Thanks, solved my problem 在2023年1月17日星期二 UTC+8 00:49:03<Ian Lance Taylor> 写道：
> On Mon, Jan 16, 2023 at 8:43 AM j2gg0s <feys...@gmail.com> wrote: > > > > As a newbie of golang's assembly, i cant understand why we MOVQ DX CX > twice in runtime.gogo. WHY? > > I don't see any MOVQ DX, CX instructions here. Can you clarify by > saying exactly which instructions you are asking about? > > Note that MOVQ 0(DX), CX treats DX as a memory address, and moves the > 8-byte value at that address into CX. And MOVQ DX, g(CX) treats CX as > a memory address, and moves the value in DX into the address as "g" > bytes offset from the address in CX. > > Ian > > > > Source code: > > ``` > > 255 // func gogo(buf *gobuf) > > 256 // restore state from Gobuf; longjmp > > 257 TEXT runtime·gogo(SB), NOSPLIT, $0-8 > > 258 MOVQ buf+0(FP), BX // gobuf > > 259 MOVQ gobuf_g(BX), DX > > 260 MOVQ 0(DX), CX // make sure g != nil > > 261 JMP gogo<>(SB) > > 262 > > 263 TEXT gogo<>(SB), NOSPLIT, $0 > > 264 get_tls(CX) > > 265 MOVQ DX, g(CX) > > 266 MOVQ DX, R14 // set the g register > > 267 MOVQ gobuf_sp(BX), SP // restore SP > > 268 MOVQ gobuf_ret(BX), AX > > 269 MOVQ gobuf_ctxt(BX), DX > > 270 MOVQ gobuf_bp(BX), BP > > 271 MOVQ $0, gobuf_sp(BX) // clear to help garbage collector > > 272 MOVQ $0, gobuf_ret(BX) > > 273 MOVQ $0, gobuf_ctxt(BX) > > 274 MOVQ $0, gobuf_bp(BX) > > 275 MOVQ gobuf_pc(BX), BX > > 276 JMP BX > > ``` > > > > Link: > https://github.com/golang/go/blob/go1.17.13/src/runtime/asm_amd64.s#L255 > > > > > > -- > > You received this message because you are subscribed to the Google > Groups "golang-nuts" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to golang-nuts...@googlegroups.com. > > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/5fafeb38-1bc7-4a96-b386-41e14c431273n%40googlegroups.com > . > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/3ba1a60a-f0be-497c-bdda-f72316cc1d2an%40googlegroups.com.
