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wasm linker: distinguish symbol name vs import name, and implement weak

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This commit is contained in:
Andrew Kelley 2025-01-08 16:25:00 -08:00
parent 3474057e5e
commit 5186c6c4ee
3 changed files with 115 additions and 30 deletions
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87
src/link/Wasm.zig
View File

@ -91,6 +91,7 @@ objects: std.ArrayListUnmanaged(Object) = .{},
func_types: std.AutoArrayHashMapUnmanaged(FunctionType, void) = .empty,
/// Provides a mapping of both imports and provided functions to symbol name.
/// Local functions may be unnamed.
/// Key is symbol name, however the `FunctionImport` may have an name override for the import name.
object_function_imports: std.AutoArrayHashMapUnmanaged(String, FunctionImport) = .empty,
/// All functions for all objects.
object_functions: std.ArrayListUnmanaged(ObjectFunction) = .empty,
@ -164,7 +165,7 @@ object_host_name: OptionalString,
/// Memory section
memories: std.wasm.Memory = .{ .limits = .{
.min = 0,
.max = undefined,
.max = 0,
.flags = .{ .has_max = false, .is_shared = false },
} },
@ -371,6 +372,17 @@ pub const OutputFunctionIndex = enum(u32) {
return fromResolution(wasm, .fromObjectFunction(wasm, index)).?;
}
pub fn fromObjectFunctionHandlingWeak(wasm: *const Wasm, index: ObjectFunctionIndex) OutputFunctionIndex {
const ptr = index.ptr(wasm);
if (ptr.flags.binding == .weak) {
const name = ptr.name.unwrap().?;
const import = wasm.object_function_imports.getPtr(name).?;
assert(import.resolution != .unresolved);
return fromResolution(wasm, import.resolution).?;
}
return fromResolution(wasm, .fromObjectFunction(wasm, index)).?;
}
pub fn fromIpIndex(wasm: *const Wasm, ip_index: InternPool.Index) OutputFunctionIndex {
const zcu = wasm.base.comp.zcu.?;
const ip = &zcu.intern_pool;
@ -923,6 +935,8 @@ const DebugSection = struct {};
pub const FunctionImport = extern struct {
flags: SymbolFlags,
module_name: OptionalString,
/// May be different than the key which is a symbol name.
name: String,
source_location: SourceLocation,
resolution: Resolution,
type: FunctionType.Index,
@ -1042,10 +1056,14 @@ pub const FunctionImport = extern struct {
return &wasm.object_function_imports.values()[@intFromEnum(index)];
}
pub fn name(index: Index, wasm: *const Wasm) String {
pub fn symbolName(index: Index, wasm: *const Wasm) String {
return index.key(wasm).*;
}
pub fn importName(index: Index, wasm: *const Wasm) String {
return index.value(wasm).name;
}
pub fn moduleName(index: Index, wasm: *const Wasm) OptionalString {
return index.value(wasm).module_name;
}
@ -1079,6 +1097,8 @@ pub const ObjectFunction = extern struct {
pub const GlobalImport = extern struct {
flags: SymbolFlags,
module_name: OptionalString,
/// May be different than the key which is a symbol name.
name: String,
source_location: SourceLocation,
resolution: Resolution,
@ -1194,10 +1214,14 @@ pub const GlobalImport = extern struct {
return &wasm.object_global_imports.values()[@intFromEnum(index)];
}
pub fn name(index: Index, wasm: *const Wasm) String {
pub fn symbolName(index: Index, wasm: *const Wasm) String {
return index.key(wasm).*;
}
pub fn importName(index: Index, wasm: *const Wasm) String {
return index.value(wasm).name;
}
pub fn moduleName(index: Index, wasm: *const Wasm) OptionalString {
return index.value(wasm).module_name;
}
@ -1260,6 +1284,8 @@ pub const RefType1 = enum(u1) {
pub const TableImport = extern struct {
flags: SymbolFlags,
module_name: String,
/// May be different than the key which is a symbol name.
name: String,
source_location: SourceLocation,
resolution: Resolution,
limits_min: u32,
@ -1387,6 +1413,15 @@ pub const ObjectTableIndex = enum(u32) {
pub fn ptr(index: ObjectTableIndex, wasm: *const Wasm) *Table {
return &wasm.object_tables.items[@intFromEnum(index)];
}
pub fn chaseWeak(i: ObjectTableIndex, wasm: *const Wasm) ObjectTableIndex {
const table = ptr(i, wasm);
if (table.flags.binding != .weak) return i;
const name = table.name.unwrap().?;
const import = wasm.object_table_imports.getPtr(name).?;
assert(import.resolution != .unresolved); // otherwise it should resolve to this one.
return import.resolution.unpack().object_table;
}
};
/// Index into `Wasm.object_globals`.
@ -1400,6 +1435,15 @@ pub const ObjectGlobalIndex = enum(u32) {
pub fn name(index: ObjectGlobalIndex, wasm: *const Wasm) OptionalString {
return index.ptr(wasm).name;
}
pub fn chaseWeak(i: ObjectGlobalIndex, wasm: *const Wasm) ObjectGlobalIndex {
const global = ptr(i, wasm);
if (global.flags.binding != .weak) return i;
const import_name = global.name.unwrap().?;
const import = wasm.object_global_imports.getPtr(import_name).?;
assert(import.resolution != .unresolved); // otherwise it should resolve to this one.
return import.resolution.unpack(wasm).object_global;
}
};
pub const ObjectMemory = extern struct {
@ -1442,6 +1486,15 @@ pub const ObjectFunctionIndex = enum(u32) {
assert(result != .none);
return result;
}
pub fn chaseWeak(i: ObjectFunctionIndex, wasm: *const Wasm) ObjectFunctionIndex {
const func = ptr(i, wasm);
if (func.flags.binding != .weak) return i;
const name = func.name.unwrap().?;
const import = wasm.object_function_imports.getPtr(name).?;
assert(import.resolution != .unresolved); // otherwise it should resolve to this one.
return import.resolution.unpack(wasm).object_function;
}
};
/// Index into `object_functions`, or null.
@ -2131,7 +2184,7 @@ pub const ZcuImportIndex = enum(u32) {
return &wasm.imports.keys()[@intFromEnum(index)];
}
pub fn name(index: ZcuImportIndex, wasm: *const Wasm) String {
pub fn importName(index: ZcuImportIndex, wasm: *const Wasm) String {
const zcu = wasm.base.comp.zcu.?;
const ip = &zcu.intern_pool;
const nav_index = index.ptr(wasm).*;
@ -2217,9 +2270,9 @@ pub const FunctionImportId = enum(u32) {
}
}
pub fn name(id: FunctionImportId, wasm: *const Wasm) String {
pub fn importName(id: FunctionImportId, wasm: *const Wasm) String {
return switch (unpack(id, wasm)) {
inline .object_function_import, .zcu_import => |i| i.name(wasm),
inline .object_function_import, .zcu_import => |i| i.importName(wasm),
};
}
@ -2300,9 +2353,9 @@ pub const GlobalImportId = enum(u32) {
}
}
pub fn name(id: GlobalImportId, wasm: *const Wasm) String {
pub fn importName(id: GlobalImportId, wasm: *const Wasm) String {
return switch (unpack(id, wasm)) {
inline .object_global_import, .zcu_import => |i| i.name(wasm),
inline .object_global_import, .zcu_import => |i| i.importName(wasm),
};
}
@ -3297,6 +3350,14 @@ pub fn prelink(wasm: *Wasm, prog_node: std.Progress.Node) link.File.FlushError!v
try markDataImport(wasm, name, import, @enumFromInt(i));
}
}
// This is a wild ass guess at how to merge memories, haven't checked yet
// what the proper way to do this is.
for (wasm.object_memory_imports.values()) |*memory_import| {
wasm.memories.limits.min = @min(wasm.memories.limits.min, memory_import.limits_min);
wasm.memories.limits.max = @max(wasm.memories.limits.max, memory_import.limits_max);
wasm.memories.limits.flags.has_max = wasm.memories.limits.flags.has_max or memory_import.limits_has_max;
}
}
fn markFunctionImport(
@ -3532,12 +3593,12 @@ fn markRelocations(wasm: *Wasm, relocs: ObjectRelocation.IterableSlice) link.Fil
.table_index_i64,
.table_index_rel_sleb,
.table_index_rel_sleb64,
=> try markFunction(wasm, pointee.function),
=> try markFunction(wasm, pointee.function.chaseWeak(wasm)),
.global_index_leb,
.global_index_i32,
=> try markGlobal(wasm, pointee.global),
=> try markGlobal(wasm, pointee.global.chaseWeak(wasm)),
.table_number_leb,
=> try wasm.tables.put(wasm.base.comp.gpa, .fromObjectTable(pointee.table), {}),
=> try markTable(wasm, pointee.table.chaseWeak(wasm)),
.section_offset_i32 => {
log.warn("TODO: ensure section {d} is included in output", .{pointee.section});
@ -3561,6 +3622,10 @@ fn markRelocations(wasm: *Wasm, relocs: ObjectRelocation.IterableSlice) link.Fil
}
}
fn markTable(wasm: *Wasm, i: ObjectTableIndex) link.File.FlushError!void {
try wasm.tables.put(wasm.base.comp.gpa, .fromObjectTable(i), {});
}
pub fn flushModule(
wasm: *Wasm,
arena: Allocator,

15
src/link/Wasm/Flush.zig
View File

@ -459,7 +459,7 @@ pub fn finish(f: *Flush, wasm: *Wasm) !void {
try leb.writeUleb128(binary_writer, @as(u32, @intCast(module_name.len)));
try binary_writer.writeAll(module_name);
const name = id.name(wasm).slice(wasm);
const name = id.importName(wasm).slice(wasm);
try leb.writeUleb128(binary_writer, @as(u32, @intCast(name.len)));
try binary_writer.writeAll(name);
@ -474,7 +474,7 @@ pub fn finish(f: *Flush, wasm: *Wasm) !void {
try leb.writeUleb128(binary_writer, @as(u32, @intCast(module_name.len)));
try binary_writer.writeAll(module_name);
const name = id.key(wasm).slice(wasm);
const name = table_import.name.slice(wasm);
try leb.writeUleb128(binary_writer, @as(u32, @intCast(name.len)));
try binary_writer.writeAll(name);
@ -484,10 +484,7 @@ pub fn finish(f: *Flush, wasm: *Wasm) !void {
}
total_imports += wasm.table_imports.entries.len;
for (wasm.object_memory_imports.keys(), wasm.object_memory_imports.values()) |name, *memory_import| {
try emitMemoryImport(wasm, binary_bytes, name, memory_import);
total_imports += 1;
} else if (import_memory) {
if (import_memory) {
const name = if (is_obj) wasm.preloaded_strings.__linear_memory else wasm.preloaded_strings.memory;
try emitMemoryImport(wasm, binary_bytes, name, &.{
// TODO the import_memory option needs to specify from which module
@ -506,7 +503,7 @@ pub fn finish(f: *Flush, wasm: *Wasm) !void {
try leb.writeUleb128(binary_writer, @as(u32, @intCast(module_name.len)));
try binary_writer.writeAll(module_name);
const name = id.name(wasm).slice(wasm);
const name = id.importName(wasm).slice(wasm);
try leb.writeUleb128(binary_writer, @as(u32, @intCast(name.len)));
try binary_writer.writeAll(name);
@ -1458,8 +1455,8 @@ fn applyRelocs(code: []u8, code_offset: u32, relocs: Wasm.ObjectRelocation.Itera
if (offset >= relocs.end) break;
const sliced_code = code[offset - code_offset ..];
switch (tag) {
.function_index_i32 => reloc_u32_function(sliced_code, .fromObjectFunction(wasm, pointee.function)),
.function_index_leb => reloc_leb_function(sliced_code, .fromObjectFunction(wasm, pointee.function)),
.function_index_i32 => reloc_u32_function(sliced_code, .fromObjectFunctionHandlingWeak(wasm, pointee.function)),
.function_index_leb => reloc_leb_function(sliced_code, .fromObjectFunctionHandlingWeak(wasm, pointee.function)),
.function_offset_i32 => @panic("TODO this value is not known yet"),
.function_offset_i64 => @panic("TODO this value is not known yet"),
.table_index_i32 => @panic("TODO indirect function table needs to support object functions too"),

43
src/link/Wasm/Object.zig
View File

@ -972,7 +972,7 @@ pub fn parse(
for (ss.symbol_table.items) |symbol| switch (symbol.pointee) {
.function_import => |index| {
const ptr = index.ptr(ss);
const name = symbol.name.unwrap().?;
const name = symbol.name.unwrap() orelse ptr.name;
if (symbol.flags.binding == .local) {
diags.addParseError(path, "local symbol '{s}' references import", .{name.slice(wasm)});
continue;
@ -1000,10 +1000,18 @@ pub fn parse(
source_location.addNote(&err, "module '{s}' here", .{ptr.module_name.slice(wasm)});
continue;
}
if (gop.value_ptr.name != ptr.name) {
var err = try diags.addErrorWithNotes(2);
try err.addMsg("symbol '{s}' mismatching import names", .{name.slice(wasm)});
gop.value_ptr.source_location.addNote(&err, "imported as '{s}' here", .{gop.value_ptr.name.slice(wasm)});
source_location.addNote(&err, "imported as '{s}' here", .{ptr.name.slice(wasm)});
continue;
}
} else {
gop.value_ptr.* = .{
.flags = symbol.flags,
.module_name = ptr.module_name.toOptional(),
.name = ptr.name,
.source_location = source_location,
.resolution = .unresolved,
.type = fn_ty_index,
@ -1012,7 +1020,7 @@ pub fn parse(
},
.global_import => |index| {
const ptr = index.ptr(ss);
const name = symbol.name.unwrap().?;
const name = symbol.name.unwrap() orelse ptr.name;
if (symbol.flags.binding == .local) {
diags.addParseError(path, "local symbol '{s}' references import", .{name.slice(wasm)});
continue;
@ -1049,10 +1057,18 @@ pub fn parse(
source_location.addNote(&err, "module '{s}' here", .{ptr.module_name.slice(wasm)});
continue;
}
if (gop.value_ptr.name != ptr.name) {
var err = try diags.addErrorWithNotes(2);
try err.addMsg("symbol '{s}' mismatching import names", .{name.slice(wasm)});
gop.value_ptr.source_location.addNote(&err, "imported as '{s}' here", .{gop.value_ptr.name.slice(wasm)});
source_location.addNote(&err, "imported as '{s}' here", .{ptr.name.slice(wasm)});
continue;
}
} else {
gop.value_ptr.* = .{
.flags = symbol.flags,
.module_name = ptr.module_name.toOptional(),
.name = ptr.name,
.source_location = source_location,
.resolution = .unresolved,
};
@ -1064,7 +1080,7 @@ pub fn parse(
},
.table_import => |index| {
const ptr = index.ptr(ss);
const name = symbol.name.unwrap().?;
const name = symbol.name.unwrap() orelse ptr.name;
if (symbol.flags.binding == .local) {
diags.addParseError(path, "local symbol '{s}' references import", .{name.slice(wasm)});
continue;
@ -1088,6 +1104,13 @@ pub fn parse(
source_location.addNote(&err, "module '{s}' here", .{ptr.module_name.slice(wasm)});
continue;
}
if (gop.value_ptr.name != ptr.name) {
var err = try diags.addErrorWithNotes(2);
try err.addMsg("symbol '{s}' mismatching import names", .{name.slice(wasm)});
gop.value_ptr.source_location.addNote(&err, "imported as '{s}' here", .{gop.value_ptr.name.slice(wasm)});
source_location.addNote(&err, "imported as '{s}' here", .{ptr.name.slice(wasm)});
continue;
}
if (symbol.flags.binding == .strong) gop.value_ptr.flags.binding = .strong;
if (!symbol.flags.visibility_hidden) gop.value_ptr.flags.visibility_hidden = false;
if (symbol.flags.no_strip) gop.value_ptr.flags.no_strip = true;
@ -1095,6 +1118,7 @@ pub fn parse(
gop.value_ptr.* = .{
.flags = symbol.flags,
.module_name = ptr.module_name,
.name = ptr.name,
.source_location = source_location,
.resolution = .unresolved,
.limits_min = ptr.limits_min,
@ -1158,6 +1182,7 @@ pub fn parse(
gop.value_ptr.* = .{
.flags = symbol.flags,
.module_name = host_name,
.name = name,
.source_location = source_location,
.resolution = .fromObjectFunction(wasm, index),
.type = ptr.type_index,
@ -1214,8 +1239,9 @@ pub fn parse(
gop.value_ptr.* = .{
.flags = symbol.flags,
.module_name = .none,
.name = name,
.source_location = source_location,
.resolution = .unresolved,
.resolution = .fromObjectGlobal(wasm, index),
};
gop.value_ptr.flags.global_type = .{
.valtype = .from(new_ty.valtype),
@ -1258,7 +1284,7 @@ pub fn parse(
gop.value_ptr.* = .{
.flags = symbol.flags,
.source_location = source_location,
.resolution = .unresolved,
.resolution = .fromObjectDataIndex(wasm, index),
};
}
},
@ -1280,11 +1306,8 @@ pub fn parse(
switch (exp.pointee) {
inline .function, .table, .memory, .global => |index| {
const ptr = index.ptr(wasm);
if (ptr.name == .none) {
// Missing symbol table entry; use defaults for exported things.
ptr.name = exp.name.toOptional();
ptr.flags.exported = true;
}
ptr.name = exp.name.toOptional();
ptr.flags.exported = true;
},
}
}