// Copyright 2018 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.

#include "go_asm.h"
#include "textflag.h"

// memequal(a, b unsafe.Pointer, size uintptr) bool
TEXT runtime·memequal(SB),NOSPLIT,$0-13
	MOVL	a+0(FP), SI
	MOVL	b+4(FP), DI
	CMPL	SI, DI
	JEQ	eq
	MOVL	size+8(FP), BX
	LEAL	ret+12(FP), AX
	JMP	memeqbody<>(SB)
eq:

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

//go:build mips64 || mips64le

#include "go_asm.h"
#include "textflag.h"

#define	REGCTXT	R22

// memequal(a, b unsafe.Pointer, size uintptr) bool
TEXT runtime·memequal(SB),NOSPLIT|NOFRAME,$0-25
	MOVV	a+0(FP), R1
	MOVV	b+8(FP), R2
	BEQ	R1, R2, eq
	MOVV	size+16(FP), R3
	ADDV	R1, R3, R4

	// chunk size is 16

#define PAGE_OFFSET 4095

// Likewise, the BC opcode is hard to read, and no extended
// mnemonics are offered for these forms.
#define BGELR_CR6 BC  4, CR6LT, (LR)
#define BEQLR     BC 12, CR0EQ, (LR)

// memequal(a, b unsafe.Pointer, size uintptr) bool
TEXT runtime·memequal<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-25
	// R3 = a
	// R4 = b
	// R5 = size
	BR	memeqbody<>(SB)

// memequal_varlen(a, b unsafe.Pointer) bool

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

#include "go_asm.h"
#include "asm_amd64.h"
#include "textflag.h"

// memequal(a, b unsafe.Pointer, size uintptr) bool
TEXT runtime·memequal<ABIInternal>(SB),NOSPLIT,$0-25
	// AX = a    (want in SI)
	// BX = b    (want in DI)
	// CX = size (want in BX)
	CMPQ	AX, BX
	JNE	neq

// Copyright 2018 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.

#include "go_asm.h"
#include "textflag.h"

// memequal(a, b unsafe.Pointer, size uintptr) bool
TEXT runtime·memequal<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-25
	// short path to handle 0-byte case
	CBZ	R2, equal
	// short path to handle equal pointers
	CMP	R0, R1
	BEQ	equal

// in internal/bytealg/equal_*.s
//
// memequal should be an internal detail,
// but widely used packages access it using linkname.
// Notable members of the hall of shame include:
//   - github.com/bytedance/sonic
//
// Do not remove or change the type signature.
// See go.dev/issue/67401.
//
//go:linkname memequal
//go:noescape
func memequal(a, b unsafe.Pointer, size uintptr) bool

		// quick check of len before full compare for == or !=.
		// memequal then tests equality up to length len.
		if n.Op() == ir.OEQ {
			// len(left) == len(right) && memequal(left, right, len)
			r = ir.NewLogicalExpr(base.Pos, ir.OANDAND, eqlen, eqmem)
		} else {
			// len(left) != len(right) || !memequal(left, right, len)
			eqlen.SetOp(ir.ONE)

			// we must have lost the race, and therefore n is not nil
			// anymore.
			n = (*traceMapNode)(m.Load())
		}
		if n.hash == hash && uintptr(len(n.data)) == size {
			if memequal(unsafe.Pointer(&n.data[0]), data, size) {
				return n.id, false
			}
		}
		m = &n.children[hashIter>>(8*goarch.PtrSize-2)]
		hashIter <<= 2
	}
}

(NilCheck ptr:(Convert (Addr {_} (SB)) _) _) => ptr

// for late-expanded calls, recognize memequal applied to a single constant byte
// Support is limited by 1, 2, 4, 8 byte sizes
(StaticLECall {callAux} sptr (Addr {scon} (SB)) (Const64 [1]) mem)
  && isSameCall(callAux, "runtime.memequal")
  && symIsRO(scon)
  => (MakeResult (Eq8 (Load <typ.Int8> sptr mem) (Const8 <typ.Int8> [int8(read8(scon,0))])) mem)

	// cond: isSameCall(callAux, "runtime.memequal") && isSamePtr(p, q)
	// result: (MakeResult (ConstBool <typ.Bool> [true]) mem)
	for {
		if len(v.Args) != 4 {
			break
		}
		callAux := auxToCall(v.Aux)
		mem := v.Args[3]
		p := v.Args[0]
		q := v.Args[1]
		if !(isSameCall(callAux, "runtime.memequal") && isSamePtr(p, q)) {
			break
		}
		v.reset(OpMakeResult)