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-rw-r--r--src/link/Wasm.zig340
1 files changed, 278 insertions, 62 deletions
diff --git a/src/link/Wasm.zig b/src/link/Wasm.zig
index 523d4c8a64..2dd15db1d4 100644
--- a/src/link/Wasm.zig
+++ b/src/link/Wasm.zig
@@ -16,21 +16,11 @@ const link = @import("../link.zig");
const trace = @import("../tracy.zig").trace;
const build_options = @import("build_options");
const Cache = @import("../Cache.zig");
+const TypedValue = @import("../TypedValue.zig");
pub const base_tag = link.File.Tag.wasm;
-pub const FnData = struct {
- /// Generated code for the type of the function
- functype: std.ArrayListUnmanaged(u8) = .{},
- /// Generated code for the body of the function
- code: std.ArrayListUnmanaged(u8) = .{},
- /// Locations in the generated code where function indexes must be filled in.
- /// This must be kept ordered by offset.
- idx_refs: std.ArrayListUnmanaged(struct { offset: u32, decl: *Module.Decl }) = .{},
-};
-
base: link.File,
-
/// List of all function Decls to be written to the output file. The index of
/// each Decl in this list at the time of writing the binary is used as the
/// function index. In the event where ext_funcs' size is not 0, the index of
@@ -45,6 +35,77 @@ ext_funcs: std.ArrayListUnmanaged(*Module.Decl) = .{},
/// to support existing code.
/// TODO: Allow setting this through a flag?
host_name: []const u8 = "env",
+/// The last `DeclBlock` that was initialized will be saved here.
+last_block: ?*DeclBlock = null,
+/// Table with offsets, each element represents an offset with the value being
+/// the offset into the 'data' section where the data lives
+offset_table: std.ArrayListUnmanaged(u32) = .{},
+/// List of offset indexes which are free to be used for new decl's.
+/// Each element's value points to an index into the offset_table.
+offset_table_free_list: std.ArrayListUnmanaged(u32) = .{},
+/// List of all `Decl` that are currently alive.
+/// This is ment for bookkeeping so we can safely cleanup all codegen memory
+/// when calling `deinit`
+symbols: std.ArrayListUnmanaged(*Module.Decl) = .{},
+
+pub const FnData = struct {
+ /// Generated code for the type of the function
+ functype: std.ArrayListUnmanaged(u8),
+ /// Generated code for the body of the function
+ code: std.ArrayListUnmanaged(u8),
+ /// Locations in the generated code where function indexes must be filled in.
+ /// This must be kept ordered by offset.
+ idx_refs: std.ArrayListUnmanaged(struct { offset: u32, decl: *Module.Decl }),
+
+ pub const empty: FnData = .{
+ .functype = .{},
+ .code = .{},
+ .idx_refs = .{},
+ };
+};
+
+pub const DeclBlock = struct {
+ /// Determines whether the `DeclBlock` has been initialized for codegen.
+ init: bool,
+ /// Index into the `symbols` list.
+ symbol_index: u32,
+ /// Index into the offset table
+ offset_index: u32,
+ /// The size of the block and how large part of the data section it occupies.
+ /// Will be 0 when the Decl will not live inside the data section and `data` will be undefined.
+ size: u32,
+ /// Points to the previous and next blocks.
+ /// Can be used to find the total size, and used to calculate the `offset` based on the previous block.
+ prev: ?*DeclBlock,
+ next: ?*DeclBlock,
+ /// Pointer to data that will be written to the 'data' section.
+ /// This data either lives in `FnData.code` or is externally managed.
+ /// For data that does not live inside the 'data' section, this field will be undefined. (size == 0).
+ data: [*]const u8,
+
+ pub const empty: DeclBlock = .{
+ .init = false,
+ .symbol_index = 0,
+ .offset_index = 0,
+ .size = 0,
+ .prev = null,
+ .next = null,
+ .data = undefined,
+ };
+
+ /// Unplugs the `DeclBlock` from the chain
+ fn unplug(self: *DeclBlock) void {
+ if (self.prev) |prev| {
+ prev.next = self.next;
+ }
+
+ if (self.next) |next| {
+ next.prev = self.prev;
+ }
+ self.next = null;
+ self.prev = null;
+ }
+};
pub fn openPath(allocator: *Allocator, sub_path: []const u8, options: link.Options) !*Wasm {
assert(options.object_format == .wasm);
@@ -52,7 +113,7 @@ pub fn openPath(allocator: *Allocator, sub_path: []const u8, options: link.Optio
if (options.use_llvm) return error.LLVM_BackendIsTODO_ForWasm; // TODO
if (options.use_lld) return error.LLD_LinkingIsTODO_ForWasm; // TODO
- // TODO: read the file and keep vaild parts instead of truncating
+ // TODO: read the file and keep valid parts instead of truncating
const file = try options.emit.?.directory.handle.createFile(sub_path, .{ .truncate = true, .read = true });
errdefer file.close();
@@ -80,50 +141,67 @@ pub fn createEmpty(gpa: *Allocator, options: link.Options) !*Wasm {
}
pub fn deinit(self: *Wasm) void {
- for (self.funcs.items) |decl| {
- decl.fn_link.wasm.?.functype.deinit(self.base.allocator);
- decl.fn_link.wasm.?.code.deinit(self.base.allocator);
- decl.fn_link.wasm.?.idx_refs.deinit(self.base.allocator);
- }
- for (self.ext_funcs.items) |decl| {
- decl.fn_link.wasm.?.functype.deinit(self.base.allocator);
- decl.fn_link.wasm.?.code.deinit(self.base.allocator);
- decl.fn_link.wasm.?.idx_refs.deinit(self.base.allocator);
+ for (self.symbols.items) |decl| {
+ decl.fn_link.wasm.functype.deinit(self.base.allocator);
+ decl.fn_link.wasm.code.deinit(self.base.allocator);
+ decl.fn_link.wasm.idx_refs.deinit(self.base.allocator);
}
+
self.funcs.deinit(self.base.allocator);
self.ext_funcs.deinit(self.base.allocator);
+ self.offset_table.deinit(self.base.allocator);
+ self.offset_table_free_list.deinit(self.base.allocator);
+ self.symbols.deinit(self.base.allocator);
}
-// Generate code for the Decl, storing it in memory to be later written to
-// the file on flush().
-pub fn updateDecl(self: *Wasm, module: *Module, decl: *Module.Decl) !void {
- const typed_value = decl.typed_value.most_recent.typed_value;
- if (typed_value.ty.zigTypeTag() != .Fn)
- return error.TODOImplementNonFnDeclsForWasm;
+pub fn allocateDeclIndexes(self: *Wasm, decl: *Module.Decl) !void {
+ if (decl.link.wasm.init) return;
+
+ try self.offset_table.ensureCapacity(self.base.allocator, self.offset_table.items.len + 1);
+ try self.symbols.ensureCapacity(self.base.allocator, self.symbols.items.len + 1);
- if (decl.fn_link.wasm) |*fn_data| {
- fn_data.functype.items.len = 0;
- fn_data.code.items.len = 0;
- fn_data.idx_refs.items.len = 0;
+ const block = &decl.link.wasm;
+ block.init = true;
+
+ block.symbol_index = @intCast(u32, self.symbols.items.len);
+ self.symbols.appendAssumeCapacity(decl);
+
+ if (self.offset_table_free_list.popOrNull()) |index| {
+ block.offset_index = index;
} else {
- decl.fn_link.wasm = .{};
- // dependent on function type, appends it to the correct list
- switch (decl.typed_value.most_recent.typed_value.val.tag()) {
+ block.offset_index = @intCast(u32, self.offset_table.items.len);
+ _ = self.offset_table.addOneAssumeCapacity();
+ }
+
+ self.offset_table.items[block.offset_index] = 0;
+
+ const typed_value = decl.typed_value.most_recent.typed_value;
+ if (typed_value.ty.zigTypeTag() == .Fn) {
+ switch (typed_value.val.tag()) {
+ // dependent on function type, appends it to the correct list
.function => try self.funcs.append(self.base.allocator, decl),
.extern_fn => try self.ext_funcs.append(self.base.allocator, decl),
- else => return error.TODOImplementNonFnDeclsForWasm,
+ else => unreachable,
}
}
- const fn_data = &decl.fn_link.wasm.?;
+}
- var managed_functype = fn_data.functype.toManaged(self.base.allocator);
- var managed_code = fn_data.code.toManaged(self.base.allocator);
+// Generate code for the Decl, storing it in memory to be later written to
+// the file on flush().
+pub fn updateDecl(self: *Wasm, module: *Module, decl: *Module.Decl) !void {
+ std.debug.assert(decl.link.wasm.init); // Must call allocateDeclIndexes()
+
+ const typed_value = decl.typed_value.most_recent.typed_value;
+ const fn_data = &decl.fn_link.wasm;
+ fn_data.functype.items.len = 0;
+ fn_data.code.items.len = 0;
+ fn_data.idx_refs.items.len = 0;
var context = codegen.Context{
.gpa = self.base.allocator,
.values = .{},
- .code = managed_code,
- .func_type_data = managed_functype,
+ .code = fn_data.code.toManaged(self.base.allocator),
+ .func_type_data = fn_data.functype.toManaged(self.base.allocator),
.decl = decl,
.err_msg = undefined,
.locals = .{},
@@ -132,7 +210,7 @@ pub fn updateDecl(self: *Wasm, module: *Module, decl: *Module.Decl) !void {
defer context.deinit();
// generate the 'code' section for the function declaration
- context.gen() catch |err| switch (err) {
+ const result = context.gen(typed_value) catch |err| switch (err) {
error.CodegenFail => {
decl.analysis = .codegen_failure;
try module.failed_decls.put(module.gpa, decl, context.err_msg);
@@ -141,15 +219,38 @@ pub fn updateDecl(self: *Wasm, module: *Module, decl: *Module.Decl) !void {
else => |e| return err,
};
- // as locals are patched afterwards, the offsets of funcidx's are off,
- // here we update them to correct them
- for (decl.fn_link.wasm.?.idx_refs.items) |*func| {
- // For each local, add 6 bytes (count + type)
- func.offset += @intCast(u32, context.locals.items.len * 6);
- }
+ const code: []const u8 = switch (result) {
+ .appended => @as([]const u8, context.code.items),
+ .externally_managed => |payload| payload,
+ };
- fn_data.functype = context.func_type_data.toUnmanaged();
fn_data.code = context.code.toUnmanaged();
+ fn_data.functype = context.func_type_data.toUnmanaged();
+
+ const block = &decl.link.wasm;
+ if (typed_value.ty.zigTypeTag() == .Fn) {
+ // as locals are patched afterwards, the offsets of funcidx's are off,
+ // here we update them to correct them
+ for (fn_data.idx_refs.items) |*func| {
+ // For each local, add 6 bytes (count + type)
+ func.offset += @intCast(u32, context.locals.items.len * 6);
+ }
+ } else {
+ block.size = @intCast(u32, code.len);
+ block.data = code.ptr;
+ }
+
+ // If we're updating an existing decl, unplug it first
+ // to avoid infinite loops due to earlier links
+ block.unplug();
+
+ if (self.last_block) |last| {
+ if (last != block) {
+ last.next = block;
+ block.prev = last;
+ }
+ }
+ self.last_block = block;
}
pub fn updateDeclExports(
@@ -160,18 +261,34 @@ pub fn updateDeclExports(
) !void {}
pub fn freeDecl(self: *Wasm, decl: *Module.Decl) void {
- // TODO: remove this assert when non-function Decls are implemented
- assert(decl.typed_value.most_recent.typed_value.ty.zigTypeTag() == .Fn);
- const func_idx = self.getFuncidx(decl).?;
- switch (decl.typed_value.most_recent.typed_value.val.tag()) {
- .function => _ = self.funcs.swapRemove(func_idx),
- .extern_fn => _ = self.ext_funcs.swapRemove(func_idx),
- else => unreachable,
+ if (self.getFuncidx(decl)) |func_idx| {
+ switch (decl.typed_value.most_recent.typed_value.val.tag()) {
+ .function => _ = self.funcs.swapRemove(func_idx),
+ .extern_fn => _ = self.ext_funcs.swapRemove(func_idx),
+ else => unreachable,
+ }
+ }
+ const block = &decl.link.wasm;
+
+ if (self.last_block == block) {
+ self.last_block = block.prev;
}
- decl.fn_link.wasm.?.functype.deinit(self.base.allocator);
- decl.fn_link.wasm.?.code.deinit(self.base.allocator);
- decl.fn_link.wasm.?.idx_refs.deinit(self.base.allocator);
- decl.fn_link.wasm = null;
+
+ block.unplug();
+
+ self.offset_table_free_list.append(self.base.allocator, decl.link.wasm.offset_index) catch {};
+ _ = self.symbols.swapRemove(block.symbol_index);
+
+ // update symbol_index as we swap removed the last symbol into the removed's position
+ if (block.symbol_index < self.symbols.items.len)
+ self.symbols.items[block.symbol_index].link.wasm.symbol_index = block.symbol_index;
+
+ block.init = false;
+
+ decl.fn_link.wasm.functype.deinit(self.base.allocator);
+ decl.fn_link.wasm.code.deinit(self.base.allocator);
+ decl.fn_link.wasm.idx_refs.deinit(self.base.allocator);
+ decl.fn_link.wasm = undefined;
}
pub fn flush(self: *Wasm, comp: *Compilation) !void {
@@ -188,6 +305,25 @@ pub fn flushModule(self: *Wasm, comp: *Compilation) !void {
const file = self.base.file.?;
const header_size = 5 + 1;
+ // ptr_width in bytes
+ const ptr_width = self.base.options.target.cpu.arch.ptrBitWidth() / 8;
+ // The size of the offset table in bytes
+ // The table contains all decl's with its corresponding offset into
+ // the 'data' section
+ const offset_table_size = @intCast(u32, self.offset_table.items.len * ptr_width);
+
+ // The size of the data, this together with `offset_table_size` amounts to the
+ // total size of the 'data' section
+ var first_decl: ?*DeclBlock = null;
+ const data_size: u32 = if (self.last_block) |last| blk: {
+ var size = last.size;
+ var cur = last;
+ while (cur.prev) |prev| : (cur = prev) {
+ size += prev.size;
+ }
+ first_decl = cur;
+ break :blk size;
+ } else 0;
// No need to rewrite the magic/version header
try file.setEndPos(@sizeOf(@TypeOf(wasm.magic ++ wasm.version)));
@@ -199,8 +335,8 @@ pub fn flushModule(self: *Wasm, comp: *Compilation) !void {
// extern functions are defined in the wasm binary first through the `import`
// section, so define their func types first
- for (self.ext_funcs.items) |decl| try file.writeAll(decl.fn_link.wasm.?.functype.items);
- for (self.funcs.items) |decl| try file.writeAll(decl.fn_link.wasm.?.functype.items);
+ for (self.ext_funcs.items) |decl| try file.writeAll(decl.fn_link.wasm.functype.items);
+ for (self.funcs.items) |decl| try file.writeAll(decl.fn_link.wasm.functype.items);
try writeVecSectionHeader(
file,
@@ -257,6 +393,31 @@ pub fn flushModule(self: *Wasm, comp: *Compilation) !void {
);
}
+ // Memory section
+ if (data_size != 0) {
+ const header_offset = try reserveVecSectionHeader(file);
+ const writer = file.writer();
+
+ try leb.writeULEB128(writer, @as(u32, 0));
+ // Calculate the amount of memory pages are required and write them.
+ // Wasm uses 64kB page sizes. Round up to ensure the data segments fit into the memory
+ try leb.writeULEB128(
+ writer,
+ try std.math.divCeil(
+ u32,
+ offset_table_size + data_size,
+ std.wasm.page_size,
+ ),
+ );
+ try writeVecSectionHeader(
+ file,
+ header_offset,
+ .memory,
+ @intCast(u32, (try file.getPos()) - header_offset - header_size),
+ @as(u32, 1), // wasm currently only supports 1 linear memory segment
+ );
+ }
+
// Export section
if (self.base.options.module) |module| {
const header_offset = try reserveVecSectionHeader(file);
@@ -281,6 +442,16 @@ pub fn flushModule(self: *Wasm, comp: *Compilation) !void {
count += 1;
}
}
+
+ // export memory if size is not 0
+ if (data_size != 0) {
+ try leb.writeULEB128(writer, @intCast(u32, "memory".len));
+ try writer.writeAll("memory");
+ try writer.writeByte(wasm.externalKind(.memory));
+ try leb.writeULEB128(writer, @as(u32, 0)); // only 1 memory 'object' can exist
+ count += 1;
+ }
+
try writeVecSectionHeader(
file,
header_offset,
@@ -295,7 +466,7 @@ pub fn flushModule(self: *Wasm, comp: *Compilation) !void {
const header_offset = try reserveVecSectionHeader(file);
const writer = file.writer();
for (self.funcs.items) |decl| {
- const fn_data = &decl.fn_link.wasm.?;
+ const fn_data = &decl.fn_link.wasm;
// Write the already generated code to the file, inserting
// function indexes where required.
@@ -320,6 +491,51 @@ pub fn flushModule(self: *Wasm, comp: *Compilation) !void {
@intCast(u32, self.funcs.items.len),
);
}
+
+ // Data section
+ if (data_size != 0) {
+ const header_offset = try reserveVecSectionHeader(file);
+ const writer = file.writer();
+ var len: u32 = 0;
+ // index to memory section (currently, there can only be 1 memory section in wasm)
+ try leb.writeULEB128(writer, @as(u32, 0));
+
+ // offset into data section
+ try writer.writeByte(wasm.opcode(.i32_const));
+ try leb.writeILEB128(writer, @as(i32, 0));
+ try writer.writeByte(wasm.opcode(.end));
+
+ const total_size = offset_table_size + data_size;
+
+ // offset table + data size
+ try leb.writeULEB128(writer, total_size);
+
+ // fill in the offset table and the data segments
+ const file_offset = try file.getPos();
+ var cur = first_decl;
+ var data_offset = offset_table_size;
+ while (cur) |cur_block| : (cur = cur_block.next) {
+ if (cur_block.size == 0) continue;
+ std.debug.assert(cur_block.init);
+
+ const offset = (cur_block.offset_index) * ptr_width;
+ var buf: [4]u8 = undefined;
+ std.mem.writeIntLittle(u32, &buf, data_offset);
+
+ try file.pwriteAll(&buf, file_offset + offset);
+ try file.pwriteAll(cur_block.data[0..cur_block.size], file_offset + data_offset);
+ data_offset += cur_block.size;
+ }
+
+ try file.seekTo(file_offset + data_offset);
+ try writeVecSectionHeader(
+ file,
+ header_offset,
+ .data,
+ @intCast(u32, (file_offset + data_offset) - header_offset - header_size),
+ @intCast(u32, 1), // only 1 data section
+ );
+ }
}
fn linkWithLLD(self: *Wasm, comp: *Compilation) !void {
generated by cgit v1.2.3 (git 2.39.1) at 2025-12-27 22:46:53 +0000