package backend

import (
	

	
	
)

type (
	// FunctionABI represents the ABI information for a function which corresponds to a ssa.Signature.
	FunctionABI struct {
		Initialized bool

		Args, Rets                 []ABIArg
		ArgStackSize, RetStackSize int64

		ArgIntRealRegs   byte
		ArgFloatRealRegs byte
		RetIntRealRegs   byte
		RetFloatRealRegs byte
	}

	// ABIArg represents either argument or return value's location.
	ABIArg struct {
		// Index is the index of the argument.
		Index int
		// Kind is the kind of the argument.
		Kind ABIArgKind
		// Reg is valid if Kind == ABIArgKindReg.
		// This VReg must be based on RealReg.
		Reg regalloc.VReg
		// Offset is valid if Kind == ABIArgKindStack.
		// This is the offset from the beginning of either arg or ret stack slot.
		Offset int64
		// Type is the type of the argument.
		Type ssa.Type
	}

	// ABIArgKind is the kind of ABI argument.
	ABIArgKind byte
)

const (
	// ABIArgKindReg represents an argument passed in a register.
	ABIArgKindReg = iota
	// ABIArgKindStack represents an argument passed in the stack.
	ABIArgKindStack
)

// String implements fmt.Stringer.
func ( *ABIArg) () string {
	return fmt.Sprintf("args[%d]: %s", .Index, .Kind)
}

// String implements fmt.Stringer.
func ( ABIArgKind) () string {
	switch  {
	case ABIArgKindReg:
		return "reg"
	case ABIArgKindStack:
		return "stack"
	default:
		panic("BUG")
	}
}

// Init initializes the abiImpl for the given signature.
func ( *FunctionABI) ( *ssa.Signature, ,  []regalloc.RealReg) {
	if len(.Rets) < len(.Results) {
		.Rets = make([]ABIArg, len(.Results))
	}
	.Rets = .Rets[:len(.Results)]
	.RetStackSize = .setABIArgs(.Rets, .Results, , )
	if  := len(.Params); len(.Args) <  {
		.Args = make([]ABIArg, )
	}
	.Args = .Args[:len(.Params)]
	.ArgStackSize = .setABIArgs(.Args, .Params, , )

	// Gather the real registers usages in arg/return.
	.ArgIntRealRegs, .ArgFloatRealRegs = 0, 0
	.RetIntRealRegs, .RetFloatRealRegs = 0, 0
	for  := range .Rets {
		 := &.Rets[]
		if .Kind == ABIArgKindReg {
			if .Type.IsInt() {
				.RetIntRealRegs++
			} else {
				.RetFloatRealRegs++
			}
		}
	}
	for  := range .Args {
		 := &.Args[]
		if .Kind == ABIArgKindReg {
			if .Type.IsInt() {
				.ArgIntRealRegs++
			} else {
				.ArgFloatRealRegs++
			}
		}
	}

	.Initialized = true
}

// setABIArgs sets the ABI arguments in the given slice. This assumes that len(s) >= len(types)
// where if len(s) > len(types), the last elements of s is for the multi-return slot.
func ( *FunctionABI) ( []ABIArg,  []ssa.Type, ,  []regalloc.RealReg) ( int64) {
	,  := len(), len()

	var  int64
	,  := 0, 0
	for ,  := range  {
		 := &[]
		.Index = 
		.Type = 
		if .IsInt() {
			if  >=  {
				.Kind = ABIArgKindStack
				const  = 8 // Align 8 bytes.
				.Offset = 
				 += 
			} else {
				.Kind = ABIArgKindReg
				.Reg = regalloc.FromRealReg([], regalloc.RegTypeInt)
				++
			}
		} else {
			if  >=  {
				.Kind = ABIArgKindStack
				 := int64(8)   // Align at least 8 bytes.
				if .Bits() == 128 { // Vector.
					 = 16
				}
				.Offset = 
				 += 
			} else {
				.Kind = ABIArgKindReg
				.Reg = regalloc.FromRealReg([], regalloc.RegTypeFloat)
				++
			}
		}
	}
	return 
}

func ( *FunctionABI) () uint32 {
	 := .RetStackSize + .ArgStackSize
	// Align stackSlotSize to 16 bytes.
	 = ( + 15) &^ 15
	// Check overflow 32-bit.
	if  > 0xFFFFFFFF {
		panic("ABI stack slot size overflow")
	}
	return uint32()
}

func ( *FunctionABI) () uint64 {
	return uint64(.ArgIntRealRegs)<<56 |
		uint64(.ArgFloatRealRegs)<<48 |
		uint64(.RetIntRealRegs)<<40 |
		uint64(.RetFloatRealRegs)<<32 |
		uint64(.AlignedArgResultStackSlotSize())
}

func ( uint64) (, , ,  byte,  uint32) {
	return byte( >> 56), byte( >> 48), byte( >> 40), byte( >> 32), uint32()
}