Section Rewriter API

Constants

I32: 32-bit integer type.

I64: 64-bit integer type.

F32: 32-bit floating point type.

F64: 64-bit floating point type.

Section Rewriter class

SectionRewriter

class SectionRewriter(module, **section)

Attributes:

module: The Wasm module to be rewrited.

section

The Wasm section to be rewrited. It receives a dictionary as input, such as SectionRewriter(module, typesec=module.typesec). The optional keys are as follows:

typesec
importsec
funcsec
tablesec
memsec
globalsec
exportsec
startsec
elemsec
codesec
datasec
customsec

select(query) → list:

Select elements in the section by condition query.

Parameters:: query (Query are represented by the element in each section, such as Global(globalidx=1). If query is passed by None, the function will return all elements in corresponding section.) – The query to select element objects.
Returns:: A list of section element objects.
Return type:: list

insert(query, inserted_item):

Insert a element in the section by condition query.

Parameters:

query (Query are represented by the element in each section, such as Global(globalidx=1). If you passed None, it equals to append operation, which means a new item will be appended at end of the section.) – The query to the location of the element to be inserted.
inserted_item (There is no need to specify the index of the inserted element because it has already been identified by the param query.) – The element to be inserted.

update(query, new_item):

Update a element in the section by condition query.

Parameters:

query (As function insert.) – The query to the location of the element to be updated.
new_item (If you only want to update a certain property, you don’t need to specify other irrelevant parameters. For example, Type(arg_types=[I32, I64])) – The new element.

delete(query):

Delete a element in the section by condition query.

Parameters:: query (As function insert.) – The query to the location of the element to be deleted.

Section element classes

Type section

class Type(typeidx, arg_types, ret_types)

Attributes:

typeidx: The index of the element in the section (int).

arg_types: The argument of the type. Example: `arg_types=[I32, F32]`

ret_types: The return of the type. Example: `ret_types=[I32, F32]`

Import section

class Import(importidx, module, name, typeidx)

Attributes:

importidx: The index of the element in the section.

module: The module name of the import elment. Example: `module="wasi"`

name: The name of the import element. Example: `name="fd_write"`

typeidx: The index of the function type (int).

Function section

class Function(funcidx, typeidx)

Attributes:

funcidx: The index of the element in the section (int).

typeidx: The index of the function type (int).

Table section

class Table(min, max)

Attributes:

min: Specifies a limit on the number of elements. The required lower limit (int).

max: The optional upper (int).

Memory section

class Memory(min, max)

Attributes:

min: The required Minimum pages of the linear memory (int).

max: The optional maximum pages (int).

Global section

class Global(globalidx, valtype, mut, val)

Attributes:

globalidx: The index of the element in the section (int).

valtype: The value type of the global variable. Example: `valtype=I32`

mut: The mutable of the global variable. Mutable is 1, immutable is 0.

val: The initial value of the global variable.

Export section

class Export(exportidx, name, funcidx)

Attributes:

exportidx: The index of the element in the section (int).

name: The name of the export function.

funcidx: The index of the exported function.

Start section

Element section

class Element(elemidx, tableidx, offset, funcidx_list)

Attributes:

elemidx: The index of the element in the section (int).

tableidx: The table which this element belongs. Its value is fixed at 1.

offset: The offset of the funcidx_list in final indirect function table (int).

funcidx_list: The function indices of the indirect function table.

Code section

class Code(funcidx, local_vec, instr_list)

Attributes:

funcidx: The index of the element in the section (int).

local_vec: The name of the export function (Local). Note that all local variables should be indexed from 0.

instr_list: The function body.

Note

There is no need to consider the nest relation of instructions. Just flatten all the instructions. For example, [Instruction(Block), Instruction(I32Const, 1), Instruction(Drop), Instruction(End)]

class Local(localidx, valtype)

Attributes:

localidx: The index of this local variable (int).

valtype: The value type of this local variable

Data section

class Data(dataidx, offset, init_data)

Attributes:

dataidx: The index of the element in the section (int).

offset: The offset of the init_data in final Linear memory(int).

init_data: The initial bytes of this data (bytes).

Custom section

class CustomName(name_type, idx, name)

Attributes:

name_type

The type of the debug name. The preset types are as follows:

FunctionName
GlobalName
DataName

idx: The index of the debug name.

name: The debug name (str).

Instruction classes

Instruction

class Instruction(opcode, args)

The type of the args depends on the opcode: * If the opcode are control instruction such as Block and Loop. args must be None * Most of the other instructions only need constant argument.

Attributes:

opcode

Operation code (int). BREWasm has pre-defined the instruction constants, as follows:

Unreachable = 0x00
Nop = 0x01
Block = 0x02
Loop = 0x03
If = 0x04
Else_ = 0x05
End_ = 0x0B
Br = 0x0C
BrIf = 0x0D
BrTable = 0x0E
Return = 0x0F
Call = 0x10
CallIndirect = 0x11
Drop = 0x1A
Select = 0x1B
LocalGet = 0x20
LocalSet = 0x21
LocalTee = 0x22
GlobalGet = 0x23
GlobalSet = 0x24
I32Load = 0x28
I64Load = 0x29
F32Load = 0x2A
F64Load = 0x2B
I32Load8S = 0x2C
I32Load8U = 0x2D
I32Load16S = 0x2E
I32Load16U = 0x2F
I64Load8S = 0x30
I64Load8U = 0x31
I64Load16S = 0x32
I64Load16U = 0x33
I64Load32S = 0x34
I64Load32U = 0x35
I32Store = 0x36
I64Store = 0x37
F32Store = 0x38
F64Store = 0x39
I32Store8 = 0x3A
I32Store16 = 0x3B
I64Store8 = 0x3C
I64Store16 = 0x3D
I64Store32 = 0x3E
MemorySize = 0x3F
MemoryGrow = 0x40
I32Const = 0x41
I64Const = 0x42
F32Const = 0x43
F64Const = 0x44
I32Eqz = 0x45
I32Eq = 0x46
I32Ne = 0x47
I32LtS = 0x48
I32LtU = 0x49
I32GtS = 0x4A
I32GtU = 0x4B
I32LeS = 0x4C
I32LeU = 0x4D
I32GeS = 0x4E
I32GeU = 0x4F
I64Eqz = 0x50
I64Eq = 0x51
I64Ne = 0x52
I64LtS = 0x53
I64LtU = 0x54
I64GtS = 0x55
I64GtU = 0x56
I64LeS = 0x57
I64LeU = 0x58
I64GeS = 0x59
I64GeU = 0x5A
F32Eq = 0x5B
F32Ne = 0x5C
F32Lt = 0x5D
F32Gt = 0x5E
F32Le = 0x5F
F32Ge = 0x60
F64Eq = 0x61
F64Ne = 0x62
F64Lt = 0x63
F64Gt = 0x64
F64Le = 0x65
F64Ge = 0x66
I32Clz = 0x67
I32Ctz = 0x68
I32PopCnt = 0x69
I32Add = 0x6A
I32Sub = 0x6B
I32Mul = 0x6C
I32DivS = 0x6D
I32DivU = 0x6E
I32RemS = 0x6F
I32RemU = 0x70
I32And = 0x71
I32Or = 0x72
I32Xor = 0x73
I32Shl = 0x74
I32ShrS = 0x75
I32ShrU = 0x76
I32Rotl = 0x77
I32Rotr = 0x78
I64Clz = 0x79
I64Ctz = 0x7A
I64PopCnt = 0x7B
I64Add = 0x7C
I64Sub = 0x7D
I64Mul = 0x7E
I64DivS = 0x7F
I64DivU = 0x80
I64RemS = 0x81
I64RemU = 0x82
I64And = 0x83
I64Or = 0x84
I64Xor = 0x85
I64Shl = 0x86
I64ShrS = 0x87
I64ShrU = 0x88
I64Rotl = 0x89
I64Rotr = 0x8A
F32Abs = 0x8B
F32Neg = 0x8C
F32Ceil = 0x8D
F32Floor = 0x8E
F32Trunc = 0x8F
F32Nearest = 0x90
F32Sqrt = 0x91
F32Add = 0x92
F32Sub = 0x93
F32Mul = 0x94
F32Div = 0x95
F32Min = 0x96
F32Max = 0x97
F32CopySign = 0x98
F32CopySign = 0x98
F64Abs = 0x99
F64Neg = 0x9A
F64Ceil = 0x9B
F64Floor = 0x9C
F64Trunc = 0x9D
F64Nearest = 0x9E
F64Sqrt = 0x9F
F64Add = 0xA0
F64Sub = 0xA1
F64Mul = 0xA2
F64Div = 0xA3
F64Min = 0xA4
F64Max = 0xA5
F64CopySign = 0xA6
I32WrapI64 = 0xA7
I32TruncF32S = 0xA8
I32TruncF32U = 0xA9
I32TruncF64S = 0xAA
I32TruncF64U = 0xAB
I64ExtendI32S = 0xAC
I64ExtendI32U = 0xAD
I64TruncF32S = 0xAE
I64TruncF32U = 0xAF
I64TruncF64S = 0xB0
I64TruncF64U = 0xB1
F32ConvertI32S = 0xB2
F32ConvertI32U = 0xB3
F32ConvertI64S = 0xB4
F32ConvertI64U = 0xB5
F32DemoteF64 = 0xB6
F64ConvertI32S = 0xB7
F64ConvertI32U = 0xB8
F64ConvertI64S = 0xB9
F64ConvertI64U = 0xBA
F64PromoteF32 = 0xBB
I32ReinterpretF32 = 0xBC
I64ReinterpretF64 = 0xBD
F32ReinterpretI32 = 0xBE
F64ReinterpretI64 = 0xBF
I32Extend8S = 0xC0
I32Extend16S = 0xC1
I64Extend8S = 0xC2
I64Extend16S = 0xC3
I64Extend32S = 0xC4
TruncSat = 0xFC

args: Operand (int) or None