From 5fe83543fd7b9dcba87747ca2ccab12dfeea40c7 Mon Sep 17 00:00:00 2001
From: Eduard Urbach <admin@akyoto.dev>
Date: Sun, 29 Oct 2023 16:16:36 +0100
Subject: [PATCH] Improved build performance

---
 go.mod                                  |  2 -
 go.sum                                  |  2 -
 main_test.go                            | 11 ++--
 src/asm/Address.go                      |  2 +-
 src/asm/Assembler.go                    | 68 +++++++++++++------------
 src/asm/Data.go                         | 19 +++++++
 src/asm/Pointer.go                      |  9 ++++
 src/asm/Result.go                       | 22 --------
 src/asm/x64/Move.go                     | 11 ----
 src/asm/x64/Syscall.go                  | 11 ----
 src/asm/x64/x64.go                      | 11 ----
 src/build/Build.go                      | 29 ++++++-----
 src/cli/Build.go                        |  3 ++
 src/{syscall => linux}/syscall_linux.go |  3 +-
 src/{asm => }/x64/Call.go               | 14 +++--
 src/x64/Move.go                         | 13 +++++
 src/{asm => }/x64/Return.go             |  6 +--
 src/x64/Syscall.go                      |  6 +++
 18 files changed, 122 insertions(+), 120 deletions(-)
 delete mode 100644 go.sum
 create mode 100644 src/asm/Data.go
 create mode 100644 src/asm/Pointer.go
 delete mode 100644 src/asm/Result.go
 delete mode 100644 src/asm/x64/Move.go
 delete mode 100644 src/asm/x64/Syscall.go
 delete mode 100644 src/asm/x64/x64.go
 rename src/{syscall => linux}/syscall_linux.go (99%)
 rename src/{asm => }/x64/Call.go (51%)
 create mode 100644 src/x64/Move.go
 rename src/{asm => }/x64/Return.go (73%)
 create mode 100644 src/x64/Syscall.go

diff --git a/go.mod b/go.mod
index e78e48b..2c2b156 100644
--- a/go.mod
+++ b/go.mod
@@ -1,5 +1,3 @@
 module git.akyoto.dev/cli/q
 
 go 1.21
-
-require git.akyoto.dev/go/assert v0.1.3
diff --git a/go.sum b/go.sum
deleted file mode 100644
index 9fc2547..0000000
--- a/go.sum
+++ /dev/null
@@ -1,2 +0,0 @@
-git.akyoto.dev/go/assert v0.1.3 h1:QwCUbmG4aZYsNk/OuRBz1zWVKmGlDUHhOnnDBfn8Qw8=
-git.akyoto.dev/go/assert v0.1.3/go.mod h1:0GzMaM0eURuDwtGkJJkCsI7r2aUKr+5GmWNTFPgDocM=
diff --git a/main_test.go b/main_test.go
index cc45c58..4aac58f 100644
--- a/main_test.go
+++ b/main_test.go
@@ -7,7 +7,6 @@ import (
 
 	"git.akyoto.dev/cli/q/src/cli"
 	"git.akyoto.dev/cli/q/src/log"
-	"git.akyoto.dev/go/assert"
 )
 
 func TestMain(m *testing.M) {
@@ -28,14 +27,18 @@ func TestCLI(t *testing.T) {
 		{[]string{"system"}, 0},
 		{[]string{"build", "non-existing-directory"}, 1},
 		{[]string{"build", "examples/hello/hello.q"}, 1},
-		{[]string{"build", "examples/hello", "--dry"}, 0},
 		{[]string{"build", "examples/hello", "--invalid"}, 2},
+		{[]string{"build", "examples/hello", "--dry"}, 0},
 	}
 
 	for _, test := range tests {
-		exitCode := cli.Main(test.arguments)
 		t.Log(test.arguments)
-		assert.Equal(t, exitCode, test.expectedExitCode)
+		exitCode := cli.Main(test.arguments)
+
+		if exitCode != test.expectedExitCode {
+			t.Errorf("exit code %d (expected %d)", exitCode, test.expectedExitCode)
+			t.FailNow()
+		}
 	}
 }
 
diff --git a/src/asm/Address.go b/src/asm/Address.go
index 9c1651d..8e32c5a 100644
--- a/src/asm/Address.go
+++ b/src/asm/Address.go
@@ -4,4 +4,4 @@ package asm
 type Address = uint32
 
 // Index references an instruction by its position.
-type Index = uint32
+// type Index = uint32
diff --git a/src/asm/Assembler.go b/src/asm/Assembler.go
index a92fc62..552ff91 100644
--- a/src/asm/Assembler.go
+++ b/src/asm/Assembler.go
@@ -1,74 +1,76 @@
 package asm
 
 import (
-	"bytes"
 	"encoding/binary"
 
-	"git.akyoto.dev/cli/q/src/asm/x64"
 	"git.akyoto.dev/cli/q/src/config"
 	"git.akyoto.dev/cli/q/src/log"
 	"git.akyoto.dev/cli/q/src/register"
+	"git.akyoto.dev/cli/q/src/x64"
 )
 
 // Assembler contains a list of instructions.
 type Assembler struct {
-	instructions []Instruction
-	labels       map[string]Index
-	verbose      bool
+	Instructions []Instruction
+	// labels       map[string]Index
+	Verbose bool
 }
 
 // New creates a new assembler.
 func New() *Assembler {
 	return &Assembler{
-		instructions: make([]Instruction, 0, 8),
-		labels:       map[string]Index{},
-		verbose:      true,
+		Instructions: make([]Instruction, 0, 8),
+		// labels:       map[string]Index{},
 	}
 }
 
 // Finalize generates the final machine code.
-func (a *Assembler) Finalize() *Result {
-	result := &Result{}
-	pointers := map[Address]Address{}
-	code := bytes.NewBuffer(result.Code)
-
-	for _, x := range a.instructions {
-		if a.verbose {
-			log.Info.Println(x.String())
-		}
+func (a *Assembler) Finalize() ([]byte, []byte) {
+	code := make([]byte, 0, len(a.Instructions)*8)
+	data := make(Data, 0, 16)
+	pointers := []Pointer{}
 
+	for _, x := range a.Instructions {
 		switch x.Mnemonic {
 		case MOV:
-			x64.MoveRegNum32(code, uint8(x.Destination), uint32(x.Number))
+			code = x64.MoveRegNum32(code, uint8(x.Destination), uint32(x.Number))
 
 		case MOVDATA:
-			position := result.AddData(x.Data)
-			x64.MoveRegNum32(code, uint8(x.Destination), 0)
-			pointers[Address(code.Len()-4)] = position
+			code = x64.MoveRegNum32(code, uint8(x.Destination), 0)
+
+			pointers = append(pointers, Pointer{
+				Position: Address(len(code) - 4),
+				Address:  data.Add(x.Data),
+			})
 
 		case SYSCALL:
-			x64.Syscall(code)
+			code = x64.Syscall(code)
+		}
+
+		if a.Verbose {
+			log.Info.Println(x.String())
 		}
 	}
 
-	result.Code = code.Bytes()
-	dataStart := config.BaseAddress + config.CodeOffset + Address(len(result.Code))
+	dataStart := config.BaseAddress + config.CodeOffset + Address(len(code))
 
-	for codePos, dataPos := range pointers {
-		binary.LittleEndian.PutUint32(result.Code[codePos:codePos+4], dataStart+dataPos)
+	for _, pointer := range pointers {
+		slice := code[pointer.Position : pointer.Position+4]
+		address := dataStart + pointer.Address
+		binary.LittleEndian.PutUint32(slice, address)
 	}
 
-	return result
+	return code, data
 }
 
 // AddLabel creates a new label at the current position.
-func (a *Assembler) AddLabel(name string) {
-	a.labels[name] = Index(len(a.instructions))
-}
+// func (a *Assembler) AddLabel(name string) {
+// 	a.labels[name] = Index(len(a.instructions))
+// }
 
 // MoveRegisterData moves a data section address into the given register.
 func (a *Assembler) MoveRegisterData(reg register.ID, data []byte) {
-	a.instructions = append(a.instructions, Instruction{
+	a.Instructions = append(a.Instructions, Instruction{
 		Mnemonic:    MOVDATA,
 		Destination: reg,
 		Data:        data,
@@ -77,7 +79,7 @@ func (a *Assembler) MoveRegisterData(reg register.ID, data []byte) {
 
 // MoveRegisterNumber moves a number into the given register.
 func (a *Assembler) MoveRegisterNumber(reg register.ID, number uint64) {
-	a.instructions = append(a.instructions, Instruction{
+	a.Instructions = append(a.Instructions, Instruction{
 		Mnemonic:    MOV,
 		Destination: reg,
 		Number:      number,
@@ -86,7 +88,7 @@ func (a *Assembler) MoveRegisterNumber(reg register.ID, number uint64) {
 
 // Syscall executes a kernel function.
 func (a *Assembler) Syscall() {
-	a.instructions = append(a.instructions, Instruction{
+	a.Instructions = append(a.Instructions, Instruction{
 		Mnemonic: SYSCALL,
 	})
 }
diff --git a/src/asm/Data.go b/src/asm/Data.go
new file mode 100644
index 0000000..9268c99
--- /dev/null
+++ b/src/asm/Data.go
@@ -0,0 +1,19 @@
+package asm
+
+import "bytes"
+
+// Data represents the static read-only data.
+type Data []byte
+
+// Add adds the given bytes to the data block and returns the address relative to the start of the data section.
+func (data *Data) Add(block []byte) Address {
+	position := bytes.Index(*data, block)
+
+	if position != -1 {
+		return Address(position)
+	}
+
+	address := Address(len(*data))
+	*data = append(*data, block...)
+	return address
+}
diff --git a/src/asm/Pointer.go b/src/asm/Pointer.go
new file mode 100644
index 0000000..5d13b4f
--- /dev/null
+++ b/src/asm/Pointer.go
@@ -0,0 +1,9 @@
+package asm
+
+// Pointer stores a relative memory address that we can later turn into an absolute one.
+// Position: The machine code offset where the address was inserted.
+// Address:  The offset inside the section.
+type Pointer struct {
+	Position uint32
+	Address  uint32
+}
diff --git a/src/asm/Result.go b/src/asm/Result.go
deleted file mode 100644
index 8261d82..0000000
--- a/src/asm/Result.go
+++ /dev/null
@@ -1,22 +0,0 @@
-package asm
-
-import "bytes"
-
-// Result is the compilation result and contains the machine code as well as the data.
-type Result struct {
-	Code []byte
-	Data []byte
-}
-
-// AddData adds the given bytes to the data block and returns the address relative to the start of the data section.
-func (result *Result) AddData(block []byte) Address {
-	position := bytes.Index(result.Data, block)
-
-	if position != -1 {
-		return Address(position)
-	}
-
-	address := Address(len(result.Data))
-	result.Data = append(result.Data, block...)
-	return address
-}
diff --git a/src/asm/x64/Move.go b/src/asm/x64/Move.go
deleted file mode 100644
index d130195..0000000
--- a/src/asm/x64/Move.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package x64
-
-import (
-	"io"
-)
-
-// MoveRegNum32 moves a 32 bit integer into the given register.
-func MoveRegNum32(w io.ByteWriter, register uint8, number uint32) {
-	w.WriteByte(0xb8 + register)
-	appendUint32(w, number)
-}
diff --git a/src/asm/x64/Syscall.go b/src/asm/x64/Syscall.go
deleted file mode 100644
index 145f5a3..0000000
--- a/src/asm/x64/Syscall.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package x64
-
-import (
-	"io"
-)
-
-// Syscall is the primary way to communicate with the OS kernel.
-func Syscall(w io.ByteWriter) {
-	w.WriteByte(0x0f)
-	w.WriteByte(0x05)
-}
diff --git a/src/asm/x64/x64.go b/src/asm/x64/x64.go
deleted file mode 100644
index f6ab914..0000000
--- a/src/asm/x64/x64.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package x64
-
-import "io"
-
-// appendUint32 appends a 32 bit integer in Little Endian to the given writer.
-func appendUint32(w io.ByteWriter, number uint32) {
-	w.WriteByte(byte(number))
-	w.WriteByte(byte(number >> 8))
-	w.WriteByte(byte(number >> 16))
-	w.WriteByte(byte(number >> 24))
-}
diff --git a/src/build/Build.go b/src/build/Build.go
index 197665e..80d16c5 100644
--- a/src/build/Build.go
+++ b/src/build/Build.go
@@ -10,27 +10,31 @@ import (
 	"git.akyoto.dev/cli/q/src/directory"
 	"git.akyoto.dev/cli/q/src/elf"
 	"git.akyoto.dev/cli/q/src/errors"
+	"git.akyoto.dev/cli/q/src/linux"
 	"git.akyoto.dev/cli/q/src/log"
 	"git.akyoto.dev/cli/q/src/register"
-	"git.akyoto.dev/cli/q/src/syscall"
 )
 
 // Build describes a compiler build.
 type Build struct {
-	Name            string
 	Directory       string
+	Verbose         bool
 	WriteExecutable bool
 }
 
 // New creates a new build.
 func New(directory string) *Build {
 	return &Build{
-		Name:            filepath.Base(directory),
 		Directory:       directory,
 		WriteExecutable: true,
 	}
 }
 
+var (
+	hello = []byte("Hello\n")
+	world = []byte("World\n")
+)
+
 // Run parses the input files and generates an executable file.
 func (build *Build) Run() error {
 	// err := build.Compile()
@@ -39,33 +43,34 @@ func (build *Build) Run() error {
 	// 	return err
 	// }
 
-	a := asm.New()
+	a := asm.Assembler{
+		Instructions: make([]asm.Instruction, 0, 8),
+		Verbose:      build.Verbose,
+	}
 
-	a.MoveRegisterNumber(register.Syscall0, syscall.Write)
+	a.MoveRegisterNumber(register.Syscall0, linux.Write)
 	a.MoveRegisterNumber(register.Syscall1, 1)
-	hello := []byte("Hello\n")
 	a.MoveRegisterData(register.Syscall2, hello)
 	a.MoveRegisterNumber(register.Syscall3, uint64(len(hello)))
 	a.Syscall()
 
-	a.MoveRegisterNumber(register.Syscall0, syscall.Write)
+	a.MoveRegisterNumber(register.Syscall0, linux.Write)
 	a.MoveRegisterNumber(register.Syscall1, 1)
-	world := []byte("World\n")
 	a.MoveRegisterData(register.Syscall2, world)
 	a.MoveRegisterNumber(register.Syscall3, uint64(len(world)))
 	a.Syscall()
 
-	a.MoveRegisterNumber(register.Syscall0, syscall.Exit)
+	a.MoveRegisterNumber(register.Syscall0, linux.Exit)
 	a.MoveRegisterNumber(register.Syscall1, 0)
 	a.Syscall()
 
-	result := a.Finalize()
+	code, data := a.Finalize()
 
 	if !build.WriteExecutable {
 		return nil
 	}
 
-	return writeToDisk(build.Executable(), result.Code, result.Data)
+	return writeToDisk(build.Executable(), code, data)
 }
 
 // Compile compiles all the functions.
@@ -93,7 +98,7 @@ func (build *Build) Compile() error {
 
 // Executable returns the path to the executable.
 func (build *Build) Executable() string {
-	return filepath.Join(build.Directory, build.Name)
+	return filepath.Join(build.Directory, filepath.Base(build.Directory))
 }
 
 // writeToDisk writes the executable file to disk.
diff --git a/src/cli/Build.go b/src/cli/Build.go
index 47e76db..761d418 100644
--- a/src/cli/Build.go
+++ b/src/cli/Build.go
@@ -20,6 +20,9 @@ func Build(args []string) int {
 		case "--dry":
 			b.WriteExecutable = false
 
+		case "--verbose", "-v":
+			b.Verbose = true
+
 		default:
 			log.Error.Printf("Unknown parameter: %s\n", args[i])
 			return 2
diff --git a/src/syscall/syscall_linux.go b/src/linux/syscall_linux.go
similarity index 99%
rename from src/syscall/syscall_linux.go
rename to src/linux/syscall_linux.go
index 7c5d6f8..c535786 100644
--- a/src/syscall/syscall_linux.go
+++ b/src/linux/syscall_linux.go
@@ -1,6 +1,5 @@
-package syscall
+package linux
 
-// Linux syscalls
 const (
 	Read = iota
 	Write
diff --git a/src/asm/x64/Call.go b/src/x64/Call.go
similarity index 51%
rename from src/asm/x64/Call.go
rename to src/x64/Call.go
index d3958bf..1ada6fd 100644
--- a/src/asm/x64/Call.go
+++ b/src/x64/Call.go
@@ -1,10 +1,14 @@
 package x64
 
-import "io"
-
 // Call places the return address on the top of the stack and continues
 // program flow at the new address. The address is relative to the next instruction.
-func Call(w io.ByteWriter, address uint32) {
-	w.WriteByte(0xe8)
-	appendUint32(w, address)
+func Call(code []byte, address uint32) []byte {
+	return append(
+		code,
+		0xe8,
+		byte(address),
+		byte(address>>8),
+		byte(address>>16),
+		byte(address>>24),
+	)
 }
diff --git a/src/x64/Move.go b/src/x64/Move.go
new file mode 100644
index 0000000..6d9fd57
--- /dev/null
+++ b/src/x64/Move.go
@@ -0,0 +1,13 @@
+package x64
+
+// MoveRegNum32 moves a 32 bit integer into the given register.
+func MoveRegNum32(code []byte, register uint8, number uint32) []byte {
+	return append(
+		code,
+		0xb8+register,
+		byte(number),
+		byte(number>>8),
+		byte(number>>16),
+		byte(number>>24),
+	)
+}
diff --git a/src/asm/x64/Return.go b/src/x64/Return.go
similarity index 73%
rename from src/asm/x64/Return.go
rename to src/x64/Return.go
index 47a5b34..dc185da 100644
--- a/src/asm/x64/Return.go
+++ b/src/x64/Return.go
@@ -1,9 +1,7 @@
 package x64
 
-import "io"
-
 // Return transfers program control to a return address located on the top of the stack.
 // The address is usually placed on the stack by a Call instruction.
-func Return(w io.ByteWriter) {
-	w.WriteByte(0xc3)
+func Return(code []byte) []byte {
+	return append(code, 0xc3)
 }
diff --git a/src/x64/Syscall.go b/src/x64/Syscall.go
new file mode 100644
index 0000000..94b07d2
--- /dev/null
+++ b/src/x64/Syscall.go
@@ -0,0 +1,6 @@
+package x64
+
+// Syscall is the primary way to communicate with the OS kernel.
+func Syscall(code []byte) []byte {
+	return append(code, 0x0f, 0x05)
+}