The type `Zcu.Decl` in the compiler is problematic: over time it has
gained many responsibilities. Every source declaration, container type,
generic instantiation, and `@extern` has a `Decl`. The functions of
these `Decl`s are in some cases entirely disjoint.
After careful analysis, I determined that the two main responsibilities
of `Decl` are as follows:
* A `Decl` acts as the "subject" of semantic analysis at comptime. A
single unit of analysis is either a runtime function body, or a
`Decl`. It registers incremental dependencies, tracks analysis errors,
etc.
* A `Decl` acts as a "global variable": a pointer to it is consistent,
and it may be lowered to a specific symbol by the codegen backend.
This commit eliminates `Decl` and introduces new types to model these
responsibilities: `Cau` (Comptime Analysis Unit) and `Nav` (Named
Addressable Value).
Every source declaration, and every container type requiring resolution
(so *not* including `opaque`), has a `Cau`. For a source declaration,
this `Cau` performs the resolution of its value. (When #131 is
implemented, it is unsolved whether type and value resolution will share
a `Cau` or have two distinct `Cau`s.) For a type, this `Cau` is the
context in which type resolution occurs.
Every non-`comptime` source declaration, every generic instantiation,
and every distinct `extern` has a `Nav`. These are sent to codegen/link:
the backends by definition do not care about `Cau`s.
This commit has some minor technically-breaking changes surrounding
`usingnamespace`. I don't think they'll impact anyone, since the changes
are fixes around semantics which were previously inconsistent (the
behavior changed depending on hashmap iteration order!).
Aside from that, this changeset has no significant user-facing changes.
Instead, it is an internal refactor which makes it easier to correctly
model the responsibilities of different objects, particularly regarding
incremental compilation. The performance impact should be negligible,
but I will take measurements before merging this work into `master`.
Co-authored-by: Jacob Young <jacobly0@users.noreply.github.com>
Co-authored-by: Jakub Konka <kubkon@jakubkonka.com>
* Rename isPPC() -> isPowerPC32().
* Rename isPPC64() -> isPowerPC64().
* Add new isPowerPC() function which covers both.
There was confusion even in the standard library about what isPPC() meant. This
change makes these functions work how I think most people actually expect them
to work, and makes them consistent with isMIPS(), isSPARC(), etc.
I chose to rename from PPC to PowerPC because 1) it's more consistent with the
other functions, and 2) it'll cause loud rather than silent breakage for anyone
who might have been depending on isPPC() while misunderstanding it.
What is `sparcel`, you might ask? Good question!
If you take a peek in the SPARC v8 manual, §2.2, it is quite explicit that SPARC
v8 is a big-endian architecture. No little-endian or mixed-endian support to be
found here.
On the other hand, the SPARC v9 manual, in §3.2.1.2, states that it has support
for mixed-endian operation, with big-endian mode being the default.
Ok, so `sparcel` must just be referring to SPARC v9 running in little-endian
mode, surely?
Nope:
* 40b4fd7a3e/llvm/lib/Target/Sparc/SparcTargetMachine.cpp (L226)
* 40b4fd7a3e/llvm/lib/Target/Sparc/SparcTargetMachine.cpp (L104)
So, `sparcel` in LLVM is referring to some sort of fantastical little-endian
SPARC v8 architecture. I've scoured the internet and I can find absolutely no
evidence that such a thing exists or has ever existed. In fact, I can find no
evidence that a little-endian implementation of SPARC v9 ever existed, either.
Or any SPARC version, actually!
The support was added here: https://reviews.llvm.org/D8741
Notably, there is no mention whatsoever of what CPU this might be referring to,
and no justification given for the "but some are little" comment added in the
patch.
My best guess is that this might have been some private exercise in creating a
little-endian version of SPARC that never saw the light of day. Given that SPARC
v8 explicitly doesn't support little-endian operation (let alone little-endian
instruction encoding!), and no CPU is known to be implemented as such, I think
it's very reasonable for us to just remove this support.
This is a misfeature that we inherited from LLVM:
* https://reviews.llvm.org/D61259
* https://reviews.llvm.org/D61939
(`aarch64_32` and `arm64_32` are equivalent.)
I truly have no idea why this triple passed review in LLVM. It is, to date, the
*only* tag in the architecture component that is not, in fact, an architecture.
In reality, it is just an ILP32 ABI for AArch64 (*not* AArch32).
The triples that use `aarch64_32` look like `aarch64_32-apple-watchos`. Yes,
that triple is exactly what you think; it has no ABI component. They really,
seriously did this.
Since only Apple could come up with silliness like this, it should come as no
surprise that no one else uses `aarch64_32`. Later on, a GNU ILP32 ABI for
AArch64 was developed, and support was added to LLVM:
* https://reviews.llvm.org/D94143
* https://reviews.llvm.org/D104931
Here, sanity seems to have prevailed, and a triple using this ABI looks like
`aarch64-linux-gnu_ilp32` as you would expect.
As can be seen from the diffs in this commit, there was plenty of confusion
throughout the Zig codebase about what exactly `aarch64_32` was. So let's just
remove it. In its place, we'll use `aarch64-watchos-ilp32`,
`aarch64-linux-gnuilp32`, and so on. We'll then translate these appropriately
when talking to LLVM. Hence, this commit adds the `ilp32` ABI tag (we already
have `gnuilp32`).
with this rewrite we can call functions inside of
inline assembly, enabling us to use the default start.zig logic
all that's left is to implement lr/sc loops for atomically manipulating
1 and 2 byte values, after which we can use the segfault handler logic.
I was doing duplicate work with `elemOffset` multiplying by the abi size and then the `ptr_add` `genBinOp` also multiplying.
This led to having writes happening in the wrong place.
the csrs `avl` and `vtype` are considered caller-saved so it could have changed while inside of the function.
the easiest way to handle this is to just set the cached `vtype` and `avl` to null, so that the next time something
needs to set it, it'll emit an instruction instead of relying on a potentially invalid setting.
