/*
 * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package ssa

import (
	"runtime"

	"github.com/goplus/llvm"
)

// -----------------------------------------------------------------------------

type Target struct {
	GOOS   string
	GOARCH string
	GOARM  string // "5", "6", "7" (default)
}

func (p *Target) targetData() llvm.TargetData {
	spec := p.Spec()
	if spec.Triple == "" {
		spec.Triple = llvm.DefaultTargetTriple()
	}
	t, err := llvm.GetTargetFromTriple(spec.Triple)
	if err != nil {
		panic(err)
	}
	machine := t.CreateTargetMachine(spec.Triple, spec.CPU, spec.Features, llvm.CodeGenLevelDefault, llvm.RelocDefault, llvm.CodeModelDefault)
	return machine.CreateTargetData()
}

/*
func (p *Program) targetMachine() llvm.TargetMachine {
	if p.tm.C == nil {
		spec := p.target.toSpec()
		target, err := llvm.GetTargetFromTriple(spec.triple)
		if err != nil {
			panic(err)
		}
		p.tm = target.CreateTargetMachine(
			spec.triple,
			spec.cpu,
			spec.features,
			llvm.CodeGenLevelDefault,
			llvm.RelocDefault,
			llvm.CodeModelDefault,
		)
	}
	return p.tm
}
*/

type TargetSpec struct {
	Triple   string
	CPU      string
	Features string
}

func (p *Target) Spec() (spec TargetSpec) {
	// Configure based on GOOS/GOARCH environment variables (falling back to
	// runtime.GOOS/runtime.GOARCH), and generate a LLVM target based on it.
	var llvmarch string
	var goarch = p.GOARCH
	var goos = p.GOOS
	if goarch == "" {
		goarch = runtime.GOARCH
	}
	if goos == "" {
		goos = runtime.GOOS
	}
	switch goarch {
	case "386":
		llvmarch = "i386"
	case "amd64":
		llvmarch = "x86_64"
	case "arm64":
		llvmarch = "aarch64"
	case "arm":
		switch p.GOARM {
		case "5":
			llvmarch = "armv5"
		case "6":
			llvmarch = "armv6"
		default:
			llvmarch = "armv7"
		}
	case "wasm":
		llvmarch = "wasm32"
	default:
		llvmarch = goarch
	}
	llvmvendor := "unknown"
	llvmos := goos
	switch goos {
	case "darwin":
		// Use macosx* instead of darwin, otherwise darwin/arm64 will refer
		// to iOS!
		llvmos = "macosx"
		if llvmarch == "aarch64" {
			// Looks like Apple prefers to call this architecture ARM64
			// instead of AArch64.
			llvmarch = "arm64"
			llvmos = "macosx"
		}
		llvmvendor = "apple"
	case "wasip1":
		llvmos = "wasip1"
	}
	// Target triples (which actually have four components, but are called
	// triples for historical reasons) have the form:
	//   arch-vendor-os-environment
	spec.Triple = llvmarch + "-" + llvmvendor + "-" + llvmos
	if llvmos == "windows" {
		spec.Triple += "-gnu"
	} else if goarch == "arm" {
		spec.Triple += "-gnueabihf"
	}
	switch goarch {
	case "386":
		spec.CPU = "pentium4"
		spec.Features = "+cx8,+fxsr,+mmx,+sse,+sse2,+x87"
	case "amd64":
		spec.CPU = "x86-64"
		spec.Features = "+cx8,+fxsr,+mmx,+sse,+sse2,+x87"
	case "arm":
		spec.CPU = "generic"
		switch llvmarch {
		case "armv5":
			spec.Features = "+armv5t,+strict-align,-aes,-bf16,-d32,-dotprod,-fp-armv8,-fp-armv8d16,-fp-armv8d16sp,-fp-armv8sp,-fp16,-fp16fml,-fp64,-fpregs,-fullfp16,-mve.fp,-neon,-sha2,-thumb-mode,-vfp2,-vfp2sp,-vfp3,-vfp3d16,-vfp3d16sp,-vfp3sp,-vfp4,-vfp4d16,-vfp4d16sp,-vfp4sp"
		case "armv6":
			spec.Features = "+armv6,+dsp,+fp64,+strict-align,+vfp2,+vfp2sp,-aes,-d32,-fp-armv8,-fp-armv8d16,-fp-armv8d16sp,-fp-armv8sp,-fp16,-fp16fml,-fullfp16,-neon,-sha2,-thumb-mode,-vfp3,-vfp3d16,-vfp3d16sp,-vfp3sp,-vfp4,-vfp4d16,-vfp4d16sp,-vfp4sp"
		case "armv7":
			spec.Features = "+armv7-a,+d32,+dsp,+fp64,+neon,+vfp2,+vfp2sp,+vfp3,+vfp3d16,+vfp3d16sp,+vfp3sp,-aes,-fp-armv8,-fp-armv8d16,-fp-armv8d16sp,-fp-armv8sp,-fp16,-fp16fml,-fullfp16,-sha2,-thumb-mode,-vfp4,-vfp4d16,-vfp4d16sp,-vfp4sp"
		}
	case "arm64":
		spec.CPU = "generic"
		if goos == "darwin" {
			spec.Features = "+neon"
		} else { // windows, linux
			spec.Features = "+neon,-fmv"
		}
	case "wasm":
		spec.CPU = "generic"
		spec.Features = "+bulk-memory,+mutable-globals,+nontrapping-fptoint,+sign-ext"
	}
	return
}

// -----------------------------------------------------------------------------