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

package codegen

// This file contains code generation tests related to the handling of
// struct types.

// ------------- //
//    Zeroing    //
// ------------- //

type Z1 struct {
	a, b, c int
}

func Zero1(t *Z1) { // Issue #18370
	// amd64:`MOVUPS\tX[0-9]+, \(.*\)`,`MOVQ\t\$0, 16\(.*\)`
	*t = Z1{}
}

type Z2 struct {

// void runtime·memclrNoHeapPointers(void*, uintptr)
TEXT runtime·memclrNoHeapPointers<ABIInternal>(SB),NOSPLIT,$0-16
	// X10 = ptr
	// X11 = n

	// If less than 8 bytes, do single byte zeroing.
	MOV	$8, X9
	BLT	X11, X9, check4

	// Check alignment
	AND	$7, X10, X5
	BEQZ	X5, aligned

	// Zero one byte at a time until we reach 8 byte alignment.
	SUB	X5, X9, X5
	SUB	X5, X11, X11
align:

		h -= pow * uint32(s[i+n])
		if h == hashss && string(s[i:i+n]) == string(sep) {
			return i
		}
	}
	return -1
}

// MakeNoZero makes a slice of length n and capacity of at least n Bytes
// without zeroing the bytes (including the bytes between len and cap).
// It is the caller's responsibility to ensure uninitialized bytes
// do not leak to the end user.

// Malloc uses a FixAlloc wrapped around sysAlloc to manage its
// mcache and mspan objects.
//
// Memory returned by fixalloc.alloc is zeroed by default, but the
// caller may take responsibility for zeroing allocations by setting
// the zero flag to false. This is only safe if the memory never
// contains heap pointers.
//
// The caller is responsible for locking around FixAlloc calls.

   before they become visible as GC roots. Otherwise, the GC may
   observe stale heap pointers. See "Zero-initialization versus
   zeroing".

Zero-initialization versus zeroing
==================================

There are two types of zeroing in the runtime, depending on whether
the memory is already initialized to a type-safe state.

If memory is not in a type-safe state, meaning it potentially contains

func FilterInPlace[E any](s []E, f func(E) bool) []E {
	n := 0
	for _, val := range s {
		if f(val) {
			s[n] = val
			n++
		}
	}

	// If those elements contain pointers you might consider zeroing those elements
	// so that objects they reference can be garbage collected."
	var empty E
	for i := n; i < len(s); i++ {
		s[i] = empty
	}

	s = s[:n]
	return s
}

	REG_AR14
	REG_AR15

	REG_RESERVED // end of allocated registers

	REGARG  = -1      // -1 disables passing the first argument in register
	REGRT1  = REG_R3  // used during zeroing of the stack - not reserved
	REGRT2  = REG_R4  // used during zeroing of the stack - not reserved
	REGTMP  = REG_R10 // scratch register used in the assembler and linker
	REGTMP2 = REG_R11 // scratch register used in the assembler and linker

	var to unsafe.Pointer
	if !et.Pointers() {
		to = mallocgc(tomem, nil, false)
		if copymem < tomem {
			memclrNoHeapPointers(add(to, copymem), tomem-copymem)
		}
	} else {
		// Note: can't use rawmem (which avoids zeroing of memory), because then GC can scan uninitialized memory.
		to = mallocgc(tomem, et, true)
		if copymem > 0 && writeBarrier.enabled {
			// Only shade the pointers in old.array since we know the destination slice to

func (d *state) BlockSize() int { return d.rate }

// Size returns the output size of the hash function in bytes.
func (d *state) Size() int { return d.outputLen }

// Reset clears the internal state by zeroing the sponge state and
// the buffer indexes, and setting Sponge.state to absorbing.
func (d *state) Reset() {
	// Zero the permutation's state.
	for i := range d.a {
		d.a[i] = 0
	}
	d.state = spongeAbsorbing

	if goexperiment.CgoCheck2 {
		cgoCheckMemmove2(typ, dst, src, 0, typ.Size_)
	}
}

// wbZero performs the write barrier operations necessary before
// zeroing a region of memory at address dst of type typ.
// Does not actually do the zeroing.
//
//go:nowritebarrierrec
//go:nosplit
func wbZero(typ *_type, dst unsafe.Pointer) {
	// This always copies a full value of type typ so it's safe