// 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
	}

			// endless recursion occurs if the cycle is not detected.
			//
			// If x and y were compared before, they must be equal
			// (if they were not, the recursion would have stopped);
			// search the ifacePair stack for the same pair.
			//
			// This is a quadratic algorithm, but in practice these stacks
			// are extremely short (bounded by the nesting depth of interface

				}
				lv.unsafePoints.Set(int32(v.ID))
			}
		}
	}
}

// Returns true for instructions that must have a stack map.
//
// This does not necessarily mean the instruction is a safe-point. In
// particular, call Values can have a stack map in case the callee
// grows the stack, but not themselves be a safe-point.
func (lv *liveness) hasStackMap(v *ssa.Value) bool {
	if !v.Op.IsCall() {
		return false
	}

program to simply exit by pressing ^C, and you can cause it to exit
with a stack dump by pressing ^\.

# Default behavior of signals in Go programs

By default, a synchronous signal is converted into a run-time panic. A
SIGHUP, SIGINT, or SIGTERM signal causes the program to exit. A
SIGQUIT, SIGILL, SIGTRAP, SIGABRT, SIGSTKFLT, SIGEMT, or SIGSYS signal
causes the program to exit with a stack dump. A SIGTSTP, SIGTTIN, or

			// endless recursion occurs if the cycle is not detected.
			//
			// If x and y were compared before, they must be equal
			// (if they were not, the recursion would have stopped);
			// search the ifacePair stack for the same pair.
			//
			// This is a quadratic algorithm, but in practice these stacks
			// are extremely short (bounded by the nesting depth of interface

		if raceenabled {
			racefingo()
		}
		for fb != nil {
			for i := fb.cnt; i > 0; i-- {
				f := &fb.fin[i-1]

				var regs abi.RegArgs
				// The args may be passed in registers or on stack. Even for
				// the register case, we still need the spill slots.
				// TODO: revisit if we remove spill slots.
				//
				// Unfortunately because we can have an arbitrary

		if v == "2" {
			// Obtain the caller stack. (This is equivalent to runtime/debug.Stack,
			// copied to avoid importing the whole package.)
			stack := make([]byte, 1024)
			for {
				n := runtime.Stack(stack, false)
				if n < len(stack) {
					stack = stack[:n]
					break
				}
				stack = make([]byte, 2*len(stack))
			}

			if i := bytes.Index(stack, []byte("\nos/exec.Command(")); i >= 0 {

func Trace(op, path string) {
	if !doTrace {
		return
	}
	traceMu.Lock()
	defer traceMu.Unlock()
	fmt.Fprintf(traceFile, "%d gofsystrace %s %s\n", os.Getpid(), op, path)
	if pattern := gofsystracestack.Value(); pattern != "" {
		if match, _ := pathpkg.Match(pattern, path); match {
			traceFile.Write(debug.Stack())
		}
	}
}

var (
	doTrace   bool

	nn := typecheck.TempAt(pos, f.fe.Func(), typ) // Note: adds new auto to fn.Dcl list
	nn.SetNonMergeable(true)
	return nn
}

// IsMergeCandidate returns true if variable n could participate in
// stack slot merging. For now we're restricting the set to things to
// items larger than what CanSSA would allow (approximateky, we disallow things
// marked as open defer slots so as to avoid complicating liveness
// analysis.