return nil, fmt.Errorf("unexpected addr2line output: %s", resp)
	}

	var stack []plugin.Frame
	for {
		frame, end := d.readFrame()
		if end {
			break
		}

		if frame != (plugin.Frame{}) {
			stack = append(stack, frame)
		}
	}
	return stack, err
}

// addrInfo returns the stack frame information for a specific program
// address. It returns nil if the address could not be identified.

// Argument/return areas are part of the parent frame, not the frame itself,
// so they need to be handled separately.

package main

// >1GB to trigger failure, <2GB to work on 32-bit platforms.
type large struct {
	b [1500000000]byte
}

func (x large) f1() int { // GC_ERROR "stack frame too large"
	return 5
}

func f2(x large) int { // GC_ERROR "stack frame too large"
	return 5
}

// walkFrames calls visit for each call frame represented by pcs.
//
// pcs should be a slice of PCs, as returned by runtime.Callers.
func walkFrames(pcs []uintptr, visit frameVisitor) {
	if len(pcs) == 0 {
		return
	}

	frames := runtime.CallersFrames(pcs)
	for {
		frame, more := frames.Next()
		visit(frame.File, frame.Line, frame.Function, frame.PC-frame.Entry)
		if !more {
			return
		}
	}
}

	line   uint64
}

// makeTraceFrame sets up a traceFrame for a frame.
func makeTraceFrame(gen uintptr, f Frame) traceFrame {
	var frame traceFrame
	frame.PC = f.PC

	fn := f.Function
	const maxLen = 1 << 10
	if len(fn) > maxLen {
		fn = fn[len(fn)-maxLen:]
	}
	frame.funcID = trace.stringTab[gen%2].put(gen, fn)
	frame.line = uint64(f.Line)
	file := f.File
	if len(file) > maxLen {

}

//go:noinline
func testCaller(skp int) frame {
	skip = skp
	f() // line 42
	frame := globalFrame
	if !frame.ok {
		panic(fmt.Sprintf("skip=%d runtime.Caller failed", skp))
	}
	return frame
}

type wantFrame struct {
	funcName string
	line     int
}

// -1 means don't care
var expected = []wantFrame{
	0: {"main.h", 36},
	1: {"main.g", 31},
	2: {"main.f", 27},

	ci := runtime.CallersFrames(wg.Callers)
	frames := make([]runtime.Frame, 0, 4)
	for {
		frame, more := ci.Next()
		frames = append(frames, frame)
		if !more {
			break
		}
	}
	expecting := []string{
		"test/mysync.(*WaitGroup).Add",
		"test/mysync.(*WaitGroup).Done",
	}
	for i := 0; i < 2; i++ {
		if frames[i].Function != expecting[i] {
			log.Fatalf("frame %d: got %s, want %s", i, frames[i].Function, expecting[i])
		}
	}

	// the stack frame but we're not going back there
	// anyway.
	sp := c.sp() - sys.StackAlign // needs only sizeof uint64, but must align the stack
	c.set_sp(sp)
	*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.lr()
	// Make sure a valid frame pointer is saved on the stack so that the
	// frame pointer checks in adjustframe are happy, if they're enabled.
	// Frame pointer unwinding won't visit the sigpanic frame, since

			// Return now to avoid processing the zero Frame that would
			// otherwise be returned by frames.Next below.
			return
		}

		pc = pc[:n] // pass only valid pcs to runtime.CallersFrames
		frames := runtime.CallersFrames(pc)

		// Loop to get frames.
		// A fixed number of PCs can expand to an indefinite number of Frames.
		for {
			frame, more := frames.Next()

			// Process this frame.
			//

func.func @enter_parallel_iterations(%arg0: tensor<*xf32>, %arg1: i1) -> tensor<*xf32> {
  %result = tf_executor.graph {
// CHECK: tf_executor.Enter %{{.*}} frame "some/frame" parallel_iterations 42 : tensor<*xf32>
    %res:2 = tf_executor.Enter %arg0 frame "some/frame" parallel_iterations 42 : tensor<*xf32>
    tf_executor.fetch %res#0 : tensor<*xf32>
  }
  func.return %result : tensor<*xf32>
}

				if hogRegion != nil && ev.Goroutine() == hogRegion.Goroutine() {
					traceSamples++
					var fns []string
					ev.Stack().Frames(func(frame trace.StackFrame) bool {
						if frame.Func != "runtime.goexit" {
							fns = append(fns, fmt.Sprintf("%s:%d", frame.Func, frame.Line))
						}
						return true
					})
					stack := strings.Join(fns, "|")
					traceStacks[stack]++
				}
			}