// preparePanic sets up the stack to look like a call to sigpanic.
func (c *sigctxt) preparePanic(sig uint32, gp *g) {
	// We arrange link, and pc to pretend the panicking
	// function calls sigpanic directly.
	// Always save LINK to stack so that panics in leaf
	// functions are correctly handled. This smashes
	// the stack frame but we're not going back there
	// anyway.

// preparePanic sets up the stack to look like a call to sigpanic.
func (c *sigctxt) preparePanic(sig uint32, gp *g) {
	// We arrange link, and pc to pretend the panicking
	// function calls sigpanic directly.
	// Always save LINK to stack so that panics in leaf
	// functions are correctly handled. This smashes
	// the stack frame but we're not going back there
	// anyway.
	sp := c.sp() - goarch.PtrSize

		_ = v
	}
}

type R struct{ *T }

type Q interface {
	Foo([]interface{})
}

func main() {
	var count = 10000
	if runtime.Compiler == "gccgo" {
		// On targets without split-stack libgo allocates
		// a large stack for each goroutine. On 32-bit
		// systems this test can run out of memory.
		const intSize = 32 << (^uint(0) >> 63) // 32 or 64
		if intSize < 64 {
			count = 100
		}
	}

	var q Q = &R{&T{}}

	_PAGE_READWRITE = 0x0004
	_PAGE_NOACCESS  = 0x0001

	_ERROR_NOT_ENOUGH_MEMORY = 8
	_ERROR_COMMITMENT_LIMIT  = 1455
)

// Don't split the stack as this function may be invoked without a valid G,
// which prevents us from allocating more stack.
//
//go:nosplit
func sysAllocOS(n uintptr) unsafe.Pointer {
	return unsafe.Pointer(stdcall4(_VirtualAlloc, 0, n, _MEM_COMMIT|_MEM_RESERVE, _PAGE_READWRITE))
}

	// Duff-adjusted address will be spilled and loaded

	*x = T{} // DUFFZERO
	runtime.GC()
	(*x)[0] = 1
	g()      // call a function with large frame, trigger a stack move
	*x = T{} // DUFFZERO again
}

//go:noinline
// a function with large frame
func g() {
	var x [1000]int
	_ = x
}

func main() {

	testenv.MustHaveGoBuild(t)

	// This test does a build of a specific canned package to
	// check whether merging of stack slots is taking place.
	// The idea is to do the compile with a trace option turned
	// on and then pick up on the frame offsets of specific
	// variables.
	//
	// Stack slot merging is a greedy algorithm, and there can
	// be many possible ways to overlap a given set of candidate

package a

import (
	"fmt"
	"runtime"
	"strings"
)

var x = f() // line 15

func f() int {
	var b [4096]byte
	n := runtime.Stack(b[:], false) // line 19
	s := string(b[:n])
	var pcs [10]uintptr
	n = runtime.Callers(1, pcs[:]) // line 22

	// Check the Stack results.
	if debug {
		println(s)
	}
	if strings.Contains(s, "autogenerated") {
		panic("autogenerated code in traceback")
	}

	recurseThenCallGo(w, numGoroutines, numFrames, true)
	<-w
	printStack()
	close(w)
}

var ignoreGoroutines = make(map[string]bool)

func printStack() {
	buf := make([]byte, 1024)
	for {
		n := runtime.Stack(buf, true)
		if n < len(buf) {
			all := string(buf[:n])
			var saved string

			// Delete any ignored goroutines, if present.
			for all != "" {
				var g string
				g, all, _ = strings.Cut(all, "\n\n")

	// the buffer if the stack has been shaded, or even avoid
	// putting them in the buffer at all (which would double its
	// capacity). This is slightly complicated with the buffer; we
	// could track whether any un-shaded goroutine has used the
	// buffer, or just track globally whether there are any
	// un-shaded stacks and flush after each stack scan.
	gcw := &pp.gcw
	pos := 0

profMemActive < profMemFuture;

# Stack allocation and copying
gcBitsArenas,
  netpollInit,
  profBlock,
  profInsert,
  profMemFuture,
  spanSetSpine,
  fin,
  root
# Anything that can grow the stack can acquire STACKGROW.
# (Most higher layers imply STACKGROW, like MALLOC.)
< STACKGROW
# Below STACKGROW is the stack allocator/copying implementation.
< gscan;
gscan < stackpool;