Before this we would see ZIR code like this:
```
%69 = alloc_inferred_mut()
%70 = array_base_ptr(%69)
%71 = elem_ptr_imm(%70, 0)
```
This would crash the compiler because it expects to see a
`coerce_result_ptr` instruction after `alloc_inferred_mut`, but that
does not happen in this case because there is no type to coerce the
result pointer to.
In this commit I modified AstGen so that it has similar codegen as when
using a const instead of a var:
```
%69 = alloc_inferred_mut()
%76 = array_init_anon(.{%71, %73, %75})
%77 = store_to_inferred_ptr(%69, %76)
```
This does not obey result locations, meaning if you call a function
inside the initializer, it will end up doing a copy into the LHS.
Solving this problem, or changing the language to make this legal,
will be left for my future self to deal with. Hi future self!
I see you reading this commit log. Hope you're doing OK buddy.
Sema for `store_ptr` of a tuple where the pointer is in fact the same
element type as the operand had an issue where the comptime fields would
get incorrectly lowered to runtime stores to bogus addresses. This is
solved with an exception to the optimization in Sema for storing
pointers that handles tuples element-wise. In the case that we are
storing a tuple to itself, it skips the optimization. This results in
better code and avoids the problem. However this caused a regression in
GeneralPurposeAllocator from the standard library.
I regressed the test runner code back to the simpler path. It's too
hard to debug standard library code in the LLVM backend right now since
we don't have debug info hooked up. Also, we didn't have any behavior
test coverage of whatever was regressed, so let's try to get that
coverage added as a stepping stone to getting the standard library
working.
The checks detecting such no-op branches (essentially instructions
that branch to the instruction immediately following the branch) were
tightened to catch more of these occurrences.
Now it's centered around a switch on the chosen type tag which gives us
easy access to pointer data.
The logic is simplied and in some cases logic is removed when it is
sufficient to choose the type that is a better coercion target without
knowing whether such coercion will succeed ahead of time.
A bug is fixed at the bottom of the function; we were doing the opposite
of what we were supposed to with `seen_const`.
Also the bottom of the function has a more complete handling of the
possible combinations of `any_are_null`, `convert_to_slice`, and
`err_set_ty`.
In the behavior tests, not as many backends needed to be skipped.
* AIR: use pl_op instead of ty_pl for wasm_memory_size. No need to
store the type because the type is always `u32`.
* AstGen: use coerced_ty for `@wasmMemorySize` and `@wasmMemoryGrow`
and do the coercions in Sema.
* Sema: use more accurate source locations for errors.
* Provide more information in the compiler error message.
* Codegen: use liveness data to avoid lowering unused
`@wasmMemorySize`.
* LLVM backend: add implementation
- I wasn't able to test it because we are hitting a linker error for
`-target wasm32-wasi -fLLVM`.
* C backend: use `zig_unimplemented()` instead of silently doing wrong
behavior for these builtins.
* behavior tests: branch only on stage2_arch for inclusion of the
wasm.zig file. We would change it to `builtin.cpu.arch` but that is
causing a compiler crash on some backends.
This implements the wasm builtins by lowering to builtins that are supported by c-compilers.
In this case: Clang.
This also simplifies the `AIR` instruction as it now uses the payload field of `ty_pl` and `pl_op`
directly to store the index argument rather than storing it inside Extra. This saves us 4 bytes
per builtin call.
Similarly to the other wasm builtin, this implements the grow variation where the memory
index is a comptime known value. The operand as well as the result are runtime values.
This also verifies during semantic analysis the target we're building for is wasm, or else
emits a compilation error. This means that other backends do not have to handle this AIR instruction,
other than the wasm and LLVM backends.
This implements the `wasmMemorySize` builtin, in Sema and the Wasm backend.
The Stage2 implementation differs from stage1 in the way that `index` must be a comptime value.
The stage1 variant is incorrect, as the index is part of the instruction encoding, and therefore,
cannot be a runtime value.
`Module.Union.getLayout` now additionally returns a `padding` field
which tells how many bytes are between the final field end offset and
the ending offset of the union. This is used by the LLVM backend to
explicitly insert padding.
LLVM backend: lowering of unions now inserts additional padding so that
LLVM's internals will agree on the ABI size to match what ABI size zig
wants unions to be. This is an alternative to calling LLVMABISizeOfType
and LLVMABIAlignmentOfType which end up crashing when recursive struct
definitions come into play. We no longer ever call these two functions
and the bindings are deleted to avoid future footgun firings.
LLVM backend: lowering of unions now represents untagged unions
consistently. Before it was tripping an assertion.
LLVM backend: switch cases call inttoptr on the case items and condition
if necessary. Prevents tripping an LLVM assertion.
After this commit, we are no longer tripping over any LLVM assertions.
The core of this change is to re-use the escape sequence parsing logic
for parsing both string and character literals.
The actual fix is that UTF-8 encoding was missing for string literals
with \u{...} escape sequences.
* Sema: resolve type fully when emitting an alloc AIR instruction to
avoid tripping assertion for checking struct field alignment.
* LLVM backend: keep a reference to the LLVM target data alive during
lowering so that we can ask LLVM what it thinks the ABI alignment
and size of LLVM types are. We need this in order to lower tuples and
structs so that we can put in extra padding bytes when Zig disagrees
with LLVM about the size or alignment of something.
* LLVM backend: make the LLVM struct type packed that contains the most
aligned union field and the padding. This prevents the struct from
being too big according to LLVM. In the future, we may want to
consider instead emitting unions in a "flat" manner; putting the tag,
most aligned union field, and padding all in the same struct field
space.
* LLVM backend: make structs with 2 or fewer fields return isByRef=false.
This results in more efficient codegen. This required lowering of
bitcast to sometimes store the struct into an alloca, ptrcast, and
then load because LLVM does not allow bitcasting structs.
* enable more passing behavior tests.
Packed structs were tripping an LLVM assertion due to calling
`LLVMConstZExt` from i16 to i16. Solved by using instead
`LLVMConstZExtOrBitCast`.
Unions were tripping an LLVM assertion due to a typo using the union
llvm type to construct an integer value rather than the tag type.
