Files
zig/src/arch/wasm/CodeGen.zig
Luuk de Gram ec5220405b wasm: Implement optionals and ensure correct alignment
Rather than writing the alignment in its natural form, wasm binaries encode the alignment of types as the exponent of a power of 2.
So rather than performing this encoding during AIR->MIR, we do this while emitting MIR->binary encoding.
This allows us to keep alignment logic to its natural form while doing calculations (Which is what we need during linking as well).

We also implement optionals and pointers to an optional.
2021-11-21 21:07:55 +01:00

1898 lines
72 KiB
Zig

const std = @import("std");
const Allocator = std.mem.Allocator;
const ArrayList = std.ArrayList;
const assert = std.debug.assert;
const testing = std.testing;
const leb = std.leb;
const mem = std.mem;
const wasm = std.wasm;
const Module = @import("../../Module.zig");
const Decl = Module.Decl;
const Type = @import("../../type.zig").Type;
const Value = @import("../../value.zig").Value;
const Compilation = @import("../../Compilation.zig");
const LazySrcLoc = Module.LazySrcLoc;
const link = @import("../../link.zig");
const TypedValue = @import("../../TypedValue.zig");
const Air = @import("../../Air.zig");
const Liveness = @import("../../Liveness.zig");
const Mir = @import("Mir.zig");
const Emit = @import("Emit.zig");
/// Wasm Value, created when generating an instruction
const WValue = union(enum) {
/// May be referenced but is unused
none: void,
/// Index of the local variable
local: u32,
/// Holds a memoized typed value
constant: TypedValue,
/// Used for types that contains of multiple areas within
/// a memory region in the stack.
/// The local represents the position in the stack,
/// whereas the offset represents the offset from that position.
local_with_offset: struct {
/// Index of the local variable
local: u32,
/// The offset from the local's stack position
offset: u32,
},
};
/// Wasm ops, but without input/output/signedness information
/// Used for `buildOpcode`
const Op = enum {
@"unreachable",
nop,
block,
loop,
@"if",
@"else",
end,
br,
br_if,
br_table,
@"return",
call,
call_indirect,
drop,
select,
local_get,
local_set,
local_tee,
global_get,
global_set,
load,
store,
memory_size,
memory_grow,
@"const",
eqz,
eq,
ne,
lt,
gt,
le,
ge,
clz,
ctz,
popcnt,
add,
sub,
mul,
div,
rem,
@"and",
@"or",
xor,
shl,
shr,
rotl,
rotr,
abs,
neg,
ceil,
floor,
trunc,
nearest,
sqrt,
min,
max,
copysign,
wrap,
convert,
demote,
promote,
reinterpret,
extend,
};
/// Contains the settings needed to create an `Opcode` using `buildOpcode`.
///
/// The fields correspond to the opcode name. Here is an example
/// i32_trunc_f32_s
/// ^ ^ ^ ^
/// | | | |
/// valtype1 | | |
/// = .i32 | | |
/// | | |
/// op | |
/// = .trunc | |
/// | |
/// valtype2 |
/// = .f32 |
/// |
/// width |
/// = null |
/// |
/// signed
/// = true
///
/// There can be missing fields, here are some more examples:
/// i64_load8_u
/// --> .{ .valtype1 = .i64, .op = .load, .width = 8, signed = false }
/// i32_mul
/// --> .{ .valtype1 = .i32, .op = .trunc }
/// nop
/// --> .{ .op = .nop }
const OpcodeBuildArguments = struct {
/// First valtype in the opcode (usually represents the type of the output)
valtype1: ?wasm.Valtype = null,
/// The operation (e.g. call, unreachable, div, min, sqrt, etc.)
op: Op,
/// Width of the operation (e.g. 8 for i32_load8_s, 16 for i64_extend16_i32_s)
width: ?u8 = null,
/// Second valtype in the opcode name (usually represents the type of the input)
valtype2: ?wasm.Valtype = null,
/// Signedness of the op
signedness: ?std.builtin.Signedness = null,
};
/// Helper function that builds an Opcode given the arguments needed
fn buildOpcode(args: OpcodeBuildArguments) wasm.Opcode {
switch (args.op) {
.@"unreachable" => return .@"unreachable",
.nop => return .nop,
.block => return .block,
.loop => return .loop,
.@"if" => return .@"if",
.@"else" => return .@"else",
.end => return .end,
.br => return .br,
.br_if => return .br_if,
.br_table => return .br_table,
.@"return" => return .@"return",
.call => return .call,
.call_indirect => return .call_indirect,
.drop => return .drop,
.select => return .select,
.local_get => return .local_get,
.local_set => return .local_set,
.local_tee => return .local_tee,
.global_get => return .global_get,
.global_set => return .global_set,
.load => if (args.width) |width| switch (width) {
8 => switch (args.valtype1.?) {
.i32 => if (args.signedness.? == .signed) return .i32_load8_s else return .i32_load8_u,
.i64 => if (args.signedness.? == .signed) return .i64_load8_s else return .i64_load8_u,
.f32, .f64 => unreachable,
},
16 => switch (args.valtype1.?) {
.i32 => if (args.signedness.? == .signed) return .i32_load16_s else return .i32_load16_u,
.i64 => if (args.signedness.? == .signed) return .i64_load16_s else return .i64_load16_u,
.f32, .f64 => unreachable,
},
32 => switch (args.valtype1.?) {
.i64 => if (args.signedness.? == .signed) return .i64_load32_s else return .i64_load32_u,
.i32 => return .i32_load,
.f32, .f64 => unreachable,
},
else => unreachable,
} else switch (args.valtype1.?) {
.i32 => return .i32_load,
.i64 => return .i64_load,
.f32 => return .f32_load,
.f64 => return .f64_load,
},
.store => if (args.width) |width| {
switch (width) {
8 => switch (args.valtype1.?) {
.i32 => return .i32_store8,
.i64 => return .i64_store8,
.f32, .f64 => unreachable,
},
16 => switch (args.valtype1.?) {
.i32 => return .i32_store16,
.i64 => return .i64_store16,
.f32, .f64 => unreachable,
},
32 => switch (args.valtype1.?) {
.i64 => return .i64_store32,
.i32 => return .i32_store,
.f32 => return .f32_store,
.f64 => unreachable,
},
64 => switch (args.valtype1.?) {
.i64 => return .i64_store,
else => unreachable,
},
else => unreachable,
}
} else {
switch (args.valtype1.?) {
.i32 => return .i32_store,
.i64 => return .i64_store,
.f32 => return .f32_store,
.f64 => return .f64_store,
}
},
.memory_size => return .memory_size,
.memory_grow => return .memory_grow,
.@"const" => switch (args.valtype1.?) {
.i32 => return .i32_const,
.i64 => return .i64_const,
.f32 => return .f32_const,
.f64 => return .f64_const,
},
.eqz => switch (args.valtype1.?) {
.i32 => return .i32_eqz,
.i64 => return .i64_eqz,
.f32, .f64 => unreachable,
},
.eq => switch (args.valtype1.?) {
.i32 => return .i32_eq,
.i64 => return .i64_eq,
.f32 => return .f32_eq,
.f64 => return .f64_eq,
},
.ne => switch (args.valtype1.?) {
.i32 => return .i32_ne,
.i64 => return .i64_ne,
.f32 => return .f32_ne,
.f64 => return .f64_ne,
},
.lt => switch (args.valtype1.?) {
.i32 => if (args.signedness.? == .signed) return .i32_lt_s else return .i32_lt_u,
.i64 => if (args.signedness.? == .signed) return .i64_lt_s else return .i64_lt_u,
.f32 => return .f32_lt,
.f64 => return .f64_lt,
},
.gt => switch (args.valtype1.?) {
.i32 => if (args.signedness.? == .signed) return .i32_gt_s else return .i32_gt_u,
.i64 => if (args.signedness.? == .signed) return .i64_gt_s else return .i64_gt_u,
.f32 => return .f32_gt,
.f64 => return .f64_gt,
},
.le => switch (args.valtype1.?) {
.i32 => if (args.signedness.? == .signed) return .i32_le_s else return .i32_le_u,
.i64 => if (args.signedness.? == .signed) return .i64_le_s else return .i64_le_u,
.f32 => return .f32_le,
.f64 => return .f64_le,
},
.ge => switch (args.valtype1.?) {
.i32 => if (args.signedness.? == .signed) return .i32_ge_s else return .i32_ge_u,
.i64 => if (args.signedness.? == .signed) return .i64_ge_s else return .i64_ge_u,
.f32 => return .f32_ge,
.f64 => return .f64_ge,
},
.clz => switch (args.valtype1.?) {
.i32 => return .i32_clz,
.i64 => return .i64_clz,
.f32, .f64 => unreachable,
},
.ctz => switch (args.valtype1.?) {
.i32 => return .i32_ctz,
.i64 => return .i64_ctz,
.f32, .f64 => unreachable,
},
.popcnt => switch (args.valtype1.?) {
.i32 => return .i32_popcnt,
.i64 => return .i64_popcnt,
.f32, .f64 => unreachable,
},
.add => switch (args.valtype1.?) {
.i32 => return .i32_add,
.i64 => return .i64_add,
.f32 => return .f32_add,
.f64 => return .f64_add,
},
.sub => switch (args.valtype1.?) {
.i32 => return .i32_sub,
.i64 => return .i64_sub,
.f32 => return .f32_sub,
.f64 => return .f64_sub,
},
.mul => switch (args.valtype1.?) {
.i32 => return .i32_mul,
.i64 => return .i64_mul,
.f32 => return .f32_mul,
.f64 => return .f64_mul,
},
.div => switch (args.valtype1.?) {
.i32 => if (args.signedness.? == .signed) return .i32_div_s else return .i32_div_u,
.i64 => if (args.signedness.? == .signed) return .i64_div_s else return .i64_div_u,
.f32 => return .f32_div,
.f64 => return .f64_div,
},
.rem => switch (args.valtype1.?) {
.i32 => if (args.signedness.? == .signed) return .i32_rem_s else return .i32_rem_u,
.i64 => if (args.signedness.? == .signed) return .i64_rem_s else return .i64_rem_u,
.f32, .f64 => unreachable,
},
.@"and" => switch (args.valtype1.?) {
.i32 => return .i32_and,
.i64 => return .i64_and,
.f32, .f64 => unreachable,
},
.@"or" => switch (args.valtype1.?) {
.i32 => return .i32_or,
.i64 => return .i64_or,
.f32, .f64 => unreachable,
},
.xor => switch (args.valtype1.?) {
.i32 => return .i32_xor,
.i64 => return .i64_xor,
.f32, .f64 => unreachable,
},
.shl => switch (args.valtype1.?) {
.i32 => return .i32_shl,
.i64 => return .i64_shl,
.f32, .f64 => unreachable,
},
.shr => switch (args.valtype1.?) {
.i32 => if (args.signedness.? == .signed) return .i32_shr_s else return .i32_shr_u,
.i64 => if (args.signedness.? == .signed) return .i64_shr_s else return .i64_shr_u,
.f32, .f64 => unreachable,
},
.rotl => switch (args.valtype1.?) {
.i32 => return .i32_rotl,
.i64 => return .i64_rotl,
.f32, .f64 => unreachable,
},
.rotr => switch (args.valtype1.?) {
.i32 => return .i32_rotr,
.i64 => return .i64_rotr,
.f32, .f64 => unreachable,
},
.abs => switch (args.valtype1.?) {
.i32, .i64 => unreachable,
.f32 => return .f32_abs,
.f64 => return .f64_abs,
},
.neg => switch (args.valtype1.?) {
.i32, .i64 => unreachable,
.f32 => return .f32_neg,
.f64 => return .f64_neg,
},
.ceil => switch (args.valtype1.?) {
.i32, .i64 => unreachable,
.f32 => return .f32_ceil,
.f64 => return .f64_ceil,
},
.floor => switch (args.valtype1.?) {
.i32, .i64 => unreachable,
.f32 => return .f32_floor,
.f64 => return .f64_floor,
},
.trunc => switch (args.valtype1.?) {
.i32 => switch (args.valtype2.?) {
.i32 => unreachable,
.i64 => unreachable,
.f32 => if (args.signedness.? == .signed) return .i32_trunc_f32_s else return .i32_trunc_f32_u,
.f64 => if (args.signedness.? == .signed) return .i32_trunc_f64_s else return .i32_trunc_f64_u,
},
.i64 => unreachable,
.f32 => return .f32_trunc,
.f64 => return .f64_trunc,
},
.nearest => switch (args.valtype1.?) {
.i32, .i64 => unreachable,
.f32 => return .f32_nearest,
.f64 => return .f64_nearest,
},
.sqrt => switch (args.valtype1.?) {
.i32, .i64 => unreachable,
.f32 => return .f32_sqrt,
.f64 => return .f64_sqrt,
},
.min => switch (args.valtype1.?) {
.i32, .i64 => unreachable,
.f32 => return .f32_min,
.f64 => return .f64_min,
},
.max => switch (args.valtype1.?) {
.i32, .i64 => unreachable,
.f32 => return .f32_max,
.f64 => return .f64_max,
},
.copysign => switch (args.valtype1.?) {
.i32, .i64 => unreachable,
.f32 => return .f32_copysign,
.f64 => return .f64_copysign,
},
.wrap => switch (args.valtype1.?) {
.i32 => switch (args.valtype2.?) {
.i32 => unreachable,
.i64 => return .i32_wrap_i64,
.f32, .f64 => unreachable,
},
.i64, .f32, .f64 => unreachable,
},
.convert => switch (args.valtype1.?) {
.i32, .i64 => unreachable,
.f32 => switch (args.valtype2.?) {
.i32 => if (args.signedness.? == .signed) return .f32_convert_i32_s else return .f32_convert_i32_u,
.i64 => if (args.signedness.? == .signed) return .f32_convert_i64_s else return .f32_convert_i64_u,
.f32, .f64 => unreachable,
},
.f64 => switch (args.valtype2.?) {
.i32 => if (args.signedness.? == .signed) return .f64_convert_i32_s else return .f64_convert_i32_u,
.i64 => if (args.signedness.? == .signed) return .f64_convert_i64_s else return .f64_convert_i64_u,
.f32, .f64 => unreachable,
},
},
.demote => if (args.valtype1.? == .f32 and args.valtype2.? == .f64) return .f32_demote_f64 else unreachable,
.promote => if (args.valtype1.? == .f64 and args.valtype2.? == .f32) return .f64_promote_f32 else unreachable,
.reinterpret => switch (args.valtype1.?) {
.i32 => if (args.valtype2.? == .f32) return .i32_reinterpret_f32 else unreachable,
.i64 => if (args.valtype2.? == .f64) return .i64_reinterpret_f64 else unreachable,
.f32 => if (args.valtype2.? == .i32) return .f32_reinterpret_i32 else unreachable,
.f64 => if (args.valtype2.? == .i64) return .f64_reinterpret_i64 else unreachable,
},
.extend => switch (args.valtype1.?) {
.i32 => switch (args.width.?) {
8 => if (args.signedness.? == .signed) return .i32_extend8_s else unreachable,
16 => if (args.signedness.? == .signed) return .i32_extend16_s else unreachable,
else => unreachable,
},
.i64 => switch (args.width.?) {
8 => if (args.signedness.? == .signed) return .i64_extend8_s else unreachable,
16 => if (args.signedness.? == .signed) return .i64_extend16_s else unreachable,
32 => if (args.signedness.? == .signed) return .i64_extend32_s else unreachable,
else => unreachable,
},
.f32, .f64 => unreachable,
},
}
}
test "Wasm - buildOpcode" {
// Make sure buildOpcode is referenced, and test some examples
const i32_const = buildOpcode(.{ .op = .@"const", .valtype1 = .i32 });
const end = buildOpcode(.{ .op = .end });
const local_get = buildOpcode(.{ .op = .local_get });
const i64_extend32_s = buildOpcode(.{ .op = .extend, .valtype1 = .i64, .width = 32, .signedness = .signed });
const f64_reinterpret_i64 = buildOpcode(.{ .op = .reinterpret, .valtype1 = .f64, .valtype2 = .i64 });
try testing.expectEqual(@as(wasm.Opcode, .i32_const), i32_const);
try testing.expectEqual(@as(wasm.Opcode, .end), end);
try testing.expectEqual(@as(wasm.Opcode, .local_get), local_get);
try testing.expectEqual(@as(wasm.Opcode, .i64_extend32_s), i64_extend32_s);
try testing.expectEqual(@as(wasm.Opcode, .f64_reinterpret_i64), f64_reinterpret_i64);
}
pub const Result = union(enum) {
/// The codegen bytes have been appended to `Context.code`
appended: void,
/// The data is managed externally and are part of the `Result`
externally_managed: []const u8,
};
/// Hashmap to store generated `WValue` for each `Air.Inst.Ref`
pub const ValueTable = std.AutoHashMapUnmanaged(Air.Inst.Index, WValue);
const Self = @This();
/// Reference to the function declaration the code
/// section belongs to
decl: *Decl,
air: Air,
liveness: Liveness,
gpa: *mem.Allocator,
/// Table to save `WValue`'s generated by an `Air.Inst`
values: ValueTable,
/// Mapping from Air.Inst.Index to block ids
blocks: std.AutoArrayHashMapUnmanaged(Air.Inst.Index, u32) = .{},
/// `bytes` contains the wasm bytecode belonging to the 'code' section.
code: ArrayList(u8),
/// Contains the generated function type bytecode for the current function
/// found in `decl`
func_type_data: ArrayList(u8),
/// The index the next local generated will have
/// NOTE: arguments share the index with locals therefore the first variable
/// will have the index that comes after the last argument's index
local_index: u32 = 0,
/// The index of the current argument.
/// Used to track which argument is being referenced in `airArg`.
arg_index: u32 = 0,
/// If codegen fails, an error messages will be allocated and saved in `err_msg`
err_msg: *Module.ErrorMsg,
/// Current block depth. Used to calculate the relative difference between a break
/// and block
block_depth: u32 = 0,
/// List of all locals' types generated throughout this declaration
/// used to emit locals count at start of 'code' section.
locals: std.ArrayListUnmanaged(u8),
/// The Target we're emitting (used to call intInfo)
target: std.Target,
/// Represents the wasm binary file that is being linked.
bin_file: *link.File,
/// Table with the global error set. Consists of every error found in
/// the compiled code. Each error name maps to a `Module.ErrorInt` which is emitted
/// during codegen to determine the error value.
global_error_set: std.StringHashMapUnmanaged(Module.ErrorInt),
/// List of MIR Instructions
mir_instructions: std.MultiArrayList(Mir.Inst) = .{},
/// Contains extra data for MIR
mir_extra: std.ArrayListUnmanaged(u32) = .{},
/// When a function is executing, we store the the current stack pointer's value within this local.
/// This value is then used to restore the stack pointer to the original value at the return of the function.
initial_stack_value: WValue = .none,
/// Arguments of this function declaration
/// This will be set after `resolveCallingConventionValues`
args: []WValue = undefined,
/// This will only be `.none` if the function returns void, or returns an immediate.
/// When it returns a pointer to the stack, the `.local` tag will be active and must be populated
/// before this function returns its execution to the caller.
return_value: WValue = .none,
const InnerError = error{
OutOfMemory,
/// An error occured when trying to lower AIR to MIR.
CodegenFail,
/// Can occur when dereferencing a pointer that points to a `Decl` of which the analysis has failed
AnalysisFail,
/// Failed to emit MIR instructions to binary/textual representation.
EmitFail,
};
pub fn deinit(self: *Self) void {
self.values.deinit(self.gpa);
self.blocks.deinit(self.gpa);
self.locals.deinit(self.gpa);
self.mir_instructions.deinit(self.gpa);
self.mir_extra.deinit(self.gpa);
self.* = undefined;
}
/// Sets `err_msg` on `Context` and returns `error.CodegemFail` which is caught in link/Wasm.zig
fn fail(self: *Self, comptime fmt: []const u8, args: anytype) InnerError {
const src: LazySrcLoc = .{ .node_offset = 0 };
const src_loc = src.toSrcLoc(self.decl);
self.err_msg = try Module.ErrorMsg.create(self.gpa, src_loc, fmt, args);
return error.CodegenFail;
}
/// Resolves the `WValue` for the given instruction `inst`
/// When the given instruction has a `Value`, it returns a constant instead
fn resolveInst(self: Self, ref: Air.Inst.Ref) WValue {
const inst_index = Air.refToIndex(ref) orelse {
const tv = Air.Inst.Ref.typed_value_map[@enumToInt(ref)];
if (!tv.ty.hasCodeGenBits()) {
return WValue.none;
}
return WValue{ .constant = tv };
};
const inst_type = self.air.typeOfIndex(inst_index);
if (!inst_type.hasCodeGenBits()) return .none;
if (self.air.instructions.items(.tag)[inst_index] == .constant) {
const ty_pl = self.air.instructions.items(.data)[inst_index].ty_pl;
return WValue{ .constant = .{ .ty = inst_type, .val = self.air.values[ty_pl.payload] } };
}
return self.values.get(inst_index).?; // Instruction does not dominate all uses!
}
/// Appends a MIR instruction and returns its index within the list of instructions
fn addInst(self: *Self, inst: Mir.Inst) error{OutOfMemory}!void {
try self.mir_instructions.append(self.gpa, inst);
}
/// Inserts a Mir instruction at the given `offset`.
/// Asserts offset is within bound.
fn addInstAt(self: *Self, offset: usize, inst: Mir.Inst) error{OutOfMemory}!void {
try self.mir_instructions.ensureUnusedCapacity(self.gpa, 1);
self.mir_instructions.insertAssumeCapacity(offset, inst);
}
fn addTag(self: *Self, tag: Mir.Inst.Tag) error{OutOfMemory}!void {
try self.addInst(.{ .tag = tag, .data = .{ .tag = {} } });
}
fn addLabel(self: *Self, tag: Mir.Inst.Tag, label: u32) error{OutOfMemory}!void {
try self.addInst(.{ .tag = tag, .data = .{ .label = label } });
}
fn addImm32(self: *Self, imm: i32) error{OutOfMemory}!void {
try self.addInst(.{ .tag = .i32_const, .data = .{ .imm32 = imm } });
}
/// Accepts an unsigned 64bit integer rather than a signed integer to
/// prevent us from having to bitcast multiple times as most values
/// within codegen are represented as unsigned rather than signed.
fn addImm64(self: *Self, imm: u64) error{OutOfMemory}!void {
const extra_index = try self.addExtra(Mir.Imm64.fromU64(imm));
try self.addInst(.{ .tag = .i64_const, .data = .{ .payload = extra_index } });
}
fn addFloat64(self: *Self, float: f64) error{OutOfMemory}!void {
const extra_index = try self.addExtra(Mir.Float64.fromFloat64(float));
try self.addInst(.{ .tag = .f64_const, .data = .{ .payload = extra_index } });
}
/// Appends entries to `mir_extra` based on the type of `extra`.
/// Returns the index into `mir_extra`
fn addExtra(self: *Self, extra: anytype) error{OutOfMemory}!u32 {
const fields = std.meta.fields(@TypeOf(extra));
try self.mir_extra.ensureUnusedCapacity(self.gpa, fields.len);
return self.addExtraAssumeCapacity(extra);
}
/// Appends entries to `mir_extra` based on the type of `extra`.
/// Returns the index into `mir_extra`
fn addExtraAssumeCapacity(self: *Self, extra: anytype) error{OutOfMemory}!u32 {
const fields = std.meta.fields(@TypeOf(extra));
const result = @intCast(u32, self.mir_extra.items.len);
inline for (fields) |field| {
self.mir_extra.appendAssumeCapacity(switch (field.field_type) {
u32 => @field(extra, field.name),
else => |field_type| @compileError("Unsupported field type " ++ @typeName(field_type)),
});
}
return result;
}
/// Using a given `Type`, returns the corresponding wasm Valtype
fn typeToValtype(self: *Self, ty: Type) InnerError!wasm.Valtype {
return switch (ty.zigTypeTag()) {
.Float => blk: {
const bits = ty.floatBits(self.target);
if (bits == 16 or bits == 32) break :blk wasm.Valtype.f32;
if (bits == 64) break :blk wasm.Valtype.f64;
return self.fail("Float bit size not supported by wasm: '{d}'", .{bits});
},
.Int => blk: {
const info = ty.intInfo(self.target);
if (info.bits <= 32) break :blk wasm.Valtype.i32;
if (info.bits > 32 and info.bits <= 64) break :blk wasm.Valtype.i64;
return self.fail("Integer bit size not supported by wasm: '{d}'", .{info.bits});
},
.Enum => switch (ty.tag()) {
.enum_simple => wasm.Valtype.i32,
else => self.typeToValtype(ty.cast(Type.Payload.EnumFull).?.data.tag_ty),
},
.Bool,
.Pointer,
.ErrorSet,
.Struct,
.ErrorUnion,
.Optional,
=> wasm.Valtype.i32,
else => self.fail("TODO - Wasm valtype for type '{}'", .{ty}),
};
}
/// Using a given `Type`, returns the byte representation of its wasm value type
fn genValtype(self: *Self, ty: Type) InnerError!u8 {
return wasm.valtype(try self.typeToValtype(ty));
}
/// Using a given `Type`, returns the corresponding wasm value type
/// Differently from `genValtype` this also allows `void` to create a block
/// with no return type
fn genBlockType(self: *Self, ty: Type) InnerError!u8 {
return switch (ty.tag()) {
.void, .noreturn => wasm.block_empty,
else => self.genValtype(ty),
};
}
/// Writes the bytecode depending on the given `WValue` in `val`
fn emitWValue(self: *Self, val: WValue) InnerError!void {
switch (val) {
.none => {}, // no-op
.local_with_offset => |with_off| try self.addLabel(.local_get, with_off.local),
.local => |idx| try self.addLabel(.local_get, idx),
.constant => |tv| try self.emitConstant(tv.val, tv.ty), // Creates a new constant on the stack
}
}
/// Creates one locals for a given `Type`.
/// Returns a corresponding `Wvalue` with `local` as active tag
fn allocLocal(self: *Self, ty: Type) InnerError!WValue {
const initial_index = self.local_index;
const valtype = try self.genValtype(ty);
try self.locals.append(self.gpa, valtype);
self.local_index += 1;
return WValue{ .local = initial_index };
}
fn genFunctype(self: *Self) InnerError!void {
assert(self.decl.has_tv);
const ty = self.decl.ty;
const writer = self.func_type_data.writer();
try writer.writeByte(wasm.function_type);
// param types
try leb.writeULEB128(writer, @intCast(u32, ty.fnParamLen()));
if (ty.fnParamLen() != 0) {
const params = try self.gpa.alloc(Type, ty.fnParamLen());
defer self.gpa.free(params);
ty.fnParamTypes(params);
for (params) |param_type| {
// Can we maybe get the source index of each param?
const val_type = try self.genValtype(param_type);
try writer.writeByte(val_type);
}
}
// return type
const return_type = ty.fnReturnType();
switch (return_type.zigTypeTag()) {
.Void, .NoReturn => try leb.writeULEB128(writer, @as(u32, 0)),
.Struct => return self.fail("TODO: Implement struct as return type for wasm", .{}),
.Optional => return self.fail("TODO: Implement optionals as return type for wasm", .{}),
else => {
try leb.writeULEB128(writer, @as(u32, 1));
const val_type = try self.genValtype(return_type);
try writer.writeByte(val_type);
},
}
}
pub fn genFunc(self: *Self) InnerError!Result {
try self.genFunctype();
// TODO: check for and handle death of instructions
var cc_result = try self.resolveCallingConventionValues(self.decl.ty);
defer cc_result.deinit(self.gpa);
self.args = cc_result.args;
self.return_value = cc_result.return_value;
// Generate MIR for function body
try self.genBody(self.air.getMainBody());
// End of function body
try self.addTag(.end);
var mir: Mir = .{
.instructions = self.mir_instructions.toOwnedSlice(),
.extra = self.mir_extra.toOwnedSlice(self.gpa),
};
defer mir.deinit(self.gpa);
var emit: Emit = .{
.mir = mir,
.bin_file = self.bin_file,
.code = &self.code,
.locals = self.locals.items,
.decl = self.decl,
};
emit.emitMir() catch |err| switch (err) {
error.EmitFail => {
self.err_msg = emit.error_msg.?;
return error.EmitFail;
},
else => |e| return e,
};
// codegen data has been appended to `code`
return Result.appended;
}
/// Generates the wasm bytecode for the declaration belonging to `Context`
pub fn gen(self: *Self, ty: Type, val: Value) InnerError!Result {
switch (ty.zigTypeTag()) {
.Fn => {
try self.genFunctype();
if (val.tag() == .extern_fn) {
return Result.appended; // don't need code body for extern functions
}
return self.fail("TODO implement wasm codegen for function pointers", .{});
},
.Array => {
if (val.castTag(.bytes)) |payload| {
if (ty.sentinel()) |sentinel| {
try self.code.appendSlice(payload.data);
switch (try self.gen(ty.childType(), sentinel)) {
.appended => return Result.appended,
.externally_managed => |data| {
try self.code.appendSlice(data);
return Result.appended;
},
}
}
return Result{ .externally_managed = payload.data };
} else return self.fail("TODO implement gen for more kinds of arrays", .{});
},
.Int => {
const info = ty.intInfo(self.target);
if (info.bits == 8 and info.signedness == .unsigned) {
const int_byte = val.toUnsignedInt();
try self.code.append(@intCast(u8, int_byte));
return Result.appended;
}
return self.fail("TODO: Implement codegen for int type: '{}'", .{ty});
},
.Enum => {
try self.emitConstant(val, ty);
return Result.appended;
},
.Struct => {
// TODO write the fields for real
try self.code.writer().writeByteNTimes(0xaa, ty.abiSize(self.target));
return Result{ .appended = {} };
},
else => |tag| return self.fail("TODO: Implement zig type codegen for type: '{s}'", .{tag}),
}
}
const CallWValues = struct {
args: []WValue,
return_value: WValue,
fn deinit(self: *CallWValues, gpa: *Allocator) void {
gpa.free(self.args);
self.* = undefined;
}
};
fn resolveCallingConventionValues(self: *Self, fn_ty: Type) InnerError!CallWValues {
const cc = fn_ty.fnCallingConvention();
const param_types = try self.gpa.alloc(Type, fn_ty.fnParamLen());
defer self.gpa.free(param_types);
fn_ty.fnParamTypes(param_types);
var result: CallWValues = .{
.args = try self.gpa.alloc(WValue, param_types.len),
.return_value = .none,
};
errdefer self.gpa.free(result.args);
switch (cc) {
.Naked => return result,
.Unspecified, .C => {
for (param_types) |ty, ty_index| {
if (!ty.hasCodeGenBits()) {
result.args[ty_index] = .{ .none = {} };
continue;
}
result.args[ty_index] = .{ .local = self.local_index };
self.local_index += 1;
}
const ret_ty = fn_ty.fnReturnType();
switch (ret_ty.zigTypeTag()) {
.ErrorUnion, .Optional => result.return_value = try self.allocLocal(Type.initTag(.i32)),
.Int, .Float, .Bool, .Void, .NoReturn => {},
else => return self.fail("TODO: Implement function return type {}", .{ret_ty}),
}
// Check if we store the result as a pointer to the stack rather than
// by value
if (result.return_value != .none) {
if (self.initial_stack_value == .none) try self.initializeStack();
const offset = std.math.cast(u32, ret_ty.abiSize(self.target)) catch {
return self.fail("Return type '{}' too big for stack frame", .{ret_ty});
};
try self.moveStack(offset, result.return_value.local);
}
},
else => return self.fail("TODO implement function parameters for cc '{}' on wasm", .{cc}),
}
return result;
}
/// Retrieves the stack pointer's value from the global variable and stores
/// it in a local
/// Asserts `initial_stack_value` is `.none`
fn initializeStack(self: *Self) !void {
assert(self.initial_stack_value == .none);
// reserve space for immediate value
// get stack pointer global
// TODO: For now, we hardcode the stack pointer to index '0',
// once the linker is further implemented, we can replace this by inserting
// a relocation and have the linker resolve the correct index to the stack pointer global.
// NOTE: relocations of the type GLOBAL_INDEX_LEB are 5-bytes big
try self.addLabel(.global_get, 0);
// Reserve a local to store the current stack pointer
// We can later use this local to set the stack pointer back to the value
// we have stored here.
self.initial_stack_value = try self.allocLocal(Type.initTag(.i32));
// save the value to the local
try self.addLabel(.local_set, self.initial_stack_value.local);
}
/// Reads the stack pointer from `Context.initial_stack_value` and writes it
/// to the global stack pointer variable
fn restoreStackPointer(self: *Self) !void {
// only restore the pointer if it was initialized
if (self.initial_stack_value == .none) return;
// Get the original stack pointer's value
try self.emitWValue(self.initial_stack_value);
// save its value in the global stack pointer
try self.addLabel(.global_set, 0);
}
/// Moves the stack pointer by given `offset`
/// It does this by retrieving the stack pointer, subtracting `offset` and storing
/// the result back into the stack pointer.
fn moveStack(self: *Self, offset: u32, local: u32) !void {
if (offset == 0) return;
// TODO: Rather than hardcode the stack pointer to position 0,
// have the linker resolve its relocation
try self.addLabel(.global_get, 0);
try self.addImm32(@bitCast(i32, offset));
try self.addTag(.i32_sub);
try self.addLabel(.local_tee, local);
try self.addLabel(.global_set, 0);
}
fn genInst(self: *Self, inst: Air.Inst.Index) !WValue {
const air_tags = self.air.instructions.items(.tag);
return switch (air_tags[inst]) {
.add => self.airBinOp(inst, .add),
.addwrap => self.airWrapBinOp(inst, .add),
.sub => self.airBinOp(inst, .sub),
.subwrap => self.airWrapBinOp(inst, .sub),
.mul => self.airBinOp(inst, .mul),
.mulwrap => self.airWrapBinOp(inst, .mul),
.div_trunc => self.airBinOp(inst, .div),
.bit_and => self.airBinOp(inst, .@"and"),
.bit_or => self.airBinOp(inst, .@"or"),
.bool_and => self.airBinOp(inst, .@"and"),
.bool_or => self.airBinOp(inst, .@"or"),
.xor => self.airBinOp(inst, .xor),
.cmp_eq => self.airCmp(inst, .eq),
.cmp_gte => self.airCmp(inst, .gte),
.cmp_gt => self.airCmp(inst, .gt),
.cmp_lte => self.airCmp(inst, .lte),
.cmp_lt => self.airCmp(inst, .lt),
.cmp_neq => self.airCmp(inst, .neq),
.alloc => self.airAlloc(inst),
.arg => self.airArg(inst),
.bitcast => self.airBitcast(inst),
.block => self.airBlock(inst),
.breakpoint => self.airBreakpoint(inst),
.br => self.airBr(inst),
.call => self.airCall(inst),
.cond_br => self.airCondBr(inst),
.constant => unreachable,
.dbg_stmt => WValue.none,
.intcast => self.airIntcast(inst),
.is_err => self.airIsErr(inst, .i32_eq),
.is_non_err => self.airIsErr(inst, .i32_ne),
.is_null => self.airIsNull(inst, .i32_ne),
.is_non_null => self.airIsNull(inst, .i32_eq),
.is_null_ptr => self.airIsNull(inst, .i32_ne),
.is_non_null_ptr => self.airIsNull(inst, .i32_eq),
.load => self.airLoad(inst),
.loop => self.airLoop(inst),
.not => self.airNot(inst),
.ret => self.airRet(inst),
.store => self.airStore(inst),
.struct_field_ptr => self.airStructFieldPtr(inst),
.struct_field_ptr_index_0 => self.airStructFieldPtrIndex(inst, 0),
.struct_field_ptr_index_1 => self.airStructFieldPtrIndex(inst, 1),
.struct_field_ptr_index_2 => self.airStructFieldPtrIndex(inst, 2),
.struct_field_ptr_index_3 => self.airStructFieldPtrIndex(inst, 3),
.struct_field_val => self.airStructFieldVal(inst),
.switch_br => self.airSwitchBr(inst),
.unreach => self.airUnreachable(inst),
.wrap_optional => self.airWrapOptional(inst),
.unwrap_errunion_payload => self.airUnwrapErrUnionPayload(inst),
.wrap_errunion_payload => self.airWrapErrUnionPayload(inst),
.optional_payload => self.airOptionalPayload(inst),
.optional_payload_ptr => self.airOptionalPayload(inst),
.optional_payload_ptr_set => self.airOptionalPayloadPtrSet(inst),
else => |tag| self.fail("TODO: Implement wasm inst: {s}", .{@tagName(tag)}),
};
}
fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
for (body) |inst| {
const result = try self.genInst(inst);
try self.values.putNoClobber(self.gpa, inst, result);
}
}
fn airRet(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const un_op = self.air.instructions.items(.data)[inst].un_op;
const operand = self.resolveInst(un_op);
// result must be stored in the stack and we return a pointer
// to the stack instead
if (self.return_value != .none) {
try self.store(self.return_value, operand, self.decl.ty.fnReturnType(), 0);
try self.emitWValue(self.return_value);
} else {
try self.emitWValue(operand);
}
try self.restoreStackPointer();
try self.addTag(.@"return");
return .none;
}
fn airCall(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const pl_op = self.air.instructions.items(.data)[inst].pl_op;
const extra = self.air.extraData(Air.Call, pl_op.payload);
const args = self.air.extra[extra.end..][0..extra.data.args_len];
const target: *Decl = blk: {
const func_val = self.air.value(pl_op.operand).?;
if (func_val.castTag(.function)) |func| {
break :blk func.data.owner_decl;
} else if (func_val.castTag(.extern_fn)) |ext_fn| {
break :blk ext_fn.data;
}
return self.fail("Expected a function, but instead found type '{s}'", .{func_val.tag()});
};
for (args) |arg| {
const arg_val = self.resolveInst(@intToEnum(Air.Inst.Ref, arg));
try self.emitWValue(arg_val);
}
try self.addLabel(.call, target.link.wasm.symbol_index);
const ret_ty = target.ty.fnReturnType();
switch (ret_ty.zigTypeTag()) {
.ErrorUnion, .Optional => {
const result_local = try self.allocLocal(ret_ty);
try self.addLabel(.local_set, result_local.local);
return result_local;
},
else => return WValue.none,
}
}
fn airAlloc(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const child_type = self.air.typeOfIndex(inst).childType();
// Initialize the stack
if (self.initial_stack_value == .none) {
try self.initializeStack();
}
const abi_size = child_type.abiSize(self.target);
if (abi_size == 0) return WValue{ .none = {} };
// local, containing the offset to the stack position
const local = try self.allocLocal(child_type);
try self.moveStack(@intCast(u32, abi_size), local.local);
return local;
}
fn airStore(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const bin_op = self.air.instructions.items(.data)[inst].bin_op;
const lhs = self.resolveInst(bin_op.lhs);
const rhs = self.resolveInst(bin_op.rhs);
const ty = self.air.typeOf(bin_op.lhs).childType();
const offset: u32 = switch (lhs) {
.local_with_offset => |with_off| with_off.offset,
else => 0,
};
try self.store(lhs, rhs, ty, offset);
return .none;
}
fn store(self: *Self, lhs: WValue, rhs: WValue, ty: Type, offset: u32) InnerError!void {
switch (ty.zigTypeTag()) {
.ErrorUnion, .Optional => {
var buf: Type.Payload.ElemType = undefined;
const payload_ty = if (ty.zigTypeTag() == .ErrorUnion) ty.errorUnionPayload() else ty.optionalChild(&buf);
const tag_ty = if (ty.zigTypeTag() == .ErrorUnion) ty.errorUnionSet() else Type.initTag(.u8);
const payload_offset = @intCast(u32, tag_ty.abiSize(self.target));
if (rhs == .constant) {
// constant will contain both tag and payload,
// so save those in 2 temporary locals before storing them
// in memory
try self.emitWValue(rhs);
const tag_local = try self.allocLocal(tag_ty);
const payload_local = try self.allocLocal(payload_ty);
try self.addLabel(.local_set, payload_local.local);
try self.addLabel(.local_set, tag_local.local);
try self.store(lhs, tag_local, tag_ty, 0);
return try self.store(lhs, payload_local, payload_ty, payload_offset);
} else {
// Load values from `rhs` stack position and store in `lhs` instead
const tag_local = try self.load(rhs, tag_ty, 0);
const payload_local = try self.load(rhs, payload_ty, payload_offset);
try self.store(lhs, tag_local, tag_ty, 0);
return try self.store(lhs, payload_local, payload_ty, payload_offset);
}
},
else => {},
}
try self.emitWValue(lhs);
try self.emitWValue(rhs);
const valtype = try self.typeToValtype(ty);
const opcode = buildOpcode(.{
.valtype1 = valtype,
.width = @intCast(u8, Type.abiSize(ty, self.target) * 8), // use bitsize instead of byte size
.op = .store,
});
// store rhs value at stack pointer's location in memory
const mem_arg_index = try self.addExtra(Mir.MemArg{
.offset = offset,
.alignment = ty.abiAlignment(self.target),
});
try self.addInst(.{
.tag = Mir.Inst.Tag.fromOpcode(opcode),
.data = .{ .payload = mem_arg_index },
});
}
fn airLoad(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const ty_op = self.air.instructions.items(.data)[inst].ty_op;
const operand = self.resolveInst(ty_op.operand);
const ty = self.air.getRefType(ty_op.ty);
return switch (ty.zigTypeTag()) {
.Struct, .ErrorUnion, .Optional => operand, // pass as pointer
else => switch (operand) {
.local_with_offset => |with_offset| try self.load(operand, ty, with_offset.offset),
else => try self.load(operand, ty, 0),
},
};
}
fn load(self: *Self, operand: WValue, ty: Type, offset: u32) InnerError!WValue {
// load local's value from memory by its stack position
try self.emitWValue(operand);
// Build the opcode with the right bitsize
const signedness: std.builtin.Signedness = if (ty.isUnsignedInt()) .unsigned else .signed;
const opcode = buildOpcode(.{
.valtype1 = try self.typeToValtype(ty),
.width = @intCast(u8, Type.abiSize(ty, self.target) * 8), // use bitsize instead of byte size
.op = .load,
.signedness = signedness,
});
const mem_arg_index = try self.addExtra(Mir.MemArg{
.offset = offset,
.alignment = ty.abiAlignment(self.target),
});
try self.addInst(.{
.tag = Mir.Inst.Tag.fromOpcode(opcode),
.data = .{ .payload = mem_arg_index },
});
// store the result in a local
const result = try self.allocLocal(ty);
try self.addLabel(.local_set, result.local);
return result;
}
fn airArg(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
_ = inst;
defer self.arg_index += 1;
return self.args[self.arg_index];
}
fn airBinOp(self: *Self, inst: Air.Inst.Index, op: Op) InnerError!WValue {
const bin_op = self.air.instructions.items(.data)[inst].bin_op;
const lhs = self.resolveInst(bin_op.lhs);
const rhs = self.resolveInst(bin_op.rhs);
try self.emitWValue(lhs);
try self.emitWValue(rhs);
const bin_ty = self.air.typeOf(bin_op.lhs);
const opcode: wasm.Opcode = buildOpcode(.{
.op = op,
.valtype1 = try self.typeToValtype(bin_ty),
.signedness = if (bin_ty.isSignedInt()) .signed else .unsigned,
});
try self.addTag(Mir.Inst.Tag.fromOpcode(opcode));
// save the result in a temporary
const bin_local = try self.allocLocal(bin_ty);
try self.addLabel(.local_set, bin_local.local);
return bin_local;
}
fn airWrapBinOp(self: *Self, inst: Air.Inst.Index, op: Op) InnerError!WValue {
const bin_op = self.air.instructions.items(.data)[inst].bin_op;
const lhs = self.resolveInst(bin_op.lhs);
const rhs = self.resolveInst(bin_op.rhs);
try self.emitWValue(lhs);
try self.emitWValue(rhs);
const bin_ty = self.air.typeOf(bin_op.lhs);
const opcode: wasm.Opcode = buildOpcode(.{
.op = op,
.valtype1 = try self.typeToValtype(bin_ty),
.signedness = if (bin_ty.isSignedInt()) .signed else .unsigned,
});
try self.addTag(Mir.Inst.Tag.fromOpcode(opcode));
const int_info = bin_ty.intInfo(self.target);
const bitsize = int_info.bits;
const is_signed = int_info.signedness == .signed;
// if target type bitsize is x < 32 and 32 > x < 64, we perform
// result & ((1<<N)-1) where N = bitsize or bitsize -1 incase of signed.
if (bitsize != 32 and bitsize < 64) {
// first check if we can use a single instruction,
// wasm provides those if the integers are signed and 8/16-bit.
// For arbitrary integer sizes, we use the algorithm mentioned above.
if (is_signed and bitsize == 8) {
try self.addTag(.i32_extend8_s);
} else if (is_signed and bitsize == 16) {
try self.addTag(.i32_extend16_s);
} else {
const result = (@as(u64, 1) << @intCast(u6, bitsize - @boolToInt(is_signed))) - 1;
if (bitsize < 32) {
try self.addImm32(@bitCast(i32, @intCast(u32, result)));
try self.addTag(.i32_and);
} else {
try self.addImm64(result);
try self.addTag(.i64_and);
}
}
} else if (int_info.bits > 64) {
return self.fail("TODO wasm: Integer wrapping for bitsizes larger than 64", .{});
}
// save the result in a temporary
const bin_local = try self.allocLocal(bin_ty);
try self.addLabel(.local_set, bin_local.local);
return bin_local;
}
fn emitConstant(self: *Self, val: Value, ty: Type) InnerError!void {
switch (ty.zigTypeTag()) {
.Int => {
const int_info = ty.intInfo(self.target);
// write constant
switch (int_info.signedness) {
.signed => switch (int_info.bits) {
0...32 => try self.addImm32(@intCast(i32, val.toSignedInt())),
33...64 => try self.addImm64(@bitCast(u64, val.toSignedInt())),
else => |bits| return self.fail("Wasm todo: emitConstant for integer with {d} bits", .{bits}),
},
.unsigned => switch (int_info.bits) {
0...32 => try self.addImm32(@bitCast(i32, @intCast(u32, val.toUnsignedInt()))),
33...64 => try self.addImm64(val.toUnsignedInt()),
else => |bits| return self.fail("Wasm TODO: emitConstant for integer with {d} bits", .{bits}),
},
}
},
.Bool => try self.addImm32(@intCast(i32, val.toSignedInt())),
.Float => {
// write constant
switch (ty.floatBits(self.target)) {
0...32 => try self.addInst(.{ .tag = .f32_const, .data = .{ .float32 = val.toFloat(f32) } }),
64 => try self.addFloat64(val.toFloat(f64)),
else => |bits| return self.fail("Wasm TODO: emitConstant for float with {d} bits", .{bits}),
}
},
.Pointer => {
if (val.castTag(.decl_ref)) |payload| {
const decl = payload.data;
decl.alive = true;
// offset into the offset table within the 'data' section
const ptr_width = self.target.cpu.arch.ptrBitWidth() / 8;
try self.addImm32(@bitCast(i32, decl.link.wasm.offset_index * ptr_width));
// memory instruction followed by their memarg immediate
// memarg ::== x:u32, y:u32 => {align x, offset y}
const extra_index = try self.addExtra(Mir.MemArg{ .offset = 0, .alignment = 4 });
try self.addInst(.{ .tag = .i32_load, .data = .{ .payload = extra_index } });
} else return self.fail("Wasm TODO: emitConstant for other const pointer tag {s}", .{val.tag()});
},
.Void => {},
.Enum => {
if (val.castTag(.enum_field_index)) |field_index| {
switch (ty.tag()) {
.enum_simple => try self.addImm32(@bitCast(i32, field_index.data)),
.enum_full, .enum_nonexhaustive => {
const enum_full = ty.cast(Type.Payload.EnumFull).?.data;
if (enum_full.values.count() != 0) {
const tag_val = enum_full.values.keys()[field_index.data];
try self.emitConstant(tag_val, enum_full.tag_ty);
} else {
try self.addImm32(@bitCast(i32, field_index.data));
}
},
else => unreachable,
}
} else {
var int_tag_buffer: Type.Payload.Bits = undefined;
const int_tag_ty = ty.intTagType(&int_tag_buffer);
try self.emitConstant(val, int_tag_ty);
}
},
.ErrorSet => {
const error_index = self.global_error_set.get(val.getError().?).?;
try self.addImm32(@bitCast(i32, error_index));
},
.ErrorUnion => {
const error_type = ty.errorUnionSet();
const payload_type = ty.errorUnionPayload();
if (val.castTag(.eu_payload)) |pl| {
const payload_val = pl.data;
// no error, so write a '0' const
try self.addImm32(0);
// after the error code, we emit the payload
try self.emitConstant(payload_val, payload_type);
} else {
// write the error val
try self.emitConstant(val, error_type);
// no payload, so write a '0' const
try self.addImm32(0);
}
},
.Optional => {
var buf: Type.Payload.ElemType = undefined;
const payload_type = ty.optionalChild(&buf);
if (ty.isPtrLikeOptional()) {
return self.fail("Wasm TODO: emitConstant for optional pointer", .{});
}
// When constant has value 'null', set is_null local to '1'
// and payload to '0'
if (val.castTag(.opt_payload)) |pl| {
const payload_val = pl.data;
try self.addImm32(0);
try self.emitConstant(payload_val, payload_type);
} else {
// set null-tag
try self.addImm32(1);
// null-tag is set, so write a '0' const
try self.addImm32(0);
}
},
else => |zig_type| return self.fail("Wasm TODO: emitConstant for zigTypeTag {s}", .{zig_type}),
}
}
/// Returns a `Value` as a signed 32 bit value.
/// It's illegal to provide a value with a type that cannot be represented
/// as an integer value.
fn valueAsI32(self: Self, val: Value, ty: Type) i32 {
switch (ty.zigTypeTag()) {
.Enum => {
if (val.castTag(.enum_field_index)) |field_index| {
switch (ty.tag()) {
.enum_simple => return @bitCast(i32, field_index.data),
.enum_full, .enum_nonexhaustive => {
const enum_full = ty.cast(Type.Payload.EnumFull).?.data;
if (enum_full.values.count() != 0) {
const tag_val = enum_full.values.keys()[field_index.data];
return self.valueAsI32(tag_val, enum_full.tag_ty);
} else return @bitCast(i32, field_index.data);
},
else => unreachable,
}
} else {
var int_tag_buffer: Type.Payload.Bits = undefined;
const int_tag_ty = ty.intTagType(&int_tag_buffer);
return self.valueAsI32(val, int_tag_ty);
}
},
.Int => switch (ty.intInfo(self.target).signedness) {
.signed => return @truncate(i32, val.toSignedInt()),
.unsigned => return @bitCast(i32, @truncate(u32, val.toUnsignedInt())),
},
.ErrorSet => {
const error_index = self.global_error_set.get(val.getError().?).?;
return @bitCast(i32, error_index);
},
else => unreachable, // Programmer called this function for an illegal type
}
}
fn airBlock(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const ty_pl = self.air.instructions.items(.data)[inst].ty_pl;
const block_ty = try self.genBlockType(self.air.getRefType(ty_pl.ty));
const extra = self.air.extraData(Air.Block, ty_pl.payload);
const body = self.air.extra[extra.end..][0..extra.data.body_len];
try self.startBlock(.block, block_ty, null);
// Here we set the current block idx, so breaks know the depth to jump
// to when breaking out.
try self.blocks.putNoClobber(self.gpa, inst, self.block_depth);
try self.genBody(body);
try self.endBlock();
return .none;
}
/// appends a new wasm block to the code section and increases the `block_depth` by 1
fn startBlock(self: *Self, block_tag: wasm.Opcode, valtype: u8, with_offset: ?usize) !void {
self.block_depth += 1;
const offset = with_offset orelse self.mir_instructions.len;
try self.addInstAt(offset, .{
.tag = Mir.Inst.Tag.fromOpcode(block_tag),
.data = .{ .block_type = valtype },
});
}
/// Ends the current wasm block and decreases the `block_depth` by 1
fn endBlock(self: *Self) !void {
try self.addTag(.end);
self.block_depth -= 1;
}
fn airLoop(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const ty_pl = self.air.instructions.items(.data)[inst].ty_pl;
const loop = self.air.extraData(Air.Block, ty_pl.payload);
const body = self.air.extra[loop.end..][0..loop.data.body_len];
// result type of loop is always 'noreturn', meaning we can always
// emit the wasm type 'block_empty'.
try self.startBlock(.loop, wasm.block_empty, null);
try self.genBody(body);
// breaking to the index of a loop block will continue the loop instead
try self.addLabel(.br, 0);
try self.endBlock();
return .none;
}
fn airCondBr(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const pl_op = self.air.instructions.items(.data)[inst].pl_op;
const condition = self.resolveInst(pl_op.operand);
const extra = self.air.extraData(Air.CondBr, pl_op.payload);
const then_body = self.air.extra[extra.end..][0..extra.data.then_body_len];
const else_body = self.air.extra[extra.end + then_body.len ..][0..extra.data.else_body_len];
// TODO: Handle death instructions for then and else body
// insert blocks at the position of `offset` so
// the condition can jump to it
const offset = self.mir_instructions.len;
try self.emitWValue(condition);
// result type is always noreturn, so use `block_empty` as type.
try self.startBlock(.block, wasm.block_empty, offset);
// we inserted the block in front of the condition
// so now check if condition matches. If not, break outside this block
// and continue with the then codepath
try self.addLabel(.br_if, 0);
try self.genBody(else_body);
try self.endBlock();
// Outer block that matches the condition
try self.genBody(then_body);
return .none;
}
fn airCmp(self: *Self, inst: Air.Inst.Index, op: std.math.CompareOperator) InnerError!WValue {
const data: Air.Inst.Data = self.air.instructions.items(.data)[inst];
const lhs = self.resolveInst(data.bin_op.lhs);
const rhs = self.resolveInst(data.bin_op.rhs);
const lhs_ty = self.air.typeOf(data.bin_op.lhs);
try self.emitWValue(lhs);
try self.emitWValue(rhs);
const signedness: std.builtin.Signedness = blk: {
// by default we tell the operand type is unsigned (i.e. bools and enum values)
if (lhs_ty.zigTypeTag() != .Int) break :blk .unsigned;
// incase of an actual integer, we emit the correct signedness
break :blk lhs_ty.intInfo(self.target).signedness;
};
const opcode: wasm.Opcode = buildOpcode(.{
.valtype1 = try self.typeToValtype(lhs_ty),
.op = switch (op) {
.lt => .lt,
.lte => .le,
.eq => .eq,
.neq => .ne,
.gte => .ge,
.gt => .gt,
},
.signedness = signedness,
});
try self.addTag(Mir.Inst.Tag.fromOpcode(opcode));
const cmp_tmp = try self.allocLocal(lhs_ty);
try self.addLabel(.local_set, cmp_tmp.local);
return cmp_tmp;
}
fn airBr(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const br = self.air.instructions.items(.data)[inst].br;
// if operand has codegen bits we should break with a value
if (self.air.typeOf(br.operand).hasCodeGenBits()) {
try self.emitWValue(self.resolveInst(br.operand));
}
// We map every block to its block index.
// We then determine how far we have to jump to it by subtracting it from current block depth
const idx: u32 = self.block_depth - self.blocks.get(br.block_inst).?;
try self.addLabel(.br, idx);
return .none;
}
fn airNot(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const ty_op = self.air.instructions.items(.data)[inst].ty_op;
const operand = self.resolveInst(ty_op.operand);
try self.emitWValue(operand);
// wasm does not have booleans nor the `not` instruction, therefore compare with 0
// to create the same logic
try self.addImm32(0);
try self.addTag(.i32_eq);
// save the result in the local
const not_tmp = try self.allocLocal(self.air.getRefType(ty_op.ty));
try self.addLabel(.local_set, not_tmp.local);
return not_tmp;
}
fn airBreakpoint(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
_ = self;
_ = inst;
// unsupported by wasm itself. Can be implemented once we support DWARF
// for wasm
return .none;
}
fn airUnreachable(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
_ = inst;
try self.addTag(.@"unreachable");
return .none;
}
fn airBitcast(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const ty_op = self.air.instructions.items(.data)[inst].ty_op;
return self.resolveInst(ty_op.operand);
}
fn airStructFieldPtr(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const ty_pl = self.air.instructions.items(.data)[inst].ty_pl;
const extra = self.air.extraData(Air.StructField, ty_pl.payload);
const struct_ptr = self.resolveInst(extra.data.struct_operand);
const struct_ty = self.air.typeOf(extra.data.struct_operand).childType();
const offset = std.math.cast(u32, struct_ty.structFieldOffset(extra.data.field_index, self.target)) catch {
return self.fail("Field type '{}' too big to fit into stack frame", .{
struct_ty.structFieldType(extra.data.field_index),
});
};
return structFieldPtr(struct_ptr, offset);
}
fn airStructFieldPtrIndex(self: *Self, inst: Air.Inst.Index, index: u32) InnerError!WValue {
const ty_op = self.air.instructions.items(.data)[inst].ty_op;
const struct_ptr = self.resolveInst(ty_op.operand);
const struct_ty = self.air.typeOf(ty_op.operand).childType();
const offset = std.math.cast(u32, struct_ty.structFieldOffset(index, self.target)) catch {
return self.fail("Field type '{}' too big to fit into stack frame", .{
struct_ty.structFieldType(index),
});
};
return structFieldPtr(struct_ptr, offset);
}
fn structFieldPtr(struct_ptr: WValue, offset: u32) InnerError!WValue {
return WValue{ .local_with_offset = .{ .local = struct_ptr.local, .offset = offset } };
}
fn airStructFieldVal(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
if (self.liveness.isUnused(inst)) return WValue.none;
const ty_pl = self.air.instructions.items(.data)[inst].ty_pl;
const struct_field = self.air.extraData(Air.StructField, ty_pl.payload).data;
const struct_ty = self.air.typeOf(struct_field.struct_operand);
const operand = self.resolveInst(struct_field.struct_operand);
const field_index = struct_field.field_index;
const field_ty = struct_ty.structFieldType(field_index);
if (!field_ty.hasCodeGenBits()) return WValue.none;
const offset = std.math.cast(u32, struct_ty.structFieldOffset(field_index, self.target)) catch {
return self.fail("Field type '{}' too big to fit into stack frame", .{field_ty});
};
return try self.load(operand, field_ty, offset);
}
fn airSwitchBr(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
// result type is always 'noreturn'
const blocktype = wasm.block_empty;
const pl_op = self.air.instructions.items(.data)[inst].pl_op;
const target = self.resolveInst(pl_op.operand);
const target_ty = self.air.typeOf(pl_op.operand);
const switch_br = self.air.extraData(Air.SwitchBr, pl_op.payload);
var extra_index: usize = switch_br.end;
var case_i: u32 = 0;
// a list that maps each value with its value and body based on the order inside the list.
const CaseValue = struct { integer: i32, value: Value };
var case_list = try std.ArrayList(struct {
values: []const CaseValue,
body: []const Air.Inst.Index,
}).initCapacity(self.gpa, switch_br.data.cases_len);
defer for (case_list.items) |case| {
self.gpa.free(case.values);
} else case_list.deinit();
var lowest: i32 = 0;
var highest: i32 = 0;
while (case_i < switch_br.data.cases_len) : (case_i += 1) {
const case = self.air.extraData(Air.SwitchBr.Case, extra_index);
const items = @bitCast([]const Air.Inst.Ref, self.air.extra[case.end..][0..case.data.items_len]);
const case_body = self.air.extra[case.end + items.len ..][0..case.data.body_len];
extra_index = case.end + items.len + case_body.len;
const values = try self.gpa.alloc(CaseValue, items.len);
errdefer self.gpa.free(values);
for (items) |ref, i| {
const item_val = self.air.value(ref).?;
const int_val = self.valueAsI32(item_val, target_ty);
if (int_val < lowest) {
lowest = int_val;
}
if (int_val > highest) {
highest = int_val;
}
values[i] = .{ .integer = int_val, .value = item_val };
}
case_list.appendAssumeCapacity(.{ .values = values, .body = case_body });
try self.startBlock(.block, blocktype, null);
}
// When the highest and lowest values are seperated by '50',
// we define it as sparse and use an if/else-chain, rather than a jump table.
// When the target is an integer size larger than u32, we have no way to use the value
// as an index, therefore we also use an if/else-chain for those cases.
// TODO: Benchmark this to find a proper value, LLVM seems to draw the line at '40~45'.
const is_sparse = highest - lowest > 50 or target_ty.bitSize(self.target) > 32;
const else_body = self.air.extra[extra_index..][0..switch_br.data.else_body_len];
const has_else_body = else_body.len != 0;
if (has_else_body) {
try self.startBlock(.block, blocktype, null);
}
if (!is_sparse) {
// Generate the jump table 'br_table' when the prongs are not sparse.
// The value 'target' represents the index into the table.
// Each index in the table represents a label to the branch
// to jump to.
try self.startBlock(.block, blocktype, null);
try self.emitWValue(target);
if (lowest < 0) {
// since br_table works using indexes, starting from '0', we must ensure all values
// we put inside, are atleast 0.
try self.addImm32(lowest * -1);
try self.addTag(.i32_add);
}
// Account for default branch so always add '1'
const depth = @intCast(u32, highest - lowest + @boolToInt(has_else_body)) + 1;
const jump_table: Mir.JumpTable = .{ .length = depth };
const table_extra_index = try self.addExtra(jump_table);
try self.addInst(.{ .tag = .br_table, .data = .{ .payload = table_extra_index } });
try self.mir_extra.ensureUnusedCapacity(self.gpa, depth);
while (lowest <= highest) : (lowest += 1) {
// idx represents the branch we jump to
const idx = blk: {
for (case_list.items) |case, idx| {
for (case.values) |case_value| {
if (case_value.integer == lowest) break :blk @intCast(u32, idx);
}
}
break :blk if (has_else_body) case_i else unreachable;
};
self.mir_extra.appendAssumeCapacity(idx);
} else if (has_else_body) {
self.mir_extra.appendAssumeCapacity(case_i); // default branch
}
try self.endBlock();
}
const signedness: std.builtin.Signedness = blk: {
// by default we tell the operand type is unsigned (i.e. bools and enum values)
if (target_ty.zigTypeTag() != .Int) break :blk .unsigned;
// incase of an actual integer, we emit the correct signedness
break :blk target_ty.intInfo(self.target).signedness;
};
for (case_list.items) |case| {
// when sparse, we use if/else-chain, so emit conditional checks
if (is_sparse) {
// for single value prong we can emit a simple if
if (case.values.len == 1) {
try self.emitWValue(target);
try self.emitConstant(case.values[0].value, target_ty);
const opcode = buildOpcode(.{
.valtype1 = try self.typeToValtype(target_ty),
.op = .ne, // not equal, because we want to jump out of this block if it does not match the condition.
.signedness = signedness,
});
try self.addTag(Mir.Inst.Tag.fromOpcode(opcode));
try self.addLabel(.br_if, 0);
} else {
// in multi-value prongs we must check if any prongs match the target value.
try self.startBlock(.block, blocktype, null);
for (case.values) |value| {
try self.emitWValue(target);
try self.emitConstant(value.value, target_ty);
const opcode = buildOpcode(.{
.valtype1 = try self.typeToValtype(target_ty),
.op = .eq,
.signedness = signedness,
});
try self.addTag(Mir.Inst.Tag.fromOpcode(opcode));
try self.addLabel(.br_if, 0);
}
// value did not match any of the prong values
try self.addLabel(.br, 1);
try self.endBlock();
}
}
try self.genBody(case.body);
try self.endBlock();
}
if (has_else_body) {
try self.genBody(else_body);
try self.endBlock();
}
return .none;
}
fn airIsErr(self: *Self, inst: Air.Inst.Index, opcode: wasm.Opcode) InnerError!WValue {
const un_op = self.air.instructions.items(.data)[inst].un_op;
const operand = self.resolveInst(un_op);
const err_ty = self.air.typeOf(un_op).errorUnionSet();
// load the error tag value
try self.emitWValue(operand);
const mem_arg_index = try self.addExtra(Mir.MemArg{
.offset = 0,
.alignment = err_ty.abiAlignment(self.target),
});
try self.addInst(.{
.tag = .i32_load,
.data = .{ .payload = mem_arg_index },
});
// Compare the error value with '0'
try self.addImm32(0);
try self.addTag(Mir.Inst.Tag.fromOpcode(opcode));
const is_err_tmp = try self.allocLocal(err_ty);
try self.addLabel(.local_set, is_err_tmp.local);
return is_err_tmp;
}
fn airUnwrapErrUnionPayload(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const ty_op = self.air.instructions.items(.data)[inst].ty_op;
const operand = self.resolveInst(ty_op.operand);
const err_ty = self.air.typeOf(ty_op.operand);
const offset = @intCast(u32, err_ty.errorUnionSet().abiSize(self.target) / 8);
return self.load(operand, self.air.getRefType(ty_op.ty), offset);
}
fn airWrapErrUnionPayload(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const ty_op = self.air.instructions.items(.data)[inst].ty_op;
return self.resolveInst(ty_op.operand);
}
fn airIntcast(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const ty_op = self.air.instructions.items(.data)[inst].ty_op;
const ty = self.air.getRefType(ty_op.ty);
const operand = self.resolveInst(ty_op.operand);
const ref_ty = self.air.typeOf(ty_op.operand);
const ref_info = ref_ty.intInfo(self.target);
const op_bits = ref_info.bits;
const wanted_bits = ty.intInfo(self.target).bits;
try self.emitWValue(operand);
if (op_bits > 32 and wanted_bits <= 32) {
try self.addTag(.i32_wrap_i64);
} else if (op_bits <= 32 and wanted_bits > 32) {
try self.addTag(switch (ref_info.signedness) {
.signed => .i64_extend_i32_s,
.unsigned => .i64_extend_i32_u,
});
}
// other cases are no-op
return .none;
}
fn airIsNull(self: *Self, inst: Air.Inst.Index, opcode: wasm.Opcode) InnerError!WValue {
const un_op = self.air.instructions.items(.data)[inst].un_op;
const operand = self.resolveInst(un_op);
// load the null tag value
try self.emitWValue(operand);
const mem_arg_index = try self.addExtra(Mir.MemArg{ .offset = 0, .alignment = 1 });
try self.addInst(.{
.tag = .i32_load8_u,
.data = .{ .payload = mem_arg_index },
});
// Compare the error value with '0'
try self.addImm32(0);
try self.addTag(Mir.Inst.Tag.fromOpcode(opcode));
const is_null_tmp = try self.allocLocal(Type.initTag(.u8));
try self.addLabel(.local_set, is_null_tmp.local);
return is_null_tmp;
}
fn airOptionalPayload(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const ty_op = self.air.instructions.items(.data)[inst].ty_op;
const operand = self.resolveInst(ty_op.operand);
const opt_ty = self.air.typeOf(ty_op.operand);
// For pointers we simply return its stack address, rather than
// loading its value
if (opt_ty.zigTypeTag() == .Pointer) {
return WValue{ .local_with_offset = .{ .local = operand.local, .offset = 1 } };
}
if (opt_ty.isPtrLikeOptional()) return operand;
var buf: Type.Payload.ElemType = undefined;
const child_ty = opt_ty.optionalChild(&buf);
return self.load(operand, child_ty, @as(u32, 1)); // null tag is 1 byte
}
fn airOptionalPayloadPtrSet(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const ty_op = self.air.instructions.items(.data)[inst].ty_op;
const operand = self.resolveInst(ty_op.operand);
_ = operand;
return self.fail("TODO - wasm codegen for optional_payload_ptr_set", .{});
}
fn airWrapOptional(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const ty_op = self.air.instructions.items(.data)[inst].ty_op;
return self.resolveInst(ty_op.operand);
}