traceEvHeapObjectFree  // heap object free [timestamp, id]

	// Experimental goroutine stack events. IDs map reversibly to addresses.
	traceEvGoroutineStack      // stack exists [timestamp, id, order]
	traceEvGoroutineStackAlloc // stack alloc [timestamp, id, order]
	traceEvGoroutineStackFree  // stack free [timestamp, id]

			fmt.Fprintf(os.Stderr, "%s: %d bytes of stack space saved via stack slot merging (%d nonpointer %d pointer)\n", ir.FuncName(fn), savedNP+savedP, savedNP, savedP)
			if base.Debug.MergeLocalsTrace > 1 {
				fmt.Fprintf(os.Stderr, "=-= merge locals state for %v:\n%v",
					fn, mls)
			}
		}
		leaders = make(map[*ir.Name]int64)
	}

	// Use sort.SliceStable instead of sort.Slice so stack layout (and thus

	{"-fno-pie"},
	{"-fPIE"},
	{"-fno-PIE"},
	{"-fsplit-stack"},
	{"-fno-split-stack"},
	{"-fstack-xxx"},
	{"-fno-stack-xxx"},
	{"-fsanitize=hands"},
	{"-g"},
	{"-ggdb"},
	{"-march=souza"},
	{"-mcmodel=medium"},
	{"-mcpu=123"},
	{"-mfpu=123"},
	{"-mlarge-data-threshold=16"},
	{"-mtune=happybirthday"},
	{"-mstack-overflow"},
	{"-mno-stack-overflow"},
	{"-mmacosx-version"},
	{"-mnop-fun-dllimport"},

				call = funcs[call.target]
			}
			// Seeing this error in a failed CI run? It indicates that
			// a function in the runtime package marked nowritebarrierrec
			// (the outermost stack element) was found, by a static
			// reachability analysis over the fully lowered optimized code,
			// to call a function (fn) that involves a write barrier.
			//
			// Even if the call path is infeasable,

	execution tracer to double-check stack ownership before taking a stack trace.

	asyncpreemptoff: asyncpreemptoff=1 disables signal-based
	asynchronous goroutine preemption. This makes some loops
	non-preemptible for long periods, which may delay GC and
	goroutine scheduling. This is useful for debugging GC issues
	because it also disables the conservative stack scanning used
	for asynchronously preempted goroutines.

		// Stack was deallocated in gfput or just above. Allocate a new one.
		systemstack(func() {
			gp.stack = stackalloc(startingStackSize)
		})
		gp.stackguard0 = gp.stack.lo + stackGuard
	} else {
		if raceenabled {
			racemalloc(unsafe.Pointer(gp.stack.lo), gp.stack.hi-gp.stack.lo)
		}
		if msanenabled {
			msanmalloc(unsafe.Pointer(gp.stack.lo), gp.stack.hi-gp.stack.lo)
		}
		if asanenabled {

		},
	}
	e.base.args[0] = uint64(s.stack)
	return e
}

// stack represents a goroutine stack sample.
type stack struct {
	pcs []uint64
}

func (s stack) String() string {
	var sb strings.Builder
	for _, frame := range s.pcs {
		fmt.Fprintf(&sb, "\t%#v\n", frame)
	}
	return sb.String()
}

// frame represents a single stack frame.
type frame struct {
	pc     uint64

	asmArchMipsLE   = asmArch{name: "mipsle", bigEndian: false, stack: "R29", lr: true}
	asmArchMips64   = asmArch{name: "mips64", bigEndian: true, stack: "R29", lr: true}
	asmArchMips64LE = asmArch{name: "mips64le", bigEndian: false, stack: "R29", lr: true}
	asmArchPpc64    = asmArch{name: "ppc64", bigEndian: true, stack: "R1", lr: true, retRegs: []string{"R3", "F1"}}

	// further move the stack.
	new2 := uintptr(unsafe.Pointer(new))

	t.Logf("old stack pointer %x, new stack pointer %x", old, new2)
	if new2 == old {
		// Check that we didn't screw up the test's escape analysis.
		if cls := runtime.GCTestPointerClass(unsafe.Pointer(new)); cls != "stack" {
			t.Fatalf("test bug: new (%#x) should be a stack pointer, not %s", new2, cls)
		}
		// This was a real failure.
		return false
	}

	// There are unlocked sudogs that point into gp's stack. Stack
	// copying must lock the channels of those sudogs.
	// Set activeStackChans here instead of before we try parking
	// because we could self-deadlock in stack growth on the
	// channel lock.
	gp.activeStackChans = true
	// Mark that it's safe for stack shrinking to occur now,
	// because any thread acquiring this G's stack for shrinking