This branch introduced an arena allocator for temporary allocations in
Compilation.update. Almost every implementation of flush() inside the
linker code was already creating a local arena that had the lifetime of
the function call. This commit passes the update arena so that all those
local ones can be deleted, resulting in slightly more efficient memory
usage with every compilation update.
While at it, this commit also removes the Compilation parameter from the
linker flush function API since a reference to the Compilation is now
already stored in `link.File`.
This is necessary because on COFF, the entry symbol name is not known
until the linker has looked at the set of global symbol names to
determine which of the four possible main entry points is present.
Now that we always pass --image-base to LLD, including when Zig chooses
the default value, LLD is complaining about 32-bit architectures because
it requires being at least equal to the max page size, which is 64K.
* fix relationship between createEmpty/open (similar logic as
607111aa758002bc51914b7dc800b23927c931b8)
* still resolve the start symbol when linking libc because when zig is
the linker it still needs to know the entry symbol.
* make use_llvm=false when there is no zig compilation unit.
implement builtin.zig file population for all modules rather than
assuming there is only one global builtin.zig module.
move some fields from link.File to Compilation
move some fields from Module to Compilation
compute debug_format in global Compilation config resolution
wire up C compilation to the concept of owner modules
make whole cache mode call link.File.createEmpty() instead of
link.File.open()
These options are only supposed to be provided to the initialization
functions, resolved, and then computed values stored in the appropriate
place (base struct or the object-format-specific structs).
Many more to go...
Much of the logic from Compilation.create() is extracted into
Compilation.Config.resolve() which accepts many optional settings and
produces concrete settings. This separate step is needed by API users of
Compilation so that they can pass the resolved global settings to the
Module creation function, which itself needs to resolve per-Module
settings.
Since the target and other things are no longer global settings, I did
not want them stored in link.File (in the `options` field). That options
field was already a kludge; those options should be resolved into
concrete settings. This commit also starts to work on that, deleting
link.Options, moving the fields into Compilation and
ObjectFormat-specific structs instead. Some fields were ephemeral and
should not have been stored at all, such as symbol_size_hint.
The link.File object of Compilation is now a `?*link.File` and `null`
when -fno-emit-bin is passed. It is now arena-allocated along with
Compilation itself, avoiding some messy cleanup code that was there
before.
On the command line, it is now possible to configure the standard
library itself by using `--mod std` just like any other module. This
meant that the CLI needed to create the standard library module rather
than having Compilation create it.
There are a lot of changes in this commit and it's still not done. I
didn't realize how quickly this changeset was going to balloon out of
control, and there are still many lines that need to be changed before
it even compiles successfully.
* introduce std.Build.Cache.HashHelper.oneShot
* add error_tracing to std.Build.Module
* extract build.zig file generation into src/Builtin.zig
* each CSourceFile and RcSourceFile now has a Module owner, which
determines some of the C compiler flags.
