Revert "cmd/compile, cmd/link, runtime: make defers low-cost through inline code and extra funcdata"

This reverts CL 190098.

Reason for revert: broke several builders.

Change-Id: I69161352f9ded02537d8815f259c4d391edd9220
Reviewed-on: https://go-review.googlesource.com/c/go/+/201519
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Dan Scales <danscales@google.com>

1 files changed, 7 insertions, 23 deletions

diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go
index 20813d09eb..dd399e00a6 100644
--- a/src/runtime/runtime2.go
+++ b/src/runtime/runtime2.go
@@ -701,7 +701,7 @@ type _func struct {
 	nameoff int32   // function name
 
 	args        int32  // in/out args size
-	deferreturn uint32 // offset of start of a deferreturn call instruction from entry, if any.
+	deferreturn uint32 // offset of a deferreturn block from entry, if any.
 
 	pcsp      int32
 	pcfile    int32
@@ -774,7 +774,7 @@ func extendRandom(r []byte, n int) {
 }
 
 // A _defer holds an entry on the list of deferred calls.
-// If you add a field here, add code to clear it in freedefer and deferProcStack
+// If you add a field here, add code to clear it in freedefer.
 // This struct must match the code in cmd/compile/internal/gc/reflect.go:deferstruct
 // and cmd/compile/internal/gc/ssa.go:(*state).call.
 // Some defers will be allocated on the stack and some on the heap.
@@ -785,27 +785,11 @@ type _defer struct {
 	siz     int32 // includes both arguments and results
 	started bool
 	heap    bool
-	// openDefer indicates that this _defer is for a frame with open-coded
-	// defers. We have only one defer record for the entire frame (which may
-	// currently have 0, 1, or more defers active).
-	openDefer bool
-	sp        uintptr // sp at time of defer
-	pc        uintptr // pc at time of defer
-	fn        *funcval
-	_panic    *_panic // panic that is running defer
-	link      *_defer
-
-	// If openDefer is true, the fields below record values about the stack
-	// frame and associated function that has the open-coded defer(s). sp
-	// above will be the sp for the frame, and pc will be address of the
-	// deferreturn call in the function.
-	fd   unsafe.Pointer // funcdata for the function associated with the frame
-	varp uintptr        // value of varp for the stack frame
-	// framepc is the current pc associated with the stack frame. Together,
-	// with sp above (which is the sp associated with the stack frame),
-	// framepc/sp can be used as pc/sp pair to continue a stack trace via
-	// gentraceback().
-	framepc uintptr
+	sp      uintptr // sp at time of defer
+	pc      uintptr
+	fn      *funcval
+	_panic  *_panic // panic that is running defer
+	link    *_defer
 }
 
 // A _panic holds information about an active panic.