zig/lib/std /
debug/Dwarf/expression.zig
Expressions can be evaluated in different contexts, each requiring its own set of inputs. Callers should specify all the fields relevant to their context. If a field is required by the expression and it isn't in the context, error.IncompleteExpressionContext is returned.
const builtin = @import("builtin");
const native_arch = builtin.cpu.arch;
const native_endian = native_arch.endian();
Context
The dwarf format of the section this expression is in
const std = @import("std");
const leb = std.leb;
const OP = std.dwarf.OP;
const abi = std.debug.Dwarf.abi;
const mem = std.mem;
const assert = std.debug.assert;
Options
If specified, any addresses will pass through before being accessed
/// Expressions can be evaluated in different contexts, each requiring its own set of inputs.
/// Callers should specify all the fields relevant to their context. If a field is required
/// by the expression and it isn't in the context, error.IncompleteExpressionContext is returned.
pub const Context = struct {
/// The dwarf format of the section this expression is in
format: std.dwarf.Format = .@"32",
/// If specified, any addresses will pass through before being accessed
memory_accessor: ?*std.debug.MemoryAccessor = null,
/// The compilation unit this expression relates to, if any
compile_unit: ?*const std.debug.Dwarf.CompileUnit = null,
/// When evaluating a user-presented expression, this is the address of the object being evaluated
object_address: ?*const anyopaque = null,
/// .debug_addr section
debug_addr: ?[]const u8 = null,
/// Thread context
thread_context: ?*std.debug.ThreadContext = null,
reg_context: ?abi.RegisterContext = null,
/// Call frame address, if in a CFI context
cfa: ?usize = null,
/// This expression is a sub-expression from an OP.entry_value instruction
entry_value_context: bool = false,
};
Error
The compilation unit this expression relates to, if any
pub const Options = struct {
/// The address size of the target architecture
addr_size: u8 = @sizeOf(usize),
/// Endianness of the target architecture
endian: std.builtin.Endian = native_endian,
/// Restrict the stack machine to a subset of opcodes used in call frame instructions
call_frame_context: bool = false,
};
StackMachine()
When evaluating a user-presented expression, this is the address of the object being evaluated
// Explicitly defined to support executing sub-expressions
pub const Error = error{
UnimplementedExpressionCall,
UnimplementedOpcode,
UnimplementedUserOpcode,
UnimplementedTypedComparison,
UnimplementedTypeConversion,
asIntegral()
.debug_addr section
UnknownExpressionOpcode,
reset()
Thread context
IncompleteExpressionContext,
deinit()
Call frame address, if in a CFI context
InvalidCFAOpcode,
InvalidExpression,
InvalidFrameBase,
InvalidIntegralTypeSize,
InvalidRegister,
InvalidSubExpression,
InvalidTypeLength,
readOperand()
This expression is a sub-expression from an OP.entry_value instruction
TruncatedIntegralType,
} || abi.RegBytesError || error{ EndOfStream, Overflow, OutOfMemory, DivisionByZero };
run()
The address size of the target architecture
/// A stack machine that can decode and run DWARF expressions.
/// Expressions can be decoded for non-native address size and endianness,
/// but can only be executed if the current target matches the configuration.
pub fn StackMachine(comptime options: Options) type {
const addr_type = switch (options.addr_size) {
2 => u16,
4 => u32,
8 => u64,
else => @compileError("Unsupported address size of " ++ options.addr_size),
};
step()
Endianness of the target architecture
const addr_type_signed = switch (options.addr_size) {
2 => i16,
4 => i32,
8 => i64,
else => @compileError("Unsupported address size of " ++ options.addr_size),
};
Builder()
Restrict the stack machine to a subset of opcodes used in call frame instructions
return struct {
const Self = @This();
writeOpcode()
A stack machine that can decode and run DWARF expressions. Expressions can be decoded for non-native address size and endianness, but can only be executed if the current target matches the configuration.
const Operand = union(enum) {
generic: addr_type,
register: u8,
type_size: u8,
branch_offset: i16,
base_register: struct {
base_register: u8,
offset: i64,
},
composite_location: struct {
size: u64,
offset: i64,
},
block: []const u8,
register_type: struct {
register: u8,
type_offset: addr_type,
},
const_type: struct {
type_offset: addr_type,
value_bytes: []const u8,
},
deref_type: struct {
size: u8,
type_offset: addr_type,
},
};
writeLiteral()
Reads an opcode and its operands from stream, then executes it
const Value = union(enum) {
generic: addr_type,
writeConst()
Zero-operand instructions
// Typed value with a maximum size of a register
regval_type: struct {
// Offset of DW_TAG_base_type DIE
type_offset: addr_type,
type_size: u8,
value: addr_type,
},
writeConstx()
// Typed value specified directly in the instruction stream
const_type: struct {
// Offset of DW_TAG_base_type DIE
type_offset: addr_type,
// Backed by the instruction stream
value_bytes: []const u8,
},
writeConstType()
pub fn asIntegral(self: Value) !addr_type {
return switch (self) {
.generic => |v| v,
writeAddr()
// TODO: For these two prongs, look up the type and assert it's integral?
.regval_type => |regval_type| regval_type.value,
.const_type => |const_type| {
const value: u64 = switch (const_type.value_bytes.len) {
1 => mem.readInt(u8, const_type.value_bytes[0..1], native_endian),
2 => mem.readInt(u16, const_type.value_bytes[0..2], native_endian),
4 => mem.readInt(u32, const_type.value_bytes[0..4], native_endian),
8 => mem.readInt(u64, const_type.value_bytes[0..8], native_endian),
else => return error.InvalidIntegralTypeSize,
};
writeAddrx()
return std.math.cast(addr_type, value) orelse error.TruncatedIntegralType;
},
};
}
};
writeFbreg()
stack: std.ArrayListUnmanaged(Value) = .empty,
writeBreg()
pub fn reset(self: *Self) void {
self.stack.clearRetainingCapacity();
}
writeBregx()
pub fn deinit(self: *Self, allocator: std.mem.Allocator) void {
self.stack.deinit(allocator);
}
writeRegvalType()
fn generic(value: anytype) Operand {
const int_info = @typeInfo(@TypeOf(value)).int;
if (@sizeOf(@TypeOf(value)) > options.addr_size) {
return .{ .generic = switch (int_info.signedness) {
.signed => @bitCast(@as(addr_type_signed, @truncate(value))),
.unsigned => @truncate(value),
} };
} else {
return .{ .generic = switch (int_info.signedness) {
.signed => @bitCast(@as(addr_type_signed, @intCast(value))),
.unsigned => @intCast(value),
} };
}
}
writePick()
pub fn readOperand(stream: *std.io.FixedBufferStream([]const u8), opcode: u8, context: Context) !?Operand {
const reader = stream.reader();
return switch (opcode) {
OP.addr => generic(try reader.readInt(addr_type, options.endian)),
OP.call_ref => switch (context.format) {
.@"32" => generic(try reader.readInt(u32, options.endian)),
.@"64" => generic(try reader.readInt(u64, options.endian)),
},
OP.const1u,
OP.pick,
=> generic(try reader.readByte()),
OP.deref_size,
OP.xderef_size,
=> .{ .type_size = try reader.readByte() },
OP.const1s => generic(try reader.readByteSigned()),
OP.const2u,
OP.call2,
=> generic(try reader.readInt(u16, options.endian)),
OP.call4 => generic(try reader.readInt(u32, options.endian)),
OP.const2s => generic(try reader.readInt(i16, options.endian)),
OP.bra,
OP.skip,
=> .{ .branch_offset = try reader.readInt(i16, options.endian) },
OP.const4u => generic(try reader.readInt(u32, options.endian)),
OP.const4s => generic(try reader.readInt(i32, options.endian)),
OP.const8u => generic(try reader.readInt(u64, options.endian)),
OP.const8s => generic(try reader.readInt(i64, options.endian)),
OP.constu,
OP.plus_uconst,
OP.addrx,
OP.constx,
OP.convert,
OP.reinterpret,
=> generic(try leb.readUleb128(u64, reader)),
OP.consts,
OP.fbreg,
=> generic(try leb.readIleb128(i64, reader)),
OP.lit0...OP.lit31 => |n| generic(n - OP.lit0),
OP.reg0...OP.reg31 => |n| .{ .register = n - OP.reg0 },
OP.breg0...OP.breg31 => |n| .{ .base_register = .{
.base_register = n - OP.breg0,
.offset = try leb.readIleb128(i64, reader),
} },
OP.regx => .{ .register = try leb.readUleb128(u8, reader) },
OP.bregx => blk: {
const base_register = try leb.readUleb128(u8, reader);
const offset = try leb.readIleb128(i64, reader);
break :blk .{ .base_register = .{
.base_register = base_register,
.offset = offset,
} };
},
OP.regval_type => blk: {
const register = try leb.readUleb128(u8, reader);
const type_offset = try leb.readUleb128(addr_type, reader);
break :blk .{ .register_type = .{
.register = register,
.type_offset = type_offset,
} };
},
OP.piece => .{
.composite_location = .{
.size = try leb.readUleb128(u8, reader),
.offset = 0,
},
},
OP.bit_piece => blk: {
const size = try leb.readUleb128(u8, reader);
const offset = try leb.readIleb128(i64, reader);
break :blk .{ .composite_location = .{
.size = size,
.offset = offset,
} };
},
OP.implicit_value, OP.entry_value => blk: {
const size = try leb.readUleb128(u8, reader);
if (stream.pos + size > stream.buffer.len) return error.InvalidExpression;
const block = stream.buffer[stream.pos..][0..size];
stream.pos += size;
break :blk .{
.block = block,
};
},
OP.const_type => blk: {
const type_offset = try leb.readUleb128(addr_type, reader);
const size = try reader.readByte();
if (stream.pos + size > stream.buffer.len) return error.InvalidExpression;
const value_bytes = stream.buffer[stream.pos..][0..size];
stream.pos += size;
break :blk .{ .const_type = .{
.type_offset = type_offset,
.value_bytes = value_bytes,
} };
},
OP.deref_type,
OP.xderef_type,
=> .{
.deref_type = .{
.size = try reader.readByte(),
.type_offset = try leb.readUleb128(addr_type, reader),
},
},
OP.lo_user...OP.hi_user => return error.UnimplementedUserOpcode,
else => null,
};
}
writeDerefSize()
pub fn run(
self: *Self,
expression: []const u8,
allocator: std.mem.Allocator,
context: Context,
initial_value: ?usize,
) Error!?Value {
if (initial_value) |i| try self.stack.append(allocator, .{ .generic = i });
var stream = std.io.fixedBufferStream(expression);
while (try self.step(&stream, allocator, context)) {}
if (self.stack.items.len == 0) return null;
return self.stack.items[self.stack.items.len - 1];
}
writeXDerefSize()
/// Reads an opcode and its operands from `stream`, then executes it
pub fn step(
self: *Self,
stream: *std.io.FixedBufferStream([]const u8),
allocator: std.mem.Allocator,
context: Context,
) Error!bool {
if (@sizeOf(usize) != @sizeOf(addr_type) or options.endian != native_endian)
@compileError("Execution of non-native address sizes / endianness is not supported");
writeDerefType()
const opcode = try stream.reader().readByte();
if (options.call_frame_context and !isOpcodeValidInCFA(opcode)) return error.InvalidCFAOpcode;
const operand = try readOperand(stream, opcode, context);
switch (opcode) {
writeXDerefType()
// 2.5.1.1: Literal Encodings
OP.lit0...OP.lit31,
OP.addr,
OP.const1u,
OP.const2u,
OP.const4u,
OP.const8u,
OP.const1s,
OP.const2s,
OP.const4s,
OP.const8s,
OP.constu,
OP.consts,
=> try self.stack.append(allocator, .{ .generic = operand.?.generic }),
writePlusUconst()
OP.const_type => {
const const_type = operand.?.const_type;
try self.stack.append(allocator, .{ .const_type = .{
.type_offset = const_type.type_offset,
.value_bytes = const_type.value_bytes,
} });
},
writeSkip()
OP.addrx,
OP.constx,
=> {
if (context.compile_unit == null) return error.IncompleteExpressionContext;
if (context.debug_addr == null) return error.IncompleteExpressionContext;
const debug_addr_index = operand.?.generic;
const offset = context.compile_unit.?.addr_base + debug_addr_index;
if (offset >= context.debug_addr.?.len) return error.InvalidExpression;
const value = mem.readInt(usize, context.debug_addr.?[offset..][0..@sizeOf(usize)], native_endian);
try self.stack.append(allocator, .{ .generic = value });
},
writeBra()
// 2.5.1.2: Register Values
OP.fbreg => {
if (context.compile_unit == null) return error.IncompleteExpressionContext;
if (context.compile_unit.?.frame_base == null) return error.IncompleteExpressionContext;
writeCall()
const offset: i64 = @intCast(operand.?.generic);
_ = offset;
writeCallRef()
switch (context.compile_unit.?.frame_base.?.*) {
.exprloc => {
// TODO: Run this expression in a nested stack machine
return error.UnimplementedOpcode;
},
.loclistx => {
// TODO: Read value from .debug_loclists
return error.UnimplementedOpcode;
},
.sec_offset => {
// TODO: Read value from .debug_loclists
return error.UnimplementedOpcode;
},
else => return error.InvalidFrameBase,
}
},
OP.breg0...OP.breg31,
OP.bregx,
=> {
if (context.thread_context == null) return error.IncompleteExpressionContext;
writeConvert()
const base_register = operand.?.base_register;
var value: i64 = @intCast(mem.readInt(usize, (try abi.regBytes(
context.thread_context.?,
base_register.base_register,
context.reg_context,
))[0..@sizeOf(usize)], native_endian));
value += base_register.offset;
try self.stack.append(allocator, .{ .generic = @intCast(value) });
},
OP.regval_type => {
const register_type = operand.?.register_type;
const value = mem.readInt(usize, (try abi.regBytes(
context.thread_context.?,
register_type.register,
context.reg_context,
))[0..@sizeOf(usize)], native_endian);
try self.stack.append(allocator, .{
.regval_type = .{
.type_offset = register_type.type_offset,
.type_size = @sizeOf(addr_type),
.value = value,
},
});
},
writeReinterpret()
// 2.5.1.3: Stack Operations
OP.dup => {
if (self.stack.items.len == 0) return error.InvalidExpression;
try self.stack.append(allocator, self.stack.items[self.stack.items.len - 1]);
},
OP.drop => {
_ = self.stack.pop();
},
OP.pick, OP.over => {
const stack_index = if (opcode == OP.over) 1 else operand.?.generic;
if (stack_index >= self.stack.items.len) return error.InvalidExpression;
try self.stack.append(allocator, self.stack.items[self.stack.items.len - 1 - stack_index]);
},
OP.swap => {
if (self.stack.items.len < 2) return error.InvalidExpression;
mem.swap(Value, &self.stack.items[self.stack.items.len - 1], &self.stack.items[self.stack.items.len - 2]);
},
OP.rot => {
if (self.stack.items.len < 3) return error.InvalidExpression;
const first = self.stack.items[self.stack.items.len - 1];
self.stack.items[self.stack.items.len - 1] = self.stack.items[self.stack.items.len - 2];
self.stack.items[self.stack.items.len - 2] = self.stack.items[self.stack.items.len - 3];
self.stack.items[self.stack.items.len - 3] = first;
},
OP.deref,
OP.xderef,
OP.deref_size,
OP.xderef_size,
OP.deref_type,
OP.xderef_type,
=> {
if (self.stack.items.len == 0) return error.InvalidExpression;
const addr = try self.stack.items[self.stack.items.len - 1].asIntegral();
const addr_space_identifier: ?usize = switch (opcode) {
OP.xderef,
OP.xderef_size,
OP.xderef_type,
=> blk: {
_ = self.stack.pop();
if (self.stack.items.len == 0) return error.InvalidExpression;
break :blk try self.stack.items[self.stack.items.len - 1].asIntegral();
},
else => null,
};
writeEntryValue()
// Usage of addr_space_identifier in the address calculation is implementation defined.
// This code will need to be updated to handle any architectures that utilize this.
_ = addr_space_identifier;
writeReg()
const size = switch (opcode) {
OP.deref,
OP.xderef,
=> @sizeOf(addr_type),
OP.deref_size,
OP.xderef_size,
=> operand.?.type_size,
OP.deref_type,
OP.xderef_type,
=> operand.?.deref_type.size,
else => unreachable,
};
writeRegx()
if (context.memory_accessor) |memory_accessor| {
if (!switch (size) {
1 => memory_accessor.load(u8, addr) != null,
2 => memory_accessor.load(u16, addr) != null,
4 => memory_accessor.load(u32, addr) != null,
8 => memory_accessor.load(u64, addr) != null,
else => return error.InvalidExpression,
}) return error.InvalidExpression;
}
writeImplicitValue()
const value: addr_type = std.math.cast(addr_type, @as(u64, switch (size) {
1 => @as(*const u8, @ptrFromInt(addr)).*,
2 => @as(*const u16, @ptrFromInt(addr)).*,
4 => @as(*const u32, @ptrFromInt(addr)).*,
8 => @as(*const u64, @ptrFromInt(addr)).*,
else => return error.InvalidExpression,
})) orelse return error.InvalidExpression;
Test:
DWARF expressions
switch (opcode) {
OP.deref_type,
OP.xderef_type,
=> {
self.stack.items[self.stack.items.len - 1] = .{
.regval_type = .{
.type_offset = operand.?.deref_type.type_offset,
.type_size = operand.?.deref_type.size,
.value = value,
},
};
},
else => {
self.stack.items[self.stack.items.len - 1] = .{ .generic = value };
},
}
},
OP.push_object_address => {
// In sub-expressions, `push_object_address` is not meaningful (as per the
// spec), so treat it like a nop
if (!context.entry_value_context) {
if (context.object_address == null) return error.IncompleteExpressionContext;
try self.stack.append(allocator, .{ .generic = @intFromPtr(context.object_address.?) });
}
},
OP.form_tls_address => {
return error.UnimplementedOpcode;
},
OP.call_frame_cfa => {
if (context.cfa) |cfa| {
try self.stack.append(allocator, .{ .generic = cfa });
} else return error.IncompleteExpressionContext;
},
// 2.5.1.4: Arithmetic and Logical Operations
OP.abs => {
if (self.stack.items.len == 0) return error.InvalidExpression;
const value: isize = @bitCast(try self.stack.items[self.stack.items.len - 1].asIntegral());
self.stack.items[self.stack.items.len - 1] = .{
.generic = @abs(value),
};
},
OP.@"and" => {
if (self.stack.items.len < 2) return error.InvalidExpression;
const a = try self.stack.pop().?.asIntegral();
self.stack.items[self.stack.items.len - 1] = .{
.generic = a & try self.stack.items[self.stack.items.len - 1].asIntegral(),
};
},
OP.div => {
if (self.stack.items.len < 2) return error.InvalidExpression;
const a: isize = @bitCast(try self.stack.pop().?.asIntegral());
const b: isize = @bitCast(try self.stack.items[self.stack.items.len - 1].asIntegral());
self.stack.items[self.stack.items.len - 1] = .{
.generic = @bitCast(try std.math.divTrunc(isize, b, a)),
};
},
OP.minus => {
if (self.stack.items.len < 2) return error.InvalidExpression;
const b = try self.stack.pop().?.asIntegral();
self.stack.items[self.stack.items.len - 1] = .{
.generic = try std.math.sub(addr_type, try self.stack.items[self.stack.items.len - 1].asIntegral(), b),
};
},
OP.mod => {
if (self.stack.items.len < 2) return error.InvalidExpression;
const a: isize = @bitCast(try self.stack.pop().?.asIntegral());
const b: isize = @bitCast(try self.stack.items[self.stack.items.len - 1].asIntegral());
self.stack.items[self.stack.items.len - 1] = .{
.generic = @bitCast(@mod(b, a)),
};
},
OP.mul => {
if (self.stack.items.len < 2) return error.InvalidExpression;
const a: isize = @bitCast(try self.stack.pop().?.asIntegral());
const b: isize = @bitCast(try self.stack.items[self.stack.items.len - 1].asIntegral());
self.stack.items[self.stack.items.len - 1] = .{
.generic = @bitCast(@mulWithOverflow(a, b)[0]),
};
},
OP.neg => {
if (self.stack.items.len == 0) return error.InvalidExpression;
self.stack.items[self.stack.items.len - 1] = .{
.generic = @bitCast(
try std.math.negate(
@as(isize, @bitCast(try self.stack.items[self.stack.items.len - 1].asIntegral())),
),
),
};
},
OP.not => {
if (self.stack.items.len == 0) return error.InvalidExpression;
self.stack.items[self.stack.items.len - 1] = .{
.generic = ~try self.stack.items[self.stack.items.len - 1].asIntegral(),
};
},
OP.@"or" => {
if (self.stack.items.len < 2) return error.InvalidExpression;
const a = try self.stack.pop().?.asIntegral();
self.stack.items[self.stack.items.len - 1] = .{
.generic = a | try self.stack.items[self.stack.items.len - 1].asIntegral(),
};
},
OP.plus => {
if (self.stack.items.len < 2) return error.InvalidExpression;
const b = try self.stack.pop().?.asIntegral();
self.stack.items[self.stack.items.len - 1] = .{
.generic = try std.math.add(addr_type, try self.stack.items[self.stack.items.len - 1].asIntegral(), b),
};
},
OP.plus_uconst => {
if (self.stack.items.len == 0) return error.InvalidExpression;
const constant = operand.?.generic;
self.stack.items[self.stack.items.len - 1] = .{
.generic = try std.math.add(addr_type, try self.stack.items[self.stack.items.len - 1].asIntegral(), constant),
};
},
OP.shl => {
if (self.stack.items.len < 2) return error.InvalidExpression;
const a = try self.stack.pop().?.asIntegral();
const b = try self.stack.items[self.stack.items.len - 1].asIntegral();
self.stack.items[self.stack.items.len - 1] = .{
.generic = std.math.shl(usize, b, a),
};
},
OP.shr => {
if (self.stack.items.len < 2) return error.InvalidExpression;
const a = try self.stack.pop().?.asIntegral();
const b = try self.stack.items[self.stack.items.len - 1].asIntegral();
self.stack.items[self.stack.items.len - 1] = .{
.generic = std.math.shr(usize, b, a),
};
},
OP.shra => {
if (self.stack.items.len < 2) return error.InvalidExpression;
const a = try self.stack.pop().?.asIntegral();
const b: isize = @bitCast(try self.stack.items[self.stack.items.len - 1].asIntegral());
self.stack.items[self.stack.items.len - 1] = .{
.generic = @bitCast(std.math.shr(isize, b, a)),
};
},
OP.xor => {
if (self.stack.items.len < 2) return error.InvalidExpression;
const a = try self.stack.pop().?.asIntegral();
self.stack.items[self.stack.items.len - 1] = .{
.generic = a ^ try self.stack.items[self.stack.items.len - 1].asIntegral(),
};
},
// 2.5.1.5: Control Flow Operations
OP.le,
OP.ge,
OP.eq,
OP.lt,
OP.gt,
OP.ne,
=> {
if (self.stack.items.len < 2) return error.InvalidExpression;
const a = self.stack.pop().?;
const b = self.stack.items[self.stack.items.len - 1];
if (a == .generic and b == .generic) {
const a_int: isize = @bitCast(a.asIntegral() catch unreachable);
const b_int: isize = @bitCast(b.asIntegral() catch unreachable);
const result = @intFromBool(switch (opcode) {
OP.le => b_int <= a_int,
OP.ge => b_int >= a_int,
OP.eq => b_int == a_int,
OP.lt => b_int < a_int,
OP.gt => b_int > a_int,
OP.ne => b_int != a_int,
else => unreachable,
});
self.stack.items[self.stack.items.len - 1] = .{ .generic = result };
} else {
// TODO: Load the types referenced by these values, find their comparison operator, and run it
return error.UnimplementedTypedComparison;
}
},
OP.skip, OP.bra => {
const branch_offset = operand.?.branch_offset;
const condition = if (opcode == OP.bra) blk: {
if (self.stack.items.len == 0) return error.InvalidExpression;
break :blk try self.stack.pop().?.asIntegral() != 0;
} else true;
if (condition) {
const new_pos = std.math.cast(
usize,
try std.math.add(isize, @as(isize, @intCast(stream.pos)), branch_offset),
) orelse return error.InvalidExpression;
if (new_pos < 0 or new_pos > stream.buffer.len) return error.InvalidExpression;
stream.pos = new_pos;
}
},
OP.call2,
OP.call4,
OP.call_ref,
=> {
const debug_info_offset = operand.?.generic;
_ = debug_info_offset;
// TODO: Load a DIE entry at debug_info_offset in a .debug_info section (the spec says that it
// can be in a separate exe / shared object from the one containing this expression).
// Transfer control to the DW_AT_location attribute, with the current stack as input.
return error.UnimplementedExpressionCall;
},
// 2.5.1.6: Type Conversions
OP.convert => {
if (self.stack.items.len == 0) return error.InvalidExpression;
const type_offset = operand.?.generic;
// TODO: Load the DW_TAG_base_type entries in context.compile_unit and verify both types are the same size
const value = self.stack.items[self.stack.items.len - 1];
if (type_offset == 0) {
self.stack.items[self.stack.items.len - 1] = .{ .generic = try value.asIntegral() };
} else {
// TODO: Load the DW_TAG_base_type entry in context.compile_unit, find a conversion operator
// from the old type to the new type, run it.
return error.UnimplementedTypeConversion;
}
},
OP.reinterpret => {
if (self.stack.items.len == 0) return error.InvalidExpression;
const type_offset = operand.?.generic;
// TODO: Load the DW_TAG_base_type entries in context.compile_unit and verify both types are the same size
const value = self.stack.items[self.stack.items.len - 1];
if (type_offset == 0) {
self.stack.items[self.stack.items.len - 1] = .{ .generic = try value.asIntegral() };
} else {
self.stack.items[self.stack.items.len - 1] = switch (value) {
.generic => |v| .{
.regval_type = .{
.type_offset = type_offset,
.type_size = @sizeOf(addr_type),
.value = v,
},
},
.regval_type => |r| .{
.regval_type = .{
.type_offset = type_offset,
.type_size = r.type_size,
.value = r.value,
},
},
.const_type => |c| .{
.const_type = .{
.type_offset = type_offset,
.value_bytes = c.value_bytes,
},
},
};
}
},
// 2.5.1.7: Special Operations
OP.nop => {},
OP.entry_value => {
const block = operand.?.block;
if (block.len == 0) return error.InvalidSubExpression;
// TODO: The spec states that this sub-expression needs to observe the state (ie. registers)
// as it was upon entering the current subprogram. If this isn't being called at the
// end of a frame unwind operation, an additional ThreadContext with this state will be needed.
if (isOpcodeRegisterLocation(block[0])) {
if (context.thread_context == null) return error.IncompleteExpressionContext;
var block_stream = std.io.fixedBufferStream(block);
const register = (try readOperand(&block_stream, block[0], context)).?.register;
const value = mem.readInt(usize, (try abi.regBytes(context.thread_context.?, register, context.reg_context))[0..@sizeOf(usize)], native_endian);
try self.stack.append(allocator, .{ .generic = value });
} else {
var stack_machine: Self = .{};
defer stack_machine.deinit(allocator);
var sub_context = context;
sub_context.entry_value_context = true;
const result = try stack_machine.run(block, allocator, sub_context, null);
try self.stack.append(allocator, result orelse return error.InvalidSubExpression);
}
},
// These have already been handled by readOperand
OP.lo_user...OP.hi_user => unreachable,
else => {
//std.debug.print("Unknown DWARF expression opcode: {x}\n", .{opcode});
return error.UnknownExpressionOpcode;
},
}
return stream.pos < stream.buffer.len;
}
};
}
pub fn Builder(comptime options: Options) type {
const addr_type = switch (options.addr_size) {
2 => u16,
4 => u32,
8 => u64,
else => @compileError("Unsupported address size of " ++ options.addr_size),
};
return struct {
/// Zero-operand instructions
pub fn writeOpcode(writer: anytype, comptime opcode: u8) !void {
if (options.call_frame_context and !comptime isOpcodeValidInCFA(opcode)) return error.InvalidCFAOpcode;
switch (opcode) {
OP.dup,
OP.drop,
OP.over,
OP.swap,
OP.rot,
OP.deref,
OP.xderef,
OP.push_object_address,
OP.form_tls_address,
OP.call_frame_cfa,
OP.abs,
OP.@"and",
OP.div,
OP.minus,
OP.mod,
OP.mul,
OP.neg,
OP.not,
OP.@"or",
OP.plus,
OP.shl,
OP.shr,
OP.shra,
OP.xor,
OP.le,
OP.ge,
OP.eq,
OP.lt,
OP.gt,
OP.ne,
OP.nop,
OP.stack_value,
=> try writer.writeByte(opcode),
else => @compileError("This opcode requires operands, use `write<Opcode>()` instead"),
}
}
// 2.5.1.1: Literal Encodings
pub fn writeLiteral(writer: anytype, literal: u8) !void {
switch (literal) {
0...31 => |n| try writer.writeByte(n + OP.lit0),
else => return error.InvalidLiteral,
}
}
pub fn writeConst(writer: anytype, comptime T: type, value: T) !void {
if (@typeInfo(T) != .int) @compileError("Constants must be integers");
switch (T) {
u8, i8, u16, i16, u32, i32, u64, i64 => {
try writer.writeByte(switch (T) {
u8 => OP.const1u,
i8 => OP.const1s,
u16 => OP.const2u,
i16 => OP.const2s,
u32 => OP.const4u,
i32 => OP.const4s,
u64 => OP.const8u,
i64 => OP.const8s,
else => unreachable,
});
try writer.writeInt(T, value, options.endian);
},
else => switch (@typeInfo(T).int.signedness) {
.unsigned => {
try writer.writeByte(OP.constu);
try leb.writeUleb128(writer, value);
},
.signed => {
try writer.writeByte(OP.consts);
try leb.writeIleb128(writer, value);
},
},
}
}
pub fn writeConstx(writer: anytype, debug_addr_offset: anytype) !void {
try writer.writeByte(OP.constx);
try leb.writeUleb128(writer, debug_addr_offset);
}
pub fn writeConstType(writer: anytype, die_offset: anytype, value_bytes: []const u8) !void {
if (options.call_frame_context) return error.InvalidCFAOpcode;
if (value_bytes.len > 0xff) return error.InvalidTypeLength;
try writer.writeByte(OP.const_type);
try leb.writeUleb128(writer, die_offset);
try writer.writeByte(@intCast(value_bytes.len));
try writer.writeAll(value_bytes);
}
pub fn writeAddr(writer: anytype, value: addr_type) !void {
try writer.writeByte(OP.addr);
try writer.writeInt(addr_type, value, options.endian);
}
pub fn writeAddrx(writer: anytype, debug_addr_offset: anytype) !void {
if (options.call_frame_context) return error.InvalidCFAOpcode;
try writer.writeByte(OP.addrx);
try leb.writeUleb128(writer, debug_addr_offset);
}
// 2.5.1.2: Register Values
pub fn writeFbreg(writer: anytype, offset: anytype) !void {
try writer.writeByte(OP.fbreg);
try leb.writeIleb128(writer, offset);
}
pub fn writeBreg(writer: anytype, register: u8, offset: anytype) !void {
if (register > 31) return error.InvalidRegister;
try writer.writeByte(OP.breg0 + register);
try leb.writeIleb128(writer, offset);
}
pub fn writeBregx(writer: anytype, register: anytype, offset: anytype) !void {
try writer.writeByte(OP.bregx);
try leb.writeUleb128(writer, register);
try leb.writeIleb128(writer, offset);
}
pub fn writeRegvalType(writer: anytype, register: anytype, offset: anytype) !void {
if (options.call_frame_context) return error.InvalidCFAOpcode;
try writer.writeByte(OP.regval_type);
try leb.writeUleb128(writer, register);
try leb.writeUleb128(writer, offset);
}
// 2.5.1.3: Stack Operations
pub fn writePick(writer: anytype, index: u8) !void {
try writer.writeByte(OP.pick);
try writer.writeByte(index);
}
pub fn writeDerefSize(writer: anytype, size: u8) !void {
try writer.writeByte(OP.deref_size);
try writer.writeByte(size);
}
pub fn writeXDerefSize(writer: anytype, size: u8) !void {
try writer.writeByte(OP.xderef_size);
try writer.writeByte(size);
}
pub fn writeDerefType(writer: anytype, size: u8, die_offset: anytype) !void {
if (options.call_frame_context) return error.InvalidCFAOpcode;
try writer.writeByte(OP.deref_type);
try writer.writeByte(size);
try leb.writeUleb128(writer, die_offset);
}
pub fn writeXDerefType(writer: anytype, size: u8, die_offset: anytype) !void {
try writer.writeByte(OP.xderef_type);
try writer.writeByte(size);
try leb.writeUleb128(writer, die_offset);
}
// 2.5.1.4: Arithmetic and Logical Operations
pub fn writePlusUconst(writer: anytype, uint_value: anytype) !void {
try writer.writeByte(OP.plus_uconst);
try leb.writeUleb128(writer, uint_value);
}
// 2.5.1.5: Control Flow Operations
pub fn writeSkip(writer: anytype, offset: i16) !void {
try writer.writeByte(OP.skip);
try writer.writeInt(i16, offset, options.endian);
}
pub fn writeBra(writer: anytype, offset: i16) !void {
try writer.writeByte(OP.bra);
try writer.writeInt(i16, offset, options.endian);
}
pub fn writeCall(writer: anytype, comptime T: type, offset: T) !void {
if (options.call_frame_context) return error.InvalidCFAOpcode;
switch (T) {
u16 => try writer.writeByte(OP.call2),
u32 => try writer.writeByte(OP.call4),
else => @compileError("Call operand must be a 2 or 4 byte offset"),
}
try writer.writeInt(T, offset, options.endian);
}
pub fn writeCallRef(writer: anytype, comptime is_64: bool, value: if (is_64) u64 else u32) !void {
if (options.call_frame_context) return error.InvalidCFAOpcode;
try writer.writeByte(OP.call_ref);
try writer.writeInt(if (is_64) u64 else u32, value, options.endian);
}
pub fn writeConvert(writer: anytype, die_offset: anytype) !void {
if (options.call_frame_context) return error.InvalidCFAOpcode;
try writer.writeByte(OP.convert);
try leb.writeUleb128(writer, die_offset);
}
pub fn writeReinterpret(writer: anytype, die_offset: anytype) !void {
if (options.call_frame_context) return error.InvalidCFAOpcode;
try writer.writeByte(OP.reinterpret);
try leb.writeUleb128(writer, die_offset);
}
// 2.5.1.7: Special Operations
pub fn writeEntryValue(writer: anytype, expression: []const u8) !void {
try writer.writeByte(OP.entry_value);
try leb.writeUleb128(writer, expression.len);
try writer.writeAll(expression);
}
// 2.6: Location Descriptions
pub fn writeReg(writer: anytype, register: u8) !void {
try writer.writeByte(OP.reg0 + register);
}
pub fn writeRegx(writer: anytype, register: anytype) !void {
try writer.writeByte(OP.regx);
try leb.writeUleb128(writer, register);
}
pub fn writeImplicitValue(writer: anytype, value_bytes: []const u8) !void {
try writer.writeByte(OP.implicit_value);
try leb.writeUleb128(writer, value_bytes.len);
try writer.writeAll(value_bytes);
}
};
}
// Certain opcodes are not allowed in a CFA context, see 6.4.2
fn isOpcodeValidInCFA(opcode: u8) bool {
return switch (opcode) {
OP.addrx,
OP.call2,
OP.call4,
OP.call_ref,
OP.const_type,
OP.constx,
OP.convert,
OP.deref_type,
OP.regval_type,
OP.reinterpret,
OP.push_object_address,
OP.call_frame_cfa,
=> false,
else => true,
};
}
fn isOpcodeRegisterLocation(opcode: u8) bool {
return switch (opcode) {
OP.reg0...OP.reg31, OP.regx => true,
else => false,
};
}
const testing = std.testing;
test "DWARF expressions" {
const allocator = std.testing.allocator;
const options = Options{};
var stack_machine = StackMachine(options){};
defer stack_machine.deinit(allocator);
const b = Builder(options);
var program = std.array_list.Managed(u8).init(allocator);
defer program.deinit();
const writer = program.writer();
// Literals
{
const context = Context{};
for (0..32) |i| {
try b.writeLiteral(writer, @intCast(i));
}
_ = try stack_machine.run(program.items, allocator, context, 0);
for (0..32) |i| {
const expected = 31 - i;
try testing.expectEqual(expected, stack_machine.stack.pop().?.generic);
}
}
// Constants
{
stack_machine.reset();
program.clearRetainingCapacity();
const input = [_]comptime_int{
1,
-1,
@as(usize, @truncate(0x0fff)),
@as(isize, @truncate(-0x0fff)),
@as(usize, @truncate(0x0fffffff)),
@as(isize, @truncate(-0x0fffffff)),
@as(usize, @truncate(0x0fffffffffffffff)),
@as(isize, @truncate(-0x0fffffffffffffff)),
@as(usize, @truncate(0x8000000)),
@as(isize, @truncate(-0x8000000)),
@as(usize, @truncate(0x12345678_12345678)),
@as(usize, @truncate(0xffffffff_ffffffff)),
@as(usize, @truncate(0xeeeeeeee_eeeeeeee)),
};
try b.writeConst(writer, u8, input[0]);
try b.writeConst(writer, i8, input[1]);
try b.writeConst(writer, u16, input[2]);
try b.writeConst(writer, i16, input[3]);
try b.writeConst(writer, u32, input[4]);
try b.writeConst(writer, i32, input[5]);
try b.writeConst(writer, u64, input[6]);
try b.writeConst(writer, i64, input[7]);
try b.writeConst(writer, u28, input[8]);
try b.writeConst(writer, i28, input[9]);
try b.writeAddr(writer, input[10]);
var mock_compile_unit: std.debug.Dwarf.CompileUnit = undefined;
mock_compile_unit.addr_base = 1;
var mock_debug_addr = std.array_list.Managed(u8).init(allocator);
defer mock_debug_addr.deinit();
try mock_debug_addr.writer().writeInt(u16, 0, native_endian);
try mock_debug_addr.writer().writeInt(usize, input[11], native_endian);
try mock_debug_addr.writer().writeInt(usize, input[12], native_endian);
const context = Context{
.compile_unit = &mock_compile_unit,
.debug_addr = mock_debug_addr.items,
};
try b.writeConstx(writer, @as(usize, 1));
try b.writeAddrx(writer, @as(usize, 1 + @sizeOf(usize)));
const die_offset: usize = @truncate(0xaabbccdd);
const type_bytes: []const u8 = &.{ 1, 2, 3, 4 };
try b.writeConstType(writer, die_offset, type_bytes);
_ = try stack_machine.run(program.items, allocator, context, 0);
const const_type = stack_machine.stack.pop().?.const_type;
try testing.expectEqual(die_offset, const_type.type_offset);
try testing.expectEqualSlices(u8, type_bytes, const_type.value_bytes);
const expected = .{
.{ usize, input[12], usize },
.{ usize, input[11], usize },
.{ usize, input[10], usize },
.{ isize, input[9], isize },
.{ usize, input[8], usize },
.{ isize, input[7], isize },
.{ usize, input[6], usize },
.{ isize, input[5], isize },
.{ usize, input[4], usize },
.{ isize, input[3], isize },
.{ usize, input[2], usize },
.{ isize, input[1], isize },
.{ usize, input[0], usize },
};
inline for (expected) |e| {
try testing.expectEqual(@as(e[0], e[1]), @as(e[2], @bitCast(stack_machine.stack.pop().?.generic)));
}
}
// Register values
if (@sizeOf(std.debug.ThreadContext) != 0) {
stack_machine.reset();
program.clearRetainingCapacity();
const reg_context = abi.RegisterContext{
.eh_frame = true,
.is_macho = builtin.os.tag == .macos,
};
var thread_context: std.debug.ThreadContext = undefined;
std.debug.relocateContext(&thread_context);
const context = Context{
.thread_context = &thread_context,
.reg_context = reg_context,
};
// Only test register operations on arch / os that have them implemented
if (abi.regBytes(&thread_context, 0, reg_context)) |reg_bytes| {
// TODO: Test fbreg (once implemented): mock a DIE and point compile_unit.frame_base at it
mem.writeInt(usize, reg_bytes[0..@sizeOf(usize)], 0xee, native_endian);
(try abi.regValueNative(&thread_context, abi.fpRegNum(native_arch, reg_context), reg_context)).* = 1;
(try abi.regValueNative(&thread_context, abi.spRegNum(native_arch, reg_context), reg_context)).* = 2;
(try abi.regValueNative(&thread_context, abi.ipRegNum(native_arch).?, reg_context)).* = 3;
try b.writeBreg(writer, abi.fpRegNum(native_arch, reg_context), @as(usize, 100));
try b.writeBreg(writer, abi.spRegNum(native_arch, reg_context), @as(usize, 200));
try b.writeBregx(writer, abi.ipRegNum(native_arch).?, @as(usize, 300));
try b.writeRegvalType(writer, @as(u8, 0), @as(usize, 400));
_ = try stack_machine.run(program.items, allocator, context, 0);
const regval_type = stack_machine.stack.pop().?.regval_type;
try testing.expectEqual(@as(usize, 400), regval_type.type_offset);
try testing.expectEqual(@as(u8, @sizeOf(usize)), regval_type.type_size);
try testing.expectEqual(@as(usize, 0xee), regval_type.value);
try testing.expectEqual(@as(usize, 303), stack_machine.stack.pop().?.generic);
try testing.expectEqual(@as(usize, 202), stack_machine.stack.pop().?.generic);
try testing.expectEqual(@as(usize, 101), stack_machine.stack.pop().?.generic);
} else |err| {
switch (err) {
error.UnimplementedArch,
error.UnimplementedOs,
error.ThreadContextNotSupported,
=> {},
else => return err,
}
}
}
// Stack operations
{
var context = Context{};
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u8, 1);
try b.writeOpcode(writer, OP.dup);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 1), stack_machine.stack.pop().?.generic);
try testing.expectEqual(@as(usize, 1), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u8, 1);
try b.writeOpcode(writer, OP.drop);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expect(stack_machine.stack.pop() == null);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u8, 4);
try b.writeConst(writer, u8, 5);
try b.writeConst(writer, u8, 6);
try b.writePick(writer, 2);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 4), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u8, 4);
try b.writeConst(writer, u8, 5);
try b.writeConst(writer, u8, 6);
try b.writeOpcode(writer, OP.over);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 5), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u8, 5);
try b.writeConst(writer, u8, 6);
try b.writeOpcode(writer, OP.swap);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 5), stack_machine.stack.pop().?.generic);
try testing.expectEqual(@as(usize, 6), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u8, 4);
try b.writeConst(writer, u8, 5);
try b.writeConst(writer, u8, 6);
try b.writeOpcode(writer, OP.rot);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 5), stack_machine.stack.pop().?.generic);
try testing.expectEqual(@as(usize, 4), stack_machine.stack.pop().?.generic);
try testing.expectEqual(@as(usize, 6), stack_machine.stack.pop().?.generic);
const deref_target: usize = @truncate(0xffeeffee_ffeeffee);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeAddr(writer, @intFromPtr(&deref_target));
try b.writeOpcode(writer, OP.deref);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(deref_target, stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeLiteral(writer, 0);
try b.writeAddr(writer, @intFromPtr(&deref_target));
try b.writeOpcode(writer, OP.xderef);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(deref_target, stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeAddr(writer, @intFromPtr(&deref_target));
try b.writeDerefSize(writer, 1);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, @as(*const u8, @ptrCast(&deref_target)).*), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeLiteral(writer, 0);
try b.writeAddr(writer, @intFromPtr(&deref_target));
try b.writeXDerefSize(writer, 1);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, @as(*const u8, @ptrCast(&deref_target)).*), stack_machine.stack.pop().?.generic);
const type_offset: usize = @truncate(0xaabbaabb_aabbaabb);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeAddr(writer, @intFromPtr(&deref_target));
try b.writeDerefType(writer, 1, type_offset);
_ = try stack_machine.run(program.items, allocator, context, null);
const deref_type = stack_machine.stack.pop().?.regval_type;
try testing.expectEqual(type_offset, deref_type.type_offset);
try testing.expectEqual(@as(u8, 1), deref_type.type_size);
try testing.expectEqual(@as(usize, @as(*const u8, @ptrCast(&deref_target)).*), deref_type.value);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeLiteral(writer, 0);
try b.writeAddr(writer, @intFromPtr(&deref_target));
try b.writeXDerefType(writer, 1, type_offset);
_ = try stack_machine.run(program.items, allocator, context, null);
const xderef_type = stack_machine.stack.pop().?.regval_type;
try testing.expectEqual(type_offset, xderef_type.type_offset);
try testing.expectEqual(@as(u8, 1), xderef_type.type_size);
try testing.expectEqual(@as(usize, @as(*const u8, @ptrCast(&deref_target)).*), xderef_type.value);
context.object_address = &deref_target;
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeOpcode(writer, OP.push_object_address);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, @intFromPtr(context.object_address.?)), stack_machine.stack.pop().?.generic);
// TODO: Test OP.form_tls_address
context.cfa = @truncate(0xccddccdd_ccddccdd);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeOpcode(writer, OP.call_frame_cfa);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(context.cfa.?, stack_machine.stack.pop().?.generic);
}
// Arithmetic and Logical Operations
{
const context = Context{};
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, i16, -4096);
try b.writeOpcode(writer, OP.abs);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 4096), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u16, 0xff0f);
try b.writeConst(writer, u16, 0xf0ff);
try b.writeOpcode(writer, OP.@"and");
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 0xf00f), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, i16, -404);
try b.writeConst(writer, i16, 100);
try b.writeOpcode(writer, OP.div);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(isize, -404 / 100), @as(isize, @bitCast(stack_machine.stack.pop().?.generic)));
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u16, 200);
try b.writeConst(writer, u16, 50);
try b.writeOpcode(writer, OP.minus);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 150), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u16, 123);
try b.writeConst(writer, u16, 100);
try b.writeOpcode(writer, OP.mod);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 23), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u16, 0xff);
try b.writeConst(writer, u16, 0xee);
try b.writeOpcode(writer, OP.mul);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 0xed12), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u16, 5);
try b.writeOpcode(writer, OP.neg);
try b.writeConst(writer, i16, -6);
try b.writeOpcode(writer, OP.neg);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 6), stack_machine.stack.pop().?.generic);
try testing.expectEqual(@as(isize, -5), @as(isize, @bitCast(stack_machine.stack.pop().?.generic)));
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u16, 0xff0f);
try b.writeOpcode(writer, OP.not);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(~@as(usize, 0xff0f), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u16, 0xff0f);
try b.writeConst(writer, u16, 0xf0ff);
try b.writeOpcode(writer, OP.@"or");
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 0xffff), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, i16, 402);
try b.writeConst(writer, i16, 100);
try b.writeOpcode(writer, OP.plus);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 502), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u16, 4096);
try b.writePlusUconst(writer, @as(usize, 8192));
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 4096 + 8192), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u16, 0xfff);
try b.writeConst(writer, u16, 1);
try b.writeOpcode(writer, OP.shl);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 0xfff << 1), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u16, 0xfff);
try b.writeConst(writer, u16, 1);
try b.writeOpcode(writer, OP.shr);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 0xfff >> 1), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u16, 0xfff);
try b.writeConst(writer, u16, 1);
try b.writeOpcode(writer, OP.shr);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, @bitCast(@as(isize, 0xfff) >> 1)), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u16, 0xf0ff);
try b.writeConst(writer, u16, 0xff0f);
try b.writeOpcode(writer, OP.xor);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 0x0ff0), stack_machine.stack.pop().?.generic);
}
// Control Flow Operations
{
const context = Context{};
const expected = .{
.{ OP.le, 1, 1, 0 },
.{ OP.ge, 1, 0, 1 },
.{ OP.eq, 1, 0, 0 },
.{ OP.lt, 0, 1, 0 },
.{ OP.gt, 0, 0, 1 },
.{ OP.ne, 0, 1, 1 },
};
inline for (expected) |e| {
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConst(writer, u16, 0);
try b.writeConst(writer, u16, 0);
try b.writeOpcode(writer, e[0]);
try b.writeConst(writer, u16, 0);
try b.writeConst(writer, u16, 1);
try b.writeOpcode(writer, e[0]);
try b.writeConst(writer, u16, 1);
try b.writeConst(writer, u16, 0);
try b.writeOpcode(writer, e[0]);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, e[3]), stack_machine.stack.pop().?.generic);
try testing.expectEqual(@as(usize, e[2]), stack_machine.stack.pop().?.generic);
try testing.expectEqual(@as(usize, e[1]), stack_machine.stack.pop().?.generic);
}
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeLiteral(writer, 2);
try b.writeSkip(writer, 1);
try b.writeLiteral(writer, 3);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 2), stack_machine.stack.pop().?.generic);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeLiteral(writer, 2);
try b.writeBra(writer, 1);
try b.writeLiteral(writer, 3);
try b.writeLiteral(writer, 0);
try b.writeBra(writer, 1);
try b.writeLiteral(writer, 4);
try b.writeLiteral(writer, 5);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 5), stack_machine.stack.pop().?.generic);
try testing.expectEqual(@as(usize, 4), stack_machine.stack.pop().?.generic);
try testing.expect(stack_machine.stack.pop() == null);
// TODO: Test call2, call4, call_ref once implemented
}
// Type conversions
{
const context = Context{};
stack_machine.reset();
program.clearRetainingCapacity();
// TODO: Test typed OP.convert once implemented
const value: usize = @truncate(0xffeeffee_ffeeffee);
var value_bytes: [options.addr_size]u8 = undefined;
mem.writeInt(usize, &value_bytes, value, native_endian);
// Convert to generic type
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConstType(writer, @as(usize, 0), &value_bytes);
try b.writeConvert(writer, @as(usize, 0));
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(value, stack_machine.stack.pop().?.generic);
// Reinterpret to generic type
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConstType(writer, @as(usize, 0), &value_bytes);
try b.writeReinterpret(writer, @as(usize, 0));
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(value, stack_machine.stack.pop().?.generic);
// Reinterpret to new type
const die_offset: usize = 0xffee;
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeConstType(writer, @as(usize, 0), &value_bytes);
try b.writeReinterpret(writer, die_offset);
_ = try stack_machine.run(program.items, allocator, context, null);
const const_type = stack_machine.stack.pop().?.const_type;
try testing.expectEqual(die_offset, const_type.type_offset);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeLiteral(writer, 0);
try b.writeReinterpret(writer, die_offset);
_ = try stack_machine.run(program.items, allocator, context, null);
const regval_type = stack_machine.stack.pop().?.regval_type;
try testing.expectEqual(die_offset, regval_type.type_offset);
}
// Special operations
{
var context = Context{};
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeOpcode(writer, OP.nop);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expect(stack_machine.stack.pop() == null);
// Sub-expression
{
var sub_program = std.array_list.Managed(u8).init(allocator);
defer sub_program.deinit();
const sub_writer = sub_program.writer();
try b.writeLiteral(sub_writer, 3);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeEntryValue(writer, sub_program.items);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 3), stack_machine.stack.pop().?.generic);
}
// Register location description
const reg_context = abi.RegisterContext{
.eh_frame = true,
.is_macho = builtin.os.tag == .macos,
};
var thread_context: std.debug.ThreadContext = undefined;
std.debug.relocateContext(&thread_context);
context = Context{
.thread_context = &thread_context,
.reg_context = reg_context,
};
if (abi.regBytes(&thread_context, 0, reg_context)) |reg_bytes| {
mem.writeInt(usize, reg_bytes[0..@sizeOf(usize)], 0xee, native_endian);
var sub_program = std.array_list.Managed(u8).init(allocator);
defer sub_program.deinit();
const sub_writer = sub_program.writer();
try b.writeReg(sub_writer, 0);
stack_machine.reset();
program.clearRetainingCapacity();
try b.writeEntryValue(writer, sub_program.items);
_ = try stack_machine.run(program.items, allocator, context, null);
try testing.expectEqual(@as(usize, 0xee), stack_machine.stack.pop().?.generic);
} else |err| {
switch (err) {
error.UnimplementedArch,
error.UnimplementedOs,
error.ThreadContextNotSupported,
=> {},
else => return err,
}
}
}
}