[dev.cc] runtime: merge power64 onM/onM_signalok into systemstack

This is the power64 component of CL 174950043.

With this, dev.cc compiles on power64 and power64le and passes
most tests if GOGC=off (but crashes in go_bootstrap if GC is
on).

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/175290043

diff --git a/src/runtime/asm_power64x.s b/src/runtime/asm_power64x.s
index 901dedbe5915615ee5b8b47e2d55d045c978729f..3f2ab6d0e6519b6180b1f773e0665a4f35c516d0 100644 (file)
--- a/src/runtime/asm_power64x.s
+++ b/src/runtime/asm_power64x.s
@@ -145,58 +145,44 @@ TEXT runtime·mcall(SB), NOSPLIT, $-8-8
        BL      (CTR)
        BR      runtime·badmcall2(SB)
 
-// switchtoM is a dummy routine that onM leaves at the bottom
+// 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 M stack because the one at the top of
-// the M stack terminates the stack walk (see topofstack()).
-TEXT runtime·switchtoM(SB), NOSPLIT, $0-0
+// 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
        BL      (LR)    // make sure this function is not leaf
        RETURN
 
-// func onM_signalok(fn func())
-TEXT runtime·onM_signalok(SB), NOSPLIT, $8-8
-       MOVD    g, R3                   // R3 = g
-       MOVD    g_m(R3), R4             // R4 = g->m
-       MOVD    m_gsignal(R4), R4       // R4 = g->m->gsignal
-       MOVD    fn+0(FP), R11           // context for call below
-       CMP     R3, R4
-       BEQ     onsignal
-       MOVD    R11, 8(R1)
-       BL      runtime·onM(SB)
-       RETURN
-
-onsignal:
-       MOVD    0(R11), R3              // code pointer
-       MOVD    R3, CTR
-       BL      (CTR)
-       RETURN
-
-// void onM(fn func())
-TEXT runtime·onM(SB), NOSPLIT, $0-8
+// func systemstack(fn func())
+TEXT runtime·systemstack(SB), NOSPLIT, $0-8
        MOVD    fn+0(FP), R3    // R3 = fn
        MOVD    R3, R11         // context
        MOVD    g_m(g), R4      // R4 = m
 
+       MOVD    m_gsignal(R4), R5       // R5 = gsignal
+       CMP     g, R5
+       BEQ     noswitch
+
        MOVD    m_g0(R4), R5    // R5 = g0
        CMP     g, R5
-       BEQ     onm
+       BEQ     noswitch
 
        MOVD    m_curg(R4), R6
        CMP     g, R6
-       BEQ     oncurg
+       BEQ     switch
 
-       // Not g0, not curg. Must be gsignal, but that's not allowed.
+       // Bad: g is not gsignal, not g0, not curg. What is it?
        // Hide call from linker nosplit analysis.
-       MOVD    $runtime·badonm(SB), R3
+       MOVD    $runtime·badsystemstack(SB), R3
        MOVD    R3, CTR
        BL      (CTR)
 
-oncurg:
+switch:
        // save our state in g->sched.  Pretend to
-       // be switchtoM if the G stack is scanned.
-       MOVD    $runtime·switchtoM(SB), R6
+       // be systemstack_switch if the G stack is scanned.
+       MOVD    $runtime·systemstack_switch(SB), R6
        ADD     $8, R6  // get past prologue
        MOVD    R6, (g_sched+gobuf_pc)(g)
        MOVD    R1, (g_sched+gobuf_sp)(g)
@@ -206,7 +192,7 @@ oncurg:
        // switch to g0
        MOVD    R5, g
        MOVD    (g_sched+gobuf_sp)(g), R3
-       // make it look like mstart called onM on g0, to stop traceback
+       // make it look like mstart called systemstack on g0, to stop traceback
        SUB     $8, R3
        MOVD    $runtime·mstart(SB), R4
        MOVD    R4, 0(R3)
@@ -224,7 +210,7 @@ oncurg:
        MOVD    R0, (g_sched+gobuf_sp)(g)
        RETURN
 
-onm:
+noswitch:
        // already on m stack, just call directly
        MOVD    0(R11), R3      // code pointer
        MOVD    R3, CTR