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go/src/runtime/asm_mipsx.s
Wei Xiao 20102594a0 cmd/compile: intrinsify runtime.getcallerpc on all link register architectures 
Add a compiler intrinsic for getcallerpc on following architectures:
  arm
  mips mipsle mips64 mips64le
  ppc64 ppc64le
  s390x

Change-Id: I758f3d4742fc214b206bcd07d90408622c17dbef
Reviewed-on: https://go-review.googlesource.com/110835
Run-TryBot: Wei Xiao <Wei.Xiao@arm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2018-05-02 16:59:27 +00:00

770 lines
20 KiB
ArmAsm
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// Copyright 2016 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.
// +build mips mipsle
#include "go_asm.h"
#include "go_tls.h"
#include "funcdata.h"
#include "textflag.h"
#define REGCTXT R22
TEXT runtime·rt0_go(SB),NOSPLIT,$0
// R29 = stack; R4 = argc; R5 = argv
ADDU $-12, R29
MOVW R4, 4(R29) // argc
MOVW R5, 8(R29) // argv
// create istack out of the given (operating system) stack.
// _cgo_init may update stackguard.
MOVW $runtime·g0(SB), g
MOVW $(-64*1024), R23
ADD R23, R29, R1
MOVW R1, g_stackguard0(g)
MOVW R1, g_stackguard1(g)
MOVW R1, (g_stack+stack_lo)(g)
MOVW R29, (g_stack+stack_hi)(g)
// if there is a _cgo_init, call it using the gcc ABI.
MOVW _cgo_init(SB), R25
BEQ R25, nocgo
ADDU $-16, R29
MOVW R0, R7 // arg 3: not used
MOVW R0, R6 // arg 2: not used
MOVW $setg_gcc<>(SB), R5 // arg 1: setg
MOVW g, R4 // arg 0: G
JAL (R25)
ADDU $16, R29
nocgo:
// update stackguard after _cgo_init
MOVW (g_stack+stack_lo)(g), R1
ADD $const__StackGuard, R1
MOVW R1, g_stackguard0(g)
MOVW R1, g_stackguard1(g)
// set the per-goroutine and per-mach "registers"
MOVW $runtime·m0(SB), R1
// save m->g0 = g0
MOVW g, m_g0(R1)
// save m0 to g0->m
MOVW R1, g_m(g)
JAL runtime·check(SB)
// args are already prepared
JAL runtime·args(SB)
JAL runtime·osinit(SB)
JAL runtime·schedinit(SB)
// create a new goroutine to start program
MOVW $runtime·mainPC(SB), R1 // entry
ADDU $-12, R29
MOVW R1, 8(R29)
MOVW R0, 4(R29)
MOVW R0, 0(R29)
JAL runtime·newproc(SB)
ADDU $12, R29
// start this M
JAL runtime·mstart(SB)
UNDEF
RET
DATA runtime·mainPC+0(SB)/4,$runtime·main(SB)
GLOBL runtime·mainPC(SB),RODATA,$4
TEXT runtime·breakpoint(SB),NOSPLIT,$0-0
BREAK
RET
TEXT runtime·asminit(SB),NOSPLIT,$0-0
RET
/*
* go-routine
*/
// void gosave(Gobuf*)
// save state in Gobuf; setjmp
TEXT runtime·gosave(SB),NOSPLIT|NOFRAME,$0-4
MOVW buf+0(FP), R1
MOVW R29, gobuf_sp(R1)
MOVW R31, gobuf_pc(R1)
MOVW g, gobuf_g(R1)
MOVW R0, gobuf_lr(R1)
MOVW R0, gobuf_ret(R1)
// Assert ctxt is zero. See func save.
MOVW gobuf_ctxt(R1), R1
BEQ R1, 2(PC)
JAL runtime·badctxt(SB)
RET
// void gogo(Gobuf*)
// restore state from Gobuf; longjmp
TEXT runtime·gogo(SB),NOSPLIT,$8-4
MOVW buf+0(FP), R3
MOVW gobuf_g(R3), g // make sure g is not nil
JAL runtime·save_g(SB)
MOVW 0(g), R2
MOVW gobuf_sp(R3), R29
MOVW gobuf_lr(R3), R31
MOVW gobuf_ret(R3), R1
MOVW gobuf_ctxt(R3), REGCTXT
MOVW R0, gobuf_sp(R3)
MOVW R0, gobuf_ret(R3)
MOVW R0, gobuf_lr(R3)
MOVW R0, gobuf_ctxt(R3)
MOVW gobuf_pc(R3), R4
JMP (R4)
// void 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|NOFRAME,$0-4
// Save caller state in g->sched
MOVW R29, (g_sched+gobuf_sp)(g)
MOVW R31, (g_sched+gobuf_pc)(g)
MOVW R0, (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), R3
MOVW m_g0(R3), g
JAL runtime·save_g(SB)
BNE g, R1, 2(PC)
JMP runtime·badmcall(SB)
MOVW fn+0(FP), REGCTXT // context
MOVW 0(REGCTXT), R4 // code pointer
MOVW (g_sched+gobuf_sp)(g), R29 // sp = m->g0->sched.sp
ADDU $-8, R29 // make room for 1 arg and fake LR
MOVW R1, 4(R29)
MOVW R0, 0(R29)
JAL (R4)
JMP runtime·badmcall2(SB)
// 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
UNDEF
JAL (R31) // make sure this function is not leaf
RET
// func systemstack(fn func())
TEXT runtime·systemstack(SB),NOSPLIT,$0-4
MOVW fn+0(FP), R1 // R1 = fn
MOVW R1, REGCTXT // context
MOVW g_m(g), R2 // R2 = m
MOVW m_gsignal(R2), R3 // R3 = gsignal
BEQ g, R3, noswitch
MOVW m_g0(R2), R3 // R3 = g0
BEQ g, R3, noswitch
MOVW m_curg(R2), R4
BEQ g, R4, switch
// Bad: g is not gsignal, not g0, not curg. What is it?
// Hide call from linker nosplit analysis.
MOVW $runtime·badsystemstack(SB), R4
JAL (R4)
JAL runtime·abort(SB)
switch:
// save our state in g->sched. Pretend to
// be systemstack_switch if the G stack is scanned.
MOVW $runtime·systemstack_switch(SB), R4
ADDU $8, R4 // get past prologue
MOVW R4, (g_sched+gobuf_pc)(g)
MOVW R29, (g_sched+gobuf_sp)(g)
MOVW R0, (g_sched+gobuf_lr)(g)
MOVW g, (g_sched+gobuf_g)(g)
// switch to g0
MOVW R3, g
JAL runtime·save_g(SB)
MOVW (g_sched+gobuf_sp)(g), R1
// make it look like mstart called systemstack on g0, to stop traceback
ADDU $-4, R1
MOVW $runtime·mstart(SB), R2
MOVW R2, 0(R1)
MOVW R1, R29
// call target function
MOVW 0(REGCTXT), R4 // code pointer
JAL (R4)
// switch back to g
MOVW g_m(g), R1
MOVW m_curg(R1), g
JAL runtime·save_g(SB)
MOVW (g_sched+gobuf_sp)(g), R29
MOVW R0, (g_sched+gobuf_sp)(g)
RET
noswitch:
// already on m stack, just call directly
// Using a tail call here cleans up tracebacks since we won't stop
// at an intermediate systemstack.
MOVW 0(REGCTXT), R4 // code pointer
MOVW 0(R29), R31 // restore LR
ADD $4, R29
JMP (R4)
/*
* support for morestack
*/
// Called during function prolog when more stack is needed.
// Caller has already loaded:
// R1: framesize, R2: argsize, R3: LR
//
// 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|NOFRAME,$0-0
// Cannot grow scheduler stack (m->g0).
MOVW g_m(g), R7
MOVW m_g0(R7), R8
BNE g, R8, 3(PC)
JAL runtime·badmorestackg0(SB)
JAL runtime·abort(SB)
// Cannot grow signal stack (m->gsignal).
MOVW m_gsignal(R7), R8
BNE g, R8, 3(PC)
JAL runtime·badmorestackgsignal(SB)
JAL runtime·abort(SB)
// Called from f.
// Set g->sched to context in f.
MOVW R29, (g_sched+gobuf_sp)(g)
MOVW R31, (g_sched+gobuf_pc)(g)
MOVW R3, (g_sched+gobuf_lr)(g)
MOVW REGCTXT, (g_sched+gobuf_ctxt)(g)
// Called from f.
// Set m->morebuf to f's caller.
MOVW R3, (m_morebuf+gobuf_pc)(R7) // f's caller's PC
MOVW R29, (m_morebuf+gobuf_sp)(R7) // f's caller's SP
MOVW g, (m_morebuf+gobuf_g)(R7)
// Call newstack on m->g0's stack.
MOVW m_g0(R7), g
JAL runtime·save_g(SB)
MOVW (g_sched+gobuf_sp)(g), R29
// Create a stack frame on g0 to call newstack.
MOVW R0, -4(R29) // Zero saved LR in frame
ADDU $-4, R29
JAL 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.
UNDEF
TEXT runtime·morestack_noctxt(SB),NOSPLIT,$0-0
MOVW R0, REGCTXT
JMP runtime·morestack(SB)
// 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.
#define DISPATCH(NAME,MAXSIZE) \
MOVW $MAXSIZE, R23; \
SGTU R1, R23, R23; \
BNE R23, 3(PC); \
MOVW $NAME(SB), R4; \
JMP (R4)
TEXT reflect·call(SB),NOSPLIT,$0-20
JMP ·reflectcall(SB)
TEXT ·reflectcall(SB),NOSPLIT|NOFRAME,$0-20
MOVW argsize+12(FP), R1
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 $runtime·badreflectcall(SB), R4
JMP (R4)
#define CALLFN(NAME,MAXSIZE) \
TEXT NAME(SB),WRAPPER,$MAXSIZE-20; \
NO_LOCAL_POINTERS; \
/* copy arguments to stack */ \
MOVW arg+8(FP), R1; \
MOVW argsize+12(FP), R2; \
MOVW R29, R3; \
ADDU $4, R3; \
ADDU R3, R2; \
BEQ R3, R2, 6(PC); \
MOVBU (R1), R4; \
ADDU $1, R1; \
MOVBU R4, (R3); \
ADDU $1, R3; \
JMP -5(PC); \
/* call function */ \
MOVW f+4(FP), REGCTXT; \
MOVW (REGCTXT), R4; \
PCDATA $PCDATA_StackMapIndex, $0; \
JAL (R4); \
/* copy return values back */ \
MOVW argtype+0(FP), R5; \
MOVW arg+8(FP), R1; \
MOVW n+12(FP), R2; \
MOVW retoffset+16(FP), R4; \
ADDU $4, R29, R3; \
ADDU R4, R3; \
ADDU R4, R1; \
SUBU R4, R2; \
JAL callRet<>(SB); \
RET
// callRet copies return values back at the end of call*. This is a
// separate function so it can allocate stack space for the arguments
// to reflectcallmove. It does not follow the Go ABI; it expects its
// arguments in registers.
TEXT callRet<>(SB), NOSPLIT, $16-0
MOVW R5, 4(R29)
MOVW R1, 8(R29)
MOVW R3, 12(R29)
MOVW R2, 16(R29)
JAL runtime·reflectcallmove(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)
TEXT runtime·procyield(SB),NOSPLIT,$0-4
RET
// void jmpdefer(fv, sp);
// called from deferreturn.
// 1. grab stored LR for caller
// 2. sub 8 bytes to get back to JAL deferreturn
// 3. JMP to fn
TEXT runtime·jmpdefer(SB),NOSPLIT,$0-8
MOVW 0(R29), R31
ADDU $-8, R31
MOVW fv+0(FP), REGCTXT
MOVW argp+4(FP), R29
ADDU $-4, R29
NOR R0, R0 // prevent scheduling
MOVW 0(REGCTXT), R4
JMP (R4)
// Save state of caller into g->sched. Smashes R1.
TEXT gosave<>(SB),NOSPLIT|NOFRAME,$0
MOVW R31, (g_sched+gobuf_pc)(g)
MOVW R29, (g_sched+gobuf_sp)(g)
MOVW R0, (g_sched+gobuf_lr)(g)
MOVW R0, (g_sched+gobuf_ret)(g)
// Assert ctxt is zero. See func save.
MOVW (g_sched+gobuf_ctxt)(g), R1
BEQ R1, 2(PC)
JAL runtime·badctxt(SB)
RET
// func asmcgocall(fn, arg unsafe.Pointer) int32
// Call fn(arg) on the scheduler stack,
// aligned appropriately for the gcc ABI.
// See cgocall.go for more details.
TEXT ·asmcgocall(SB),NOSPLIT,$0-12
MOVW fn+0(FP), R25
MOVW arg+4(FP), R4
MOVW R29, R3 // save original stack pointer
MOVW g, R2
// 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), R5
MOVW m_g0(R5), R6
BEQ R6, g, g0
JAL gosave<>(SB)
MOVW R6, g
JAL runtime·save_g(SB)
MOVW (g_sched+gobuf_sp)(g), R29
// Now on a scheduling stack (a pthread-created stack).
g0:
// Save room for two of our pointers and O32 frame.
ADDU $-24, R29
AND $~7, R29 // O32 ABI expects 8-byte aligned stack on function entry
MOVW R2, 16(R29) // save old g on stack
MOVW (g_stack+stack_hi)(R2), R2
SUBU R3, R2
MOVW R2, 20(R29) // save depth in old g stack (can't just save SP, as stack might be copied during a callback)
JAL (R25)
// Restore g, stack pointer. R2 is return value.
MOVW 16(R29), g
JAL runtime·save_g(SB)
MOVW (g_stack+stack_hi)(g), R5
MOVW 20(R29), R6
SUBU R6, R5
MOVW R5, R29
MOVW R2, ret+8(FP)
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,$16-16
MOVW $fn+0(FP), R1
MOVW R1, 4(R29)
MOVW frame+4(FP), R1
MOVW R1, 8(R29)
MOVW framesize+8(FP), R1
MOVW R1, 12(R29)
MOVW ctxt+12(FP), R1
MOVW R1, 16(R29)
MOVW $runtime·cgocallback_gofunc(SB), R1
JAL (R1)
RET
// cgocallback_gofunc(FuncVal*, void *frame, uintptr framesize, uintptr ctxt)
// See cgocall.go for more details.
TEXT ·cgocallback_gofunc(SB),NOSPLIT,$8-16
NO_LOCAL_POINTERS
// Load m and g from thread-local storage.
MOVB runtime·iscgo(SB), R1
BEQ R1, nocgo
JAL runtime·load_g(SB)
nocgo:
// 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.
BEQ g, needm
MOVW g_m(g), R3
MOVW R3, savedm-4(SP)
JMP havem
needm:
MOVW g, savedm-4(SP) // g is zero, so is m.
MOVW $runtime·needm(SB), R4
JAL (R4)
// 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), R3
MOVW m_g0(R3), R1
MOVW R29, (g_sched+gobuf_sp)(R1)
havem:
// 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(R29) aka savedsp-8(SP).
MOVW m_g0(R3), R1
MOVW (g_sched+gobuf_sp)(R1), R2
MOVW R2, savedsp-8(SP)
MOVW R29, (g_sched+gobuf_sp)(R1)
// 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, -4(SP) is unused (where SP refers to
// m->curg's SP while we're setting it up, before we've adjusted it).
MOVW m_curg(R3), g
JAL runtime·save_g(SB)
MOVW (g_sched+gobuf_sp)(g), R2 // prepare stack as R2
MOVW (g_sched+gobuf_pc)(g), R4
MOVW R4, -12(R2)
MOVW ctxt+12(FP), R1
MOVW R1, -8(R2)
MOVW $-12(R2), R29
JAL runtime·cgocallbackg(SB)
// Restore g->sched (== m->curg->sched) from saved values.
MOVW 0(R29), R4
MOVW R4, (g_sched+gobuf_pc)(g)
MOVW $12(R29), R2
MOVW R2, (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), R3
MOVW m_g0(R3), g
JAL runtime·save_g(SB)
MOVW (g_sched+gobuf_sp)(g), R29
MOVW savedsp-8(SP), R2
MOVW R2, (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), R3
BNE R3, droppedm
MOVW $runtime·dropm(SB), R4
JAL (R4)
droppedm:
// Done!
RET
// void setg(G*); set g. for use by needm.
// This only happens if iscgo, so jump straight to save_g
TEXT runtime·setg(SB),NOSPLIT,$0-4
MOVW gg+0(FP), g
JAL runtime·save_g(SB)
RET
// void setg_gcc(G*); set g in C TLS.
// Must obey the gcc calling convention.
TEXT setg_gcc<>(SB),NOSPLIT,$0
MOVW R4, g
JAL runtime·save_g(SB)
RET
TEXT runtime·abort(SB),NOSPLIT,$0-0
UNDEF
// Not implemented.
TEXT runtime·aeshash(SB),NOSPLIT,$0
UNDEF
// Not implemented.
TEXT runtime·aeshash32(SB),NOSPLIT,$0
UNDEF
// Not implemented.
TEXT runtime·aeshash64(SB),NOSPLIT,$0
UNDEF
// Not implemented.
TEXT runtime·aeshashstr(SB),NOSPLIT,$0
UNDEF
TEXT runtime·return0(SB),NOSPLIT,$0
MOVW $0, R1
RET
// Called from cgo wrappers, this function returns g->m->curg.stack.hi.
// Must obey the gcc calling convention.
TEXT _cgo_topofstack(SB),NOSPLIT|NOFRAME,$0
// g (R30), R3 and REGTMP (R23) might be clobbered by load_g. R30 and R23
// are callee-save in the gcc calling convention, so save them.
MOVW R23, R8
MOVW g, R9
MOVW R31, R10 // this call frame does not save LR
JAL runtime·load_g(SB)
MOVW g_m(g), R1
MOVW m_curg(R1), R1
MOVW (g_stack+stack_hi)(R1), R2 // return value in R2
MOVW R8, R23
MOVW R9, g
MOVW R10, R31
RET
// The top-most function running on a goroutine
// returns to goexit+PCQuantum.
TEXT runtime·goexit(SB),NOSPLIT|NOFRAME,$0-0
NOR R0, R0 // NOP
JAL runtime·goexit1(SB) // does not return
// traceback from goexit1 must hit code range of goexit
NOR R0, R0 // NOP
TEXT ·checkASM(SB),NOSPLIT,$0-1
MOVW $1, R1
MOVB R1, ret+0(FP)
RET
// gcWriteBarrier performs a heap pointer write and informs the GC.
//
// gcWriteBarrier does NOT follow the Go ABI. It takes two arguments:
// - R20 is the destination of the write
// - R21 is the value being written at R20.
// It clobbers R23 (the linker temp register).
// The act of CALLing gcWriteBarrier will clobber R31 (LR).
// It does not clobber any other general-purpose registers,
// but may clobber others (e.g., floating point registers).
TEXT runtime·gcWriteBarrier(SB),NOSPLIT,$104
// Save the registers clobbered by the fast path.
MOVW R1, 100(R29)
MOVW R2, 104(R29)
MOVW g_m(g), R1
MOVW m_p(R1), R1
MOVW (p_wbBuf+wbBuf_next)(R1), R2
// Increment wbBuf.next position.
ADD $8, R2
MOVW R2, (p_wbBuf+wbBuf_next)(R1)
MOVW (p_wbBuf+wbBuf_end)(R1), R1
MOVW R1, R23 // R23 is linker temp register
// Record the write.
MOVW R21, -8(R2) // Record value
MOVW (R20), R1 // TODO: This turns bad writes into bad reads.
MOVW R1, -4(R2) // Record *slot
// Is the buffer full?
BEQ R2, R23, flush
ret:
MOVW 100(R29), R1
MOVW 104(R29), R2
// Do the write.
MOVW R21, (R20)
RET
flush:
// Save all general purpose registers since these could be
// clobbered by wbBufFlush and were not saved by the caller.
MOVW R20, 4(R29) // Also first argument to wbBufFlush
MOVW R21, 8(R29) // Also second argument to wbBufFlush
// R1 already saved
// R2 already saved
MOVW R3, 12(R29)
MOVW R4, 16(R29)
MOVW R5, 20(R29)
MOVW R6, 24(R29)
MOVW R7, 28(R29)
MOVW R8, 32(R29)
MOVW R9, 36(R29)
MOVW R10, 40(R29)
MOVW R11, 44(R29)
MOVW R12, 48(R29)
MOVW R13, 52(R29)
MOVW R14, 56(R29)
MOVW R15, 60(R29)
MOVW R16, 64(R29)
MOVW R17, 68(R29)
MOVW R18, 72(R29)
MOVW R19, 76(R29)
MOVW R20, 80(R29)
// R21 already saved
// R22 already saved.
MOVW R22, 84(R29)
// R23 is tmp register.
MOVW R24, 88(R29)
MOVW R25, 92(R29)
// R26 is reserved by kernel.
// R27 is reserved by kernel.
MOVW R28, 96(R29)
// R29 is SP.
// R30 is g.
// R31 is LR, which was saved by the prologue.
// This takes arguments R20 and R21.
CALL runtime·wbBufFlush(SB)
MOVW 4(R29), R20
MOVW 8(R29), R21
MOVW 12(R29), R3
MOVW 16(R29), R4
MOVW 20(R29), R5
MOVW 24(R29), R6
MOVW 28(R29), R7
MOVW 32(R29), R8
MOVW 36(R29), R9
MOVW 40(R29), R10
MOVW 44(R29), R11
MOVW 48(R29), R12
MOVW 52(R29), R13
MOVW 56(R29), R14
MOVW 60(R29), R15
MOVW 64(R29), R16
MOVW 68(R29), R17
MOVW 72(R29), R18
MOVW 76(R29), R19
MOVW 80(R29), R20
MOVW 84(R29), R22
MOVW 88(R29), R24
MOVW 92(R29), R25
MOVW 96(R29), R28
JMP ret
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