After a discussion about language specs, this seems like the best way to
go, because it's simpler to reason about both for humans and compilers.
The `bitcast_result_ptr` ZIR instruction is no longer needed.
This commit also implements writing enums, arrays, and vectors to
virtual memory at compile-time.
This unlocked some more of compiler-rt being able to build, which
in turn unlocks saturating arithmetic behavior tests.
There was also a memory leak in the comptime closure system which is now
fixed.
* New AIR instruction: slice, which constructs a slice out of a pointer
and a length.
* AstGen: use `coerced_ty` for start and end expressions, use `none`
for the sentinel, and don't try to load the result of the slice
operation because it returns a by-value result.
* Sema: pointer arithmetic is extracted into analyzePointerArithmetic
and it is used by the implementation of slice.
- Also I implemented comptime pointer addition.
* Sema: extract logic into analyzeSlicePtr, analyzeSliceLen and use them
inside the slice semantic analysis.
- The approach in stage2 is much cleaner than stage1 because it uses
more granular analysis calls for obtaining the slice pointer, doing
arithmetic on it, and checking if the length is comptime-known.
* Sema: use the slice Value Tag for slices when doing coercion from
pointer-to-array.
* LLVM backend: detect when emitting a GEP instruction into a
pointer-to-array and add the extra index that is required.
* Type: ptrAlignment for c_void returns 0.
* Implement Value.hash and Value.eql for slices.
* Remove accidentally duplicated behavior test.
* AstGen: Move `refToIndex` and `indexToRef` to Zir
* ZIR: the switch_block_*_* instruction tags are collapsed into one
switch_block tag which uses 4 bits for flags, and reduces the
scalar_cases_len field from 32 to 28 bits.
This freed up more ZIR tags, 2 of which are now used for
`switch_cond` and `switch_cond_ref` for producing the switch
condition value. For example, for union values it returns the
corresponding enum value.
* switching with multiple cases and ranges is not yet supported because
I want to change the ZIR encoding to store index pointers into the
extra array rather than storing prong indexes. This will avoid O(N^2)
iteration over prongs.
* AstGen now adds a `switch_cond` on the operand and then passes the
result of that to the `switch_block` instruction.
* Sema: partially implement `switch_capture_*` instructions.
* Sema: `unionToTag` notices if the enum type has only one possible value.
The remaining uses of this result location were causing a bunch of errors
problems where the pointers returned from rvalue and lvalue expressions
would be confused, allowing for extra pointers on rvalue expressions.
For example:
```zig
const X = struct {a: i32};
var x: X = .{.a = 1};
var ptr = &x;
_ = x.a;
```
In the last line, the lookup of x with result location .none_or_ref would
return a double pointer (**X). This would be dereferenced one, after which
a relative pointer to `a` would be fetched and derefenced to get the final
result.
However, this also allows us to manually construct a double pointer, and
fetch the field of the inner type of that:
```zig
_ = &(&(x)).a;
```
This problem also manifests itself with element access. There are two obvious
ways to fix the problem, both of which include replacing the usage of
.none_or_ref for field- and element accesses with something which
deterministically produce either a pointer or value: either result location
.ref or .none. In the former case, this would be paired with .elem_ptr, and
in the latter case with .elem_val.
Note that the stage 1 compiler does not have this problem, because there is
no equivalent of .elem_val and .field_val. In this way it is equivalent to
using the result location .ref for field- and element accesses.
In this case i have used .none, as this matches language behaviour more
closely.
* ZIR: the `array_type_sentinel` now has a source node attached to it
for proper error reporting.
* Refactor: move `Module.arrayType` to `Type.array`
* Value: the `bytes` and `array` tags now include the sentinel, if the
type has one. This simplifies comptime evaluation logic.
* Sema: fix `zirStructInitEmpty` to properly handle when the type is
void or a sentinel-terminated array. This handles the syntax `void{}`
and `[0:X]T{}`.
* Sema: fix the logic for reporting "cannot store runtime value in
compile time variable" as well as for emitting a runtime store when a
pointer value is comptime known but it is a global variable.
* Sema: implement elemVal for double pointer to array. This can happen
with this code for example: `var a: *[1]u8 = undefined; _ = a[0];`
* Sema: Rework the `storePtrVal` function to properly handle nested
structs and arrays.
- Also it now handles comptime stores through a bitcasted pointer.
When the pointer element type and the type according to the Decl
don't match, the element value is bitcasted before storage.
isZigPrimitiveType had a bug where it checked the integer names (e.g.
u32) before primitives, leading it to incorrectly return `false` for
`undefined` which starts with `u`.
Related: #9928
New ZIR instruction: elem_ptr_imm
This saves some memory for array literals since the element indexes are
communicated as immediate values rather than as references to other ZIR
instructions.
Companion commit to 61a53a587558ff1fe1b0ec98bb424022885edccf.
This commit also moves over a bunch of behavior test cases to the
passing-for-stage2 section.
Before, the system to replace a result location pointer with a
traditional break instruction did not notice the case when one of the
bodies was unreachable. Now, the emitted ZIR code is improved and
simplified in this case, resulting in a new passing behavior test.
* AstGen: fix emitting `store_to_inferred_ptr` when it should be emitting
`store` for a variable that has an explicit alignment.
* Compilation: fix a couple memory leaks
* Sema: implement support for locals that have specified alignment.
* Sema: implement `@intCast` when it needs to emit an AIR instruction.
* Sema: implement `@alignOf`
* Implement debug printing for extended alloc ZIR instructions.
* `@as` and `@bitCast` no longer unconditionally return `true` from
this function; they forward the question to their sub-expression.
* fix `@splat` incorrectly being marked as needing a memory location
(this function returns a SIMD vector; it definitely does not want a
memory location).
Makes AstGen generate slightly nicer ZIR, which in turn generates
slightly nicer AIR, generating slightly nicer machine code in debug
builds.
It also means I can procrastinate implementing the bitcast_result_ptr
ZIR instruction semantic analysis :^)
* Remove the builtins `@addWithSaturation`, `@subWithSaturation`,
`@mulWithSaturation`, and `@shlWithSaturation` now that we have
first-class syntax for saturating arithmetic.
* langref: Clarify the behavior of `@shlExact`.
* Ast: rename `bit_shift_left` to `shl` and `bit_shift_right` to `shr`
for consistency.
* Air: rename to include underscore separator with consistency with
the rest of the ops.
* Air: add shl_exact instruction
* Use non-extended tags for saturating arithmetic, to keep it
simple so that all the arithmetic operations can be done the same
way.
- Sema: unify analyzeArithmetic with analyzeSatArithmetic
- implement comptime `+|`, `-|`, and `*|`
- allow float operands to saturating arithmetic
* `<<|` allows any integer type for the RHS.
* C backend: fix rebase conflicts
* LLVM backend: reduce the amount of branching for arithmetic ops
* zig.h: fix magic number not matching actual size of C integer types
- modify AstGen binOpExt()/assignBinOpExt() to accept generic extended payload T
- rework Sema zirSatArithmetic() to use existing sema.analyzeArithmetic() by adding an `opt_extended` parameter.
- add airSatOp() to codegen/c.zig
- add saturating functions to src/link/C/zig.h
- adds initial support for the operators +|, -|, *|, <<|, +|=, -|=, *|=, <<|=
- uses operators in addition to builtins in behavior test
- adds binOpExt() and assignBinOpExt() to AstGen.zig. these need to be audited
* Merge call zir instructions to make space for field_call
* Fix bug with comptime known anytype args
* Delete the param_type zir instruction
* Move some passing tests to stage 2
* Implement a.b() function calls
* Add field_call_bind support for call and field builtins
* AstGen: fix not emitting `struct_init_empty` when an explicit type is
present in struct initialization syntax.
* AstGen: these two syntaxes now lower to identical ZIR:
- `var a = A{ .b = c };`
- `var a = @as(A, .{ .b = c });`
* Zir: clarify `auto_enum_tag` in the doc comments.
* LLVM Backend: fix lowering of function return types when the type has
0 bits.
* prepare compiler-rt to support being compiled by stage2
- put in a few minor workarounds that will be removed later, such as
using `builtin.stage2_arch` rather than `builtin.cpu.arch`.
- only try to export a few symbols for now - we'll move more symbols
over to the "working in stage2" section as they become functional
and gain test coverage.
- use `inline fn` at function declarations rather than `@call` with an
always_inline modifier at the callsites, to avoid depending on the
anonymous array literal syntax language feature (for now).
* AIR: replace floatcast instruction with fptrunc and fpext for
shortening and widening floating point values, respectively.
* Introduce a new ZIR instruction, `export_value`, which implements
`@export` for the case when the thing to be exported is a local
comptime value that points to a function.
- AstGen: fix `@export` not properly reporting ambiguous decl
references.
* Sema: handle ExportOptions linkage. The value is now available to all
backends.
- Implement setting global linkage as appropriate in the LLVM
backend. I did not yet inspect the LLVM IR, so this still needs to
be audited. There is already a pending task to make sure the alias
stuff is working as intended, and this is related.
- Sema almost handles section, just a tiny bit more code is needed in
`resolveExportOptions`.
* Sema: implement float widening and shortening for both `@floatCast`
and float coercion.
- Implement the LLVM backend code for this as well.
This is a property which solely belongs to pointers to functions,
not to the functions themselves. This cannot be properly represented by
stage 2 at the moment, as type with zigTypeTag() == .Fn is overloaded for
for function pointers and function prototypes.
Adds AST generation for address spaces on pointers, function prototypes,
function declarations and variable declarations. In the latter two cases,
declaration properties were already stored more efficiently in a declaration
structure. To accomodate these for address spaces, the bit indicating presence
of a linksection attribute has been extended to include either linksection,
address space, or both.
* langref: add some more "see also" links for atomics
* Add the following AIR instructions
- atomic_load
- atomic_store_unordered
- atomic_store_monotonic
- atomic_store_release
- atomic_store_seq_cst
- atomic_rmw
* Implement those AIR instructions in LLVM and C backends.
* AstGen: make the `ty` result locations for `@atomicRmw`, `@atomicLoad`,
and `@atomicStore` be `coerced_ty` to avoid unnecessary ZIR
instructions when Sema will be doing the coercions redundantly.
* Sema for `@atomicLoad` and `@atomicRmw` is done, however Sema for
`@atomicStore` is not yet implemented.
- comptime eval for `@atomicRmw` is not yet implemented.
* Sema: flesh out `coerceInMemoryAllowed` a little bit more. It can now
handle pointers.
* Implement Sema for `@cmpxchgWeak` and `@cmpxchgStrong`. Both runtime
and comptime codepaths are implement.
* Implement Codegen for LLVM backend and C backend.
* Add LazySrcLoc.node_offset_builtin_call_argX 3...5
* Sema: rework comptime control flow.
- `error.ComptimeReturn` is used to signal that a comptime function
call has returned a result (stored in the Inlining struct).
`analyzeCall` notices this and handles the result.
- The ZIR instructions `break_inline`, `block_inline`,
`condbr_inline` are now redundant and can be deleted. `break`,
`block`, and `condbr` function equivalently inside a comptime scope.
- The ZIR instructions `loop` and `repeat` also are modified to
directly perform comptime control flow inside a comptime scope,
skipping an unnecessary mechanism for analysis of runtime code.
This makes Zig perform closer to an interpreter when evaluating
comptime code.
* Sema: zirRetErrValue looks at Sema.ret_fn_ty rather than sema.func
for adding to the inferred error set. This fixes a bug for
inlined/comptime function calls.
* Implement ZIR printing for cmpxchg.
* stage1: make cmpxchg respect --single-threaded
- Our LLVM C++ API wrapper failed to expose this boolean flag before.
* Fix AIR printing for struct fields showing incorrect liveness data.
