[dev.typeparams] runtime: remove variadic defer/go calls

Now that defer/go wrapping is used, deferred/go'd functions are
always argumentless. Remove the code handling arguments.

This CL is mostly removing the fallback code path. There are more
cleanups to be done, in later CLs.

Change-Id: I87bfd3fb2d759fbeb6487b8125c0f6992863d6e5
Reviewed-on: https://go-review.googlesource.com/c/go/+/325915
Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

5 files changed, 16 insertions, 142 deletions

diff --git a/src/cmd/compile/internal/test/inl_test.go b/src/cmd/compile/internal/test/inl_test.go
index ad4e4fee97..5b0db83301 100644
--- a/src/cmd/compile/internal/test/inl_test.go
+++ b/src/cmd/compile/internal/test/inl_test.go
@@ -42,7 +42,6 @@ func TestIntendedInlining(t *testing.T) {
 			"bucketMask",
 			"bucketShift",
 			"chanbuf",
-			"deferArgs",
 			"deferclass",
 			"evacuated",
 			"fastlog2",
diff --git a/src/cmd/internal/objabi/funcid.go b/src/cmd/internal/objabi/funcid.go
index 93ebd7be94..d881cdd061 100644
--- a/src/cmd/internal/objabi/funcid.go
+++ b/src/cmd/internal/objabi/funcid.go
@@ -74,7 +74,6 @@ var funcIDs = map[string]FuncID{
 	// Don't show in call stack but otherwise not special.
 	"deferreturn":       FuncID_wrapper,
 	"runOpenDeferFrame": FuncID_wrapper,
-	"reflectcallSave":   FuncID_wrapper,
 	"deferCallSave":     FuncID_wrapper,
 }
 
diff --git a/src/runtime/panic.go b/src/runtime/panic.go
index e73d59c136..8a296a3c17 100644
--- a/src/runtime/panic.go
+++ b/src/runtime/panic.go
@@ -5,7 +5,6 @@
 package runtime
 
 import (
-	"internal/abi"
 	"runtime/internal/atomic"
 	"runtime/internal/sys"
 	"unsafe"
@@ -235,7 +234,7 @@ func deferproc(siz int32, fn *funcval) { // arguments of fn follow fn
 		throw("defer on system stack")
 	}
 
-	if true && siz != 0 {
+	if siz != 0 {
 		// TODO: Make deferproc just take a func().
 		throw("defer with non-empty frame")
 	}
@@ -246,10 +245,9 @@ func deferproc(siz int32, fn *funcval) { // arguments of fn follow fn
 	// to somewhere safe. The memmove below does that.
 	// Until the copy completes, we can only call nosplit routines.
 	sp := getcallersp()
-	argp := uintptr(unsafe.Pointer(&fn)) + unsafe.Sizeof(fn)
 	callerpc := getcallerpc()
 
-	d := newdefer(siz)
+	d := newdefer(0)
 	if d._panic != nil {
 		throw("deferproc: d.panic != nil after newdefer")
 	}
@@ -258,14 +256,6 @@ func deferproc(siz int32, fn *funcval) { // arguments of fn follow fn
 	d.fn = fn
 	d.pc = callerpc
 	d.sp = sp
-	switch siz {
-	case 0:
-		// Do nothing.
-	case sys.PtrSize:
-		*(*uintptr)(deferArgs(d)) = *(*uintptr)(unsafe.Pointer(argp))
-	default:
-		memmove(deferArgs(d), unsafe.Pointer(argp), uintptr(siz))
-	}
 
 	// deferproc returns 0 normally.
 	// a deferred func that stops a panic
@@ -292,7 +282,7 @@ func deferprocStack(d *_defer) {
 		// go code on the system stack can't defer
 		throw("defer on system stack")
 	}
-	if true && d.siz != 0 {
+	if d.siz != 0 {
 		throw("defer with non-empty frame")
 	}
 	// siz and fn are already set.
@@ -378,25 +368,11 @@ func testdefersizes() {
 	}
 }
 
-// The arguments associated with a deferred call are stored
-// immediately after the _defer header in memory.
-//go:nosplit
-func deferArgs(d *_defer) unsafe.Pointer {
-	if d.siz == 0 {
-		// Avoid pointer past the defer allocation.
-		return nil
-	}
-	return add(unsafe.Pointer(d), unsafe.Sizeof(*d))
-}
-
 // 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() {
-	if false {
-		throw("requires GOEXPERIMENT=regabidefer")
-	}
 	var fn func()
 	*(**funcval)(unsafe.Pointer(&fn)) = d.fn
 	return fn
@@ -575,14 +551,6 @@ func deferreturn() {
 	// of the arguments until the jmpdefer can flip the PC over to
 	// fn.
 	argp := getcallersp() + sys.MinFrameSize
-	switch d.siz {
-	case 0:
-		// Do nothing.
-	case sys.PtrSize:
-		*(*uintptr)(unsafe.Pointer(argp)) = *(*uintptr)(deferArgs(d))
-	default:
-		memmove(unsafe.Pointer(argp), deferArgs(d), uintptr(d.siz))
-	}
 	fn := d.fn
 	d.fn = nil
 	gp._defer = d.link
@@ -654,15 +622,9 @@ func Goexit() {
 				addOneOpenDeferFrame(gp, 0, nil)
 			}
 		} else {
-			if true {
-				// Save the pc/sp in deferCallSave(), so we can "recover" back to this
-				// loop if necessary.
-				deferCallSave(&p, deferFunc(d))
-			} else {
-				// Save the pc/sp in reflectcallSave(), so we can "recover" back to this
-				// loop if necessary.
-				reflectcallSave(&p, unsafe.Pointer(d.fn), deferArgs(d), uint32(d.siz))
-			}
+			// Save the pc/sp in deferCallSave(), so we can "recover" back to this
+			// loop if necessary.
+			deferCallSave(&p, deferFunc(d))
 		}
 		if p.aborted {
 			// We had a recursive panic in the defer d we started, and
@@ -856,7 +818,7 @@ func runOpenDeferFrame(gp *g, d *_defer) bool {
 		argWidth, fd = readvarintUnsafe(fd)
 		closureOffset, fd = readvarintUnsafe(fd)
 		nArgs, fd = readvarintUnsafe(fd)
-		if true && argWidth != 0 {
+		if argWidth != 0 || nArgs != 0 {
 			throw("defer with non-empty frame")
 		}
 		if deferBits&(1<<i) == 0 {
@@ -869,32 +831,14 @@ func runOpenDeferFrame(gp *g, d *_defer) bool {
 		}
 		closure := *(**funcval)(unsafe.Pointer(d.varp - uintptr(closureOffset)))
 		d.fn = closure
-		deferArgs := deferArgs(d)
-		// If there is an interface receiver or method receiver, it is
-		// described/included as the first arg.
-		for j := uint32(0); j < nArgs; j++ {
-			var argOffset, argLen, argCallOffset uint32
-			argOffset, fd = readvarintUnsafe(fd)
-			argLen, fd = readvarintUnsafe(fd)
-			argCallOffset, fd = readvarintUnsafe(fd)
-			memmove(unsafe.Pointer(uintptr(deferArgs)+uintptr(argCallOffset)),
-				unsafe.Pointer(d.varp-uintptr(argOffset)),
-				uintptr(argLen))
-		}
 		deferBits = deferBits &^ (1 << i)
 		*(*uint8)(unsafe.Pointer(d.varp - uintptr(deferBitsOffset))) = deferBits
 		p := d._panic
-		if true {
-			deferCallSave(p, deferFunc(d))
-		} else {
-			reflectcallSave(p, unsafe.Pointer(closure), deferArgs, argWidth)
-		}
+		deferCallSave(p, deferFunc(d))
 		if p != nil && p.aborted {
 			break
 		}
 		d.fn = nil
-		// These args are just a copy, so can be cleared immediately
-		memclrNoHeapPointers(deferArgs, uintptr(argWidth))
 		if d._panic != nil && d._panic.recovered {
 			done = deferBits == 0
 			break
@@ -904,32 +848,6 @@ func runOpenDeferFrame(gp *g, d *_defer) bool {
 	return done
 }
 
-// reflectcallSave calls reflectcall after saving the caller's pc and sp in the
-// panic record. This allows the runtime to return to the Goexit defer processing
-// loop, in the unusual case where the Goexit may be bypassed by a successful
-// recover.
-//
-// This is marked as a wrapper by the compiler so it doesn't appear in
-// tracebacks.
-func reflectcallSave(p *_panic, fn, arg unsafe.Pointer, argsize uint32) {
-	if true {
-		throw("not allowed with GOEXPERIMENT=regabidefer")
-	}
-	if p != nil {
-		p.argp = unsafe.Pointer(getargp())
-		p.pc = getcallerpc()
-		p.sp = unsafe.Pointer(getcallersp())
-	}
-	// Pass a dummy RegArgs since we'll only take this path if
-	// we're not using the register ABI.
-	var regs abi.RegArgs
-	reflectcall(nil, fn, arg, argsize, argsize, argsize, &regs)
-	if p != nil {
-		p.pc = 0
-		p.sp = unsafe.Pointer(nil)
-	}
-}
-
 // deferCallSave calls fn() after saving the caller's pc and sp in the
 // panic record. This allows the runtime to return to the Goexit defer
 // processing loop, in the unusual case where the Goexit may be
@@ -938,9 +856,6 @@ func reflectcallSave(p *_panic, fn, arg unsafe.Pointer, argsize uint32) {
 // This is marked as a wrapper by the compiler so it doesn't appear in
 // tracebacks.
 func deferCallSave(p *_panic, fn func()) {
-	if false {
-		throw("only allowed with GOEXPERIMENT=regabidefer")
-	}
 	if p != nil {
 		p.argp = unsafe.Pointer(getargp())
 		p.pc = getcallerpc()
@@ -1040,16 +955,8 @@ func gopanic(e interface{}) {
 			}
 		} else {
 			p.argp = unsafe.Pointer(getargp())
-
-			if true {
-				fn := deferFunc(d)
-				fn()
-			} else {
-				// Pass a dummy RegArgs since we'll only take this path if
-				// we're not using the register ABI.
-				var regs abi.RegArgs
-				reflectcall(nil, unsafe.Pointer(d.fn), deferArgs(d), uint32(d.siz), uint32(d.siz), uint32(d.siz), &regs)
-			}
+			fn := deferFunc(d)
+			fn()
 		}
 		p.argp = nil
 
diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index b93b337f19..be18bbc090 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -4258,7 +4258,7 @@ func newproc(siz int32, fn *funcval) {
 //
 //go:systemstack
 func newproc1(fn *funcval, argp unsafe.Pointer, narg int32, callergp *g, callerpc uintptr) *g {
-	if true && narg != 0 {
+	if narg != 0 {
 		// TODO: When we commit to GOEXPERIMENT=regabidefer,
 		// rewrite the comments for newproc and newproc1.
 		// newproc will no longer have a funny stack layout or
@@ -4273,16 +4273,6 @@ func newproc1(fn *funcval, argp unsafe.Pointer, narg int32, callergp *g, callerp
 		throw("go of nil func value")
 	}
 	acquirem() // disable preemption because it can be holding p in a local var
-	siz := narg
-	siz = (siz + 7) &^ 7
-
-	// We could allocate a larger initial stack if necessary.
-	// Not worth it: this is almost always an error.
-	// 4*PtrSize: extra space added below
-	// PtrSize: caller's LR (arm) or return address (x86, in gostartcall).
-	if siz >= _StackMin-4*sys.PtrSize-sys.PtrSize {
-		throw("newproc: function arguments too large for new goroutine")
-	}
 
 	_p_ := _g_.m.p.ptr()
 	newg := gfget(_p_)
@@ -4299,8 +4289,8 @@ func newproc1(fn *funcval, argp unsafe.Pointer, narg int32, callergp *g, callerp
 		throw("newproc1: new g is not Gdead")
 	}
 
-	totalSize := 4*sys.PtrSize + uintptr(siz) + sys.MinFrameSize // extra space in case of reads slightly beyond frame
-	totalSize += -totalSize & (sys.StackAlign - 1)               // align to StackAlign
+	totalSize := uintptr(4*sys.PtrSize + sys.MinFrameSize) // extra space in case of reads slightly beyond frame
+	totalSize = alignUp(totalSize, sys.StackAlign)
 	sp := newg.stack.hi - totalSize
 	spArg := sp
 	if usesLR {
@@ -4309,24 +4299,6 @@ func newproc1(fn *funcval, argp unsafe.Pointer, narg int32, callergp *g, callerp
 		prepGoExitFrame(sp)
 		spArg += sys.MinFrameSize
 	}
-	if narg > 0 {
-		memmove(unsafe.Pointer(spArg), argp, uintptr(narg))
-		// This is a stack-to-stack copy. If write barriers
-		// are enabled and the source stack is grey (the
-		// destination is always black), then perform a
-		// barrier copy. We do this *after* the memmove
-		// because the destination stack may have garbage on
-		// it.
-		if writeBarrier.needed && !_g_.m.curg.gcscandone {
-			f := findfunc(fn.fn)
-			stkmap := (*stackmap)(funcdata(f, _FUNCDATA_ArgsPointerMaps))
-			if stkmap.nbit > 0 {
-				// We're in the prologue, so it's always stack map index 0.
-				bv := stackmapdata(stkmap, 0)
-				bulkBarrierBitmap(spArg, spArg, uintptr(bv.n)*sys.PtrSize, 0, bv.bytedata)
-			}
-		}
-	}
 
 	memclrNoHeapPointers(unsafe.Pointer(&newg.sched), unsafe.Sizeof(newg.sched))
 	newg.sched.sp = sp
diff --git a/src/runtime/traceback.go b/src/runtime/traceback.go
index 89780edc1f..2564273a53 100644
--- a/src/runtime/traceback.go
+++ b/src/runtime/traceback.go
@@ -42,12 +42,9 @@ func tracebackdefers(gp *g, callback func(*stkframe, unsafe.Pointer) bool, v uns
 				throw("unknown pc")
 			}
 			frame.fn = f
-			frame.argp = uintptr(deferArgs(d))
-			var ok bool
-			frame.arglen, frame.argmap, ok = getArgInfoFast(f, true)
-			if !ok {
-				frame.arglen, frame.argmap = getArgInfo(&frame, f, true, fn)
-			}
+			frame.argp = 0
+			frame.arglen = 0
+			frame.argmap = nil
 		}
 		frame.continpc = frame.pc
 		if !callback((*stkframe)(noescape(unsafe.Pointer(&frame))), v) {