if p.lineDepth < len(p.stack) {
		return p.stack[p.lineDepth].builder
	}
	return nil
}

func (p *parseState) nextB() blockBuilder {
	if p.lineDepth+1 < len(p.stack) {
		return p.stack[p.lineDepth+1].builder
	}
	return nil
}
func (p *parseState) trimStack(depth int) {
	if len(p.stack) < depth {
		panic("trimStack")
	}
	for len(p.stack) > depth {
		p.closeBlock()
	}
}

	// calls that may need more stack than we think.
	//
	// The default stack reserve size directly affects only the main
	// thread.
	//
	// For other threads, the runtime explicitly asks the kernel
	// to use the default stack size so that all stacks are
	// consistent.
	//
	// At thread start, in minit, the runtime queries the OS for
	// the actual stack bounds so that the stack size doesn't need

	{name: "PanicExtend", argLength: 4, aux: "Int64", typ: "Mem", call: true}, // arg0=idxHi, arg1=idxLo, arg2=len, arg3=mem, returns memory.

	// Function calls. Arguments to the call have already been written to the stack.
	// Return values appear on the stack. The method receiver, if any, is treated
	// as a phantom first argument.
	// TODO(josharian): ClosureCall and InterCall should have Int32 aux
	// to match StaticCall's 32 bit arg size limit.

// with RFC 8032. RFC 8032's private keys correspond to seeds in this
// package.
func NewKeyFromSeed(seed []byte) PrivateKey {
	// Outline the function body so that the returned key can be stack-allocated.
	privateKey := make([]byte, PrivateKeySize)
	newKeyFromSeed(privateKey, seed)
	return privateKey
}

func newKeyFromSeed(privateKey, seed []byte) {
	if l := len(seed); l != SeedSize {

	C_WEAKEXT = 111 // Weak external symbol
	C_DWARF   = 112 // DWARF symbol
	C_GSYM    = 128 // Global variable
	C_LSYM    = 129 // Automatic variable allocated on stack
	C_PSYM    = 130 // Argument to subroutine allocated on stack
	C_RSYM    = 131 // Register variable
	C_RPSYM   = 132 // Argument to function or procedure stored in register
	C_STSYM   = 133 // Statically allocated symbol

func popDefer(gp *g) {
	d := gp._defer
	d.fn = nil // Can in theory point to the stack
	// We must not copy the stack between the updating gp._defer and setting
	// d.link to nil. Between these two steps, d is not on any defer list, so
	// stack copying won't adjust stack pointers in it (namely, d.link). Hence,
	// if we were to copy the stack, d could then contain a stale pointer.
	gp._defer = d.link
	d.link = nil

	// signal stack of the creating thread. We always create a
	// new signal stack here, to avoid having two Go threads using
	// the same signal stack. This breaks the case of a thread
	// created in C that calls sigaltstack and then calls a Go
	// function, because we will lose track of the C code's
	// sigaltstack, but it's the best we can do.
	signalstack(&gp.m.gsignal.stack)
	gp.m.newSigstack = true

			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

	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.

	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"}}