These were previously implemented as a sub/sub_wrap instruction with a
lhs of 0. Making this separate instructions however allows us to save
some memory as there is no need to store a lhs.
* free Module.Fn ZIR code when destroying the owner Decl
* unreachable_safe and unreachable_unsafe are collapsed into one ZIR
instruction with a safety flag.
* astgen: emit an unreachable instruction for unreachable literals
* don't forget to call deinit on ZIR code
* astgen: implement some builtin functions
The LLVM backend is now structured into 3 different structs, namely
Object, DeclGen and FuncGen. Object represents an object that is
generated by the LLVM backend. DeclGen is responsible for generating
a decl and FuncGen is responsible for generating llvm instructions
from tzir in a function.
We are now passing this test:
```zig
export fn _start() noreturn {}
```
```
test.zig:1:30: error: expected noreturn, found void
```
I ran into an issue where we get an integer overflow trying to compute
node index offsets from the containing Decl. The problem is that the
parser adds the Decl node after adding the child nodes. For some things,
it is easy to reserve the node index and then set it later, however, for
this case, it is not a trivial code change, because depending on tokens
after parsing the decl determines whether we want to add a new node or
not.
Possible strategies here:
1. Rework the parser code to make sure that Decl nodes are before
children nodes in the AST node array.
2. Use signed integers for Decl node offsets.
3. Just flip the order of subtraction and addition. Expect Decl Node
index to be greater than children Node indexes.
I opted for (3) because it seems like the simplest thing to do. We'll
want to unify the logic for computing the offsets though because if the
logic gets repeated, it will probably get repeated wrong.
There are some `@panic("TODO")` in there but I'm trying to get the
branch to the point where collaborators can jump in.
Next is to repair the seam between LazySrcLoc and codegen's expected
absolute file offsets.
move a boolean field to be represented implicitly with the enum tag.
Just borrowing one of the many strategies of stage2.
This simple change took the peak mem usage from std lib tests on
my machine from 8.21 GiB to 8.11 GiB.
* translate-c: Use [N:0] arrays when initializer is a string literal
Translate incomplete arrays as [N:0] when initialized by a string literal.
This preserves a bit more of the type information from the original C program.
Fixes#8215
Next up is reworking the seam between the LazySrcLoc emitted by Sema
and the byte offsets currently expected by codegen.
And then the big one: updating astgen.zig to use the new memory layout.
