// license that can be found in the LICENSE file.

package codegen

import "runtime"

// This file contains code generation tests related to the use of the
// stack.

// Check that stack stores are optimized away.

// 386:"TEXT\t.*, [$]0-"
// amd64:"TEXT\t.*, [$]0-"
// arm:"TEXT\t.*, [$]-4-"
// arm64:"TEXT\t.*, [$]0-"
// mips:"TEXT\t.*, [$]-4-"
// ppc64x:"TEXT\t.*, [$]0-"

	// allocation.
	if newsize < fixedStack {
		return
	}
	// Compute how much of the stack is currently in use and only
	// shrink the stack if gp is using less than a quarter of its
	// current stack. The currently used stack includes everything
	// down to the SP plus the stack guard space that ensures
	// there's room for nosplit functions.
	avail := gp.stack.hi - gp.stack.lo

)

// PrintStack prints to standard error the stack trace returned by runtime.Stack.
func PrintStack() {
	os.Stderr.Write(Stack())
}

// Stack returns a formatted stack trace of the goroutine that calls it.
// It calls [runtime.Stack] with a large enough buffer to capture the entire trace.
func Stack() []byte {
	buf := make([]byte, 1024)
	for {
		n := runtime.Stack(buf, false)
		if n < len(buf) {
			return buf[:n]
		}

			}

			if len(stack) > 0 {
				stack += " "
			}
			stack += FmtSprintf("%s:%d", name, line-tiuStart)
		}

		if stack != prevStack {
			prevStack = stack

			t.Logf("tiuTest+%#x: %s", pc-pc1, stack)

			if _, ok := want[stack]; ok {
				want[stack]++
			}
		}
	}

	// Check that we got all the stacks we wanted.
	for stack, count := range want {
		if count == 0 {

// explaining why.
//
//go:nosplit
func debugCallCheck(pc uintptr) string {
	// No user calls from the system stack.
	if getg() != getg().m.curg {
		return debugCallSystemStack
	}
	if sp := getcallersp(); !(getg().stack.lo < sp && sp <= getg().stack.hi) {
		// Fast syscalls (nanotime) and racecall switch to the
		// g0 stack without switching g. We can't safely make
		// a call in this state. (We can't even safely
		// systemstack.)

}

type g struct {
	// Stack parameters.
	// stack describes the actual stack memory: [stack.lo, stack.hi).
	// stackguard0 is the stack pointer compared in the Go stack growth prologue.
	// It is stack.lo+StackGuard normally, but can be StackPreempt to trigger a preemption.
	// stackguard1 is the stack pointer compared in the //go:systemstack stack growth prologue.
	// It is stack.lo+StackGuard on g0 and gsignal stacks.

	}

	var state stackScanState
	state.stack = gp.stack

	if stackTraceDebug {
		println("stack trace goroutine", gp.goid)
	}

	if debugScanConservative && gp.asyncSafePoint {
		print("scanning async preempted goroutine ", gp.goid, " stack [", hex(gp.stack.lo), ",", hex(gp.stack.hi), ")\n")
	}

	// Scan the saved context register. This is effectively a live
	// register that gets moved back and forth between the

		Name:  "process_sort_index",
		Phase: "M",
		PID:   sectionID,
		Arg:   &format.SortIndexArg{Index: priority},
	})
}

// Stack emits the given frames and returns a unique id for the stack. No
// pointers to the given data are being retained beyond the call to Stack.
func (e *Emitter) Stack(stk []*trace.Frame) int {
	return e.buildBranch(e.frameTree, stk)
}

	{
		var x Ptr
		verifyGCInfo(t, "stack Ptr", &x, infoPtr)
		runtime.KeepAlive(x)
	}
	{
		var x ScalarPtr
		verifyGCInfo(t, "stack ScalarPtr", &x, infoScalarPtr)
		runtime.KeepAlive(x)
	}
	{
		var x PtrScalar
		verifyGCInfo(t, "stack PtrScalar", &x, infoPtrScalar)
		runtime.KeepAlive(x)
	}
	{
		var x BigStruct
		verifyGCInfo(t, "stack BigStruct", &x, infoBigStruct())
		runtime.KeepAlive(x)
	}

	child6bad()
	child6() // appears in stack trace
}

//go:noinline
func child6bad() {
}

//go:noinline
func child6() { // test trace through first of two call instructions
	child7() // appears in stack trace
	child7bad()
}

//go:noinline
func child7bad() {
}

//go:noinline
func child7() {
	// Write runtime.Caller's view of the stack to stderr, for debugging.
	var pcs [16]uintptr