// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package objabi

import (
	"internal/abi"
	"internal/buildcfg"
)

func StackNosplit(race bool) int {
	// This arithmetic must match that in runtime/stack.go:stackNosplit.
	return abi.StackNosplitBase * stackGuardMultiplier(race)
}

// stackGuardMultiplier returns a multiplier to apply to the default

	fixedStack5 = fixedStack4 | (fixedStack4 >> 8)
	fixedStack6 = fixedStack5 | (fixedStack5 >> 16)
	fixedStack  = fixedStack6 + 1

	// stackNosplit is the maximum number of bytes that a chain of NOSPLIT
	// functions can use.
	// This arithmetic must match that in cmd/internal/objabi/stack.go:StackNosplit.
	stackNosplit = abi.StackNosplitBase * sys.StackGuardMultiplier

	// The stack guard is a pointer this many bytes above the
	// bottom of the stack.

	// depth, the stack check test fails.
	//
	// The call to morestack in every splittable function ensures
	// that there are at least StackLimit bytes available below SP
	// when morestack returns.
	limit := objabi.StackNosplit(*flagRace) - sc.callSize
	if buildcfg.GOARCH == "arm64" {
		// Need an extra 8 bytes below SP to save FP.
		limit -= 8
	}

	// Compute stack heights without any back-tracking information.

	f = findfunc(abi.FuncPCABIInternal(asyncPreempt2))
	total += funcMaxSPDelta(f)
	// Add some overhead for return PCs, etc.
	asyncPreemptStack = uintptr(total) + 8*goarch.PtrSize
	if asyncPreemptStack > stackNosplit {
		// We need more than the nosplit limit. This isn't
		// unsafe, but it may limit asynchronous preemption.
		//
		// This may be a problem if we start using more