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faa7a7e8ae
go/src/runtime/asm_arm.s
Austin Clements faa7a7e8ae runtime: implement GC stack barriers 
This commit implements stack barriers to minimize the amount of
stack re-scanning that must be done during mark termination.

Currently the GC scans stacks of active goroutines twice during every
GC cycle: once at the beginning during root discovery and once at the
end during mark termination. The second scan happens while the world
is stopped and guarantees that we've seen all of the roots (since
there are no write barriers on writes to local stack
variables). However, this means pause time is proportional to stack
size. In particularly recursive programs, this can drive pause time up
past our 10ms goal (e.g., it takes about 150ms to scan a 50MB heap).

Re-scanning the entire stack is rarely necessary, especially for large
stacks, because usually most of the frames on the stack were not
active between the first and second scans and hence any changes to
these frames (via non-escaping pointers passed down the stack) were
tracked by write barriers.

To efficiently track how far a stack has been unwound since the first
scan (and, hence, how much needs to be re-scanned), this commit
introduces stack barriers. During the first scan, at exponentially
spaced points in each stack, the scan overwrites return PCs with the
PC of the stack barrier function. When "returned" to, the stack
barrier function records how far the stack has unwound and jumps to
the original return PC for that point in the stack. Then the second
scan only needs to proceed as far as the lowest barrier that hasn't
been hit.

For deeply recursive programs, this substantially reduces mark
termination time (and hence pause time). For the goscheme example
linked in issue #10898, prior to this change, mark termination times
were typically between 100 and 500ms; with this change, mark
termination times are typically between 10 and 20ms. As a result of
the reduced stack scanning work, this reduces overall execution time
of the goscheme example by 20%.

Fixes #10898.

The effect of this on programs that are not deeply recursive is
minimal:

name                   old time/op    new time/op    delta
BinaryTree17              3.16s ± 2%     3.26s ± 1%  +3.31%  (p=0.000 n=19+19)
Fannkuch11                2.42s ± 1%     2.48s ± 1%  +2.24%  (p=0.000 n=17+19)
FmtFprintfEmpty          50.0ns ± 3%    49.8ns ± 1%    ~     (p=0.534 n=20+19)
FmtFprintfString          173ns ± 0%     175ns ± 0%  +1.49%  (p=0.000 n=16+19)
FmtFprintfInt             170ns ± 1%     175ns ± 1%  +2.97%  (p=0.000 n=20+19)
FmtFprintfIntInt          288ns ± 0%     295ns ± 0%  +2.73%  (p=0.000 n=16+19)
FmtFprintfPrefixedInt     242ns ± 1%     252ns ± 1%  +4.13%  (p=0.000 n=18+18)
FmtFprintfFloat           324ns ± 0%     323ns ± 0%  -0.36%  (p=0.000 n=20+19)
FmtManyArgs              1.14µs ± 0%    1.12µs ± 1%  -1.01%  (p=0.000 n=18+19)
GobDecode                8.88ms ± 1%    8.87ms ± 0%    ~     (p=0.480 n=19+18)
GobEncode                6.80ms ± 1%    6.85ms ± 0%  +0.82%  (p=0.000 n=20+18)
Gzip                      363ms ± 1%     363ms ± 1%    ~     (p=0.077 n=18+20)
Gunzip                   90.6ms ± 0%    90.0ms ± 1%  -0.71%  (p=0.000 n=17+18)
HTTPClientServer         51.5µs ± 1%    50.8µs ± 1%  -1.32%  (p=0.000 n=18+18)
JSONEncode               17.0ms ± 0%    17.1ms ± 0%  +0.40%  (p=0.000 n=18+17)
JSONDecode               61.8ms ± 0%    63.8ms ± 1%  +3.11%  (p=0.000 n=18+17)
Mandelbrot200            3.84ms ± 0%    3.84ms ± 1%    ~     (p=0.583 n=19+19)
GoParse                  3.71ms ± 1%    3.72ms ± 1%    ~     (p=0.159 n=18+19)
RegexpMatchEasy0_32       100ns ± 0%     100ns ± 1%  -0.19%  (p=0.033 n=17+19)
RegexpMatchEasy0_1K       342ns ± 1%     331ns ± 0%  -3.41%  (p=0.000 n=19+19)
RegexpMatchEasy1_32      82.5ns ± 0%    81.7ns ± 0%  -0.98%  (p=0.000 n=18+18)
RegexpMatchEasy1_1K       505ns ± 0%     494ns ± 1%  -2.16%  (p=0.000 n=18+18)
RegexpMatchMedium_32      137ns ± 1%     137ns ± 1%  -0.24%  (p=0.048 n=20+18)
RegexpMatchMedium_1K     41.6µs ± 0%    41.3µs ± 1%  -0.57%  (p=0.004 n=18+20)
RegexpMatchHard_32       2.11µs ± 0%    2.11µs ± 1%  +0.20%  (p=0.037 n=17+19)
RegexpMatchHard_1K       63.9µs ± 2%    63.3µs ± 0%  -0.99%  (p=0.000 n=20+17)
Revcomp                   560ms ± 1%     522ms ± 0%  -6.87%  (p=0.000 n=18+16)
Template                 75.0ms ± 0%    75.1ms ± 1%  +0.18%  (p=0.013 n=18+19)
TimeParse                 358ns ± 1%     364ns ± 0%  +1.74%  (p=0.000 n=20+15)
TimeFormat                360ns ± 0%     372ns ± 0%  +3.55%  (p=0.000 n=20+18)

Change-Id: If8a9bfae6c128d15a4f405e02bcfa50129df82a2
Reviewed-on: https://go-review.googlesource.com/10314
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-06-02 20:00:57 +00:00

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ArmAsm
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// Copyright 2009 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.
#include "go_asm.h"
#include "go_tls.h"
#include "funcdata.h"
#include "textflag.h"
// using frame size $-4 means do not save LR on stack.
TEXT runtime·rt0_go(SB),NOSPLIT,$-4
MOVW $0xcafebabe, R12
// copy arguments forward on an even stack
// use R13 instead of SP to avoid linker rewriting the offsets
MOVW 0(R13), R0 // argc
MOVW 4(R13), R1 // argv
SUB $64, R13 // plenty of scratch
AND $~7, R13
MOVW R0, 60(R13) // save argc, argv away
MOVW R1, 64(R13)
// set up g register
// g is R10
MOVW $runtime·g0(SB), g
MOVW $runtime·m0(SB), R8
// save m->g0 = g0
MOVW g, m_g0(R8)
// save g->m = m0
MOVW R8, g_m(g)
// create istack out of the OS stack
MOVW $(-8192+104)(R13), R0
MOVW R0, g_stackguard0(g)
MOVW R0, g_stackguard1(g)
MOVW R0, (g_stack+stack_lo)(g)
MOVW R13, (g_stack+stack_hi)(g)
BL runtime·emptyfunc(SB) // fault if stack check is wrong
BL runtime·_initcgo(SB) // will clobber R0-R3
// update stackguard after _cgo_init
MOVW (g_stack+stack_lo)(g), R0
ADD $const__StackGuard, R0
MOVW R0, g_stackguard0(g)
MOVW R0, g_stackguard1(g)
BL runtime·check(SB)
// saved argc, argv
MOVW 60(R13), R0
MOVW R0, 4(R13)
MOVW 64(R13), R1
MOVW R1, 8(R13)
BL runtime·args(SB)
BL runtime·checkgoarm(SB)
BL runtime·osinit(SB)
BL runtime·schedinit(SB)
// create a new goroutine to start program
MOVW $runtime·mainPC(SB), R0
MOVW.W R0, -4(R13)
MOVW $8, R0
MOVW.W R0, -4(R13)
MOVW $0, R0
MOVW.W R0, -4(R13) // push $0 as guard
BL runtime·newproc(SB)
MOVW $12(R13), R13 // pop args and LR
// start this M
BL runtime·mstart(SB)
MOVW $1234, R0
MOVW $1000, R1
MOVW R0, (R1) // fail hard
DATA runtime·mainPC+0(SB)/4,$runtime·main(SB)
GLOBL runtime·mainPC(SB),RODATA,$4
TEXT runtime·breakpoint(SB),NOSPLIT,$0-0
// gdb won't skip this breakpoint instruction automatically,
// so you must manually "set $pc+=4" to skip it and continue.
#ifdef GOOS_nacl
WORD $0xe125be7f // BKPT 0x5bef, NACL_INSTR_ARM_BREAKPOINT
#else
WORD $0xe7f001f0 // undefined instruction that gdb understands is a software breakpoint
#endif
RET
TEXT runtime·asminit(SB),NOSPLIT,$0-0
// disable runfast (flush-to-zero) mode of vfp if runtime.goarm > 5
MOVB runtime·goarm(SB), R11
CMP $5, R11
BLE 4(PC)
WORD $0xeef1ba10 // vmrs r11, fpscr
BIC $(1<<24), R11
WORD $0xeee1ba10 // vmsr fpscr, r11
RET
/*
* go-routine
*/
// void gosave(Gobuf*)
// save state in Gobuf; setjmp
TEXT runtime·gosave(SB),NOSPLIT,$-4-4
MOVW buf+0(FP), R0
MOVW R13, gobuf_sp(R0)
MOVW LR, gobuf_pc(R0)
MOVW g, gobuf_g(R0)
MOVW $0, R11
MOVW R11, gobuf_lr(R0)
MOVW R11, gobuf_ret(R0)
MOVW R11, gobuf_ctxt(R0)
RET
// void gogo(Gobuf*)
// restore state from Gobuf; longjmp
TEXT runtime·gogo(SB),NOSPLIT,$-4-4
MOVW buf+0(FP), R1
MOVW gobuf_g(R1), R0
BL setg<>(SB)
// NOTE: We updated g above, and we are about to update SP.
// Until LR and PC are also updated, the g/SP/LR/PC quadruple
// are out of sync and must not be used as the basis of a traceback.
// Sigprof skips the traceback when SP is not within g's bounds,
// and when the PC is inside this function, runtime.gogo.
// Since we are about to update SP, until we complete runtime.gogo
// we must not leave this function. In particular, no calls
// after this point: it must be straight-line code until the
// final B instruction.
// See large comment in sigprof for more details.
MOVW gobuf_sp(R1), R13 // restore SP==R13
MOVW gobuf_lr(R1), LR
MOVW gobuf_ret(R1), R0
MOVW gobuf_ctxt(R1), R7
MOVW $0, R11
MOVW R11, gobuf_sp(R1) // clear to help garbage collector
MOVW R11, gobuf_ret(R1)
MOVW R11, gobuf_lr(R1)
MOVW R11, gobuf_ctxt(R1)
MOVW gobuf_pc(R1), R11
CMP R11, R11 // set condition codes for == test, needed by stack split
B (R11)
// func mcall(fn func(*g))
// Switch to m->g0's stack, call fn(g).
// Fn must never return. It should gogo(&g->sched)
// to keep running g.
TEXT runtime·mcall(SB),NOSPLIT,$-4-4
// Save caller state in g->sched.
MOVW R13, (g_sched+gobuf_sp)(g)
MOVW LR, (g_sched+gobuf_pc)(g)
MOVW $0, R11
MOVW R11, (g_sched+gobuf_lr)(g)
MOVW g, (g_sched+gobuf_g)(g)
// Switch to m->g0 & its stack, call fn.
MOVW g, R1
MOVW g_m(g), R8
MOVW m_g0(R8), R0
BL setg<>(SB)
CMP g, R1
B.NE 2(PC)
B runtime·badmcall(SB)
MOVB runtime·iscgo(SB), R11
CMP $0, R11
BL.NE runtime·save_g(SB)
MOVW fn+0(FP), R0
MOVW (g_sched+gobuf_sp)(g), R13
SUB $8, R13
MOVW R1, 4(R13)
MOVW R0, R7
MOVW 0(R0), R0
BL (R0)
B runtime·badmcall2(SB)
RET
// systemstack_switch is a dummy routine that systemstack leaves at the bottom
// of the G stack. We need to distinguish the routine that
// lives at the bottom of the G stack from the one that lives
// at the top of the system stack because the one at the top of
// the system stack terminates the stack walk (see topofstack()).
TEXT runtime·systemstack_switch(SB),NOSPLIT,$0-0
MOVW $0, R0
BL (R0) // clobber lr to ensure push {lr} is kept
RET
// func systemstack(fn func())
TEXT runtime·systemstack(SB),NOSPLIT,$0-4
MOVW fn+0(FP), R0 // R0 = fn
MOVW g_m(g), R1 // R1 = m
MOVW m_gsignal(R1), R2 // R2 = gsignal
CMP g, R2
B.EQ noswitch
MOVW m_g0(R1), R2 // R2 = g0
CMP g, R2
B.EQ noswitch
MOVW m_curg(R1), R3
CMP g, R3
B.EQ switch
// Bad: g is not gsignal, not g0, not curg. What is it?
// Hide call from linker nosplit analysis.
MOVW $runtime·badsystemstack(SB), R0
BL (R0)
switch:
// save our state in g->sched. Pretend to
// be systemstack_switch if the G stack is scanned.
MOVW $runtime·systemstack_switch(SB), R3
ADD $4, R3, R3 // get past push {lr}
MOVW R3, (g_sched+gobuf_pc)(g)
MOVW R13, (g_sched+gobuf_sp)(g)
MOVW LR, (g_sched+gobuf_lr)(g)
MOVW g, (g_sched+gobuf_g)(g)
// switch to g0
MOVW R0, R5
MOVW R2, R0
BL setg<>(SB)
MOVW R5, R0
MOVW (g_sched+gobuf_sp)(R2), R3
// make it look like mstart called systemstack on g0, to stop traceback
SUB $4, R3, R3
MOVW $runtime·mstart(SB), R4
MOVW R4, 0(R3)
MOVW R3, R13
// call target function
MOVW R0, R7
MOVW 0(R0), R0
BL (R0)
// switch back to g
MOVW g_m(g), R1
MOVW m_curg(R1), R0
BL setg<>(SB)
MOVW (g_sched+gobuf_sp)(g), R13
MOVW $0, R3
MOVW R3, (g_sched+gobuf_sp)(g)
RET
noswitch:
MOVW R0, R7
MOVW 0(R0), R0
BL (R0)
RET
/*
* support for morestack
*/
// Called during function prolog when more stack is needed.
// R1 frame size
// R2 arg size
// R3 prolog's LR
// NB. we do not save R0 because we've forced 5c to pass all arguments
// on the stack.
// using frame size $-4 means do not save LR on stack.
//
// The traceback routines see morestack on a g0 as being
// the top of a stack (for example, morestack calling newstack
// calling the scheduler calling newm calling gc), so we must
// record an argument size. For that purpose, it has no arguments.
TEXT runtime·morestack(SB),NOSPLIT,$-4-0
// Cannot grow scheduler stack (m->g0).
MOVW g_m(g), R8
MOVW m_g0(R8), R4
CMP g, R4
BL.EQ runtime·abort(SB)
// Cannot grow signal stack (m->gsignal).
MOVW m_gsignal(R8), R4
CMP g, R4
BL.EQ runtime·abort(SB)
// Called from f.
// Set g->sched to context in f.
MOVW R7, (g_sched+gobuf_ctxt)(g)
MOVW R13, (g_sched+gobuf_sp)(g)
MOVW LR, (g_sched+gobuf_pc)(g)
MOVW R3, (g_sched+gobuf_lr)(g)
// Called from f.
// Set m->morebuf to f's caller.
MOVW R3, (m_morebuf+gobuf_pc)(R8) // f's caller's PC
MOVW R13, (m_morebuf+gobuf_sp)(R8) // f's caller's SP
MOVW $4(R13), R3 // f's argument pointer
MOVW g, (m_morebuf+gobuf_g)(R8)
// Call newstack on m->g0's stack.
MOVW m_g0(R8), R0
BL setg<>(SB)
MOVW (g_sched+gobuf_sp)(g), R13
BL runtime·newstack(SB)
// Not reached, but make sure the return PC from the call to newstack
// is still in this function, and not the beginning of the next.
RET
TEXT runtime·morestack_noctxt(SB),NOSPLIT,$-4-0
MOVW $0, R7
B runtime·morestack(SB)
TEXT runtime·stackBarrier(SB),NOSPLIT,$0
// We came here via a RET to an overwritten LR.
// R0 may be live. Other registers are available.
// Get the original return PC, g.stkbar[g.stkbarPos].savedLRVal.
MOVW (g_stkbar+slice_array)(g), R4
MOVW g_stkbarPos(g), R5
MOVW $stkbar__size, R6
MUL R5, R6
ADD R4, R6
MOVW stkbar_savedLRVal(R6), R6
// Record that this stack barrier was hit.
ADD $1, R5
MOVW R5, g_stkbarPos(g)
// Jump to the original return PC.
B (R6)
// reflectcall: call a function with the given argument list
// func call(argtype *_type, f *FuncVal, arg *byte, argsize, retoffset uint32).
// we don't have variable-sized frames, so we use a small number
// of constant-sized-frame functions to encode a few bits of size in the pc.
// Caution: ugly multiline assembly macros in your future!
#define DISPATCH(NAME,MAXSIZE) \
CMP $MAXSIZE, R0; \
B.HI 3(PC); \
MOVW $NAME(SB), R1; \
B (R1)
TEXT reflect·call(SB), NOSPLIT, $0-0
B ·reflectcall(SB)
TEXT ·reflectcall(SB),NOSPLIT,$-4-20
MOVW argsize+12(FP), R0
DISPATCH(runtime·call16, 16)
DISPATCH(runtime·call32, 32)
DISPATCH(runtime·call64, 64)
DISPATCH(runtime·call128, 128)
DISPATCH(runtime·call256, 256)
DISPATCH(runtime·call512, 512)
DISPATCH(runtime·call1024, 1024)
DISPATCH(runtime·call2048, 2048)
DISPATCH(runtime·call4096, 4096)
DISPATCH(runtime·call8192, 8192)
DISPATCH(runtime·call16384, 16384)
DISPATCH(runtime·call32768, 32768)
DISPATCH(runtime·call65536, 65536)
DISPATCH(runtime·call131072, 131072)
DISPATCH(runtime·call262144, 262144)
DISPATCH(runtime·call524288, 524288)
DISPATCH(runtime·call1048576, 1048576)
DISPATCH(runtime·call2097152, 2097152)
DISPATCH(runtime·call4194304, 4194304)
DISPATCH(runtime·call8388608, 8388608)
DISPATCH(runtime·call16777216, 16777216)
DISPATCH(runtime·call33554432, 33554432)
DISPATCH(runtime·call67108864, 67108864)
DISPATCH(runtime·call134217728, 134217728)
DISPATCH(runtime·call268435456, 268435456)
DISPATCH(runtime·call536870912, 536870912)
DISPATCH(runtime·call1073741824, 1073741824)
MOVW $runtime·badreflectcall(SB), R1
B (R1)
#define CALLFN(NAME,MAXSIZE) \
TEXT NAME(SB), WRAPPER, $MAXSIZE-20; \
NO_LOCAL_POINTERS; \
/* copy arguments to stack */ \
MOVW argptr+8(FP), R0; \
MOVW argsize+12(FP), R2; \
ADD $4, R13, R1; \
CMP $0, R2; \
B.EQ 5(PC); \
MOVBU.P 1(R0), R5; \
MOVBU.P R5, 1(R1); \
SUB $1, R2, R2; \
B -5(PC); \
/* call function */ \
MOVW f+4(FP), R7; \
MOVW (R7), R0; \
PCDATA $PCDATA_StackMapIndex, $0; \
BL (R0); \
/* copy return values back */ \
MOVW argptr+8(FP), R0; \
MOVW argsize+12(FP), R2; \
MOVW retoffset+16(FP), R3; \
ADD $4, R13, R1; \
ADD R3, R1; \
ADD R3, R0; \
SUB R3, R2; \
loop: \
CMP $0, R2; \
B.EQ end; \
MOVBU.P 1(R1), R5; \
MOVBU.P R5, 1(R0); \
SUB $1, R2, R2; \
B loop; \
end: \
/* execute write barrier updates */ \
MOVW argtype+0(FP), R1; \
MOVW argptr+8(FP), R0; \
MOVW argsize+12(FP), R2; \
MOVW retoffset+16(FP), R3; \
MOVW R1, 4(R13); \
MOVW R0, 8(R13); \
MOVW R2, 12(R13); \
MOVW R3, 16(R13); \
BL runtime·callwritebarrier(SB); \
RET
CALLFN(·call16, 16)
CALLFN(·call32, 32)
CALLFN(·call64, 64)
CALLFN(·call128, 128)
CALLFN(·call256, 256)
CALLFN(·call512, 512)
CALLFN(·call1024, 1024)
CALLFN(·call2048, 2048)
CALLFN(·call4096, 4096)
CALLFN(·call8192, 8192)
CALLFN(·call16384, 16384)
CALLFN(·call32768, 32768)
CALLFN(·call65536, 65536)
CALLFN(·call131072, 131072)
CALLFN(·call262144, 262144)
CALLFN(·call524288, 524288)
CALLFN(·call1048576, 1048576)
CALLFN(·call2097152, 2097152)
CALLFN(·call4194304, 4194304)
CALLFN(·call8388608, 8388608)
CALLFN(·call16777216, 16777216)
CALLFN(·call33554432, 33554432)
CALLFN(·call67108864, 67108864)
CALLFN(·call134217728, 134217728)
CALLFN(·call268435456, 268435456)
CALLFN(·call536870912, 536870912)
CALLFN(·call1073741824, 1073741824)
// void jmpdefer(fn, sp);
// called from deferreturn.
// 1. grab stored LR for caller
// 2. sub 4 bytes to get back to BL deferreturn
// 3. B to fn
// TODO(rsc): Push things on stack and then use pop
// to load all registers simultaneously, so that a profiling
// interrupt can never see mismatched SP/LR/PC.
// (And double-check that pop is atomic in that way.)
TEXT runtime·jmpdefer(SB),NOSPLIT,$0-8
MOVW 0(R13), LR
MOVW $-4(LR), LR // BL deferreturn
MOVW fv+0(FP), R7
MOVW argp+4(FP), R13
MOVW $-4(R13), R13 // SP is 4 below argp, due to saved LR
MOVW 0(R7), R1
B (R1)
// Save state of caller into g->sched. Smashes R11.
TEXT gosave<>(SB),NOSPLIT,$0
MOVW LR, (g_sched+gobuf_pc)(g)
MOVW R13, (g_sched+gobuf_sp)(g)
MOVW $0, R11
MOVW R11, (g_sched+gobuf_lr)(g)
MOVW R11, (g_sched+gobuf_ret)(g)
MOVW R11, (g_sched+gobuf_ctxt)(g)
RET
// asmcgocall(void(*fn)(void*), void *arg)
// Call fn(arg) on the scheduler stack,
// aligned appropriately for the gcc ABI.
// See cgocall.c for more details.
TEXT ·asmcgocall(SB),NOSPLIT,$0-8
MOVW fn+0(FP), R1
MOVW arg+4(FP), R0
BL asmcgocall<>(SB)
RET
TEXT ·asmcgocall_errno(SB),NOSPLIT,$0-12
MOVW fn+0(FP), R1
MOVW arg+4(FP), R0
BL asmcgocall<>(SB)
MOVW R0, ret+8(FP)
RET
TEXT asmcgocall<>(SB),NOSPLIT,$0-0
// fn in R1, arg in R0.
MOVW R13, R2
MOVW g, R4
// Figure out if we need to switch to m->g0 stack.
// We get called to create new OS threads too, and those
// come in on the m->g0 stack already.
MOVW g_m(g), R8
MOVW m_g0(R8), R3
CMP R3, g
BEQ g0
BL gosave<>(SB)
MOVW R0, R5
MOVW R3, R0
BL setg<>(SB)
MOVW R5, R0
MOVW (g_sched+gobuf_sp)(g), R13
// Now on a scheduling stack (a pthread-created stack).
g0:
SUB $24, R13
BIC $0x7, R13 // alignment for gcc ABI
MOVW R4, 20(R13) // save old g
MOVW (g_stack+stack_hi)(R4), R4
SUB R2, R4
MOVW R4, 16(R13) // save depth in stack (can't just save SP, as stack might be copied during a callback)
BL (R1)
// Restore registers, g, stack pointer.
MOVW R0, R5
MOVW 20(R13), R0
BL setg<>(SB)
MOVW (g_stack+stack_hi)(g), R1
MOVW 16(R13), R2
SUB R2, R1
MOVW R5, R0
MOVW R1, R13
RET
// cgocallback(void (*fn)(void*), void *frame, uintptr framesize)
// Turn the fn into a Go func (by taking its address) and call
// cgocallback_gofunc.
TEXT runtime·cgocallback(SB),NOSPLIT,$12-12
MOVW $fn+0(FP), R0
MOVW R0, 4(R13)
MOVW frame+4(FP), R0
MOVW R0, 8(R13)
MOVW framesize+8(FP), R0
MOVW R0, 12(R13)
MOVW $runtime·cgocallback_gofunc(SB), R0
BL (R0)
RET
// cgocallback_gofunc(void (*fn)(void*), void *frame, uintptr framesize)
// See cgocall.c for more details.
TEXT ·cgocallback_gofunc(SB),NOSPLIT,$8-12
NO_LOCAL_POINTERS
// Load m and g from thread-local storage.
MOVB runtime·iscgo(SB), R0
CMP $0, R0
BL.NE runtime·load_g(SB)
// If g is nil, Go did not create the current thread.
// Call needm to obtain one for temporary use.
// In this case, we're running on the thread stack, so there's
// lots of space, but the linker doesn't know. Hide the call from
// the linker analysis by using an indirect call.
CMP $0, g
B.NE havem
MOVW g, savedm-4(SP) // g is zero, so is m.
MOVW $runtime·needm(SB), R0
BL (R0)
// Set m->sched.sp = SP, so that if a panic happens
// during the function we are about to execute, it will
// have a valid SP to run on the g0 stack.
// The next few lines (after the havem label)
// will save this SP onto the stack and then write
// the same SP back to m->sched.sp. That seems redundant,
// but if an unrecovered panic happens, unwindm will
// restore the g->sched.sp from the stack location
// and then systemstack will try to use it. If we don't set it here,
// that restored SP will be uninitialized (typically 0) and
// will not be usable.
MOVW g_m(g), R8
MOVW m_g0(R8), R3
MOVW R13, (g_sched+gobuf_sp)(R3)
havem:
MOVW g_m(g), R8
MOVW R8, savedm-4(SP)
// Now there's a valid m, and we're running on its m->g0.
// Save current m->g0->sched.sp on stack and then set it to SP.
// Save current sp in m->g0->sched.sp in preparation for
// switch back to m->curg stack.
// NOTE: unwindm knows that the saved g->sched.sp is at 4(R13) aka savedsp-8(SP).
MOVW m_g0(R8), R3
MOVW (g_sched+gobuf_sp)(R3), R4
MOVW R4, savedsp-8(SP)
MOVW R13, (g_sched+gobuf_sp)(R3)
// Switch to m->curg stack and call runtime.cgocallbackg.
// Because we are taking over the execution of m->curg
// but *not* resuming what had been running, we need to
// save that information (m->curg->sched) so we can restore it.
// We can restore m->curg->sched.sp easily, because calling
// runtime.cgocallbackg leaves SP unchanged upon return.
// To save m->curg->sched.pc, we push it onto the stack.
// This has the added benefit that it looks to the traceback
// routine like cgocallbackg is going to return to that
// PC (because the frame we allocate below has the same
// size as cgocallback_gofunc's frame declared above)
// so that the traceback will seamlessly trace back into
// the earlier calls.
//
// In the new goroutine, -8(SP) and -4(SP) are unused.
MOVW m_curg(R8), R0
BL setg<>(SB)
MOVW (g_sched+gobuf_sp)(g), R4 // prepare stack as R4
MOVW (g_sched+gobuf_pc)(g), R5
MOVW R5, -12(R4)
MOVW $-12(R4), R13
BL runtime·cgocallbackg(SB)
// Restore g->sched (== m->curg->sched) from saved values.
MOVW 0(R13), R5
MOVW R5, (g_sched+gobuf_pc)(g)
MOVW $12(R13), R4
MOVW R4, (g_sched+gobuf_sp)(g)
// Switch back to m->g0's stack and restore m->g0->sched.sp.
// (Unlike m->curg, the g0 goroutine never uses sched.pc,
// so we do not have to restore it.)
MOVW g_m(g), R8
MOVW m_g0(R8), R0
BL setg<>(SB)
MOVW (g_sched+gobuf_sp)(g), R13
MOVW savedsp-8(SP), R4
MOVW R4, (g_sched+gobuf_sp)(g)
// If the m on entry was nil, we called needm above to borrow an m
// for the duration of the call. Since the call is over, return it with dropm.
MOVW savedm-4(SP), R6
CMP $0, R6
B.NE 3(PC)
MOVW $runtime·dropm(SB), R0
BL (R0)
// Done!
RET
// void setg(G*); set g. for use by needm.
TEXT runtime·setg(SB),NOSPLIT,$-4-4
MOVW gg+0(FP), R0
B setg<>(SB)
TEXT setg<>(SB),NOSPLIT,$-4-0
MOVW R0, g
// Save g to thread-local storage.
MOVB runtime·iscgo(SB), R0
CMP $0, R0
B.EQ 2(PC)
B runtime·save_g(SB)
MOVW g, R0
RET
TEXT runtime·getcallerpc(SB),NOSPLIT,$4-8
MOVW 8(R13), R0 // LR saved by caller
MOVW runtime·stackBarrierPC(SB), R1
CMP R0, R1
BNE nobar
// Get original return PC.
BL runtime·nextBarrierPC(SB)
MOVW 4(R13), R0
nobar:
MOVW R0, ret+4(FP)
RET
TEXT runtime·setcallerpc(SB),NOSPLIT,$4-8
MOVW pc+4(FP), R0
MOVW 8(R13), R1
MOVW runtime·stackBarrierPC(SB), R2
CMP R1, R2
BEQ setbar
MOVW R0, 8(R13) // set LR in caller
RET
setbar:
// Set the stack barrier return PC.
MOVW R0, 4(R13)
BL runtime·setNextBarrierPC(SB)
RET
TEXT runtime·getcallersp(SB),NOSPLIT,$-4-8
MOVW argp+0(FP), R0
MOVW $-4(R0), R0
MOVW R0, ret+4(FP)
RET
TEXT runtime·emptyfunc(SB),0,$0-0
RET
TEXT runtime·abort(SB),NOSPLIT,$-4-0
MOVW $0, R0
MOVW (R0), R1
// bool armcas(int32 *val, int32 old, int32 new)
// Atomically:
// if(*val == old){
// *val = new;
// return 1;
// }else
// return 0;
//
// To implement runtime·cas in sys_$GOOS_arm.s
// using the native instructions, use:
//
// TEXT runtime·cas(SB),NOSPLIT,$0
// B runtime·armcas(SB)
//
TEXT runtime·armcas(SB),NOSPLIT,$0-13
MOVW valptr+0(FP), R1
MOVW old+4(FP), R2
MOVW new+8(FP), R3
casl:
LDREX (R1), R0
CMP R0, R2
BNE casfail
STREX R3, (R1), R0
CMP $0, R0
BNE casl
MOVW $1, R0
MOVB R0, ret+12(FP)
RET
casfail:
MOVW $0, R0
MOVB R0, ret+12(FP)
RET
TEXT runtime·casuintptr(SB),NOSPLIT,$0-13
B runtime·cas(SB)
TEXT runtime·atomicloaduintptr(SB),NOSPLIT,$0-8
B runtime·atomicload(SB)
TEXT runtime·atomicloaduint(SB),NOSPLIT,$0-8
B runtime·atomicload(SB)
TEXT runtime·atomicstoreuintptr(SB),NOSPLIT,$0-8
B runtime·atomicstore(SB)
// AES hashing not implemented for ARM
TEXT runtime·aeshash(SB),NOSPLIT,$-4-0
MOVW $0, R0
MOVW (R0), R1
TEXT runtime·aeshash32(SB),NOSPLIT,$-4-0
MOVW $0, R0
MOVW (R0), R1
TEXT runtime·aeshash64(SB),NOSPLIT,$-4-0
MOVW $0, R0
MOVW (R0), R1
TEXT runtime·aeshashstr(SB),NOSPLIT,$-4-0
MOVW $0, R0
MOVW (R0), R1
// memhash_varlen(p unsafe.Pointer, h seed) uintptr
// redirects to memhash(p, h, size) using the size
// stored in the closure.
TEXT runtime·memhash_varlen(SB),NOSPLIT,$16-12
GO_ARGS
NO_LOCAL_POINTERS
MOVW p+0(FP), R0
MOVW h+4(FP), R1
MOVW 4(R7), R2
MOVW R0, 4(R13)
MOVW R1, 8(R13)
MOVW R2, 12(R13)
BL runtime·memhash(SB)
MOVW 16(R13), R0
MOVW R0, ret+8(FP)
RET
TEXT runtime·memeq(SB),NOSPLIT,$-4-13
MOVW a+0(FP), R1
MOVW b+4(FP), R2
MOVW size+8(FP), R3
ADD R1, R3, R6
MOVW $1, R0
MOVB R0, ret+12(FP)
loop:
CMP R1, R6
RET.EQ
MOVBU.P 1(R1), R4
MOVBU.P 1(R2), R5
CMP R4, R5
BEQ loop
MOVW $0, R0
MOVB R0, ret+12(FP)
RET
// memequal_varlen(a, b unsafe.Pointer) bool
TEXT runtime·memequal_varlen(SB),NOSPLIT,$16-9
MOVW a+0(FP), R0
MOVW b+4(FP), R1
CMP R0, R1
BEQ eq
MOVW 4(R7), R2 // compiler stores size at offset 4 in the closure
MOVW R0, 4(R13)
MOVW R1, 8(R13)
MOVW R2, 12(R13)
BL runtime·memeq(SB)
MOVB 16(R13), R0
MOVB R0, ret+8(FP)
RET
eq:
MOVW $1, R0
MOVB R0, ret+8(FP)
RET
TEXT runtime·cmpstring(SB),NOSPLIT,$-4-20
MOVW s1_base+0(FP), R2
MOVW s1_len+4(FP), R0
MOVW s2_base+8(FP), R3
MOVW s2_len+12(FP), R1
ADD $20, R13, R7
B runtime·cmpbody(SB)
TEXT bytes·Compare(SB),NOSPLIT,$-4-28
MOVW s1+0(FP), R2
MOVW s1+4(FP), R0
MOVW s2+12(FP), R3
MOVW s2+16(FP), R1
ADD $28, R13, R7
B runtime·cmpbody(SB)
// On entry:
// R0 is the length of s1
// R1 is the length of s2
// R2 points to the start of s1
// R3 points to the start of s2
// R7 points to return value (-1/0/1 will be written here)
//
// On exit:
// R4, R5, and R6 are clobbered
TEXT runtime·cmpbody(SB),NOSPLIT,$-4-0
CMP R0, R1
MOVW R0, R6
MOVW.LT R1, R6 // R6 is min(R0, R1)
ADD R2, R6 // R2 is current byte in s1, R6 is last byte in s1 to compare
loop:
CMP R2, R6
BEQ samebytes // all compared bytes were the same; compare lengths
MOVBU.P 1(R2), R4
MOVBU.P 1(R3), R5
CMP R4, R5
BEQ loop
// bytes differed
MOVW.LT $1, R0
MOVW.GT $-1, R0
MOVW R0, (R7)
RET
samebytes:
CMP R0, R1
MOVW.LT $1, R0
MOVW.GT $-1, R0
MOVW.EQ $0, R0
MOVW R0, (R7)
RET
// eqstring tests whether two strings are equal.
// The compiler guarantees that strings passed
// to eqstring have equal length.
// See runtime_test.go:eqstring_generic for
// equivalent Go code.
TEXT runtime·eqstring(SB),NOSPLIT,$-4-17
MOVW s1str+0(FP), R2
MOVW s2str+8(FP), R3
MOVW $1, R8
MOVB R8, v+16(FP)
CMP R2, R3
RET.EQ
MOVW s1len+4(FP), R0
ADD R2, R0, R6
loop:
CMP R2, R6
RET.EQ
MOVBU.P 1(R2), R4
MOVBU.P 1(R3), R5
CMP R4, R5
BEQ loop
MOVW $0, R8
MOVB R8, v+16(FP)
RET
// TODO: share code with memeq?
TEXT bytes·Equal(SB),NOSPLIT,$0-25
MOVW a_len+4(FP), R1
MOVW b_len+16(FP), R3
CMP R1, R3 // unequal lengths are not equal
B.NE notequal
MOVW a+0(FP), R0
MOVW b+12(FP), R2
ADD R0, R1 // end
loop:
CMP R0, R1
B.EQ equal // reached the end
MOVBU.P 1(R0), R4
MOVBU.P 1(R2), R5
CMP R4, R5
B.EQ loop
notequal:
MOVW $0, R0
MOVBU R0, ret+24(FP)
RET
equal:
MOVW $1, R0
MOVBU R0, ret+24(FP)
RET
TEXT bytes·IndexByte(SB),NOSPLIT,$0-20
MOVW s+0(FP), R0
MOVW s_len+4(FP), R1
MOVBU c+12(FP), R2 // byte to find
MOVW R0, R4 // store base for later
ADD R0, R1 // end
_loop:
CMP R0, R1
B.EQ _notfound
MOVBU.P 1(R0), R3
CMP R2, R3
B.NE _loop
SUB $1, R0 // R0 will be one beyond the position we want
SUB R4, R0 // remove base
MOVW R0, ret+16(FP)
RET
_notfound:
MOVW $-1, R0
MOVW R0, ret+16(FP)
RET
TEXT strings·IndexByte(SB),NOSPLIT,$0-16
MOVW s+0(FP), R0
MOVW s_len+4(FP), R1
MOVBU c+8(FP), R2 // byte to find
MOVW R0, R4 // store base for later
ADD R0, R1 // end
_sib_loop:
CMP R0, R1
B.EQ _sib_notfound
MOVBU.P 1(R0), R3
CMP R2, R3
B.NE _sib_loop
SUB $1, R0 // R0 will be one beyond the position we want
SUB R4, R0 // remove base
MOVW R0, ret+12(FP)
RET
_sib_notfound:
MOVW $-1, R0
MOVW R0, ret+12(FP)
RET
TEXT runtime·fastrand1(SB),NOSPLIT,$-4-4
MOVW g_m(g), R1
MOVW m_fastrand(R1), R0
ADD.S R0, R0
EOR.MI $0x88888eef, R0
MOVW R0, m_fastrand(R1)
MOVW R0, ret+0(FP)
RET
TEXT runtime·return0(SB),NOSPLIT,$0
MOVW $0, R0
RET
TEXT runtime·procyield(SB),NOSPLIT,$-4
MOVW cycles+0(FP), R1
MOVW $0, R0
yieldloop:
CMP R0, R1
B.NE 2(PC)
RET
SUB $1, R1
B yieldloop
// Called from cgo wrappers, this function returns g->m->curg.stack.hi.
// Must obey the gcc calling convention.
TEXT _cgo_topofstack(SB),NOSPLIT,$8
// R11 and g register are clobbered by load_g. They are
// callee-save in the gcc calling convention, so save them here.
MOVW R11, saveR11-4(SP)
MOVW g, saveG-8(SP)
BL runtime·load_g(SB)
MOVW g_m(g), R0
MOVW m_curg(R0), R0
MOVW (g_stack+stack_hi)(R0), R0
MOVW saveG-8(SP), g
MOVW saveR11-4(SP), R11
RET
// The top-most function running on a goroutine
// returns to goexit+PCQuantum.
TEXT runtime·goexit(SB),NOSPLIT,$-4-0
MOVW R0, R0 // NOP
BL runtime·goexit1(SB) // does not return
// traceback from goexit1 must hit code range of goexit
MOVW R0, R0 // NOP
TEXT runtime·prefetcht0(SB),NOSPLIT,$0-4
RET
TEXT runtime·prefetcht1(SB),NOSPLIT,$0-4
RET
TEXT runtime·prefetcht2(SB),NOSPLIT,$0-4
RET
TEXT runtime·prefetchnta(SB),NOSPLIT,$0-4
RET
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