Add a documentation page on the key points of the conversion to LLVM IR. This
focuses on the aspects of conversion that are relevant for integration of the
LLVM IR dialect (and produced LLVM IR that is mostly a one-to-one translation)
into other projects. In particular, it describes the type conversion rules and
the memref model supporting dynamic sizes.
PiperOrigin-RevId: 235190772
The LLVM IR pass was bootstrapped without user documentation, following LLVM's
language reference and existing conversions between MLIR standard operations
and LLVM IR instructions. Provide concise documentation of the LLVM IR dialect
operations. This documentation does not describe the semantics of the
operations, which should match that of LLVM IR, but highlights the structural
differences in operation definitions, in particular using attributes instead of
constant-only values. It also describes pseudo-operations that exist only to
make the LLVM IR dialect self-contained within MLIR.
While it could have been possible to generate operation description from
TableGen, this opts for a more concise format where groups of related
operations are described together.
PiperOrigin-RevId: 235149136
Add support for lowering DivF and RemF to LLVM::FDiv and LLMV::FRem
respectively. The lowering is a trivial one-to-one transformation.
The corresponding operations already existed in the LLVM IR dialect and can be
lowered to the LLVM IR proper. Add the necessary tests for scalar and vector
forms.
PiperOrigin-RevId: 234984608
This change introduces three new operators in EDSC: Div (also exposed
via Expr.__div__ aka /) -- floating-point division, FloorDiv and CeilDiv
for flooring/ceiling index division.
The lowering to LLVM will be implemented in b/124872679.
PiperOrigin-RevId: 234963217
Introduce support for binding MLIR functions as constant expressions. Standard
constant operation supports functions as possible constant values.
Provide C APIs to look up existing named functions in an MLIR module and expose
them to the Python bindings. Provide Python bindings to declare a function in
an MLIR module without defining it and to add a definition given a function
declaration. These declarations are useful when attempting to link MLIR
modules with, e.g., the standard library.
Introduce EDSC support for direct and indirect calls to other MLIR functions.
Internally, an indirect call is always emitted to leverage existing support for
delayed construction of MLIR Values using EDSC Exprs. If the expression is
bound to a constant function (looked up or declared beforehand), MLIR constant
folding will be able to replace an indirect call by a direct call. Currently,
only zero- and one-result functions are supported since we don't have support
for multi-valued expressions in EDSC.
Expose function calling interface to Python bindings on expressions by defining
a `__call__` function accepting a variable number of arguments.
PiperOrigin-RevId: 234959444
* Introduce a OpTrait class in C++ to wrap the TableGen definition;
* Introduce PredOpTrait and rename previous usage of OpTrait to NativeOpTrait;
* PredOpTrait allows specifying a trait of the operation by way of predicate on the operation. This will be used in future to create reusable set of trait building blocks in the definition of operations. E.g., indicating whether to operands have the same type and allowing locally documenting op requirements by trait composition.
- Some of these building blocks could later evolve into known fixed set as LLVMs backends do, but that can be considered with more data.
* Use the modelling to address one verify TODO in a very local manner.
This subsumes the current custom verify specification which will be removed in a separate mechanical CL.
PiperOrigin-RevId: 234827169
A recent change made ConstantOp::build accept a NumericAttr or assert that a
generic Attribute is in fact a NumericAttr. The rationale behind the change
was that NumericAttrs have a type that can be used as the result type of the
constant operation. FunctionAttr also has a type, and it is valid to construct
function-typed constants as exercised by the parser.mlir test. Relax
ConstantOp::build back to take a generic Attribute. In the overload that only
takes an attribute, assert that the Attribute is either a NumericAttr or a
FunctionAttr, because it is necessary to extract the type. In the overload
that takes both type type and the attribute, delegate the attribute type
checking to ConstantOp::verify to prevent non-Builder-based Op construction
mechanisms from creating invalid IR.
PiperOrigin-RevId: 234798569
The recent rework of MLIREmitter switched to using the generic call to
`builder.createOperation` from OperationState instead of individual customized
calls to `builder.create<>`. As a result, regular non-composed affine apply
operations where emitted. Introduce a special case in Expr::build to always
create composed affine maps instead, as it used to be the case before the
rework.
Such special-casing goes against the idea of EDSC generality and extensibility.
Instead, we should consider declaring the composed form canonical for
affine.apply operations and using the builder support for creating operations
and canonicalizing them immediately (ongoing effort).
PiperOrigin-RevId: 234790129
Introduce a type-safe way of building a 'for' loop with max/min bounds in EDSC.
Define new types MaxExpr and MinExpr in C++ EDSC API and expose them to Python
bindings. Use values of these type to construct 'for' loops with max/min in
newly introduced overloads of the `edsc::For` factory function. Note that in C
APIs, we still must expose MaxMinFor as a different function because C has no
overloads. Also note that MaxExpr and MinExpr do _not_ derive from Expr
because they are not allowed to be used in a regular Expr context (which may
produce `affine.apply` instructions not expecting `min` or `max`).
Factory functions `Min` and `Max` in Python can be further overloaded to
produce chains of comparisons and selects on non-index types. This is not
trivial in C++ since overloaded functions cannot differ by the return type only
(`MaxExpr` or `Expr`) and making `MaxExpr` derive from `Expr` defies the
purpose of type-safe construction.
PiperOrigin-RevId: 234786131
MLIR supports 'for' loops with lower(upper) bound defined by taking a
maximum(minimum) of a list of expressions, but does not have first-class affine
constructs for the maximum(minimum). All these expressions must have affine
provenance, similarly to a single-expression bound. Add support for
constructing such loops using EDSC. The expression factory function is called
`edsc::MaxMinFor` to (1) highlight that the maximum(minimum) operation is
applied to the lower(upper) bound expressions and (2) differentiate it from a
`edsc::For` that creates multiple perfectly nested loops (and should arguably
be called `edsc::ForNest`).
PiperOrigin-RevId: 234785996
Introduce a functionality to create EDSC expressions from typed constants.
This complements the current functionality that uses "unbound" expressions and
binds them to a specific constant before emission. It comes in handy in cases
where we want to check if something is a constant early during construciton
rather than late during emission, for example multiplications and divisions in
affine expressions. This is also consistent with MLIR vision of constants
being defined by an operation (rather than being special kinds of values in the
IR) by exposing this operation as EDSC expression.
PiperOrigin-RevId: 234758020
This CL fixes 2 recent issues with EDSCs:
1. the type of the LHS in Stmt::operator=(Expr rhs) should be the same as the (asserted unique) return type;
2. symbols coming from DimOp should be admissible as lower / upper bounds in For
The relevant tests are added.
PiperOrigin-RevId: 234750249
- compute slices precisely where the destination iteration depends on multiple source
iterations (instead of over-approximating to the whole source loop extent)
- update unionBoundingBox to deal with input with non-matching symbols
- reenable disabled backend test case
PiperOrigin-RevId: 234714069
- hoist DMAs past all loops immediately surrounding the region that the latter
is invariant on - do this at DMA generation time itself
PiperOrigin-RevId: 234628447
Originally, edsc::Expr had a long enum edsc::ExprKind with all supported types
of operations. Recent Expr extensibility support removed the need to specify
supported types in advance. Replace the no-longer-used blocks of enum values
reserved for unary/binary/ternary/variadic expressions with simple values (it
is still useful to know if an expression is, e.g., binary to access it through
a simpler API).
Furthermore, wrap string-comparison now used to identify specific ops into an
`Expr::is_op<>` function template, that acts similarly to `Instruction::isa<>`.
Introduce `{Unary,Binary,Ternary,Variadic}Expr::make<> ` function template that
creates a Expression emitting the MLIR Op specified as template argument.
PiperOrigin-RevId: 234612916
Expose the result types of edsc::Expr, which are now stored for all types of
Exprs and not only for the variadic ones. Require return types when an Expr is
constructed, if it will ever have some. An empty return type list is
interpreted as an Expr that does not create a value (e.g. `return` or `store`).
Conceptually, all edss::Exprs are now typed, with the type being a (potentially
empty) tuple of return types. Unbound expressions and Bindables must now be
constructed with a specific type they will take. This makes EDSC less
evidently type-polymorphic, but we can still write generic code such as
Expr sumOfSquares(Expr lhs, Expr rhs) { return lhs * lhs + rhs * rhs; }
and use it to construct different typed expressions as
sumOfSquares(Bindable(IndexType::get(ctx)), Bindable(IndexType::get(ctx)));
sumOfSquares(Bindable(FloatType::getF32(ctx)),
Bindable(FloatType::getF32(ctx)));
On the positive side, we get the following.
1. We can now perform type checking when constructing Exprs rather than during
MLIR emission. Nevertheless, this is still duplicates the Op::verify()
until we can factor out type checking from that.
2. MLIREmitter is significantly simplified.
3. ExprKind enum is only used for actual kinds of expressions. Data structures
are converging with AbstractOperation, and the users can now create a
VariadicExpr("canonical_op_name", {types}, {exprs}) for any operation, even
an unregistered one without having to extend the enum and make pervasive
changes to EDSCs.
On the negative side, we get the following.
1. Typed bindables are more verbose, even in Python.
2. We lose the ability to do print debugging for higher-level EDSC abstractions
that are implemented as multiple MLIR Ops, for example logical disjunction.
This is the step 2/n towards making EDSC extensible.
***
Move MLIR Op construction from MLIREmitter::emitExpr to Expr::build since Expr
now has sufficient information to build itself.
This is the step 3/n towards making EDSC extensible.
Both of these strive to minimize the amount of irrelevant changes. In
particular, this introduces more complex pretty-printing for affine and binary
expression to make sure tests continue to pass. It also relies on string
comparison to identify specific operations that an Expr produces.
PiperOrigin-RevId: 234609882
This CL extended TableGen Operator class to provide accessors for information on op
results.
In OpDefinitionGen, added checks to make sure only the last result can be variadic,
and adjusted traits and builders generation to consider variadic results.
PiperOrigin-RevId: 234596124
EDSC currently implement a block as a statement that is itself a list of
statements. This suffers from two modeling problems: (1) these blocks are not
addressable, i.e. one cannot create an instruction where thus constructed block
is a successor; (2) they support block nesting, which is not supported by MLIR
blocks. Furthermore, emitting such "compound statement" (misleadingly named
`Block` in Python bindings) does not actually produce a new Block in the IR.
Implement support for creating actual IR Blocks in EDSC. In particular, define
a new StmtBlock EDSC class that is neither an Expr nor a Stmt but contains a
list of Stmts. Additionally, StmtBlock may have (early-) typed arguments.
These arguments are Bindable expressions that can be used inside the block.
Provide two calls in the MLIREmitter, `emitBlock` that actually emits a new
block and `emitBlockBody` that only emits the instructions contained in the
block without creating a new block. In the latter case, the instructions must
not use block arguments.
Update Python bindings to make it clear when instruction emission happens
without creating a new block.
PiperOrigin-RevId: 234556474
The parameter to emitStandaloneParamBuilder() was renamed from hasResultType to
isAllSameType, which is the opposite boolean value. The logic should be changed
to make them consistent.
Also re-ordered some methods in Operator. And few other tiny improvements.
PiperOrigin-RevId: 234478316
generation pass to make it drop certain assumptions, complete TODOs.
- multiple fixes for getMemoryFootprintBytes
- pass loopDepth correctly from getMemoryFootprintBytes()
- use union while computing memory footprints
- bug fixes for addAffineForOpDomain
- take into account loop step
- add domains of other loop IVs in turn that might have been used in the bounds
- dma-generate: drop assumption of "non-unit stride loops being tile space loops
and skipping those and recursing to inner depths"; DMA generation is now purely
based on available fast mem capacity and memory footprint's calculated
- handle memory region compute failures/bailouts correctly from dma-generate
- loop tiling cleanup/NFC
- update some debug and error messages to use emitNote/emitError in
pipeline-data-transfer pass - NFC
PiperOrigin-RevId: 234245969
The existing implementation of makeFunctionType in EDSC contains a bug: the
array of input types is overwritten using output types passed as arguments and
the array of output types is never filled in. This leads to all sorts of
incorrect memory behavior. Fill in the array of output types using the proper
argument.
PiperOrigin-RevId: 234177221
A recent change introduced a possibility to run LLVM IR transformation during
JIT-compilation in the ExecutionEngine. Provide helper functions that
construct IR transformers given either clang-style optimization levels or a
list passes to run. The latter wraps the LLVM command line option parser to
parse strings rather than actual command line arguments. As a result, we can
run either of
mlir-cpu-runner -O3 input.mlir
mlir-cpu-runner -some-mlir-pass -llvm-opts="-llvm-pass -other-llvm-pass"
to combine different transformations. The transformer builder functions are
provided as a separate library that depends on LLVM pass libraries unlike the
main execution engine library. The library can be used for integrating MLIR
execution engine into external frameworks.
PiperOrigin-RevId: 234173493
*) Adds utility to LoopUtils to perform loop interchange of two AffineForOps.
*) Adds utility to LoopUtils to sink a loop to a specified depth within a loop nest, using a series of loop interchanges.
*) Computes dependences between all loads and stores in the loop nest, and classifies each loop as parallel or sequential.
*) Computes loop interchange permutation required to sink sequential loops (and raise parallel loop nests) while preserving relative order among them.
*) Checks each dependence against the permutation to make sure that dependences would not be violated by the loop interchange transformation.
*) Calls loop interchange in LoopFusion pass on consumer loop nests before fusing in producers, sinking loops with loop carried dependences deeper into the consumer loop nest.
*) Adds and updates related unit tests.
PiperOrigin-RevId: 234158370
We specify op operands and results in TableGen op definition using the same syntax.
They should be modelled similarly in TableGen driver wrapper classes.
PiperOrigin-RevId: 234153332
Add support for converting MLIR `call_indirect` instructions to the LLVM IR
dialect. In LLVM IR, the same instruction is used for direct and indirect
calls. In the dialect, we have `llvm.call` and `llvm.call0` to work around the
absence of the void type in MLIR. For direct calls, the callee is stored as
instruction attribute. Use the same pair of instructions for indirect calls by
omitting the callee attribute. In the MLIR to LLVM IR translator, check the
presence of attribute to decide whether to construct a direct or an indirect
call using different LLVM IR Builder functions.
Add support for converting constants of function type to the LLVM IR dialect
and for translating them to the LLVM IR proper. The `llvm.constant` operation
works similarly to other types: its attribute has MLIR function type but the
value it produces has LLVM IR function type wrapped in the dialect type. While
lowering, look up the pointer to the converted function in the corresponding
mapping.
PiperOrigin-RevId: 234132351
Function types are built-in in MLIR and affect the validity of the IR itself.
However, advanced target dialects such as the LLVM IR dialect may include
custom function types. Until now, dialect conversion was expecting function
types not to be converted to the custom type: although the signatures was
allowed to change, the outer type must have been an mlir::FunctionType. This
effectively prevented dialect conversion from creating instructions that
operate on values of the custom function type.
Dissociate function signature conversion from general type conversion.
Function signature conversion must still produce an mlir::FunctionType and is
used in places where built-in types are required to make IR valid. General
type conversion is used for SSA values, including function and block arguments
and function results.
Exercise this behavior in the LLVM IR dialect conversion by converting function
types to LLVM IR function pointer types. The pointer to a function is chosen
to provide consistent lowering of higher-order functions: while it is possible
to have a value of function type, it is not possible to create a function type
accepting a returning another function type.
PiperOrigin-RevId: 234124494
Update FlatAffineConstraints::getLower/UpperBounds to project to the identifier for which bounds are being computed. This change enables computing bounds on an identifier which were previously dependent on the bounds of another identifier.
PiperOrigin-RevId: 234017514
for dma-generate, loop-unroll.
- add -tile-sizes command line option for loop tiling to specify different tile
sizes for loops in a band
- clean up command line options for loop-unroll, dma-generate (remove
cl::hidden)
PiperOrigin-RevId: 234006232
If we see an add op adding a constant value to a convolution op with constant
bias, we can fuse the add into the convolution op by constant folding the
bias and the add op's constant operand.
This CL also removes dangling RewriterGen check that prevents us from using
nested DAG nodes in result patterns, which is already supported.
PiperOrigin-RevId: 233989654
For ops with the SameOperandsAndResultType trait, we know that all result types
should be the same as the first operand's type. So we can generate a build()
method without requiring result types as parameters and also invoke this method
when constructing such ops during expanding rewrite patterns.
Similarly for ops have broadcast behavior, we can define build() method to use
the deduced type as the result type. So we can also calling into this build()
method when constructing ops in RewriterGen.
PiperOrigin-RevId: 233988307
In LowerEDSCTestPass, there are two range-for loops that only do assertions on
the loop variable. With assertions disabled, the variable becomes unused and
triggers a warning promoted to error. Cast it to void in the loop to supress
the warning.
PiperOrigin-RevId: 233936171
Original implementation of the translation from MLIR to LLVM IR operated on the
Standard+BuiltIn dialect, with a later addition of the SuperVector dialect.
This required the translation to be aware of a potetially large number of other
dialects as the infrastructure extended. With the recent introduction of the
LLVM IR dialect into MLIR, the translation can be switched to only translate
the LLVM IR dialect, and the translation of the operations becomes largely
mechanical.
The reimplementation of the translator follows the lines of the original
translator in function and basic block conversion. In particular, block
arguments are converted to LLVM IR PHI nodes, which are connected to their
sources after all blocks of a function had been converted. Thanks to LLVM IR
types being wrapped in the MLIR LLVM dialect type, type conversion is
simplified to only convert function types, all other types are simply
unwrapped. Individual instructions are constructed using the LLVM IRBuilder,
which has a great potential for being table-generated from the LLVM IR dialect
operation definitions.
The input of the test/Target/llvmir.mlir is updated to use the MLIR LLVM IR
dialect. While it is now redundant with the dialect conversion test, the point
of the exercise is to guarantee exactly the same LLVM IR is emitted. (Only the
name of the allocation function is changed from `__mlir_alloc` to `alloc` in
the CHECK lines.) It will be simplified in a follow-up commit.
PiperOrigin-RevId: 233842306
EDSC expressions evolved to have different types of underlying storage.
Separate classes are used for unary, binary, ternary and variadic expressions.
The latter covers all the needs of the three special cases. Remove these
special cases and use a single ExprStorage class everywhere while maintaining
the same APIs at the Expr level (ExprStorage is an internal implementation
class).
This is step 1/n to converging EDSC expressions and Ops and making EDSCs
support custom operations.
PiperOrigin-RevId: 233704912
DimOp is converted to a constant LLVM IR dialect operation for static
dimensions and to an access to the dynamic size info stored in the memref
descriptor for the dynamic dimensions. This behavior is consistent with the
existing mlir-translator.
This completes the porting of MLIR -> LLVM lowering to the dialect conversion
infrastructure.
PiperOrigin-RevId: 233665634
- for the DMA transfers being pipelined through double buffering, generate
deallocs for the double buffers being alloc'ed
This change is along the lines of cl/233502632. We initially wanted to experiment with
scoped allocation - so the deallocation's were usually not necessary; however, they are
needed even with scoped allocations in some situations - for eg. when the enclosing loop
gets unrolled. The dealloc serves as an end of lifetime marker.
PiperOrigin-RevId: 233653463
Alex Zinenko