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wasm linker: allow undefined imports when lib name is provided

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and expose object_host_name as an option for setting the lib name for
object files, since the wasm linking standards don't specify a way to do
it.
This commit is contained in:
Andrew Kelley
2024-12-18 20:05:01 -08:00
parent 23d0882b54
commit 070b973c4a
6 changed files with 49 additions and 26 deletions
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1
src/Compilation.zig
View File

@@ -1587,6 +1587,7 @@ pub fn create(gpa: Allocator, arena: Allocator, options: CreateOptions) !*Compil
.pdb_source_path = options.pdb_source_path,
.pdb_out_path = options.pdb_out_path,
.entry_addr = null, // CLI does not expose this option (yet?)
.object_host_name = null, // TODO expose in the CLI
};
switch (options.cache_mode) {

1
src/link.zig
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@@ -400,6 +400,7 @@ pub const File = struct {
export_table: bool,
initial_memory: ?u64,
max_memory: ?u64,
object_host_name: ?[]const u8,
export_symbol_names: []const []const u8,
global_base: ?u64,
build_id: std.zig.BuildId,

59
src/link/Wasm.zig
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@@ -150,10 +150,10 @@ nav_fixups: std.ArrayListUnmanaged(NavFixup) = .empty,
symbol_table: std.AutoArrayHashMapUnmanaged(String, void) = .empty,
/// When importing objects from the host environment, a name must be supplied.
/// LLVM uses "env" by default when none is given. This would be a good default for Zig
/// to support existing code.
/// TODO: Allow setting this through a flag?
host_name: String,
/// LLVM uses "env" by default when none is given.
/// This value is passed to object files since wasm tooling conventions provides
/// no way to specify the module name in the symbol table.
object_host_name: OptionalString,
/// Memory section
memories: std.wasm.Memory = .{ .limits = .{
@@ -737,7 +737,7 @@ const DebugSection = struct {};
pub const FunctionImport = extern struct {
flags: SymbolFlags,
module_name: String,
module_name: OptionalString,
source_location: SourceLocation,
resolution: Resolution,
type: FunctionType.Index,
@@ -862,7 +862,7 @@ pub const FunctionImport = extern struct {
return index.key(wasm).*;
}
pub fn moduleName(index: Index, wasm: *const Wasm) String {
pub fn moduleName(index: Index, wasm: *const Wasm) OptionalString {
return index.value(wasm).module_name;
}
@@ -888,7 +888,7 @@ pub const Function = extern struct {
pub const GlobalImport = extern struct {
flags: SymbolFlags,
module_name: String,
module_name: OptionalString,
source_location: SourceLocation,
resolution: Resolution,
@@ -1009,7 +1009,7 @@ pub const GlobalImport = extern struct {
return index.key(wasm).*;
}
pub fn moduleName(index: Index, wasm: *const Wasm) String {
pub fn moduleName(index: Index, wasm: *const Wasm) OptionalString {
return index.value(wasm).module_name;
}
@@ -1114,7 +1114,7 @@ pub const TableImport = extern struct {
return index.key(wasm).*;
}
pub fn moduleName(index: Index, wasm: *const Wasm) String {
pub fn moduleName(index: Index, wasm: *const Wasm) OptionalString {
return index.value(wasm).module_name;
}
};
@@ -1604,7 +1604,7 @@ pub const ZcuImportIndex = enum(u32) {
return wasm.getExistingString(name_slice).?;
}
pub fn moduleName(index: ZcuImportIndex, wasm: *const Wasm) String {
pub fn moduleName(index: ZcuImportIndex, wasm: *const Wasm) OptionalString {
const zcu = wasm.base.comp.zcu.?;
const ip = &zcu.intern_pool;
const nav_index = index.ptr(wasm).*;
@@ -1613,8 +1613,8 @@ pub const ZcuImportIndex = enum(u32) {
.@"extern" => |*ext| ext,
else => unreachable,
};
const lib_name = ext.lib_name.toSlice(ip) orelse return wasm.host_name;
return wasm.getExistingString(lib_name).?;
const lib_name = ext.lib_name.toSlice(ip) orelse return .none;
return wasm.getExistingString(lib_name).?.toOptional();
}
pub fn functionType(index: ZcuImportIndex, wasm: *Wasm) FunctionType.Index {
@@ -1639,8 +1639,8 @@ pub const ZcuImportIndex = enum(u32) {
}
};
/// 0. Index into `object_function_imports`.
/// 1. Index into `imports`.
/// 0. Index into `Wasm.object_function_imports`.
/// 1. Index into `Wasm.imports`.
pub const FunctionImportId = enum(u32) {
_,
@@ -1695,7 +1695,7 @@ pub const FunctionImportId = enum(u32) {
};
}
pub fn moduleName(id: FunctionImportId, wasm: *const Wasm) String {
pub fn moduleName(id: FunctionImportId, wasm: *const Wasm) OptionalString {
return switch (unpack(id, wasm)) {
inline .object_function_import, .zcu_import => |i| i.moduleName(wasm),
};
@@ -1706,6 +1706,24 @@ pub const FunctionImportId = enum(u32) {
inline .object_function_import, .zcu_import => |i| i.functionType(wasm),
};
}
/// Asserts not emitting an object, and `Wasm.import_symbols` is false.
pub fn undefinedAllowed(id: FunctionImportId, wasm: *const Wasm) bool {
assert(!wasm.import_symbols);
assert(wasm.base.comp.config.output_mode != .Obj);
return switch (unpack(id, wasm)) {
.object_function_import => |i| {
const import = i.value(wasm);
return import.flags.binding == .strong and import.module_name != .none;
},
.zcu_import => |i| {
const zcu = wasm.base.comp.zcu.?;
const ip = &zcu.intern_pool;
const ext = ip.getNav(i.ptr(wasm).*).toExtern(ip).?;
return !ext.is_weak_linkage and ext.lib_name != .none;
},
};
}
};
/// 0. Index into `object_global_imports`.
@@ -1760,7 +1778,7 @@ pub const GlobalImportId = enum(u32) {
};
}
pub fn moduleName(id: GlobalImportId, wasm: *const Wasm) String {
pub fn moduleName(id: GlobalImportId, wasm: *const Wasm) OptionalString {
return switch (unpack(id, wasm)) {
inline .object_global_import, .zcu_import => |i| i.moduleName(wasm),
};
@@ -2082,7 +2100,7 @@ pub fn createEmpty(
.entry_name = undefined,
.dump_argv_list = .empty,
.host_name = undefined,
.object_host_name = .none,
.preloaded_strings = undefined,
};
if (use_llvm and comp.config.have_zcu) {
@@ -2090,7 +2108,7 @@ pub fn createEmpty(
}
errdefer wasm.base.destroy();
wasm.host_name = try wasm.internString("env");
if (options.object_host_name) |name| wasm.object_host_name = (try wasm.internString(name)).toOptional();
inline for (@typeInfo(PreloadedStrings).@"struct".fields) |field| {
@field(wasm.preloaded_strings, field.name) = try wasm.internString(field.name);
@@ -2162,7 +2180,7 @@ fn parseObject(wasm: *Wasm, obj: link.Input.Object) !void {
var ss: Object.ScratchSpace = .{};
defer ss.deinit(gpa);
const object = try Object.parse(wasm, file_contents, obj.path, null, wasm.host_name, &ss, obj.must_link, gc_sections);
const object = try Object.parse(wasm, file_contents, obj.path, null, wasm.object_host_name, &ss, obj.must_link, gc_sections);
wasm.objects.appendAssumeCapacity(object);
}
@@ -2201,7 +2219,7 @@ fn parseArchive(wasm: *Wasm, obj: link.Input.Object) !void {
try wasm.objects.ensureUnusedCapacity(gpa, offsets.count());
for (offsets.keys()) |file_offset| {
const contents = file_contents[file_offset..];
const object = try archive.parseObject(wasm, contents, obj.path, wasm.host_name, &ss, obj.must_link, gc_sections);
const object = try archive.parseObject(wasm, contents, obj.path, wasm.object_host_name, &ss, obj.must_link, gc_sections);
wasm.objects.appendAssumeCapacity(object);
}
}
@@ -2313,6 +2331,7 @@ pub fn updateNav(wasm: *Wasm, pt: Zcu.PerThread, nav_index: InternPool.Nav.Index
assert(!wasm.navs_exe.contains(nav_index));
}
const name = try wasm.internString(ext.name.toSlice(ip));
if (ext.lib_name.toSlice(ip)) |ext_name| _ = try wasm.internString(ext_name);
try wasm.imports.ensureUnusedCapacity(gpa, 1);
if (ip.isFunctionType(nav.typeOf(ip))) {
try wasm.function_imports.ensureUnusedCapacity(gpa, 1);

2
src/link/Wasm/Archive.zig
View File

@@ -147,7 +147,7 @@ pub fn parseObject(
wasm: *Wasm,
file_contents: []const u8,
path: Path,
host_name: Wasm.String,
host_name: Wasm.OptionalString,
scratch_space: *Object.ScratchSpace,
must_link: bool,
gc_sections: bool,

8
src/link/Wasm/Flush.zig
View File

@@ -105,6 +105,7 @@ pub fn finish(f: *Flush, wasm: *Wasm) !void {
if (!allow_undefined) {
for (f.function_imports.keys(), f.function_imports.values()) |name, function_import_id| {
if (function_import_id.undefinedAllowed(wasm)) continue;
const src_loc = function_import_id.sourceLocation(wasm);
src_loc.addError(wasm, "undefined function: {s}", .{name.slice(wasm)});
}
@@ -403,7 +404,7 @@ pub fn finish(f: *Flush, wasm: *Wasm) !void {
const header_offset = try reserveVecSectionHeader(gpa, binary_bytes);
for (f.function_imports.values()) |id| {
const module_name = id.moduleName(wasm).slice(wasm);
const module_name = id.moduleName(wasm).slice(wasm).?;
try leb.writeUleb128(binary_writer, @as(u32, @intCast(module_name.len)));
try binary_writer.writeAll(module_name);
@@ -437,7 +438,8 @@ pub fn finish(f: *Flush, wasm: *Wasm) !void {
total_imports += 1;
} else if (import_memory) {
try emitMemoryImport(wasm, binary_bytes, &.{
.module_name = wasm.host_name,
// TODO the import_memory option needs to specify from which module
.module_name = wasm.object_host_name.unwrap().?,
.name = if (is_obj) wasm.preloaded_strings.__linear_memory else wasm.preloaded_strings.memory,
.limits_min = wasm.memories.limits.min,
.limits_max = wasm.memories.limits.max,
@@ -448,7 +450,7 @@ pub fn finish(f: *Flush, wasm: *Wasm) !void {
}
for (f.global_imports.values()) |id| {
const module_name = id.moduleName(wasm).slice(wasm);
const module_name = id.moduleName(wasm).slice(wasm).?;
try leb.writeUleb128(binary_writer, @as(u32, @intCast(module_name.len)));
try binary_writer.writeAll(module_name);

4
src/link/Wasm/Object.zig
View File

@@ -179,7 +179,7 @@ pub fn parse(
bytes: []const u8,
path: Path,
archive_member_name: ?[]const u8,
host_name: Wasm.String,
host_name: Wasm.OptionalString,
ss: *ScratchSpace,
must_link: bool,
gc_sections: bool,
@@ -560,7 +560,7 @@ pub fn parse(
.mutable = mutable,
},
},
.module_name = interned_module_name,
.module_name = interned_module_name.toOptional(),
.source_location = source_location,
.resolution = .unresolved,
});