It is possible for Zig to emit field ptr instructions to fields whos
type is zero sized. In this case llvm should return a pointer which
points to the next none zero sized parameter.
const locals now detect if the value ends up being comptime known. In
such case, it replaces the runtime AIR instructions with a decl_ref
const.
In the backends, some more sophisticated logic for marking decls as
alive was needed to prevent Decls incorrectly being garbage collected
that were indirectly referenced in such manner.
This commit fixes two problems:
* `zig build-obj` regressed from the cache-mode branch. It would crash
because it assumed that dirname on the emit bin path would not be
null. This assumption was invalid when outputting to the current
working directory - a pretty common use case for `zig build-obj`.
* When using the LLVM backend, `-fno-emit-bin` combined with any other
kind of emitting, such as `-femit-asm`, emitted nothing.
Both issues are now fixed.
Doc comments reproduced here:
This function is called by the frontend before flush(). It communicates that
`options.bin_file.emit` directory needs to be renamed from
`[zig-cache]/tmp/[random]` to `[zig-cache]/o/[digest]`.
The frontend would like to simply perform a file system rename, however,
some linker backends care about the file paths of the objects they are linking.
So this function call tells linker backends to rename the paths of object files
to observe the new directory path.
Linker backends which do not have this requirement can fall back to the simple
implementation at the bottom of this function.
This function is only called when CacheMode is `whole`.
This solves stack trace regressions on Windows and macOS because the
linker backends do not observe object file paths until flush().
Effectively a small continuation of #10152
This allows the for.zig behavior tests to pass. Unfortunately to fully test everything I had to move a lot of behavior tests from array.zig; most of them now pass (sorry @rainbowbismuth!)
I'm also conflicted on how I store constants into arrays because it's kind of stupid; array's can't be re-initialized using the same syntax, so instead of initializing each element, a new array is made which is copied into the destination. This also required that renderValue can't emit string literals for byte arrays given that they need to always have an extra byte for the NULL terminator, meaning that strings are no longer grep-able in the output.
Comment from this commit reproduced here:
LLVM does not allow us to change the type of globals. So we must
create a new global with the correct type, copy all its attributes,
and then update all references to point to the new global,
delete the original, and rename the new one to the old one's name.
This is necessary because LLVM does not support const bitcasting
a struct with padding bytes, which is needed to lower a const union value
to LLVM, when a field other than the most-aligned is active. Instead,
we must lower to an unnamed struct, and pointer cast at usage sites
of the global. Such an unnamed struct is the cause of the global type
mismatch, because we don't have the LLVM type until the *value* is created,
whereas the global needs to be created based on the type alone, because
lowering the value may reference the global as a pointer.
* fix initialisation of void* fields of structs (initialises to 0xaa.. rather than {})
* don't generate struct fields when the field type does not have codegen bits
* in airAlloc generate a void* literal if the element type does not have codegen bits
Introduced a new AIR instruction: `tag_name`. Reasons to do this
instead of lowering it in Sema to a switch, function call, array
lookup, or if-else tower:
* Sema is a bottleneck; do less work in Sema whenever possible.
* If any optimization passes run, and the operand to becomes
comptime-known, then it could change to have a comptime result
value instead of lowering to a function or array or something which
would then have to be garbage-collected.
* Backends may want to choose to use a function and a switch branch,
or they may want to use a different strategy.
Codegen for `@tagName` is implemented for the LLVM backend but not any
others yet.
Introduced some new `Type` tags:
* `const_slice_u8_sentinel_0`
* `manyptr_const_u8_sentinel_0`
The motivation for this was to make typeof() on the tag_name AIR
instruction non-allocating.
A bunch more enum tests are passing now.
Layout algorithm: all `align(0)` fields are squished together as if they
were a single integer with a number of bits equal to `@bitSizeOf` each
field added together. Then the natural ABI alignment of that integer is
used for that pseudo-field.
* Extract common logic between `zirStructInitEmpty` and
`zirStructInit`.
* `resolveTypeFields` additionally sets status to `have_layout` if the
total number of fields is 0.
While this is technically incorrect, proper handling of anyopaque, as well
as regular opaque, is probably best left until pointers to zero-sized types
having no bits is abolished.
This allows the inferred error set of comptime and inline invocations to be
resolved separately from the inferred error set of the runtime version or other
comptime/inline invocations.
This branch introduced std.Target.TargetAbi when we already had
std.Target.Abi which was, unsurprisingly, already suited for this task.
Also pull out the -mabi= cc flag addition to the common area instead of
duplicating it for assembly and c files.
The target abi can also be set in build.zig via LibExeObjStep.target_abi
The value passed in is checked that it is a valid value in
std.Target.TargetAbi
The target abi is also validated against the target cpu
Previously, when a coercion needed to be inserted into a break
instruction, the `br` AIR instruction would be rewritten so that the
block operand was a sub-block that did the coercion. The problem is that
the sub-block itself was never added to the parent block, resulting in
the `br` instruction operand being a bad reference.
Now, the `br` AIR instruction that needs to have coercion instructions
added is replaced with the sub-block itself with type `noreturn`, and
then the sub-block has the coercion instructions and a new `br`
instruction that breaks from the original block.
LLVM backend needed to be fixed to lower `noreturn` blocks without
emitting an unused LLVM basic block.
* Introduce a mechanism into Sema for emitting a compile error when an
integer is too big and we need it to fit into a usize.
* Add `@intCast` where necessary
* link/MachO: fix an unnecessary allocation when all that was happening
was appending zeroes to an ArrayList.
* Add `error.Overflow` as a possible error to some codepaths, allowing
usage of `math.intCast`.
closes#9710
-airLoad and airStore now properly report an error if they are used with an array, instead of having the C compiler emit a vague error
-airStoreUndefined now works with array types
-structFieldPtr now works with array types, allowing generics' tests to pass
-add additional test cases that were found to be passing
-add basic int128 test cases which previously did not pass but weren't covered
-most test cases in cast.zig now pass
-i128/u128 or smaller int constants can now be rendered
-unsigned int constants are now always suffixed with 'u' to prevent random compile errors
-pointers with a val tag of 'zero' now just emit a 0 constant which coerces to the pointer type and fixes some warnings with ordered comparisons
-pointers with a val tag of 'one' are now casted back to the pointer type
-support pointers with a u64 val
-fix bug where rendering an array's type will emit more indirection than is needed
-render uint128_t/int128_t manually when needed
-implement ptr_add/sub AIR handlers manually so they manually cast to int types which avoids UB if the result or ptr operand is NULL
-implement airPtrElemVal/Ptr
-airAlloc for arrays will not allocate a ref as the local for the array is already a reference/pointer to the array itself
-fix airPtrToInt by casting to the int type
* wasm: Move wasm's codegen to arch/wasm/CodeGen.zig
* wasm: Define Wasm's Mir
This declares the initial most-used instructions for wasm as
well as the data that represents them.
TODO: Add binary operand opcodes.
By re-using the wasm opcode values, we can emit each opcode very easily
by simply using `@enumToInt()`. However, this poses a possible problem:
If we use all of wasm's opcodes, it leaves us no room to use synthetic opcodes such as debugging instructions.
We could use reserved opcodes, but the wasm spec may use them at some point.
TODO: Check if we should perhaps use a 16bit tag where the highest bits are used for synthetic opcodes.
* wasm: Define basic Emit structure
* wasm: Implement corresponding Emit functions for MIR
* wasm: Initial lowering to MIR
- This implements lowering to MIR from AIR for storing and loading of locals
as well as emitting immediates.
- Relocating function indexes has been simplified a lot as well as we no
longer need to patch offsets and we write a relocatable value instead.
- Locals are now emitted at the beginning of the function section entry
meaning all offsets we generate are stable.
* wasm: Lower all AIR instructions to MIR
* wasm: Implement remaining MIR instructions
* wasm: Fix function relocations
* wasm: Get all tests working
* wasm: Make `Data` 4 bytes instead of 8.
- 64bit immediates are now stored in 2 seperate u32's.
- 64bit floats are now stored in 2 seperate u32's.
- `mem_arg` is now stored as a seperate payload in extra.
This commit makes airStore() handle undefined values directly instead of
delegating to renderValue(): the call to renderValue() happens too late,
when "dest = " has already been written to the stream, at which point
there's no sane way to initialize e.g. struct values by assignment.
Instead, we make airStore() use memset(dest, 0xaa, sizeof(dest)), which
should transparently handle all types.
Also moves the newly-passing tests to the top of test/behavior.zig.
1. Changed Zig pointers to functions to be typedef'd so then we can
treat them the same as other types.
2. Distinguished between const slices (zig_L prefix) and mut slices
(zig_M prefix).
3. Changed lowering of Zig "const pointers" (e.g. *const u8) to to C
"pointers to const" (e.g. const char *) rather than C "const
pointers" (e.g. char * const)
4. Ensured that all typedefs are "linked" even if the decl doesn't
require any forward declarations
5. Added test that exercises function pointer type rendering
6. Changed .slice_ptr instruction to allocate pointer local rather than
a uintptr_t local
New AIR instruction: `optional_payload_ptr_set`
It's like `optional_payload_ptr` except it sets the non-null bit.
When storing to the payload via a result location that is an optional,
`optional_payload_ptr_set` is now emitted. There is a new algorithm in
`zirCoerceResultPtr` which stores a dummy value through the result
pointer into a temporary block, and then pops off the AIR instructions
from the temporary block in order to determine how to transform the
result location pointer in case any in-between coercions need to happen.
Fixes a couple of behavior tests regarding optionals.
