runtime: let stack copier update Panic structs for us
It already is updating parts of them; we're just getting lucky
retraversing them and not finding much to do.
Change argp to a pointer so that it will be updated too.
Existing tests break if you apply the change to adjustpanics
without also updating the type of argp.
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/139380043
diff --git a/src/runtime/panic.go b/src/runtime/panic.go
index a5a8fbd..52ab654 100644
--- a/src/runtime/panic.go
+++ b/src/runtime/panic.go
@@ -287,9 +287,9 @@
gp._defer = (*_defer)(noescape(unsafe.Pointer(&dabort)))
p._defer = d
- p.argp = getargp(0)
+ p.argp = unsafe.Pointer(getargp(0))
reflectcall(unsafe.Pointer(d.fn), unsafe.Pointer(&d.args), uint32(d.siz), uint32(d.siz))
- p.argp = 0
+ p.argp = nil
// reflectcall did not panic. Remove dabort.
if gp._defer != &dabort {
@@ -362,7 +362,7 @@
// If they match, the caller is the one who can recover.
gp := getg()
p := gp._panic
- if p != nil && !p.recovered && argp == p.argp {
+ if p != nil && !p.recovered && argp == uintptr(p.argp) {
p.recovered = true
return p.arg
}
diff --git a/src/runtime/runtime.h b/src/runtime/runtime.h
index e6db8cb..9584c5d 100644
--- a/src/runtime/runtime.h
+++ b/src/runtime/runtime.h
@@ -653,7 +653,7 @@
*/
struct Panic
{
- uintptr argp; // pointer to arguments of deferred call run during panic; cannot move - known to liblink
+ void* argp; // pointer to arguments of deferred call run during panic; cannot move - known to liblink
Eface arg; // argument to panic
Panic* link; // link to earlier panic
Defer* defer; // current executing defer
diff --git a/src/runtime/stack.c b/src/runtime/stack.c
index ca0eed0..8461c01 100644
--- a/src/runtime/stack.c
+++ b/src/runtime/stack.c
@@ -712,6 +712,10 @@
// get adjusted appropriately.
// This only happens for runtime.main and runtime.gopanic now,
// but a compiler optimization could do more of this.
+ // If such an optimization were introduced, Defer.argp should
+ // change to have pointer type so that it will be updated by
+ // the stack copying. Today both of those on-stack defers
+ // set argp = NoArgs, so no adjustment is necessary.
*dp = (Defer*)((byte*)d + adjinfo->delta);
continue;
}
@@ -751,17 +755,11 @@
static void
adjustpanics(G *gp, AdjustInfo *adjinfo)
{
- Panic *p, **l;
-
- // only the topmost panic is on the current stack
- for(l = &gp->panic; (p = *l) != nil; ) {
- if(adjinfo->oldstk <= (byte*)p && (byte*)p < adjinfo->oldbase)
- *l = (Panic*)((byte*)p + adjinfo->delta);
- l = &p->link;
-
- if(adjinfo->oldstk <= (byte*)p->argp && (byte*)p->argp < adjinfo->oldbase)
- p->argp += adjinfo->delta;
- }
+ // Panic structs are all on the stack
+ // and are adjusted by stack copying.
+ // The only pointer we need to update is gp->panic, the head of the list.
+ if(adjinfo->oldstk <= (byte*)gp->panic && (byte*)gp->panic < adjinfo->oldbase)
+ gp->panic = (Panic*)((byte*)gp->panic + adjinfo->delta);
}
static void
