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wasm-linker: Emit segment info

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When creating a relocatable object file, also emit the segment information
This commit is contained in:
Luuk de Gram 2022-02-17 22:01:12 +01:00
parent f7f3678b48
commit daf741318e
1 changed files with 27 additions and 1 deletions
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28
src/link/Wasm.zig
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@ -2049,6 +2049,7 @@ fn emitLinkSection(self: *Wasm, file: fs.File, arena: Allocator) !void {
// For each subsection type (found in types.Subsection) we can emit a section.
// Currently, we only support emitting segment info and the symbol table.
try self.emitSymbolTable(file, arena);
try self.emitSegmentInfo(file, arena);
const size = @intCast(u32, (try file.getPos()) - offset - 6);
try writeCustomSectionHeader(file, offset, size);
@ -2064,7 +2065,6 @@ fn emitSymbolTable(self: *Wasm, file: fs.File, arena: Allocator) !void {
try leb.writeULEB128(file.writer(), @enumToInt(types.SubsectionType.WASM_SYMBOL_TABLE));
var symbol_count: u32 = 0;
var atom_it = self.atoms.valueIterator();
while (atom_it.next()) |next_atom| {
var atom: ?*Atom = next_atom.*.getFirst();
@ -2073,6 +2073,7 @@ fn emitSymbolTable(self: *Wasm, file: fs.File, arena: Allocator) !void {
const symbol = sym_loc.getSymbol(self).*;
if (symbol.tag == .dead) continue; // Do not emit dead symbols
symbol_count += 1;
log.debug("Emit symbol: {}", .{symbol});
try leb.writeULEB128(writer, @enumToInt(symbol.tag));
try leb.writeULEB128(writer, symbol.flags);
@ -2116,6 +2117,31 @@ fn emitSymbolTable(self: *Wasm, file: fs.File, arena: Allocator) !void {
try file.writevAll(&.{iovec});
}
fn emitSegmentInfo(self: *Wasm, file: fs.File, arena: Allocator) !void {
var payload = std.ArrayList(u8).init(arena);
const writer = payload.writer();
try leb.writeULEB128(file.writer(), @enumToInt(types.SubsectionType.WASM_SEGMENT_INFO));
try leb.writeULEB128(writer, @intCast(u32, self.segment_info.items.len));
for (self.segment_info.items) |segment_info| {
log.debug("Emit segment: {s} align({d}) flags({b})", .{
segment_info.name,
@ctz(u32, segment_info.alignment),
segment_info.flags,
});
try leb.writeULEB128(writer, @intCast(u32, segment_info.name.len));
try writer.writeAll(segment_info.name);
try leb.writeULEB128(writer, @ctz(u32, segment_info.alignment));
try leb.writeULEB128(writer, segment_info.flags);
}
try leb.writeULEB128(file.writer(), @intCast(u32, payload.items.len));
const iovec: std.os.iovec_const = .{
.iov_base = payload.items.ptr,
.iov_len = payload.items.len,
};
try file.writevAll(&.{iovec});
}
/// Searches for an a matching function signature, when not found
/// a new entry will be made. The index of the existing/new signature will be returned.
pub fn putOrGetFuncType(self: *Wasm, func_type: wasm.Type) !u32 {