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wasm linker: handle function data references properly

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This commit is contained in:
Andrew Kelley 2025-01-10 00:42:04 -08:00
parent d999a8e33b
commit a327d238f1
3 changed files with 52 additions and 15 deletions
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37
src/codegen.zig
View File

@ -738,19 +738,32 @@ fn lowerNavRef(
dev.check(link.File.Tag.wasm.devFeature());
const wasm = lf.cast(.wasm).?;
assert(reloc_parent == .none);
if (is_obj) {
try wasm.out_relocs.append(gpa, .{
.offset = @intCast(code.items.len),
.pointee = .{ .symbol_index = try wasm.navSymbolIndex(nav_index) },
.tag = if (ptr_width_bytes == 4) .memory_addr_i32 else .memory_addr_i64,
.addend = @intCast(offset),
});
if (is_fn_body) {
const gop = try wasm.zcu_indirect_function_set.getOrPut(gpa, nav_index);
if (!gop.found_existing) gop.value_ptr.* = {};
if (is_obj) {
@panic("TODO add out_reloc for this");
} else {
try wasm.func_table_fixups.append(gpa, .{
.table_index = @enumFromInt(gop.index),
.offset = @intCast(code.items.len),
});
}
} else {
try wasm.nav_fixups.ensureUnusedCapacity(gpa, 1);
wasm.nav_fixups.appendAssumeCapacity(.{
.navs_exe_index = try wasm.refNavExe(nav_index),
.offset = @intCast(code.items.len),
});
if (is_obj) {
try wasm.out_relocs.append(gpa, .{
.offset = @intCast(code.items.len),
.pointee = .{ .symbol_index = try wasm.navSymbolIndex(nav_index) },
.tag = if (ptr_width_bytes == 4) .memory_addr_i32 else .memory_addr_i64,
.addend = @intCast(offset),
});
} else {
try wasm.nav_fixups.ensureUnusedCapacity(gpa, 1);
wasm.nav_fixups.appendAssumeCapacity(.{
.navs_exe_index = try wasm.refNavExe(nav_index),
.offset = @intCast(code.items.len),
});
}
}
code.appendNTimesAssumeCapacity(0, ptr_width_bytes);
return;

17
src/link/Wasm.zig
View File

@ -151,7 +151,11 @@ uav_fixups: std.ArrayListUnmanaged(UavFixup) = .empty,
/// List of locations within `string_bytes` that must be patched with the virtual
/// memory address of a Nav during `flush`.
/// When emitting an object file, `out_relocs` is used instead.
/// No functions here only global variables.
nav_fixups: std.ArrayListUnmanaged(NavFixup) = .empty,
/// When a nav reference is a function pointer, this tracks the required function
/// table entry index that needs to overwrite the code in the final output.
func_table_fixups: std.ArrayListUnmanaged(FuncTableFixup) = .empty,
/// Symbols to be emitted into an object file. Remains empty when not emitting
/// an object file.
symbol_table: std.AutoArrayHashMapUnmanaged(String, void) = .empty,
@ -307,6 +311,12 @@ pub const NavFixup = extern struct {
offset: u32,
};
pub const FuncTableFixup = extern struct {
table_index: ZcuIndirectFunctionSetIndex,
/// Index into `string_bytes`.
offset: u32,
};
/// Index into `objects`.
pub const ObjectIndex = enum(u32) {
_,
@ -2208,7 +2218,7 @@ pub const FunctionImportId = enum(u32) {
pub fn pack(unpacked: Unpacked, wasm: *const Wasm) FunctionImportId {
return switch (unpacked) {
.object_function_import => |i| @enumFromInt(@intFromEnum(i)),
.zcu_import => |i| @enumFromInt(@intFromEnum(i) - wasm.object_function_imports.entries.len),
.zcu_import => |i| @enumFromInt(@intFromEnum(i) + wasm.object_function_imports.entries.len),
};
}
@ -2295,7 +2305,7 @@ pub const GlobalImportId = enum(u32) {
pub fn pack(unpacked: Unpacked, wasm: *const Wasm) GlobalImportId {
return switch (unpacked) {
.object_global_import => |i| @enumFromInt(@intFromEnum(i)),
.zcu_import => |i| @enumFromInt(@intFromEnum(i) - wasm.object_global_imports.entries.len),
.zcu_import => |i| @enumFromInt(@intFromEnum(i) + wasm.object_global_imports.entries.len),
};
}
@ -2360,7 +2370,7 @@ pub const DataImportId = enum(u32) {
pub fn pack(unpacked: Unpacked, wasm: *const Wasm) DataImportId {
return switch (unpacked) {
.object_data_import => |i| @enumFromInt(@intFromEnum(i)),
.zcu_import => |i| @enumFromInt(@intFromEnum(i) - wasm.object_data_imports.entries.len),
.zcu_import => |i| @enumFromInt(@intFromEnum(i) + wasm.object_data_imports.entries.len),
};
}
@ -3027,6 +3037,7 @@ pub fn deinit(wasm: *Wasm) void {
wasm.out_relocs.deinit(gpa);
wasm.uav_fixups.deinit(gpa);
wasm.nav_fixups.deinit(gpa);
wasm.func_table_fixups.deinit(gpa);
wasm.zcu_indirect_function_set.deinit(gpa);
wasm.object_indirect_function_import_set.deinit(gpa);

13
src/link/Wasm/Flush.zig
View File

@ -54,6 +54,11 @@ const IndirectFunctionTableIndex = enum(u32) {
fn fromOutputFunctionIndex(f: *const Flush, i: Wasm.OutputFunctionIndex) IndirectFunctionTableIndex {
return @enumFromInt(f.indirect_function_table.getIndex(i).?);
}
fn fromZcuIndirectFunctionSetIndex(i: Wasm.ZcuIndirectFunctionSetIndex) IndirectFunctionTableIndex {
// These are the same since those are added to the table first.
return @enumFromInt(@intFromEnum(i));
}
};
const DataSegmentGroup = struct {
@ -755,6 +760,14 @@ pub fn finish(f: *Flush, wasm: *Wasm) !void {
mem.writeInt(u64, wasm.string_bytes.items[nav_fixup.offset..][0..8], vaddr, .little);
}
}
for (wasm.func_table_fixups.items) |fixup| {
const table_index: IndirectFunctionTableIndex = .fromZcuIndirectFunctionSetIndex(fixup.table_index);
if (!is64) {
mem.writeInt(u32, wasm.string_bytes.items[fixup.offset..][0..4], @intFromEnum(table_index), .little);
} else {
mem.writeInt(u64, wasm.string_bytes.items[fixup.offset..][0..8], @intFromEnum(table_index), .little);
}
}
}
// Data section.