runtime: remove legacy comments and code from arm morestack

CL 137410043 deleted support for split stacks, which means morestack
no longer needed to save its caller's frame or argument size or its
caller's argument pointer. However, this commit failed to update the
comment or delete the line that computed the caller's argument
pointer. Clean these up now.

Change-Id: I65725d3d42c86e8adb6645d5aa80c305d473363d
Reviewed-on: https://go-review.googlesource.com/92437
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

diff --git a/src/cmd/vet/all/whitelist/arm.txt b/src/cmd/vet/all/whitelist/arm.txt
index 839346c2d499022e0c943ccd6b2c69ec1f233a73..770008c9f04cff2eb6220aee71d09a2985fe4b87 100644 (file)
--- a/src/cmd/vet/all/whitelist/arm.txt
+++ b/src/cmd/vet/all/whitelist/arm.txt
@@ -2,9 +2,6 @@
 
 runtime/asm_ARCHSUFF.s: [GOARCH] cannot check cross-package assembly function: Compare is in package bytes
 
-// reflect trampolines intentionally omit arg size. Same for morestack.
-runtime/asm_arm.s: [arm] morestack: use of 4(R13) points beyond argument frame
-
 // Intentionally missing declarations.
 runtime/asm_arm.s: [arm] emptyfunc: function emptyfunc missing Go declaration
 runtime/asm_arm.s: [arm] abort: function abort missing Go declaration

diff --git a/src/runtime/asm_arm.s b/src/runtime/asm_arm.s
index bca08405068f053b194871a1256e5cccc0bdbdc3..d10c370a7d2775a7cf2b9ec5c547504e29a90596 100644 (file)
--- a/src/runtime/asm_arm.s
+++ b/src/runtime/asm_arm.s
@@ -370,10 +370,7 @@ noswitch:
  */
 
 // Called during function prolog when more stack is needed.
-// R1 frame size
 // R3 prolog's LR
-// NB. we do not save R0 because we've forced 5c to pass all arguments
-// on the stack.
 // using NOFRAME means do not save LR on stack.
 //
 // The traceback routines see morestack on a g0 as being
@@ -407,7 +404,6 @@ TEXT runtime·morestack(SB),NOSPLIT|NOFRAME,$0-0
        // 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.