EmitC currently models C's `&` and `*` operators via its `apply` op,
which has several drawbacks:
- Its pre-lvalue semantics combines dereferencing with memory access.
- Representing multiple opcodes (selected by an attribute) in a single
op complicates the code by adding a second, attribute-based selection
layer on top of MLIR's standard `isa<>` mechanism.
This patch adds two distinct, lvalue-based ops to model these C operators.
EmitC passes were converted to use the new ops instead of `apply`, which
is now deprecated.
Integer attributes supplied to `emitc.call_opaque` as arguments were
treated as index into the operands list. This should be the case only
for the normal arguments but not for the template arguments which can't
refer to SSA values. This commit updates the handling of template
arguments in mlir-to-cpp by removing special handling of integer
attributes.
This adds an `emitc.lvalue` type which models assignable lvlaues in the
type system. Operations modifying memory are restricted to this type
accordingly.
See also the discussion on
[discourse](https://discourse.llvm.org/t/rfc-separate-variables-from-ssa-values-in-emitc/75224/9).
The most notable changes are as follows.
- `emitc.variable` and `emitc.global` ops are restricted to return
`emitc.array` or `emitc.lvalue` types
- Taking the address of a value is restricted to operands with lvalue
type
- Conversion from lvalues into SSA values is done with the new
`emitc.load` op
- The var operand of the `emitc.assign` op is restricted to lvalue type
- The result of the `emitc.subscript` and `emitc.get_global` ops is a
lvalue type
- The operands and results of the `emitc.member` and
`emitc.member_of_ptr` ops are restricted to lvalue types
---------
Co-authored-by: Matthias Gehre <matthias.gehre@amd.com>
Emits `2.0e+00f` instead of `(float)2.0e+00`.
This helps consumers of the emitted code, especially when there are
large numbers of floating point literals, to have a simple AST.
This models a one or multi-dimensional C/C++ array.
The type implements the `ShapedTypeInterface` and prints similar to
memref/tensor:
```
%arg0: !emitc.array<1xf32>,
%arg1: !emitc.array<10x20x30xi32>,
%arg2: !emitc.array<30x!emitc.ptr<i32>>,
%arg3: !emitc.array<30x!emitc.opaque<"int">>
```
It can be translated to a C array type when used as function parameter
or as `emitc.variable` type.
This renames the `emitc.call` op to `emitc.call_opaque` as the existing
call op does not refer to the callee by symbol. The rename allows to
introduce a new call op alongside with a future `emitc.func` op to model
and facilitate functions and function calls.
This upstreams the Cpp emitter, initially presented with [1], from [2]
to MLIR core. Together with the previously upstreamed EmitC dialect [3],
the target allows to translate MLIR to C/C++.
[1] https://reviews.llvm.org/D76571
[2] https://github.com/iml130/mlir-emitc
[3] https://reviews.llvm.org/D103969
Co-authored-by: Jacques Pienaar <jpienaar@google.com>
Co-authored-by: Simon Camphausen <simon.camphausen@iml.fraunhofer.de>
Co-authored-by: Oliver Scherf <oliver.scherf@iml.fraunhofer.de>
Reviewed By: jpienaar
Differential Revision: https://reviews.llvm.org/D104632
