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https://codeberg.org/ziglang/zig.git
synced 2025-12-07 06:14:33 +00:00
3370b5f109
Thus far, we only generate the type, function, export, and code sections. These are sufficient to generate and export simple functions. Codegen is currently hardcoded to `i32.const 42`, the main goal of this commit is to create infrastructure for the container format which will work with incremental compilation.
70 lines
2.1 KiB
Zig
70 lines
2.1 KiB
Zig
const std = @import("std");
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const Allocator = std.mem.Allocator;
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const ArrayList = std.ArrayList;
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const assert = std.debug.assert;
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const leb = std.debug.leb;
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const Decl = @import("../Module.zig").Decl;
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const Type = @import("../type.zig").Type;
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fn genValtype(ty: Type) u8 {
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return switch (ty.tag()) {
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.u32, .i32 => 0x7F,
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.u64, .i64 => 0x7E,
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.f32 => 0x7D,
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.f64 => 0x7C,
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else => @panic("TODO: Implement more types for wasm."),
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};
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}
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pub fn genFunctype(buf: *ArrayList(u8), decl: *Decl) !void {
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const ty = decl.typed_value.most_recent.typed_value.ty;
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const writer = buf.writer();
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// functype magic
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try writer.writeByte(0x60);
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// param types
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try leb.writeULEB128(writer, @intCast(u32, ty.fnParamLen()));
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if (ty.fnParamLen() != 0) {
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const params = try buf.allocator.alloc(Type, ty.fnParamLen());
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defer buf.allocator.free(params);
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ty.fnParamTypes(params);
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for (params) |param_type| try writer.writeByte(genValtype(param_type));
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}
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// return type
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const return_type = ty.fnReturnType();
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switch (return_type.tag()) {
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.void, .noreturn => try leb.writeULEB128(writer, @as(u32, 0)),
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else => {
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try leb.writeULEB128(writer, @as(u32, 1));
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try writer.writeByte(genValtype(return_type));
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},
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}
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}
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pub fn genCode(buf: *ArrayList(u8), decl: *Decl) !void {
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assert(buf.items.len == 0);
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const writer = buf.writer();
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// Reserve space to write the size after generating the code
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try writer.writeAll(&([1]u8{undefined} ** 5));
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// Write the size of the locals vec
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// TODO: implement locals
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try leb.writeULEB128(writer, @as(u32, 0));
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// Write instructions
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// TODO: actually implement codegen
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try writer.writeByte(0x41); // i32.const
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try leb.writeILEB128(writer, @as(i32, 42));
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// Write 'end' opcode
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try writer.writeByte(0x0B);
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// Fill in the size of the generated code to the reserved space at the
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// beginning of the buffer.
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leb.writeUnsignedFixed(5, buf.items[0..5], @intCast(u32, buf.items.len - 5));
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}
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