code review 109050043: all: remove 'extern register M *m' from runtime

src/pkg/runtime/sys_nacl_386.s

 // Copyright 2013 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 "zasm_GOOS_GOARCH.h"
 #include "../../cmd/ld/textflag.h"
 #include "syscall_nacl.h"
 
 #define NACL_SYSCALL(code) \
         MOVL $(0x10000 + ((code)<<5)), AX; CALL AX
@@ skipping 147 matching lines @@
 TEXT runtime·setldt(SB),NOSPLIT,$8
         MOVL    addr+4(FP), BX // aka base
         ADDL    $0x8, BX
         MOVL    BX, 0(SP)
         NACL_SYSCALL(SYS_tls_init)
         RET
 
 TEXT runtime·sigtramp(SB),NOSPLIT,$0
         get_tls(CX)
 
-        // check that m exists
-        MOVL    m(CX), BX
-        CMPL    BX, $0
+        // check that g exists
+        MOVL    g(CX), DI
+        CMPL    DI, $0
         JNE     6(PC)
         MOVL    $11, BX
-        MOVL    BX, 0(SP)
+        MOVL    $0, 0(SP)
         MOVL    $runtime·badsignal(SB), AX
         CALL    AX
         JMP     sigtramp_ret
 
         // save g
-        MOVL    g(CX), DI
         MOVL    DI, 20(SP)
 ········
         // g = m->gsignal
+        MOVL    g_m(DI), BX
         MOVL    m_gsignal(BX), BX
         MOVL    BX, g(CX)
 ········
         // copy arguments for sighandler
         MOVL    $11, 0(SP) // signal
         MOVL    $0, 4(SP) // siginfo
         LEAL    ctxt+4(FP), AX
         MOVL    AX, 8(SP) // context
         MOVL    DI, 12(SP) // g
 
@@ skipping 41 matching lines @@
         MOVL    4(BP), CX
         MOVL    8(BP), DX
         MOVL    12(BP), BX
         MOVL    16(BP), SP
         // 20(BP) is saved BP, never to be seen again
         MOVL    24(BP), SI
         MOVL    28(BP), DI
         // 36(BP) is saved EFLAGS, never to be seen again
         MOVL    32(BP), BP // saved PC
         JMP     BP