This reverts commit 7cbd586ace46a8e8cebab660ebca3cfc049305d9.
This is causing a fail to build from source:
```
./lib/std/fmt.zig:492:17: error: cannot format optional without a specifier (i.e. {?} or {any})
@compileError("cannot format optional without a specifier (i.e. {?} or {any})");
^
./src/link/MachO/Atom.zig:544:26: note: called from here
log.debug(" RELA({s}) @ {x} => %{d} in object({d})", .{
^
```
I looked at the code to fix it but none of those args are optionals.
Rather than finding the original object file, we seekTo to the
object file's position within the archive file, and from there open
a new file handle. This file handle is passed to the `Object` parser
which will create the object.
Previously, the data segments were being aligned twice.
This caused us to overalign the segment and therefore allocate a much larger
size for each segment than was required. This fix ensures we align and set the size
just once, ensuring semantically correct binaries as well as smaller binaries.
When linking with an object file, verify if a relocation is a table index relocation.
If that's the case, add the relocation target to the function table.
This fixes a memory leak when an object file contains one or more element sections which
then contains one or more function indexes. This commit ensures the slice of index functions
for each element section will be freed upon resource deallocation also.
To unify the wasm backend with the other backends, we will now call `generateSymbol` to
lower a Decl into bytes. This means we also have to change some function signatures
to comply with the linker interface.
Since the general purpose generateSymbol is less featureful than wasm's, some tests are
temporarily disabled.
Symbols that have globals used to have their lookup key be the symbol name.
This key is now the offset into the string table.
Imports have both the module name (library name) and name (of the symbol), those strings are now
also being interned. This can save us up to 24bytes per import which have both their module name and name de-duplicated.
Module names are almost entirely the same for all imports, providing us with a big chance of saving us 12 bytes at least.
Just like imports, exports can also have a seperate name than the internal symbol name. Rather than storing the slice,
we now store the offset of this string instead.
For all symbols read from object files as well as generated from Zig code
will now be interned and have their offset into the string table saved on the `Symbol` instead.
Besides interning, local symbols now also use a decl's fully qualified name.
When a decl/symbol is extern/to-be-imported, the name of the decl itself will be used for symbol resolving.
Similarly for symbols that will be exported, will have their 'export name' set.
This is preliminary work for string interning in the wasm linker.
Using an arena would defeat the purpose of de-duplicating strings as we wouldn't be able to free memory
of duplicated strings.
This change also means we can simplify wasm binary parsing, by creating a general purpose parser that
parses the binary into its sections, but untyped. Doing this, allows us to re-use the base of that, for
object file, but also debug info parsing.
We now correctly allocate and create atoms for symbols from other object files.
Imports are now also resolved and appended when required.
Besides those changes, we now duplicate all symbol names, so we can correctly
generate unique names for unnamed constants.
TODO: String interning
This implements the merging of all sections, to generate a valid wasm binary where all symbols
have been resolved and their respective sections have been merged into the final binary.
This upstreams the object file parsing from zwld, bringing us closer to being able
to link stage2 code with object files/C-code as well as replacing lld with the self-hosted
linker once feature complete.
