KB	-rw-r--r--
softfloat64_test.go	4.05 KB	-rw-r--r--
stack.go	39.14 KB	-rw-r--r--
stack_test.go	19.9 KB	-rw-r--r--
string.go	11.52 KB	-rw-r--r--
string_test.go	10.35 KB	-rw-r--r--
stubs.go	13.08 KB	-rw-r--r--
stubs2.go	1.04 KB	-rw-r--r--
stubs3.go	289 B	-rw-r--r--
stubs32.go	393 B	-rw-r--r--
stubs_386.go	490 B	-rw-r--r--
stubs_amd64.go	348 B	-rw-r--r--
stubs_arm.go	454 B	-rw-r--r--
stubs_arm64.go	256 B	-rw-r--r--
stubs_linux.go	646 B	-rw-r--r--
stubs_mips64x.go	283 B	-rw-r--r--
stubs_mipsx.go	279 B	-rw-r--r--
stubs_nonlinux.go	297 B	-rw-r--r--
stubs_ppc64x.go	296 B	-rw-r--r--
stubs_s390x.go	256 B	-rw-r--r--
symtab.go	28.32 KB	-rw-r--r--
symtab_test.go	4.1 KB	-rw-r--r--
sys_aix_ppc64.s	7.17 KB	-rw-r--r--
sys_arm.go	521 B	-rw-r--r--
sys_arm64.go	469 B	-rw-r--r--
sys_darwin.go	15.96 KB	-rw-r--r--
sys_darwin_32.go	533 B	-rw-r--r--
sys_darwin_386.s	18.55 KB	-rw-r--r--
sys_darwin_64.go	513 B	-rw-r--r--
sys_darwin_amd64.s	18.07 KB	-rw-r--r--
sys_darwin_arm.s	13.7 KB	-rw-r--r--
sys_darwin_arm64.s	15.84 KB	-rw-r--r--
sys_dragonfly_amd64.s	8.32 KB	-rw-r--r--
sys_freebsd_386.s	8.92 KB	-rw-r--r--
sys_freebsd_amd64.s	10.72 KB	-rw-r--r--
sys_freebsd_arm.s	10.64 KB	-rw-r--r--
sys_freebsd_arm64.s	10.75 KB	-rw-r--r--
sys_linux_386.s	17.57 KB	-rw-r--r--
sys_linux_amd64.s	17.07 KB	-rw-r--r--
sys_linux_arm.s	14.9 KB	-rw-r--r--
sys_linux_arm64.s	14.32 KB	-rw-r--r--
sys_linux_mips64x.s	12 KB	-rw-r--r--
sys_linux_mipsx.s	11.13 KB	-rw-r--r--
sys_linux_ppc64x.s	14.71 KB	-rw-r--r--
sys_linux_riscv64.s	10.38 KB	-rw-r--r--

Code Editor : malloc.go

// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Memory allocator.
//
// This was originally based on tcmalloc, but has diverged quite a bit.
// http://goog-perftools.sourceforge.net/doc/tcmalloc.html

// The main allocator works in runs of pages.
// Small allocation sizes (up to and including 32 kB) are
// rounded to one of about 70 size classes, each of which
// has its own free set of objects of exactly that size.
// Any free page of memory can be split into a set of objects
// of one size class, which are then managed using a free bitmap.
//
// The allocator's data structures are:
//
//	fixalloc: a free-list allocator for fixed-size off-heap objects,
//		used to manage storage used by the allocator.
//	mheap: the malloc heap, managed at page (8192-byte) granularity.
//	mspan: a run of in-use pages managed by the mheap.
//	mcentral: collects all spans of a given size class.
//	mcache: a per-P cache of mspans with free space.
//	mstats: allocation statistics.
//
// Allocating a small object proceeds up a hierarchy of caches:
//
//	1. Round the size up to one of the small size classes
//	   and look in the corresponding mspan in this P's mcache.
//	   Scan the mspan's free bitmap to find a free slot.
//	   If there is a free slot, allocate it.
//	   This can all be done without acquiring a lock.
//
//	2. If the mspan has no free slots, obtain a new mspan
//	   from the mcentral's list of mspans of the required size
//	   class that have free space.
//	   Obtaining a whole span amortizes the cost of locking
//	   the mcentral.
//
//	3. If the mcentral's mspan list is empty, obtain a run
//	   of pages from the mheap to use for the mspan.
//
//	4. If the mheap is empty or has no page runs large enough,
//	   allocate a new group of pages (at least 1MB) from the
//	   operating system. Allocating a large run of pages
//	   amortizes the cost of talking to the operating system.
//
// Sweeping an mspan and freeing objects on it proceeds up a similar
// hierarchy:
//
//	1. If the mspan is being swept in response to allocation, it
//	   is returned to the mcache to satisfy the allocation.
//
//	2. Otherwise, if the mspan still has allocated objects in it,
//	   it is placed on the mcentral free list for the mspan's size
//	   class.
//
//	3. Otherwise, if all objects in the mspan are free, the mspan's
//	   pages are returned to the mheap and the mspan is now dead.
//
// Allocating and freeing a large object uses the mheap
// directly, bypassing the mcache and mcentral.
//
// If mspan.needzero is false, then free object slots in the mspan are
// already zeroed. Otherwise if needzero is true, objects are zeroed as
// they are allocated. There are various benefits to delaying zeroing
// this way:
//
//	1. Stack frame allocation can avoid zeroing altogether.
//
//	2. It exhibits better temporal locality, since the program is
//	   probably about to write to the memory.
//
//	3. We don't zero pages that never get reused.

// Virtual memory layout
//
// The heap consists of a set of arenas, which are 64MB on 64-bit and
// 4MB on 32-bit (heapArenaBytes). Each arena's start address is also
// aligned to the arena size.
//
// Each arena has an associated heapArena object that stores the
// metadata for that arena: the heap bitmap for all words in the arena
// and the span map for all pages in the arena. heapArena objects are
// themselves allocated off-heap.
//
// Since arenas are aligned, the address space can be viewed as a
// series of arena frames. The arena map (mheap_.arenas) maps from
// arena frame number to *heapArena, or nil for parts of the address
// space not backed by the Go heap. The arena map is structured as a
// two-level array consisting of a "L1" arena map and many "L2" arena
// maps; however, since arenas are large, on many architectures, the
// arena map consists of a single, large L2 map.
//
// The arena map covers the entire possible address space, allowing
// the Go heap to use any part of the address space. The allocator
// attempts to keep arenas contiguous so that large spans (and hence
// large objects) can cross arenas.

package runtime

import (
	"runtime/internal/atomic"
	"runtime/internal/math"
	"runtime/internal/sys"
	"unsafe"
)

const (
	debugMalloc = false

maxTinySize   = _TinySize
	tinySizeClass = _TinySizeClass
	maxSmallSize  = _MaxSmallSize

pageShift = _PageShift
	pageSize  = _PageSize
	pageMask  = _PageMask
	// By construction, single page spans of the smallest object class
	// have the most objects per span.
	maxObjsPerSpan = pageSize / 8

concurrentSweep = _ConcurrentSweep

_PageSize = 1 << _PageShift
	_PageMask = _PageSize - 1

// _64bit = 1 on 64-bit systems, 0 on 32-bit systems
	_64bit = 1 << (^uintptr(0) >> 63) / 2

// Tiny allocator parameters, see "Tiny allocator" comment in malloc.go.
	_TinySize      = 16
	_TinySizeClass = int8(2)

_FixAllocChunk = 16 << 10 // Chunk size for FixAlloc

// Per-P, per order stack segment cache size.
	_StackCacheSize = 32 * 1024

// Number of orders that get caching. Order 0 is FixedStack
	// and each successive order is twice as large.
	// We want to cache 2KB, 4KB, 8KB, and 16KB stacks. Larger stacks
	// will be allocated directly.
	// Since FixedStack is different on different systems, we
	// must vary NumStackOrders to keep the same maximum cached size.
	//   OS               | FixedStack | NumStackOrders
	//   -----------------+------------+---------------
	//   linux/darwin/bsd | 2KB        | 4
	//   windows/32       | 4KB        | 3
	//   windows/64       | 8KB        | 2
	//   plan9            | 4KB        | 3
	_NumStackOrders = 4 - sys.PtrSize/4*sys.GoosWindows - 1*sys.GoosPlan9

// heapAddrBits is the number of bits in a heap address. On
	// amd64, addresses are sign-extended beyond heapAddrBits. On
	// other arches, they are zero-extended.
	//
	// On most 64-bit platforms, we limit this to 48 bits based on a
	// combination of hardware and OS limitations.
	//
	// amd64 hardware limits addresses to 48 bits, sign-extended
	// to 64 bits. Addresses where the top 16 bits are not either
	// all 0 or all 1 are "non-canonical" and invalid. Because of
	// these "negative" addresses, we offset addresses by 1<<47
	// (arenaBaseOffset) on amd64 before computing indexes into
	// the heap arenas index. In 2017, amd64 hardware added
	// support for 57 bit addresses; however, currently only Linux
	// supports this extension and the kernel will never choose an
	// address above 1<<47 unless mmap is called with a hint
	// address above 1<<47 (which we never do).
	//
	// arm64 hardware (as of ARMv8) limits user addresses to 48
	// bits, in the range [0, 1<<48).
	//
	// ppc64, mips64, and s390x support arbitrary 64 bit addresses
	// in hardware. On Linux, Go leans on stricter OS limits. Based
	// on Linux's processor.h, the user address space is limited as
	// follows on 64-bit architectures:
	//
	// Architecture  Name              Maximum Value (exclusive)
	// ---------------------------------------------------------------------
	// amd64         TASK_SIZE_MAX     0x007ffffffff000 (47 bit addresses)
	// arm64         TASK_SIZE_64      0x01000000000000 (48 bit addresses)
	// ppc64{,le}    TASK_SIZE_USER64  0x00400000000000 (46 bit addresses)
	// mips64{,le}   TASK_SIZE64       0x00010000000000 (40 bit addresses)
	// s390x         TASK_SIZE         1<<64 (64 bit addresses)
	//
	// These limits may increase over time, but are currently at
	// most 48 bits except on s390x. On all architectures, Linux
	// starts placing mmap'd regions at addresses that are
	// significantly below 48 bits, so even if it's possible to
	// exceed Go's 48 bit limit, it's extremely unlikely in
	// practice.
	//
	// On 32-bit platforms, we accept the full 32-bit address
	// space because doing so is cheap.
	// mips32 only has access to the low 2GB of virtual memory, so
	// we further limit it to 31 bits.
	//
	// On darwin/arm64, although 64-bit pointers are presumably
	// available, pointers are truncated to 33 bits. Furthermore,
	// only the top 4 GiB of the address space are actually available
	// to the application, but we allow the whole 33 bits anyway for
	// simplicity.
	// TODO(mknyszek): Consider limiting it to 32 bits and using
	// arenaBaseOffset to offset into the top 4 GiB.
	//
	// WebAssembly currently has a limit of 4GB linear memory.
	heapAddrBits = (_64bit*(1-sys.GoarchWasm)*(1-sys.GoosDarwin*sys.GoarchArm64))*48 + (1-_64bit+sys.GoarchWasm)*(32-(sys.GoarchMips+sys.GoarchMipsle)) + 33*sys.GoosDarwin*sys.GoarchArm64

// maxAlloc is the maximum size of an allocation. On 64-bit,
	// it's theoretically possible to allocate 1<<heapAddrBits bytes. On
	// 32-bit, however, this is one less than 1<<32 because the
	// number of bytes in the address space doesn't actually fit
	// in a uintptr.
	maxAlloc = (1 << heapAddrBits) - (1-_64bit)*1

// The number of bits in a heap address, the size of heap
	// arenas, and the L1 and L2 arena map sizes are related by
	//
	//   (1 << addr bits) = arena size * L1 entries * L2 entries
	//
	// Currently, we balance these as follows:
	//
	//       Platform  Addr bits  Arena size  L1 entries   L2 entries
	// --------------  ---------  ----------  ----------  -----------
	//       */64-bit         48        64MB           1    4M (32MB)
	// windows/64-bit         48         4MB          64    1M  (8MB)
	//       */32-bit         32         4MB           1  1024  (4KB)
	//     */mips(le)         31         4MB           1   512  (2KB)

// heapArenaBytes is the size of a heap arena. The heap
	// consists of mappings of size heapArenaBytes, aligned to
	// heapArenaBytes. The initial heap mapping is one arena.
	//
	// This is currently 64MB on 64-bit non-Windows and 4MB on
	// 32-bit and on Windows. We use smaller arenas on Windows
	// because all committed memory is charged to the process,
	// even if it's not touched. Hence, for processes with small
	// heaps, the mapped arena space needs to be commensurate.
	// This is particularly important with the race detector,
	// since it significantly amplifies the cost of committed
	// memory.
	heapArenaBytes = 1 << logHeapArenaBytes

// logHeapArenaBytes is log_2 of heapArenaBytes. For clarity,
	// prefer using heapArenaBytes where possible (we need the
	// constant to compute some other constants).
	logHeapArenaBytes = (6+20)*(_64bit*(1-sys.GoosWindows)*(1-sys.GoarchWasm)) + (2+20)*(_64bit*sys.GoosWindows) + (2+20)*(1-_64bit) + (2+20)*sys.GoarchWasm

// heapArenaBitmapBytes is the size of each heap arena's bitmap.
	heapArenaBitmapBytes = heapArenaBytes / (sys.PtrSize * 8 / 2)

pagesPerArena = heapArenaBytes / pageSize

// arenaL1Bits is the number of bits of the arena number
	// covered by the first level arena map.
	//
	// This number should be small, since the first level arena
	// map requires PtrSize*(1<<arenaL1Bits) of space in the
	// binary's BSS. It can be zero, in which case the first level
	// index is effectively unused. There is a performance benefit
	// to this, since the generated code can be more efficient,
	// but comes at the cost of having a large L2 mapping.
	//
	// We use the L1 map on 64-bit Windows because the arena size
	// is small, but the address space is still 48 bits, and
	// there's a high cost to having a large L2.
	arenaL1Bits = 6 * (_64bit * sys.GoosWindows)

// arenaL2Bits is the number of bits of the arena number
	// covered by the second level arena index.
	//
	// The size of each arena map allocation is proportional to
	// 1<<arenaL2Bits, so it's important that this not be too
	// large. 48 bits leads to 32MB arena index allocations, which
	// is about the practical threshold.
	arenaL2Bits = heapAddrBits - logHeapArenaBytes - arenaL1Bits

// arenaL1Shift is the number of bits to shift an arena frame
	// number by to compute an index into the first level arena map.
	arenaL1Shift = arenaL2Bits

// arenaBits is the total bits in a combined arena map index.
	// This is split between the index into the L1 arena map and
	// the L2 arena map.
	arenaBits = arenaL1Bits + arenaL2Bits

// arenaBaseOffset is the pointer value that corresponds to
	// index 0 in the heap arena map.
	//
	// On amd64, the address space is 48 bits, sign extended to 64
	// bits. This offset lets us handle "negative" addresses (or
	// high addresses if viewed as unsigned).
	//
	// On aix/ppc64, this offset allows to keep the heapAddrBits to
	// 48. Otherwize, it would be 60 in order to handle mmap addresses
	// (in range 0x0a00000000000000 - 0x0afffffffffffff). But in this
	// case, the memory reserved in (s *pageAlloc).init for chunks
	// is causing important slowdowns.
	//
	// On other platforms, the user address space is contiguous
	// and starts at 0, so no offset is necessary.
	arenaBaseOffset = sys.GoarchAmd64*(1<<47) + (^0x0a00000000000000+1)&uintptrMask*sys.GoosAix

// Max number of threads to run garbage collection.
	// 2, 3, and 4 are all plausible maximums depending
	// on the hardware details of the machine. The garbage
	// collector scales well to 32 cpus.
	_MaxGcproc = 32

// minLegalPointer is the smallest possible legal pointer.
	// This is the smallest possible architectural page size,
	// since we assume that the first page is never mapped.
	//
	// This should agree with minZeroPage in the compiler.
	minLegalPointer uintptr = 4096
)

// physPageSize is the size in bytes of the OS's physical pages.
// Mapping and unmapping operations must be done at multiples of
// physPageSize.
//
// This must be set by the OS init code (typically in osinit) before
// mallocinit.
var physPageSize uintptr

// physHugePageSize is the size in bytes of the OS's default physical huge
// page size whose allocation is opaque to the application. It is assumed
// and verified to be a power of two.
//
// If set, this must be set by the OS init code (typically in osinit) before
// mallocinit. However, setting it at all is optional, and leaving the default
// value is always safe (though potentially less efficient).
//
// Since physHugePageSize is always assumed to be a power of two,
// physHugePageShift is defined as physHugePageSize == 1 << physHugePageShift.
// The purpose of physHugePageShift is to avoid doing divisions in
// performance critical functions.
var (
	physHugePageSize  uintptr
	physHugePageShift uint
)

// OS memory management abstraction layer
//
// Regions of the address space managed by the runtime may be in one of four
// states at any given time:
// 1) None - Unreserved and unmapped, the default state of any region.
// 2) Reserved - Owned by the runtime, but accessing it would cause a fault.
//               Does not count against the process' memory footprint.
// 3) Prepared - Reserved, intended not to be backed by physical memory (though
//               an OS may implement this lazily). Can transition efficiently to
//               Ready. Accessing memory in such a region is undefined (may
//               fault, may give back unexpected zeroes, etc.).
// 4) Ready - may be accessed safely.
//
// This set of states is more than is strictly necessary to support all the
// currently supported platforms. One could get by with just None, Reserved, and
// Ready. However, the Prepared state gives us flexibility for performance
// purposes. For example, on POSIX-y operating systems, Reserved is usually a
// private anonymous mmap'd region with PROT_NONE set, and to transition
// to Ready would require setting PROT_READ|PROT_WRITE. However the
// underspecification of Prepared lets us use just MADV_FREE to transition from
// Ready to Prepared. Thus with the Prepared state we can set the permission
// bits just once early on, we can efficiently tell the OS that it's free to
// take pages away from us when we don't strictly need them.
//
// For each OS there is a common set of helpers defined that transition
// memory regions between these states. The helpers are as follows:
//
// sysAlloc transitions an OS-chosen region of memory from None to Ready.
// More specifically, it obtains a large chunk of zeroed memory from the
// operating system, typically on the order of a hundred kilobytes
// or a megabyte. This memory is always immediately available for use.
//
// sysFree transitions a memory region from any state to None. Therefore, it
// returns memory unconditionally. It is used if an out-of-memory error has been
// detected midway through an allocation or to carve out an aligned section of
// the address space. It is okay if sysFree is a no-op only if sysReserve always
// returns a memory region aligned to the heap allocator's alignment
// restrictions.
//
// sysReserve transitions a memory region from None to Reserved. It reserves
// address space in such a way that it would cause a fatal fault upon access
// (either via permissions or not committing the memory). Such a reservation is
// thus never backed by physical memory.
// If the pointer passed to it is non-nil, the caller wants the
// reservation there, but sysReserve can still choose another
// location if that one is unavailable.
// NOTE: sysReserve returns OS-aligned memory, but the heap allocator
// may use larger alignment, so the caller must be careful to realign the
// memory obtained by sysReserve.
//
// sysMap transitions a memory region from Reserved to Prepared. It ensures the
// memory region can be efficiently transitioned to Ready.
//
// sysUsed transitions a memory region from Prepared to Ready. It notifies the
// operating system that the memory region is needed and ensures that the region
// may be safely accessed. This is typically a no-op on systems that don't have
// an explicit commit step and hard over-commit limits, but is critical on
// Windows, for example.
//
// sysUnused transitions a memory region from Ready to Prepared. It notifies the
// operating system that the physical pages backing this memory region are no
// longer needed and can be reused for other purposes. The contents of a
// sysUnused memory region are considered forfeit and the region must not be
// accessed again until sysUsed is called.
//
// sysFault transitions a memory region from Ready or Prepared to Reserved. It
// marks a region such that it will always fault if accessed. Used only for
// debugging the runtime.

func mallocinit() {
	if class_to_size[_TinySizeClass] != _TinySize {
		throw("bad TinySizeClass")
	}

testdefersizes()

if heapArenaBitmapBytes&(heapArenaBitmapBytes-1) != 0 {
		// heapBits expects modular arithmetic on bitmap
		// addresses to work.
		throw("heapArenaBitmapBytes not a power of 2")
	}

// Copy class sizes out for statistics table.
	for i := range class_to_size {
		memstats.by_size[i].size = uint32(class_to_size[i])
	}

// Check physPageSize.
	if physPageSize == 0 {
		// The OS init code failed to fetch the physical page size.
		throw("failed to get system page size")
	}
	if physPageSize > maxPhysPageSize {
		print("system page size (", physPageSize, ") is larger than maximum page size (", maxPhysPageSize, ")\n")
		throw("bad system page size")
	}
	if physPageSize < minPhysPageSize {
		print("system page size (", physPageSize, ") is smaller than minimum page size (", minPhysPageSize, ")\n")
		throw("bad system page size")
	}
	if physPageSize&(physPageSize-1) != 0 {
		print("system page size (", physPageSize, ") must be a power of 2\n")
		throw("bad system page size")
	}
	if physHugePageSize&(physHugePageSize-1) != 0 {
		print("system huge page size (", physHugePageSize, ") must be a power of 2\n")
		throw("bad system huge page size")
	}
	if physHugePageSize > maxPhysHugePageSize {
		// physHugePageSize is greater than the maximum supported huge page size.
		// Don't throw here, like in the other cases, since a system configured
		// in this way isn't wrong, we just don't have the code to support them.
		// Instead, silently set the huge page size to zero.
		physHugePageSize = 0
	}
	if physHugePageSize != 0 {
		// Since physHugePageSize is a power of 2, it suffices to increase
		// physHugePageShift until 1<<physHugePageShift == physHugePageSize.
		for 1<<physHugePageShift != physHugePageSize {
			physHugePageShift++
		}
	}

// Initialize the heap.
	mheap_.init()
	_g_ := getg()
	_g_.m.mcache = allocmcache()

// Create initial arena growth hints.
	if sys.PtrSize == 8 {
		// On a 64-bit machine, we pick the following hints
		// because:
		//
		// 1. Starting from the middle of the address space
		// makes it easier to grow out a contiguous range
		// without running in to some other mapping.
		//
		// 2. This makes Go heap addresses more easily
		// recognizable when debugging.
		//
		// 3. Stack scanning in gccgo is still conservative,
		// so it's important that addresses be distinguishable
		// from other data.
		//
		// Starting at 0x00c0 means that the valid memory addresses
		// will begin 0x00c0, 0x00c1, ...
		// In little-endian, that's c0 00, c1 00, ... None of those are valid
		// UTF-8 sequences, and they are otherwise as far away from
		// ff (likely a common byte) as possible. If that fails, we try other 0xXXc0
		// addresses. An earlier attempt to use 0x11f8 caused out of memory errors
		// on OS X during thread allocations.  0x00c0 causes conflicts with
		// AddressSanitizer which reserves all memory up to 0x0100.
		// These choices reduce the odds of a conservative garbage collector
		// not collecting memory because some non-pointer block of memory
		// had a bit pattern that matched a memory address.
		//
		// However, on arm64, we ignore all this advice above and slam the
		// allocation at 0x40 << 32 because when using 4k pages with 3-level
		// translation buffers, the user address space is limited to 39 bits
		// On darwin/arm64, the address space is even smaller.
		//
		// On AIX, mmaps starts at 0x0A00000000000000 for 64-bit.
		// processes.
		for i := 0x7f; i >= 0; i-- {
			var p uintptr
			switch {
			case GOARCH == "arm64" && GOOS == "darwin":
				p = uintptr(i)<<40 | uintptrMask&(0x0013<<28)
			case GOARCH == "arm64":
				p = uintptr(i)<<40 | uintptrMask&(0x0040<<32)
			case GOOS == "aix":
				if i == 0 {
					// We don't use addresses directly after 0x0A00000000000000
					// to avoid collisions with others mmaps done by non-go programs.
					continue
				}
				p = uintptr(i)<<40 | uintptrMask&(0xa0<<52)
			case raceenabled:
				// The TSAN runtime requires the heap
				// to be in the range [0x00c000000000,
				// 0x00e000000000).
				p = uintptr(i)<<32 | uintptrMask&(0x00c0<<32)
				if p >= uintptrMask&0x00e000000000 {
					continue
				}
			default:
				p = uintptr(i)<<40 | uintptrMask&(0x00c0<<32)
			}
			hint := (*arenaHint)(mheap_.arenaHintAlloc.alloc())
			hint.addr = p
			hint.next, mheap_.arenaHints = mheap_.arenaHints, hint
		}
	} else {
		// On a 32-bit machine, we're much more concerned
		// about keeping the usable heap contiguous.
		// Hence:
		//
		// 1. We reserve space for all heapArenas up front so
		// they don't get interleaved with the heap. They're
		// ~258MB, so this isn't too bad. (We could reserve a
		// smaller amount of space up front if this is a
		// problem.)
		//
		// 2. We hint the heap to start right above the end of
		// the binary so we have the best chance of keeping it
		// contiguous.
		//
		// 3. We try to stake out a reasonably large initial
		// heap reservation.

const arenaMetaSize = (1 << arenaBits) * unsafe.Sizeof(heapArena{})
		meta := uintptr(sysReserve(nil, arenaMetaSize))
		if meta != 0 {
			mheap_.heapArenaAlloc.init(meta, arenaMetaSize)
		}

// We want to start the arena low, but if we're linked
		// against C code, it's possible global constructors
		// have called malloc and adjusted the process' brk.
		// Query the brk so we can avoid trying to map the
		// region over it (which will cause the kernel to put
		// the region somewhere else, likely at a high
		// address).
		procBrk := sbrk0()

// If we ask for the end of the data segment but the
		// operating system requires a little more space
		// before we can start allocating, it will give out a
		// slightly higher pointer. Except QEMU, which is
		// buggy, as usual: it won't adjust the pointer
		// upward. So adjust it upward a little bit ourselves:
		// 1/4 MB to get away from the running binary image.
		p := firstmoduledata.end
		if p < procBrk {
			p = procBrk
		}
		if mheap_.heapArenaAlloc.next <= p && p < mheap_.heapArenaAlloc.end {
			p = mheap_.heapArenaAlloc.end
		}
		p = alignUp(p+(256<<10), heapArenaBytes)
		// Because we're worried about fragmentation on
		// 32-bit, we try to make a large initial reservation.
		arenaSizes := []uintptr{
			512 << 20,
			256 << 20,
			128 << 20,
		}
		for _, arenaSize := range arenaSizes {
			a, size := sysReserveAligned(unsafe.Pointer(p), arenaSize, heapArenaBytes)
			if a != nil {
				mheap_.arena.init(uintptr(a), size)
				p = uintptr(a) + size // For hint below
				break
			}
		}
		hint := (*arenaHint)(mheap_.arenaHintAlloc.alloc())
		hint.addr = p
		hint.next, mheap_.arenaHints = mheap_.arenaHints, hint
	}
}

// sysAlloc allocates heap arena space for at least n bytes. The
// returned pointer is always heapArenaBytes-aligned and backed by
// h.arenas metadata. The returned size is always a multiple of
// heapArenaBytes. sysAlloc returns nil on failure.
// There is no corresponding free function.
//
// sysAlloc returns a memory region in the Prepared state. This region must
// be transitioned to Ready before use.
//
// h must be locked.
func (h *mheap) sysAlloc(n uintptr) (v unsafe.Pointer, size uintptr) {
	n = alignUp(n, heapArenaBytes)

// First, try the arena pre-reservation.
	v = h.arena.alloc(n, heapArenaBytes, &memstats.heap_sys)
	if v != nil {
		size = n
		goto mapped
	}

// Try to grow the heap at a hint address.
	for h.arenaHints != nil {
		hint := h.arenaHints
		p := hint.addr
		if hint.down {
			p -= n
		}
		if p+n < p {
			// We can't use this, so don't ask.
			v = nil
		} else if arenaIndex(p+n-1) >= 1<<arenaBits {
			// Outside addressable heap. Can't use.
			v = nil
		} else {
			v = sysReserve(unsafe.Pointer(p), n)
		}
		if p == uintptr(v) {
			// Success. Update the hint.
			if !hint.down {
				p += n
			}
			hint.addr = p
			size = n
			break
		}
		// Failed. Discard this hint and try the next.
		//
		// TODO: This would be cleaner if sysReserve could be
		// told to only return the requested address. In
		// particular, this is already how Windows behaves, so
		// it would simplify things there.
		if v != nil {
			sysFree(v, n, nil)
		}
		h.arenaHints = hint.next
		h.arenaHintAlloc.free(unsafe.Pointer(hint))
	}

if size == 0 {
		if raceenabled {
			// The race detector assumes the heap lives in
			// [0x00c000000000, 0x00e000000000), but we
			// just ran out of hints in this region. Give
			// a nice failure.
			throw("too many address space collisions for -race mode")
		}

// All of the hints failed, so we'll take any
		// (sufficiently aligned) address the kernel will give
		// us.
		v, size = sysReserveAligned(nil, n, heapArenaBytes)
		if v == nil {
			return nil, 0
		}

// Create new hints for extending this region.
		hint := (*arenaHint)(h.arenaHintAlloc.alloc())
		hint.addr, hint.down = uintptr(v), true
		hint.next, mheap_.arenaHints = mheap_.arenaHints, hint
		hint = (*arenaHint)(h.arenaHintAlloc.alloc())
		hint.addr = uintptr(v) + size
		hint.next, mheap_.arenaHints = mheap_.arenaHints, hint
	}

// Check for bad pointers or pointers we can't use.
	{
		var bad string
		p := uintptr(v)
		if p+size < p {
			bad = "region exceeds uintptr range"
		} else if arenaIndex(p) >= 1<<arenaBits {
			bad = "base outside usable address space"
		} else if arenaIndex(p+size-1) >= 1<<arenaBits {
			bad = "end outside usable address space"
		}
		if bad != "" {
			// This should be impossible on most architectures,
			// but it would be really confusing to debug.
			print("runtime: memory allocated by OS [", hex(p), ", ", hex(p+size), ") not in usable address space: ", bad, "\n")
			throw("memory reservation exceeds address space limit")
		}
	}

if uintptr(v)&(heapArenaBytes-1) != 0 {
		throw("misrounded allocation in sysAlloc")
	}

// Transition from Reserved to Prepared.
	sysMap(v, size, &memstats.heap_sys)

mapped:
	// Create arena metadata.
	for ri := arenaIndex(uintptr(v)); ri <= arenaIndex(uintptr(v)+size-1); ri++ {
		l2 := h.arenas[ri.l1()]
		if l2 == nil {
			// Allocate an L2 arena map.
			l2 = (*[1 << arenaL2Bits]*heapArena)(persistentalloc(unsafe.Sizeof(*l2), sys.PtrSize, nil))
			if l2 == nil {
				throw("out of memory allocating heap arena map")
			}
			atomic.StorepNoWB(unsafe.Pointer(&h.arenas[ri.l1()]), unsafe.Pointer(l2))
		}

if l2[ri.l2()] != nil {
			throw("arena already initialized")
		}
		var r *heapArena
		r = (*heapArena)(h.heapArenaAlloc.alloc(unsafe.Sizeof(*r), sys.PtrSize, &memstats.gc_sys))
		if r == nil {
			r = (*heapArena)(persistentalloc(unsafe.Sizeof(*r), sys.PtrSize, &memstats.gc_sys))
			if r == nil {
				throw("out of memory allocating heap arena metadata")
			}
		}

// Add the arena to the arenas list.
		if len(h.allArenas) == cap(h.allArenas) {
			size := 2 * uintptr(cap(h.allArenas)) * sys.PtrSize
			if size == 0 {
				size = physPageSize
			}
			newArray := (*notInHeap)(persistentalloc(size, sys.PtrSize, &memstats.gc_sys))
			if newArray == nil {
				throw("out of memory allocating allArenas")
			}
			oldSlice := h.allArenas
			*(*notInHeapSlice)(unsafe.Pointer(&h.allArenas)) = notInHeapSlice{newArray, len(h.allArenas), int(size / sys.PtrSize)}
			copy(h.allArenas, oldSlice)
			// Do not free the old backing array because
			// there may be concurrent readers. Since we
			// double the array each time, this can lead
			// to at most 2x waste.
		}
		h.allArenas = h.allArenas[:len(h.allArenas)+1]
		h.allArenas[len(h.allArenas)-1] = ri

// Store atomically just in case an object from the
		// new heap arena becomes visible before the heap lock
		// is released (which shouldn't happen, but there's
		// little downside to this).
		atomic.StorepNoWB(unsafe.Pointer(&l2[ri.l2()]), unsafe.Pointer(r))
	}

// Tell the race detector about the new heap memory.
	if raceenabled {
		racemapshadow(v, size)
	}

return
}

// sysReserveAligned is like sysReserve, but the returned pointer is
// aligned to align bytes. It may reserve either n or n+align bytes,
// so it returns the size that was reserved.
func sysReserveAligned(v unsafe.Pointer, size, align uintptr) (unsafe.Pointer, uintptr) {
	// Since the alignment is rather large in uses of this
	// function, we're not likely to get it by chance, so we ask
	// for a larger region and remove the parts we don't need.
	retries := 0
retry:
	p := uintptr(sysReserve(v, size+align))
	switch {
	case p == 0:
		return nil, 0
	case p&(align-1) == 0:
		// We got lucky and got an aligned region, so we can
		// use the whole thing.
		return unsafe.Pointer(p), size + align
	case GOOS == "windows":
		// On Windows we can't release pieces of a
		// reservation, so we release the whole thing and
		// re-reserve the aligned sub-region. This may race,
		// so we may have to try again.
		sysFree(unsafe.Pointer(p), size+align, nil)
		p = alignUp(p, align)
		p2 := sysReserve(unsafe.Pointer(p), size)
		if p != uintptr(p2) {
			// Must have raced. Try again.
			sysFree(p2, size, nil)
			if retries++; retries == 100 {
				throw("failed to allocate aligned heap memory; too many retries")
			}
			goto retry
		}
		// Success.
		return p2, size
	default:
		// Trim off the unaligned parts.
		pAligned := alignUp(p, align)
		sysFree(unsafe.Pointer(p), pAligned-p, nil)
		end := pAligned + size
		endLen := (p + size + align) - end
		if endLen > 0 {
			sysFree(unsafe.Pointer(end), endLen, nil)
		}
		return unsafe.Pointer(pAligned), size
	}
}

// base address for all 0-byte allocations
var zerobase uintptr

// nextFreeFast returns the next free object if one is quickly available.
// Otherwise it returns 0.
func nextFreeFast(s *mspan) gclinkptr {
	theBit := sys.Ctz64(s.allocCache) // Is there a free object in the allocCache?
	if theBit < 64 {
		result := s.freeindex + uintptr(theBit)
		if result < s.nelems {
			freeidx := result + 1
			if freeidx%64 == 0 && freeidx != s.nelems {
				return 0
			}
			s.allocCache >>= uint(theBit + 1)
			s.freeindex = freeidx
			s.allocCount++
			return gclinkptr(result*s.elemsize + s.base())
		}
	}
	return 0
}

// nextFree returns the next free object from the cached span if one is available.
// Otherwise it refills the cache with a span with an available object and
// returns that object along with a flag indicating that this was a heavy
// weight allocation. If it is a heavy weight allocation the caller must
// determine whether a new GC cycle needs to be started or if the GC is active
// whether this goroutine needs to assist the GC.
//
// Must run in a non-preemptible context since otherwise the owner of
// c could change.
func (c *mcache) nextFree(spc spanClass) (v gclinkptr, s *mspan, shouldhelpgc bool) {
	s = c.alloc[spc]
	shouldhelpgc = false
	freeIndex := s.nextFreeIndex()
	if freeIndex == s.nelems {
		// The span is full.
		if uintptr(s.allocCount) != s.nelems {
			println("runtime: s.allocCount=", s.allocCount, "s.nelems=", s.nelems)
			throw("s.allocCount != s.nelems && freeIndex == s.nelems")
		}
		c.refill(spc)
		shouldhelpgc = true
		s = c.alloc[spc]

freeIndex = s.nextFreeIndex()
	}

if freeIndex >= s.nelems {
		throw("freeIndex is not valid")
	}

v = gclinkptr(freeIndex*s.elemsize + s.base())
	s.allocCount++
	if uintptr(s.allocCount) > s.nelems {
		println("s.allocCount=", s.allocCount, "s.nelems=", s.nelems)
		throw("s.allocCount > s.nelems")
	}
	return
}

// Allocate an object of size bytes.
// Small objects are allocated from the per-P cache's free lists.
// Large objects (> 32 kB) are allocated straight from the heap.
func mallocgc(size uintptr, typ *_type, needzero bool) unsafe.Pointer {
	if gcphase == _GCmarktermination {
		throw("mallocgc called with gcphase == _GCmarktermination")
	}

if size == 0 {
		return unsafe.Pointer(&zerobase)
	}

if debug.sbrk != 0 {
		align := uintptr(16)
		if typ != nil {
			// TODO(austin): This should be just
			//   align = uintptr(typ.align)
			// but that's only 4 on 32-bit platforms,
			// even if there's a uint64 field in typ (see #599).
			// This causes 64-bit atomic accesses to panic.
			// Hence, we use stricter alignment that matches
			// the normal allocator better.
			if size&7 == 0 {
				align = 8
			} else if size&3 == 0 {
				align = 4
			} else if size&1 == 0 {
				align = 2
			} else {
				align = 1
			}
		}
		return persistentalloc(size, align, &memstats.other_sys)
	}

// assistG is the G to charge for this allocation, or nil if
	// GC is not currently active.
	var assistG *g
	if gcBlackenEnabled != 0 {
		// Charge the current user G for this allocation.
		assistG = getg()
		if assistG.m.curg != nil {
			assistG = assistG.m.curg
		}
		// Charge the allocation against the G. We'll account
		// for internal fragmentation at the end of mallocgc.
		assistG.gcAssistBytes -= int64(size)

if assistG.gcAssistBytes < 0 {
			// This G is in debt. Assist the GC to correct
			// this before allocating. This must happen
			// before disabling preemption.
			gcAssistAlloc(assistG)
		}
	}

// Set mp.mallocing to keep from being preempted by GC.
	mp := acquirem()
	if mp.mallocing != 0 {
		throw("malloc deadlock")
	}
	if mp.gsignal == getg() {
		throw("malloc during signal")
	}
	mp.mallocing = 1

shouldhelpgc := false
	dataSize := size
	c := gomcache()
	var x unsafe.Pointer
	noscan := typ == nil || typ.ptrdata == 0
	if size <= maxSmallSize {
		if noscan && size < maxTinySize {
			// Tiny allocator.
			//
			// Tiny allocator combines several tiny allocation requests
			// into a single memory block. The resulting memory block
			// is freed when all subobjects are unreachable. The subobjects
			// must be noscan (don't have pointers), this ensures that
			// the amount of potentially wasted memory is bounded.
			//
			// Size of the memory block used for combining (maxTinySize) is tunable.
			// Current setting is 16 bytes, which relates to 2x worst case memory
			// wastage (when all but one subobjects are unreachable).
			// 8 bytes would result in no wastage at all, but provides less
			// opportunities for combining.
			// 32 bytes provides more opportunities for combining,
			// but can lead to 4x worst case wastage.
			// The best case winning is 8x regardless of block size.
			//
			// Objects obtained from tiny allocator must not be freed explicitly.
			// So when an object will be freed explicitly, we ensure that
			// its size >= maxTinySize.
			//
			// SetFinalizer has a special case for objects potentially coming
			// from tiny allocator, it such case it allows to set finalizers
			// for an inner byte of a memory block.
			//
			// The main targets of tiny allocator are small strings and
			// standalone escaping variables. On a json benchmark
			// the allocator reduces number of allocations by ~12% and
			// reduces heap size by ~20%.
			off := c.tinyoffset
			// Align tiny pointer for required (conservative) alignment.
			if size&7 == 0 {
				off = alignUp(off, 8)
			} else if size&3 == 0 {
				off = alignUp(off, 4)
			} else if size&1 == 0 {
				off = alignUp(off, 2)
			}
			if off+size <= maxTinySize && c.tiny != 0 {
				// The object fits into existing tiny block.
				x = unsafe.Pointer(c.tiny + off)
				c.tinyoffset = off + size
				c.local_tinyallocs++
				mp.mallocing = 0
				releasem(mp)
				return x
			}
			// Allocate a new maxTinySize block.
			span := c.alloc[tinySpanClass]
			v := nextFreeFast(span)
			if v == 0 {
				v, _, shouldhelpgc = c.nextFree(tinySpanClass)
			}
			x = unsafe.Pointer(v)
			(*[2]uint64)(x)[0] = 0
			(*[2]uint64)(x)[1] = 0
			// See if we need to replace the existing tiny block with the new one
			// based on amount of remaining free space.
			if size < c.tinyoffset || c.tiny == 0 {
				c.tiny = uintptr(x)
				c.tinyoffset = size
			}
			size = maxTinySize
		} else {
			var sizeclass uint8
			if size <= smallSizeMax-8 {
				sizeclass = size_to_class8[(size+smallSizeDiv-1)/smallSizeDiv]
			} else {
				sizeclass = size_to_class128[(size-smallSizeMax+largeSizeDiv-1)/largeSizeDiv]
			}
			size = uintptr(class_to_size[sizeclass])
			spc := makeSpanClass(sizeclass, noscan)
			span := c.alloc[spc]
			v := nextFreeFast(span)
			if v == 0 {
				v, span, shouldhelpgc = c.nextFree(spc)
			}
			x = unsafe.Pointer(v)
			if needzero && span.needzero != 0 {
				memclrNoHeapPointers(unsafe.Pointer(v), size)
			}
		}
	} else {
		var s *mspan
		shouldhelpgc = true
		systemstack(func() {
			s = largeAlloc(size, needzero, noscan)
		})
		s.freeindex = 1
		s.allocCount = 1
		x = unsafe.Pointer(s.base())
		size = s.elemsize
	}

var scanSize uintptr
	if !noscan {
		// If allocating a defer+arg block, now that we've picked a malloc size
		// large enough to hold everything, cut the "asked for" size down to
		// just the defer header, so that the GC bitmap will record the arg block
		// as containing nothing at all (as if it were unused space at the end of
		// a malloc block caused by size rounding).
		// The defer arg areas are scanned as part of scanstack.
		if typ == deferType {
			dataSize = unsafe.Sizeof(_defer{})
		}
		heapBitsSetType(uintptr(x), size, dataSize, typ)
		if dataSize > typ.size {
			// Array allocation. If there are any
			// pointers, GC has to scan to the last
			// element.
			if typ.ptrdata != 0 {
				scanSize = dataSize - typ.size + typ.ptrdata
			}
		} else {
			scanSize = typ.ptrdata
		}
		c.local_scan += scanSize
	}

// Ensure that the stores above that initialize x to
	// type-safe memory and set the heap bits occur before
	// the caller can make x observable to the garbage
	// collector. Otherwise, on weakly ordered machines,
	// the garbage collector could follow a pointer to x,
	// but see uninitialized memory or stale heap bits.
	publicationBarrier()

// Allocate black during GC.
	// All slots hold nil so no scanning is needed.
	// This may be racing with GC so do it atomically if there can be
	// a race marking the bit.
	if gcphase != _GCoff {
		gcmarknewobject(uintptr(x), size, scanSize)
	}

if raceenabled {
		racemalloc(x, size)
	}

if msanenabled {
		msanmalloc(x, size)
	}

mp.mallocing = 0
	releasem(mp)

if debug.allocfreetrace != 0 {
		tracealloc(x, size, typ)
	}

if rate := MemProfileRate; rate > 0 {
		if rate != 1 && size < c.next_sample {
			c.next_sample -= size
		} else {
			mp := acquirem()
			profilealloc(mp, x, size)
			releasem(mp)
		}
	}

if assistG != nil {
		// Account for internal fragmentation in the assist
		// debt now that we know it.
		assistG.gcAssistBytes -= int64(size - dataSize)
	}

if shouldhelpgc {
		if t := (gcTrigger{kind: gcTriggerHeap}); t.test() {
			gcStart(t)
		}
	}

return x
}

func largeAlloc(size uintptr, needzero bool, noscan bool) *mspan {
	// print("largeAlloc size=", size, "\n")

if size+_PageSize < size {
		throw("out of memory")
	}
	npages := size >> _PageShift
	if size&_PageMask != 0 {
		npages++
	}

// Deduct credit for this span allocation and sweep if
	// necessary. mHeap_Alloc will also sweep npages, so this only
	// pays the debt down to npage pages.
	deductSweepCredit(npages*_PageSize, npages)

s := mheap_.alloc(npages, makeSpanClass(0, noscan), needzero)
	if s == nil {
		throw("out of memory")
	}
	s.limit = s.base() + size
	heapBitsForAddr(s.base()).initSpan(s)
	return s
}

// implementation of new builtin
// compiler (both frontend and SSA backend) knows the signature
// of this function
func newobject(typ *_type) unsafe.Pointer {
	return mallocgc(typ.size, typ, true)
}

//go:linkname reflect_unsafe_New reflect.unsafe_New
func reflect_unsafe_New(typ *_type) unsafe.Pointer {
	return mallocgc(typ.size, typ, true)
}

//go:linkname reflectlite_unsafe_New internal/reflectlite.unsafe_New
func reflectlite_unsafe_New(typ *_type) unsafe.Pointer {
	return mallocgc(typ.size, typ, true)
}

// newarray allocates an array of n elements of type typ.
func newarray(typ *_type, n int) unsafe.Pointer {
	if n == 1 {
		return mallocgc(typ.size, typ, true)
	}
	mem, overflow := math.MulUintptr(typ.size, uintptr(n))
	if overflow || mem > maxAlloc || n < 0 {
		panic(plainError("runtime: allocation size out of range"))
	}
	return mallocgc(mem, typ, true)
}

//go:linkname reflect_unsafe_NewArray reflect.unsafe_NewArray
func reflect_unsafe_NewArray(typ *_type, n int) unsafe.Pointer {
	return newarray(typ, n)
}

func profilealloc(mp *m, x unsafe.Pointer, size uintptr) {
	mp.mcache.next_sample = nextSample()
	mProf_Malloc(x, size)
}

// nextSample returns the next sampling point for heap profiling. The goal is
// to sample allocations on average every MemProfileRate bytes, but with a
// completely random distribution over the allocation timeline; this
// corresponds to a Poisson process with parameter MemProfileRate. In Poisson
// processes, the distance between two samples follows the exponential
// distribution (exp(MemProfileRate)), so the best return value is a random
// number taken from an exponential distribution whose mean is MemProfileRate.
func nextSample() uintptr {
	if GOOS == "plan9" {
		// Plan 9 doesn't support floating point in note handler.
		if g := getg(); g == g.m.gsignal {
			return nextSampleNoFP()
		}
	}

return uintptr(fastexprand(MemProfileRate))
}

// fastexprand returns a random number from an exponential distribution with
// the specified mean.
func fastexprand(mean int) int32 {
	// Avoid overflow. Maximum possible step is
	// -ln(1/(1<<randomBitCount)) * mean, approximately 20 * mean.
	switch {
	case mean > 0x7000000:
		mean = 0x7000000
	case mean == 0:
		return 0
	}

// Take a random sample of the exponential distribution exp(-mean*x).
	// The probability distribution function is mean*exp(-mean*x), so the CDF is
	// p = 1 - exp(-mean*x), so
	// q = 1 - p == exp(-mean*x)
	// log_e(q) = -mean*x
	// -log_e(q)/mean = x
	// x = -log_e(q) * mean
	// x = log_2(q) * (-log_e(2)) * mean    ; Using log_2 for efficiency
	const randomBitCount = 26
	q := fastrand()%(1<<randomBitCount) + 1
	qlog := fastlog2(float64(q)) - randomBitCount
	if qlog > 0 {
		qlog = 0
	}
	const minusLog2 = -0.6931471805599453 // -ln(2)
	return int32(qlog*(minusLog2*float64(mean))) + 1
}

// nextSampleNoFP is similar to nextSample, but uses older,
// simpler code to avoid floating point.
func nextSampleNoFP() uintptr {
	// Set first allocation sample size.
	rate := MemProfileRate
	if rate > 0x3fffffff { // make 2*rate not overflow
		rate = 0x3fffffff
	}
	if rate != 0 {
		return uintptr(fastrand() % uint32(2*rate))
	}
	return 0
}

type persistentAlloc struct {
	base *notInHeap
	off  uintptr
}

var globalAlloc struct {
	mutex
	persistentAlloc
}

// persistentChunkSize is the number of bytes we allocate when we grow
// a persistentAlloc.
const persistentChunkSize = 256 << 10

// persistentChunks is a list of all the persistent chunks we have
// allocated. The list is maintained through the first word in the
// persistent chunk. This is updated atomically.
var persistentChunks *notInHeap

// Wrapper around sysAlloc that can allocate small chunks.
// There is no associated free operation.
// Intended for things like function/type/debug-related persistent data.
// If align is 0, uses default align (currently 8).
// The returned memory will be zeroed.
//
// Consider marking persistentalloc'd types go:notinheap.
func persistentalloc(size, align uintptr, sysStat *uint64) unsafe.Pointer {
	var p *notInHeap
	systemstack(func() {
		p = persistentalloc1(size, align, sysStat)
	})
	return unsafe.Pointer(p)
}

// Must run on system stack because stack growth can (re)invoke it.
// See issue 9174.
//go:systemstack
func persistentalloc1(size, align uintptr, sysStat *uint64) *notInHeap {
	const (
		maxBlock = 64 << 10 // VM reservation granularity is 64K on windows
	)

if size == 0 {
		throw("persistentalloc: size == 0")
	}
	if align != 0 {
		if align&(align-1) != 0 {
			throw("persistentalloc: align is not a power of 2")
		}
		if align > _PageSize {
			throw("persistentalloc: align is too large")
		}
	} else {
		align = 8
	}

if size >= maxBlock {
		return (*notInHeap)(sysAlloc(size, sysStat))
	}

mp := acquirem()
	var persistent *persistentAlloc
	if mp != nil && mp.p != 0 {
		persistent = &mp.p.ptr().palloc
	} else {
		lock(&globalAlloc.mutex)
		persistent = &globalAlloc.persistentAlloc
	}
	persistent.off = alignUp(persistent.off, align)
	if persistent.off+size > persistentChunkSize || persistent.base == nil {
		persistent.base = (*notInHeap)(sysAlloc(persistentChunkSize, &memstats.other_sys))
		if persistent.base == nil {
			if persistent == &globalAlloc.persistentAlloc {
				unlock(&globalAlloc.mutex)
			}
			throw("runtime: cannot allocate memory")
		}

// Add the new chunk to the persistentChunks list.
		for {
			chunks := uintptr(unsafe.Pointer(persistentChunks))
			*(*uintptr)(unsafe.Pointer(persistent.base)) = chunks
			if atomic.Casuintptr((*uintptr)(unsafe.Pointer(&persistentChunks)), chunks, uintptr(unsafe.Pointer(persistent.base))) {
				break
			}
		}
		persistent.off = alignUp(sys.PtrSize, align)
	}
	p := persistent.base.add(persistent.off)
	persistent.off += size
	releasem(mp)
	if persistent == &globalAlloc.persistentAlloc {
		unlock(&globalAlloc.mutex)
	}

if sysStat != &memstats.other_sys {
		mSysStatInc(sysStat, size)
		mSysStatDec(&memstats.other_sys, size)
	}
	return p
}

// inPersistentAlloc reports whether p points to memory allocated by
// persistentalloc. This must be nosplit because it is called by the
// cgo checker code, which is called by the write barrier code.
//go:nosplit
func inPersistentAlloc(p uintptr) bool {
	chunk := atomic.Loaduintptr((*uintptr)(unsafe.Pointer(&persistentChunks)))
	for chunk != 0 {
		if p >= chunk && p < chunk+persistentChunkSize {
			return true
		}
		chunk = *(*uintptr)(unsafe.Pointer(chunk))
	}
	return false
}

// linearAlloc is a simple linear allocator that pre-reserves a region
// of memory and then maps that region into the Ready state as needed. The
// caller is responsible for locking.
type linearAlloc struct {
	next   uintptr // next free byte
	mapped uintptr // one byte past end of mapped space
	end    uintptr // end of reserved space
}

func (l *linearAlloc) init(base, size uintptr) {
	l.next, l.mapped = base, base
	l.end = base + size
}

func (l *linearAlloc) alloc(size, align uintptr, sysStat *uint64) unsafe.Pointer {
	p := alignUp(l.next, align)
	if p+size > l.end {
		return nil
	}
	l.next = p + size
	if pEnd := alignUp(l.next-1, physPageSize); pEnd > l.mapped {
		// Transition from Reserved to Prepared to Ready.
		sysMap(unsafe.Pointer(l.mapped), pEnd-l.mapped, sysStat)
		sysUsed(unsafe.Pointer(l.mapped), pEnd-l.mapped)
		l.mapped = pEnd
	}
	return unsafe.Pointer(p)
}

// notInHeap is off-heap memory allocated by a lower-level allocator
// like sysAlloc or persistentAlloc.
//
// In general, it's better to use real types marked as go:notinheap,
// but this serves as a generic type for situations where that isn't
// possible (like in the allocators).
//
// TODO: Use this as the return type of sysAlloc, persistentAlloc, etc?
//
//go:notinheap
type notInHeap struct{}

func (p *notInHeap) add(bytes uintptr) *notInHeap {
	return (*notInHeap)(unsafe.Pointer(uintptr(unsafe.Pointer(p)) + bytes))
}

${this.title}

Code Editor : malloc.go