This adds just enough debug info for i32/int parameters and return
values, with a path forward for adding DWARF type metadata for other
types.
As it happens, return type information is carried separately from
parameter information:
* Return type information is carried in the `type` of the `DISubprogram`
(as a `DISubroutineType` - which does carry parameter type information
as well, but that's unused when the DWARF is emitted by LLVM)
* Parameter information is carried by `DILocalVariable`s with a non-zero
`arg` value (representing the order of function parameters)
In the absence of locations for the parameters (future work), nothing
would usually keep the `DILocalVariable` live/reachable when emitting
DWARF - so for cases where this can happen (for clang, this happens in
optimized builds where all references to the parameter variable might be
optimized away) the variables can be "retained" in a list on the
`DISubprogram` - achieved by passing `AlwaysPreserve` parameter to
`createParameterVariable` (adds them to a list, then that list gets
attached to the `DISubprogram` when it's finalized later)
For now, any unsupported types are emitted as `void*` (except void
return, which is implemented as void) as a placeholder.
Given this example:
```
import Core library "io";
class MyClass {
}
fn Unsupported(v: MyClass) {
}
fn Ret() -> i32 {
return 42;
}
fn Arg(x: i32) {
Core.Print(x);
}
fn Run() {
}
```
this is the resulting DWARF:
```
DW_TAG_compile_unit
DW_AT_name ("test.carbon")
DW_TAG_subprogram
DW_AT_name ("Unsupported")
DW_TAG_formal_parameter
DW_AT_type (0x00000066 "void *")
DW_TAG_subprogram
DW_AT_name ("Ret")
DW_AT_type (0x00000062 "int")
DW_TAG_subprogram
DW_AT_name ("Arg")
DW_TAG_formal_parameter
DW_AT_type (0x00000062 "int")
DW_TAG_subprogram
DW_AT_name ("Run")
DW_TAG_base_type
DW_AT_name ("int")
DW_TAG_pointer_type
```
And the debugger:
```
(gdb) p Ret()
$1 = 42
(gdb) p Arg(4)
4
$2 = void
```
I'm not sure if there's a way this logic should be merged with the logic
for making the `llvm::Function` type (which the `DISubroutineType`
building code was inspired by/copied from) - since they're done at
different times/places, I don't think there's an easy way to do it in
one pass, but maybe the code can be shared (even if it's run twice) in
some generic `SemIR::Function` type walker.
---------
Co-authored-by: Dana Jansens <danakj@orodu.net>
This helps at least lldb handle calling functions (currently the debug
info describes every function as `void()`, so no parameters or return
values are supported) - seems gdb and lldb both depend on demangling to
varying degrees in C code (marking a function as "prototyped" in C in
DWARF does seem to also address this problem).
Given:
```
fn PrintThree() {
Core.Print(3);
}
```
Before:
```
(lldb) p PrintThree()
error: Couldn't look up symbols:
PrintThree
Hint: The expression tried to call a function that is not present in
the target, perhaps because it was optimized out by the compiler.
```
After:
```
(lldb) p PrintThree()
3
(lldb)
```
Adds a flag `--optimize=<mode>` that specifies what to optimize for:
* `--optimize=none` turns off the optimizer as much as possible, but
still respects always_inline.
* `--optimize=debug` aims to be the equivalent of `-Og` / `-O1`, and
provides optimizations that don't affect the ability to debug the
program. This is the default.
* `--optimize=size` optimizes for the size of the produced program, and
aims to be the equivalent of `-Oz`.
* `--optimize=speed` optimizes for the execution time of the produced
program, and aims to be the equivalent of `-O3`.
Following the approach taken by Clang, the optimization level feeds into
both the configuration of the LLVM pass pipeline and the attributes
added to function definitions generated by the frontend.
Optimization is performed in a new phase, `optimize`, which runs between
`lower` and `codegen`.
---------
Co-authored-by: Dana Jansens <danakj@orodu.net>
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
Add `Dependent` value and initializing representations for types whose
representations are unknown because they are dependent. When generating
SemIR in such cases, use a worst-case initializing representation that
both provides a destination address and also propagates a potential
result value.
Use this to fix incorrect lowering and lowering crashes for specific
functions involving generic types that don't use a copy value
representation.
In lowering, be careful to distinguish between whether the initializing
representation for the generic return type uses a return slot (which
affects whether the SemIR declaration and call have one) and whether the
initializing representation for the specific return type uses a return
slot (which affects whether the LLVM IR declaration and call have one).
Adds min-preludes to a few more slowest tests, and adds them to most of
the lowering tests, with a few exceptions that make use of operators.
This take the runtime of file_test down from about 8s to about 7s on my
machine.
We add support for Negate on uints in the min-preludes.
In line with the proposal in #4682, this changes the array syntax to be
array(T, N). `array` is a builtin keyword which must be followed by
parens containing two expressions and a separating comma.
The array type expression is still fully builtin, it does not forward to
a Core.Array library type yet. It merely adds the `ArrayType`
instruction, as was done with the previous syntax.
Followup work will change the instruction to reference to Core.Array,
once the library type exists and can be used directly.
---------
Co-authored-by: zygoloid <richard@metafoo.co.uk>
- The actual reason I started this: minor lowering updates in the golden
LLVM IR
- Process.inc changed enough to need a patch context update.
- https://github.com/llvm/llvm-project/pull/123126 added `proto_library`
uses without a `load`, which is broken in bazel 8
- Just commenting these out because we don't use them. I'll follow up
separately about a possible fix, but continuing to use `WORKSPACE` is a
bigger issue LLVM probably should address.
- Note this update is also triggering removal of `migrate_cpp`, in #4887
Instead of treating `Core.Int` as the toolchain's builtin `IntType`,
model it as a class that adapts the builtin type. This aligns us better
with the intended language model, gives an associated library for
`impl`s involving `Core.Int` to live within, and opens the door adding
member functions to `Core.Int` if we decide that is desirable.
Remarkably it also seems to make the formatted SemIR a little smaller,
because a call to a generic class generates less IR than a call to a
function.
Such indexing operations are created by array initialization. Since we
switched integer literals to be of type IntLiteral we've been attempting
to index arrays with the (empty) representation of an IntLiteral rather
than with an actual integer value.
josh11bandJosh L
Richard Smith
David BlaikieandDana Jansens
Geoff Romer
Jon Ross-Perkins