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wasm linker: always passive when importing memory

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and detect passive inits from Zcu

don't forget to intern function type for __wasm_init_memory

make that function the start function if it is present

don't skip emitting passive data segment data to the binary
This commit is contained in:
Andrew Kelley
2025-01-14 18:23:38 -08:00
parent c535422423
commit b37ad5110c
2 changed files with 18 additions and 7 deletions
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7
src/link/Wasm.zig
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@@ -1968,7 +1968,7 @@ pub const DataSegmentId = enum(u32) {
pub fn isPassive(id: DataSegmentId, wasm: *const Wasm) bool {
const comp = wasm.base.comp;
if (comp.config.import_memory and !id.isBss(wasm)) return true;
if (comp.config.import_memory) return true;
return switch (unpack(id, wasm)) {
.__zig_error_names,
.__zig_error_name_table,
@@ -4614,7 +4614,10 @@ fn lowerZcuData(wasm: *Wasm, pt: Zcu.PerThread, ip_index: InternPool.Index) !Zcu
.off = .none,
.len = naive_code.len,
};
} else naive_code;
} else c: {
wasm.any_passive_inits = wasm.any_passive_inits or wasm.base.comp.config.import_memory;
break :c naive_code;
};
return .{
.code = code,

18
src/link/Wasm/Flush.zig
View File

@@ -282,6 +282,8 @@ pub fn finish(f: *Flush, wasm: *Wasm) !void {
// function.
if (wasm.any_passive_inits) {
wasm.functions.putAssumeCapacity(.__wasm_init_memory, {});
const empty = try wasm.internValtypeList(&.{});
_ = try wasm.addFuncType(.{ .params = empty, .returns = empty });
}
// When we have TLS GOT entries and shared memory is enabled,
@@ -711,9 +713,10 @@ pub fn finish(f: *Flush, wasm: *Wasm) !void {
}
// start section
if (Wasm.OutputFunctionIndex.fromResolution(wasm, wasm.entry_resolution)) |func_index| {
const header_offset = try reserveVecSectionHeader(gpa, binary_bytes);
replaceVecSectionHeader(binary_bytes, header_offset, .start, @intFromEnum(func_index));
if (wasm.functions.getIndex(.__wasm_init_memory)) |func_index| {
try emitStartSection(gpa, binary_bytes, .fromFunctionIndex(wasm, @enumFromInt(func_index)));
} else if (Wasm.OutputFunctionIndex.fromResolution(wasm, wasm.entry_resolution)) |func_index| {
try emitStartSection(gpa, binary_bytes, func_index);
}
// element section
@@ -846,10 +849,10 @@ pub fn finish(f: *Flush, wasm: *Wasm) !void {
group_end_addr = f.data_segment_groups.items[group_index].end_addr;
segment_offset = 0;
}
const flags: Object.DataSegmentFlags = if (segment_id.isPassive(wasm)) .passive else .active;
if (segment_offset == 0) {
const group_size = group_end_addr - group_start_addr;
log.debug("emit data section group, {d} bytes", .{group_size});
const flags: Object.DataSegmentFlags = if (segment_id.isPassive(wasm)) .passive else .active;
try leb.writeUleb128(binary_writer, @intFromEnum(flags));
// Passive segments are initialized at runtime.
if (flags != .passive) {
@@ -857,7 +860,7 @@ pub fn finish(f: *Flush, wasm: *Wasm) !void {
}
try leb.writeUleb128(binary_writer, group_size);
}
if (flags == .passive or segment_id.isEmpty(wasm)) {
if (segment_id.isEmpty(wasm)) {
// It counted for virtual memory but it does not go into the binary.
continue;
}
@@ -1900,6 +1903,11 @@ fn emitInitMemoryFunction(
binary_bytes.appendAssumeCapacity(@intFromEnum(std.wasm.Opcode.end));
}
fn emitStartSection(gpa: Allocator, bytes: *std.ArrayListUnmanaged(u8), i: Wasm.OutputFunctionIndex) !void {
const header_offset = try reserveVecSectionHeader(gpa, bytes);
replaceVecSectionHeader(bytes, header_offset, .start, @intFromEnum(i));
}
fn emitTagNameFunction(
wasm: *Wasm,
code: *std.ArrayListUnmanaged(u8),