// TODO: disassembler support should be compiled in unconditionally,
// instead of being decided by the build-target architecture, and be
// part of the Arch object instead.

package proc

import (
	"golang.org/x/arch/x86/x86asm"
)

// AsmDecode decodes the assembly instruction starting at mem[0:] into asmInst.
// It assumes that the Loc and AtPC fields of asmInst have already been filled.
func (a *AMD64) AsmDecode(asmInst *AsmInstruction, mem []byte, regs Registers, memrw MemoryReadWriter, bi *BinaryInfo) error {
	return x86AsmDecode(asmInst, mem, regs, memrw, bi, 64)
}

func (a *AMD64) Prologues() []opcodeSeq {
	return prologuesAMD64
}

// Possible stacksplit prologues are inserted by stacksplit in
// $GOROOT/src/cmd/internal/obj/x86/obj6.go.
// The stacksplit prologue will always begin with loading curg in CX, this
// instruction is added by load_g_cx in the same file and is either 1 or 2
// MOVs.
var prologuesAMD64 []opcodeSeq

func init() {
	var tinyStacksplit = opcodeSeq{uint64(x86asm.CMP), uint64(x86asm.JBE)}
	var smallStacksplit = opcodeSeq{uint64(x86asm.LEA), uint64(x86asm.CMP), uint64(x86asm.JBE)}
	var bigStacksplit = opcodeSeq{uint64(x86asm.MOV), uint64(x86asm.CMP), uint64(x86asm.JE), uint64(x86asm.LEA), uint64(x86asm.SUB), uint64(x86asm.CMP), uint64(x86asm.JBE)}
	var unixGetG = opcodeSeq{uint64(x86asm.MOV)}
	var windowsGetG = opcodeSeq{uint64(x86asm.MOV), uint64(x86asm.MOV)}

	prologuesAMD64 = make([]opcodeSeq, 0, 2*3)
	for _, getG := range []opcodeSeq{unixGetG, windowsGetG} {
		for _, stacksplit := range []opcodeSeq{tinyStacksplit, smallStacksplit, bigStacksplit} {
			prologue := make(opcodeSeq, 0, len(getG)+len(stacksplit))
			prologue = append(prologue, getG...)
			prologue = append(prologue, stacksplit...)
			prologuesAMD64 = append(prologuesAMD64, prologue)
		}
	}
}