cli/q
Code Issues 1 Pull Requests Activity

Simplified the assembler

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This commit is contained in:
Eduard Urbach 2025-02-02 11:48:08 +01:00
parent dd9222c162
commit 11d2521aee
Signed by: akyoto
GPG Key ID: C874F672B1AF20C0
5 changed files with 146 additions and 122 deletions
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26
src/asm/CodeOffset.go Normal file
View File

@ -0,0 +1,26 @@
package asm
import (
"git.akyoto.dev/cli/q/src/config"
"git.akyoto.dev/cli/q/src/elf"
"git.akyoto.dev/cli/q/src/fs"
"git.akyoto.dev/cli/q/src/macho"
"git.akyoto.dev/cli/q/src/pe"
)
// CodeOffset returns the file offset of the code section.
func CodeOffset() Address {
headerEnd := Address(0)
switch config.TargetOS {
case config.Linux:
headerEnd = elf.HeaderEnd
case config.Mac:
headerEnd = macho.HeaderEnd
case config.Windows:
headerEnd = pe.HeaderEnd
}
offset, _ := fs.Align(headerEnd, config.Align)
return offset
}

128
src/asm/Finalize.go
View File

@ -1,19 +1,11 @@
package asm
import (
"encoding/binary"
"fmt"
"math"
"slices"
"strings"
"git.akyoto.dev/cli/q/src/config"
"git.akyoto.dev/cli/q/src/dll"
"git.akyoto.dev/cli/q/src/elf"
"git.akyoto.dev/cli/q/src/fs"
"git.akyoto.dev/cli/q/src/macho"
"git.akyoto.dev/cli/q/src/pe"
"git.akyoto.dev/cli/q/src/sizeof"
"git.akyoto.dev/cli/q/src/x64"
)
@ -24,23 +16,12 @@ func (a Assembler) Finalize(dlls dll.List) ([]byte, []byte) {
data []byte
codeLabels = map[string]Address{}
dataLabels map[string]Address
codePointers []*Pointer
dataPointers []*Pointer
dllPointers []*Pointer
headerEnd = Address(0)
codePointers []*pointer
dataPointers []*pointer
dllPointers []*pointer
codeStart = CodeOffset()
)
switch config.TargetOS {
case config.Linux:
headerEnd = elf.HeaderEnd
case config.Mac:
headerEnd = macho.HeaderEnd
case config.Windows:
headerEnd = pe.HeaderEnd
}
codeStart, _ := fs.Align(headerEnd, config.Align)
for _, x := range a.Instructions {
switch x.Mnemonic {
case ADD:
@ -110,7 +91,7 @@ func (a Assembler) Finalize(dlls dll.List) ([]byte, []byte) {
size := 4
label := x.Data.(*Label)
pointer := &Pointer{
pointer := &pointer{
Position: Address(len(code) - size),
OpSize: 1,
Size: uint8(size),
@ -151,7 +132,7 @@ func (a Assembler) Finalize(dlls dll.List) ([]byte, []byte) {
code = x64.MoveRegisterRegister(code, x64.RSP, x64.R15)
label := x.Data.(*Label)
pointer := &Pointer{
pointer := &pointer{
Position: Address(position),
OpSize: 2,
Size: uint8(size),
@ -193,7 +174,7 @@ func (a Assembler) Finalize(dlls dll.List) ([]byte, []byte) {
size := 1
label := x.Data.(*Label)
pointer := &Pointer{
pointer := &pointer{
Position: Address(len(code) - size),
OpSize: 1,
Size: uint8(size),
@ -237,7 +218,7 @@ func (a Assembler) Finalize(dlls dll.List) ([]byte, []byte) {
regLabel := x.Data.(*RegisterLabel)
if strings.HasPrefix(regLabel.Label, "data_") {
dataPointers = append(dataPointers, &Pointer{
dataPointers = append(dataPointers, &pointer{
Position: Address(len(code) - size),
OpSize: uint8(opSize),
Size: uint8(size),
@ -252,7 +233,7 @@ func (a Assembler) Finalize(dlls dll.List) ([]byte, []byte) {
},
})
} else {
codePointers = append(codePointers, &Pointer{
codePointers = append(codePointers, &pointer{
Position: Address(len(code) - size),
OpSize: uint8(opSize),
Size: uint8(size),
@ -331,7 +312,7 @@ func (a Assembler) Finalize(dlls dll.List) ([]byte, []byte) {
opSize := len(code) - size - start
memLabel := x.Data.(*MemoryLabel)
codePointers = append(codePointers, &Pointer{
codePointers = append(codePointers, &pointer{
Position: Address(len(code) - size),
OpSize: uint8(opSize),
Size: uint8(size),
@ -369,94 +350,7 @@ func (a Assembler) Finalize(dlls dll.List) ([]byte, []byte) {
}
}
restart:
for i, pointer := range codePointers {
address := pointer.Resolve()
if sizeof.Signed(int64(address)) > int(pointer.Size) {
left := code[:pointer.Position-Address(pointer.OpSize)]
right := code[pointer.Position+Address(pointer.Size):]
size := pointer.Size + pointer.OpSize
opCode := code[pointer.Position-Address(pointer.OpSize)]
var jump []byte
switch opCode {
case 0x74: // JE
jump = []byte{0x0F, 0x84}
case 0x75: // JNE
jump = []byte{0x0F, 0x85}
case 0x7C: // JL
jump = []byte{0x0F, 0x8C}
case 0x7D: // JGE
jump = []byte{0x0F, 0x8D}
case 0x7E: // JLE
jump = []byte{0x0F, 0x8E}
case 0x7F: // JG
jump = []byte{0x0F, 0x8F}
case 0xEB: // JMP
jump = []byte{0xE9}
default:
panic(fmt.Errorf("failed to increase pointer size for instruction 0x%x", opCode))
}
pointer.Position += Address(len(jump) - int(pointer.OpSize))
pointer.OpSize = uint8(len(jump))
pointer.Size = 4
jump = binary.LittleEndian.AppendUint32(jump, uint32(address))
offset := Address(len(jump)) - Address(size)
for _, following := range codePointers[i+1:] {
following.Position += offset
}
for key, address := range codeLabels {
if address > pointer.Position {
codeLabels[key] += offset
}
}
code = slices.Concat(left, jump, right)
goto restart
}
slice := code[pointer.Position : pointer.Position+Address(pointer.Size)]
switch pointer.Size {
case 1:
slice[0] = uint8(address)
case 2:
binary.LittleEndian.PutUint16(slice, uint16(address))
case 4:
binary.LittleEndian.PutUint32(slice, uint32(address))
case 8:
binary.LittleEndian.PutUint64(slice, uint64(address))
}
}
dataStart, _ := fs.Align(codeStart+Address(len(code)), config.Align)
data, dataLabels = a.Data.Finalize()
for _, pointer := range dataPointers {
address := config.BaseAddress + Address(dataStart) + pointer.Resolve()
slice := code[pointer.Position : pointer.Position+4]
binary.LittleEndian.PutUint32(slice, uint32(address))
}
if config.TargetOS == config.Windows {
if len(data) == 0 {
data = []byte{0}
}
importsStart, _ := fs.Align(dataStart+Address(len(data)), config.Align)
for _, pointer := range dllPointers {
destination := Address(importsStart) + pointer.Resolve()
delta := destination - Address(codeStart+pointer.Position+Address(pointer.Size))
slice := code[pointer.Position : pointer.Position+4]
binary.LittleEndian.PutUint32(slice, uint32(delta))
}
}
code = a.resolvePointers(code, data, codeStart, codeLabels, codePointers, dataPointers, dllPointers)
return code, data
}

4
src/asm/Pointer.go → src/asm/pointer.go
View File

@ -3,10 +3,10 @@ package asm
// Address represents a memory address.
type Address = int32
// Pointer stores a relative memory address that we can later turn into an absolute one.
// 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.
// Resolve: The function that will return the final address.
type Pointer struct {
type pointer struct {
Resolve func() Address
Position Address
OpSize uint8

104
src/asm/resolvePointers.go Normal file
View File

@ -0,0 +1,104 @@
package asm
import (
"encoding/binary"
"fmt"
"slices"
"git.akyoto.dev/cli/q/src/config"
"git.akyoto.dev/cli/q/src/fs"
"git.akyoto.dev/cli/q/src/sizeof"
)
// resolvePointers resolves the addresses of all pointers within the code and writes the correct addresses to the code slice.
func (a Assembler) resolvePointers(code []byte, data []byte, codeStart Address, codeLabels map[string]Address, codePointers []*pointer, dataPointers []*pointer, dllPointers []*pointer) []byte {
restart:
for i, pointer := range codePointers {
address := pointer.Resolve()
if sizeof.Signed(int64(address)) > int(pointer.Size) {
left := code[:pointer.Position-Address(pointer.OpSize)]
right := code[pointer.Position+Address(pointer.Size):]
size := pointer.Size + pointer.OpSize
opCode := code[pointer.Position-Address(pointer.OpSize)]
var jump []byte
switch opCode {
case 0x74: // JE
jump = []byte{0x0F, 0x84}
case 0x75: // JNE
jump = []byte{0x0F, 0x85}
case 0x7C: // JL
jump = []byte{0x0F, 0x8C}
case 0x7D: // JGE
jump = []byte{0x0F, 0x8D}
case 0x7E: // JLE
jump = []byte{0x0F, 0x8E}
case 0x7F: // JG
jump = []byte{0x0F, 0x8F}
case 0xEB: // JMP
jump = []byte{0xE9}
default:
panic(fmt.Errorf("failed to increase pointer size for instruction 0x%x", opCode))
}
pointer.Position += Address(len(jump) - int(pointer.OpSize))
pointer.OpSize = uint8(len(jump))
pointer.Size = 4
jump = binary.LittleEndian.AppendUint32(jump, uint32(address))
offset := Address(len(jump)) - Address(size)
for _, following := range codePointers[i+1:] {
following.Position += offset
}
for key, address := range codeLabels {
if address > pointer.Position {
codeLabels[key] += offset
}
}
code = slices.Concat(left, jump, right)
goto restart
}
slice := code[pointer.Position : pointer.Position+Address(pointer.Size)]
switch pointer.Size {
case 1:
slice[0] = uint8(address)
case 2:
binary.LittleEndian.PutUint16(slice, uint16(address))
case 4:
binary.LittleEndian.PutUint32(slice, uint32(address))
case 8:
binary.LittleEndian.PutUint64(slice, uint64(address))
}
}
dataStart, _ := fs.Align(codeStart+Address(len(code)), config.Align)
for _, pointer := range dataPointers {
address := config.BaseAddress + Address(dataStart) + pointer.Resolve()
slice := code[pointer.Position : pointer.Position+4]
binary.LittleEndian.PutUint32(slice, uint32(address))
}
if config.TargetOS == config.Windows {
if len(data) == 0 {
data = []byte{0}
}
importsStart, _ := fs.Align(dataStart+Address(len(data)), config.Align)
for _, pointer := range dllPointers {
destination := Address(importsStart) + pointer.Resolve()
delta := destination - Address(codeStart+pointer.Position+Address(pointer.Size))
slice := code[pointer.Position : pointer.Position+4]
binary.LittleEndian.PutUint32(slice, uint32(delta))
}
}
return code
}

6
src/asm/Optimizer.go → src/asm/unnecessary.go
View File

@ -11,17 +11,17 @@ func (a *Assembler) unnecessary(mnemonic Mnemonic, left cpu.Register, right cpu.
last := a.Instructions[len(a.Instructions)-1]
if mnemonic == MOVE && last.Mnemonic == MOVE {
data, isRegReg := last.Data.(*RegisterRegister)
lastData, isRegReg := last.Data.(*RegisterRegister)
if !isRegReg {
return false
}
if data.Destination == left && data.Source == right {
if lastData.Destination == left && lastData.Source == right {
return true
}
if data.Destination == right && data.Source == left {
if lastData.Destination == right && lastData.Source == left {
return true
}
}