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[dev.typeparams] runtime: use func() for deferred functions

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Prior to regabi, a deferred function could have any signature, so the
runtime always manipulated them as funcvals. Now, a deferred function
is always func(). Hence, this CL makes the runtime's manipulation of
deferred functions more type-safe by using func() directly instead of
*funcval.

Change-Id: Ib55f38ed49107f74149725c65044e4690761971d
Reviewed-on: https://go-review.googlesource.com/c/go/+/337650
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This commit is contained in:
Austin Clements 2021-07-23 15:03:00 -04:00
parent 4480e3b11a
commit ea94e5d3c5
6 changed files with 19 additions and 28 deletions
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28
src/runtime/panic.go
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@ -227,7 +227,7 @@ func panicmemAddr(addr uintptr) {
// Create a new deferred function fn, which has no arguments and results.
// The compiler turns a defer statement into a call to this.
func deferproc(fn *funcval) { // TODO: Make deferproc just take a func().
func deferproc(fn func()) {
gp := getg()
if gp.m.curg != gp {
// go code on the system stack can't defer
@ -303,16 +303,6 @@ func deferprocStack(d *_defer) {
// been set and must not be clobbered.
}
// deferFunc returns d's deferred function. This is temporary while we
// support both modes of GOEXPERIMENT=regabidefer. Once we commit to
// that experiment, we should change the type of d.fn.
//go:nosplit
func deferFunc(d *_defer) func() {
var fn func()
*(**funcval)(unsafe.Pointer(&fn)) = d.fn
return fn
}
// Each P holds a pool for defers.
// Allocate a Defer, usually using per-P pool.
@ -470,9 +460,8 @@ func deferreturn() {
// If the defer function pointer is nil, force the seg fault to happen
// here rather than in jmpdefer. gentraceback() throws an error if it is
// called with a callback on an LR architecture and jmpdefer is on the
// stack, because the stack trace can be incorrect in that case - see
// issue #8153).
_ = fn.fn
// stack, because jmpdefer manipulates SP (see issue #8153).
_ = **(**funcval)(unsafe.Pointer(&fn))
jmpdefer(fn, argp)
}
@ -536,7 +525,7 @@ func Goexit() {
} else {
// Save the pc/sp in deferCallSave(), so we can "recover" back to this
// loop if necessary.
deferCallSave(&p, deferFunc(d))
deferCallSave(&p, d.fn)
}
if p.aborted {
// We had a recursive panic in the defer d we started, and
@ -728,12 +717,14 @@ func runOpenDeferFrame(gp *g, d *_defer) bool {
if deferBits&(1<<i) == 0 {
continue
}
closure := *(**funcval)(unsafe.Pointer(d.varp - uintptr(closureOffset)))
closure := *(*func())(unsafe.Pointer(d.varp - uintptr(closureOffset)))
d.fn = closure
deferBits = deferBits &^ (1 << i)
*(*uint8)(unsafe.Pointer(d.varp - uintptr(deferBitsOffset))) = deferBits
p := d._panic
deferCallSave(p, deferFunc(d))
// Call the defer. Note that this can change d.varp if
// the stack moves.
deferCallSave(p, d.fn)
if p != nil && p.aborted {
break
}
@ -854,8 +845,7 @@ func gopanic(e interface{}) {
}
} else {
p.argp = unsafe.Pointer(getargp())
fn := deferFunc(d)
fn()
d.fn()
}
p.argp = nil