fn := typecheck.LookupRuntime("mapclear", t.Key(), t.Elem())
	n := mkcallstmt1(fn, rtyp, m)
	return walkStmt(typecheck.Stmt(n))
}

// Lower n into runtime·memclr if possible, for
// fast zeroing of slices and arrays (issue 5373).
// Look for instances of
//
//	for i := range a {
//		a[i] = zero
//	}
//
// in which the evaluation of a is side-effect-free.
//

// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// runtime·duffzero is a Duff's device for zeroing memory.
// The compiler jumps to computed addresses within
// the routine to zero chunks of memory.
// Do not change duffzero without also
// changing the uses in cmd/compile/internal/*/*.go.

			break
		}
	}

	// We now own slot.
	val := *(*any)(unsafe.Pointer(slot))
	if val == dequeueNil(nil) {
		val = nil
	}

	// Tell pushHead that we're done with this slot. Zeroing the
	// slot is also important so we don't leave behind references
	// that could keep this object live longer than necessary.
	//
	// We write to val first and then publish that we're done with

			(MOVVstore [0] ptr (MOVVconst [0]) mem)))

// medium zeroing uses a duff device
// 8, and 128 are magic constants, see runtime/mkduff.go
(Zero [s] {t} ptr mem)
	&& s%8 == 0 && s > 24 && s <= 8*128
	&& t.Alignment()%8 == 0 && !config.noDuffDevice =>
	(DUFFZERO [8 * (128 - s/8)] ptr mem)

// large or unaligned zeroing uses a loop
(Zero [s] {t} ptr mem)

	} else {
		n.(*ir.AssignStmt).X = left
	}
	as := n.(*ir.AssignStmt)

	if oaslit(as, init) {
		return ir.NewBlockStmt(as.Pos(), nil)
	}

	if as.Y == nil {
		// TODO(austin): Check all "implicit zeroing"
		return as
	}

	if !base.Flag.Cfg.Instrumenting && ir.IsZero(as.Y) {
		return as
	}

	switch as.Y.Op() {
	default:
		as.Y = walkExpr(as.Y, init)

	case ir.ORECV:

	// Sort pointer-typed before non-pointer types.
	// Keeps the stack's GC bitmap compact.
	ap := a.Type().HasPointers()
	bp := b.Type().HasPointers()
	if ap != bp {
		return ap
	}

	// Group variables that need zeroing, so we can efficiently zero
	// them altogether.
	ap = a.Needzero()
	bp = b.Needzero()
	if ap != bp {
		return ap
	}

	// Sort variables in descending alignment order, so we can optimally

				(MOVDstore ptr (MOVDconst [0]) mem))))

// Medium 8-aligned zeroing uses a Duff's device
// 8 and 128 are magic constants, see runtime/mkduff.go
(Zero [s] {t} ptr mem)
	&& s%8 == 0 && s <= 8*128
	&& t.Alignment()%8 == 0 && !config.noDuffDevice =>
	(DUFFZERO [8 * (128 - s/8)] ptr mem)

// Generic zeroing uses a loop
(Zero [s] {t} ptr mem) =>
	(LoweredZero [t.Alignment()]
		ptr

	// not Linux decides to back this memory with transparent huge
	// pages. There's latency involved in this zeroing, but the hugepage
	// gains are almost always worth it. Note: it's important that we
	// clear even if it's freshly mapped and we know there's no point
	// to zeroing as *that* is the critical signal to use huge pages.
	memclrNoHeapPointers(unsafe.Pointer(s.base()), s.elemsize)
	s.needzero = 0

// already zeroed. Otherwise if needzero is true, objects are zeroed as
// they are allocated. There are various benefits to delaying zeroing
// this way:
//
//	1. Stack frame allocation can avoid zeroing altogether.
//
//	2. It exhibits better temporal locality, since the program is
//	   probably about to write to the memory.
//
//	3. We don't zero pages that never get reused.

	b.Kind = kind
	b.ResetControls()
	b.Aux = nil
	b.AuxInt = 0
	b.Controls[0] = v
	b.Controls[1] = w
	v.Uses++
	w.Uses++
}

// truncateValues truncates b.Values at the ith element, zeroing subsequent elements.
// The values in b.Values after i must already have had their args reset,
// to maintain correct value uses counts.
func (b *Block) truncateValues(i int) {
	tail := b.Values[i:]