| author |  Luuk de Gram <luuk@degram.dev> 2022-09-01 22:02:24+02:00 |
| committer | Luuk de Gram <luuk@degram.dev> 2022-09-07 18:53:16+02:00 |
| log | 46c932a2c9650f14ae8035d7382d825bfabdc0a5 |
| tree | e819d6b20acb736af12a5b7f35ce4c34e17f3600 |
| parent | c347751338a4a1e2874207674fb47908fd601484 |
| signature |  Commit is signed but in an unrecognized format. |
wasm-linker: perform debug relocations
This correctly performs a relocation for debug sections.
The result is that the wasm-linker can now correctly create
a binary from object files while preserving all debug information.3 files changed, 16 insertions(+), 6 deletions(-)
src- link
src/link/Wasm.zig+12
| ... | ... | @@ -221,6 +221,18 @@ pub const SymbolLoc = struct { |
| 221 | 221 | } |
| 222 | 222 | return wasm_bin.string_table.get(wasm_bin.symbols.items[self.index].name); |
| 223 | 223 | } |
| 224 | ||
| 225 | /// From a given symbol location, returns the final location. | |
| 226 | /// e.g. when a symbol was resolved and replaced by the symbol | |
| 227 | /// in a different file, this will return said location. | |
| 228 | /// If the symbol wasn't replaced by another, this will return | |
| 229 | /// the given location itself. | |
| 230 | pub fn finalLoc(self: SymbolLoc, wasm_bin: *const Wasm) SymbolLoc { | |
| 231 | if (wasm_bin.discarded.get(self)) |new_loc| { | |
| 232 | return new_loc.finalLoc(wasm_bin); | |
| 233 | } | |
| 234 | return self; | |
| 235 | } | |
| 224 | 236 | }; |
| 225 | 237 | |
| 226 | 238 | /// Generic string table that duplicates strings |
src/link/Wasm/Atom.zig+3-4
| ... | ... | @@ -145,7 +145,7 @@ pub fn resolveRelocs(self: *Atom, wasm_bin: *const Wasm) void { |
| 145 | 145 | /// All values will be represented as a `u64` as all values can fit within it. |
| 146 | 146 | /// The final value must be casted to the correct size. |
| 147 | 147 | fn relocationValue(self: Atom, relocation: types.Relocation, wasm_bin: *const Wasm) u64 { |
| 148 | const target_loc: Wasm.SymbolLoc = .{ .file = self.file, .index = relocation.index }; | |
| 148 | const target_loc = (Wasm.SymbolLoc{ .file = self.file, .index = relocation.index }).finalLoc(wasm_bin); | |
| 149 | 149 | const symbol = target_loc.getSymbol(wasm_bin).*; |
| 150 | 150 | switch (relocation.relocation_type) { |
| 151 | 151 | .R_WASM_FUNCTION_INDEX_LEB => return symbol.index, |
| ... | ... | @@ -174,8 +174,7 @@ fn relocationValue(self: Atom, relocation: types.Relocation, wasm_bin: *const Wa |
| 174 | 174 | => { |
| 175 | 175 | std.debug.assert(symbol.tag == .data and !symbol.isUndefined()); |
| 176 | 176 | const merge_segment = wasm_bin.base.options.output_mode != .Obj; |
| 177 | const target_atom_loc = wasm_bin.discarded.get(target_loc) orelse target_loc; | |
| 178 | const target_atom = wasm_bin.symbol_atom.get(target_atom_loc).?; | |
| 177 | const target_atom = wasm_bin.symbol_atom.get(target_loc).?; | |
| 179 | 178 | const segment_info = if (target_atom.file) |object_index| blk: { |
| 180 | 179 | break :blk wasm_bin.objects.items[object_index].segment_info; |
| 181 | 180 | } else wasm_bin.segment_info.items; |
| ... | ... | @@ -187,6 +186,6 @@ fn relocationValue(self: Atom, relocation: types.Relocation, wasm_bin: *const Wa |
| 187 | 186 | .R_WASM_EVENT_INDEX_LEB => return symbol.index, |
| 188 | 187 | .R_WASM_SECTION_OFFSET_I32, |
| 189 | 188 | .R_WASM_FUNCTION_OFFSET_I32, |
| 190 | => return relocation.offset, | |
| 189 | => return relocation.addend orelse 0, | |
| 191 | 190 | } |
| 192 | 191 | } |
src/link/Wasm/Object.zig+1-2
| ... | ... | @@ -387,11 +387,10 @@ fn Parser(comptime ReaderType: type) type { |
| 387 | 387 | .data = debug_content.ptr, |
| 388 | 388 | .size = debug_size, |
| 389 | 389 | .index = try self.object.string_table.put(gpa, name), |
| 390 | .offset = len - debug_size, | |
| 390 | .offset = 0, // debug sections only contain 1 entry, so no need to calculate offset | |
| 391 | 391 | .section_index = section_index, |
| 392 | 392 | }); |
| 393 | 393 | } else { |
| 394 | log.info("found unknown custom section '{s}' - skipping parsing", .{name}); | |
| 395 | 394 | try reader.skipBytes(reader.context.bytes_left, .{}); |
| 396 | 395 | } |
| 397 | 396 | }, |