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Simplified the assembler

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This commit is contained in:
Eduard Urbach 2025-02-02 11:48:08 +01:00
parent 6c432154e6
commit a0388ae15a
Signed by: eduard
GPG key ID: 49226B848C78F6C8
5 changed files with 146 additions and 122 deletions
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128
src/asm/Finalize.go
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@ -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
}