LLVM optimization passes handle this better, and it allows Zig to
specify pointer parameter attributes such as readonly, nonnull, noalias,
and alignment.
closes#561
This moves some logic from resolveLlvmFunction to updateFunc and takes
advantage of the iteration we already do that takes into account C ABI
lowering, making LLVM parameter attributes accurate for C ABI functions
as well as our own unspecified calling convention.
Related to #11498.
Generally, the load instruction may need to make a copy of an
isByRef=true value, such as in the case of the following code:
```zig
pub fn swap(comptime T: type, a: *T, b: *T) void {
const tmp = a.*;
a.* = b.*;
b.* = tmp;
}
```
However, it only needs to do so if there are any instructions which can
possibly write to memory. When calling functions with isByRef=true
parameters, the AIR code that is generated looks like loads followed
directly by call.
This allows for a peephole optimization when lowering loads: if the load
instruction operates on an isByRef=true type and dies before any side effects
occur, then we can safely lower the load as a no-op that returns its
operand.
This is one out of three changes I intend to make to address #11498.
However I will put these changes in separate branches and merge them
separately so that we can have three independent points on the perf
charts.
This is one out of three changes I intend to make to address #11498.
However I will put these changes in separate branches and merge them
separately so that we can have three independent points on the perf
charts.
This check for primitives is already handled by the generic logic that
checks if the body ends up being empty. I kept this commit in the git
history in case we ever want that nodePrimitive function again in the
future, it might be useful.
The main purpose of this commit is to prepare to implement support for
callconv(), align(), linksection(), and addrspace() annotations on
generic functions where the provided expression depends on comptime
parameters (making the function generic).
It's a rather involved change, so this commit only makes the necessary
changes to AstGen without regressing any behavior, and a follow-up
commit can finish the task by making the enhancements to Sema.
By my quick estimation, the new encoding for functions is a negligible
improvement - along the lines of 0.005% fewer total ZIR bytes on
average. Still, it's nice that this commit, while adding more
data into ZIR, actually ends up reducing the storage size thanks to a
slightly more sophisticated encoding.
Zir.Inst.ExtendedFunc is renamed to Zir.Inst.FuncFancy to eliminate
confusion about it being an extended instruction (it used to be but is
no longer). The encoding for this instruction is completely reworked.
The encoding for Zir.Inst.Func is also changed slightly - when the
return type body length is 1, then only a Zir.Inst.Ref is provided; not
a full body.
linksection() and addrspace() are now communicated via func_fancy ZIR
instruction rather than as part of the corresponding decl. This allows
their expressions to observe comptime parameters.
Prior to this change, for an example compiler error test case with
multiple identical errors messages such as
```
:1:2: error: foo
:1:2: error: foo
```
the test harness would never increment the error index thus only
marking the very first error message as handled yielding a false
positive.
Additionally, while here, regress `dereference_anyopaque` test case
as not passing on `wasm32-wasi` target.
SPARC does not have an explicit notion of saving/restoring registers.
The usual windowing mechanism (save/restore/return) already takes care of that
for us.
Additionally:
* Sema: fix array cat/mul not setting the sentinel value
- This required an LLVM backend enhancement to the handling of the
AIR instruction aggregate_init that likely needs to be
propagated to the other backends.
* Sema: report integer overflow of array concatenation in a proper
compile error instead of crashing.
* Sema: fix not using proper pointer address space for array cat/mul
