runtime, cmd/compile: prune unused _defer fields

These fields are no longer needed since go.dev/cl/513837.

Change-Id: I980fc9db998c293e930094bbb87e8c8f1654e39c
Reviewed-on: https://go-review.googlesource.com/c/go/+/516198
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>

diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go
index 9796978f4a6e1ff3545957411cf358a9816decc5..bb67bd6bad72a4f78a45e175cbdf34840c92c12b 100644 (file)
--- a/src/cmd/compile/internal/ssagen/ssa.go
+++ b/src/cmd/compile/internal/ssagen/ssa.go
@@ -5259,20 +5259,14 @@ func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool) *ssa.Val
                addr := s.addr(d)
 
                // Must match deferstruct() below and src/runtime/runtime2.go:_defer.
-               // 0: started, set in deferprocStack
-               // 1: heap, set in deferprocStack
-               // 2: openDefer
-               // 3: sp, set in deferprocStack
-               // 4: pc, set in deferprocStack
-               // 5: fn
+               // 0: heap, set in deferprocStack
+               // 1: sp, set in deferprocStack
+               // 2: pc, set in deferprocStack
+               // 3: fn
                s.store(closure.Type,
-                       s.newValue1I(ssa.OpOffPtr, closure.Type.PtrTo(), t.FieldOff(5), addr),
+                       s.newValue1I(ssa.OpOffPtr, closure.Type.PtrTo(), t.FieldOff(3), addr),
                        closure)
-               // 6: panic, set in deferprocStack
-               // 7: link, set in deferprocStack
-               // 8: fd
-               // 9: varp
-               // 10: framepc
+               // 4: link, set in deferprocStack
 
                // Call runtime.deferprocStack with pointer to _defer record.
                ACArgs = append(ACArgs, types.Types[types.TUINTPTR])
@@ -8113,20 +8107,14 @@ func deferstruct() *types.Type {
        // These fields must match the ones in runtime/runtime2.go:_defer and
        // (*state).call above.
        fields := []*types.Field{
-               makefield("started", types.Types[types.TBOOL]),
                makefield("heap", types.Types[types.TBOOL]),
-               makefield("openDefer", types.Types[types.TBOOL]),
                makefield("sp", types.Types[types.TUINTPTR]),
                makefield("pc", types.Types[types.TUINTPTR]),
                // Note: the types here don't really matter. Defer structures
                // are always scanned explicitly during stack copying and GC,
                // so we make them uintptr type even though they are real pointers.
                makefield("fn", types.Types[types.TUINTPTR]),
-               makefield("_panic", types.Types[types.TUINTPTR]),
                makefield("link", types.Types[types.TUINTPTR]),
-               makefield("fd", types.Types[types.TUINTPTR]),
-               makefield("varp", types.Types[types.TUINTPTR]),
-               makefield("framepc", types.Types[types.TUINTPTR]),
        }
 
        // build struct holding the above fields

diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go
index 75f009388ebc50ca32d2a29a5c5b4e63b683827f..b9547651eefd5408ac05ca82e809d58ed37a1f49 100644 (file)
--- a/src/runtime/runtime2.go
+++ b/src/runtime/runtime2.go
@@ -999,18 +999,11 @@ func extendRandom(r []byte, n int) {
 // initialize them are not required. All defers must be manually scanned,
 // and for heap defers, marked.
 type _defer struct {
-       // TODO(mdempsky): Remove blank fields and update cmd/compile.
-       _    bool // was started
        heap bool
-       _    bool           // was openDefer
-       sp   uintptr        // sp at time of defer
-       pc   uintptr        // pc at time of defer
-       fn   func()         // can be nil for open-coded defers
-       _    unsafe.Pointer // was _panic
-       link *_defer        // next defer on G; can point to either heap or stack!
-       _    unsafe.Pointer // was fd
-       _    uintptr        // was varp
-       _    uintptr        // was framepc
+       sp   uintptr // sp at time of defer
+       pc   uintptr // pc at time of defer
+       fn   func()  // can be nil for open-coded defers
+       link *_defer // next defer on G; can point to either heap or stack!
 }
 
 // A _panic holds information about an active panic.