Operations

• Operations
  • cir.alloca (::mlir::cir::AllocaOp)
    • Attributes:
    • Results:
  • cir.await (::mlir::cir::AwaitOp)
    • Attributes:
  • cir.binop (::mlir::cir::BinOp)
    • Attributes:
    • Operands:
    • Results:
  • cir.brcond (::mlir::cir::BrCondOp)
    • Operands:
    • Successors:
  • cir.br (::mlir::cir::BrOp)
    • Operands:
    • Successors:
  • cir.call (::mlir::cir::CallOp)
    • Attributes:
    • Operands:
    • Results:
  • cir.cast (::mlir::cir::CastOp)
    • Attributes:
    • Operands:
    • Results:
  • cir.cmp (::mlir::cir::CmpOp)
    • Attributes:
    • Operands:
    • Results:
  • cir.cst (::mlir::cir::ConstantOp)
    • Attributes:
    • Results:
  • cir.func (::mlir::cir::FuncOp)
    • Attributes:
  • cir.get_global (::mlir::cir::GetGlobalOp)
    • Attributes:
    • Results:
  • cir.global (::mlir::cir::GlobalOp)
    • Attributes:
  • cir.if (::mlir::cir::IfOp)
    • Operands:
  • cir.load (::mlir::cir::LoadOp)
    • Attributes:
    • Operands:
    • Results:
  • cir.loop (::mlir::cir::LoopOp)
    • Attributes:
  • cir.ptr_stride (::mlir::cir::PtrStrideOp)
    • Operands:
    • Results:
  • cir.return (::mlir::cir::ReturnOp)
    • Operands:
  • cir.scope (::mlir::cir::ScopeOp)
    • Results:
  • cir.store (::mlir::cir::StoreOp)
    • Operands:
  • cir.struct_element_addr (::mlir::cir::StructElementAddr)
    • Attributes:
    • Operands:
    • Results:
  • cir.switch (::mlir::cir::SwitchOp)
    • Attributes:
    • Operands:
  • cir.unary (::mlir::cir::UnaryOp)
    • Attributes:
    • Operands:
    • Results:
  • cir.yield (::mlir::cir::YieldOp)
    • Attributes:
    • Operands:

cir.alloca (::mlir::cir::AllocaOp)

Defines a scope-local variable

Syntax:

operation ::= `cir.alloca` $allocaType `,` `cir.ptr` type($addr) `,`
              `[` $name
              (`,` `init` $init^)?
              `]`
              (`ast` $ast^)? attr-dict

The cir.alloca operation defines a scope-local variable.

The presence init attribute indicates that the local variable represented by this alloca was originally initialized in C/C++ source code. In such cases, the first use contains the initialization (a cir.store, a cir.call to a ctor, etc).

The result type is a pointer to the input's type.

Example:

// int count = 3;
%0 = cir.alloca i32, !cir.ptr<i32>, ["count", init] {alignment = 4 : i64}

// int *ptr;
%1 = cir.alloca !cir.ptr<i32>, cir.ptr <!cir.ptr<i32>>, ["ptr"] {alignment = 8 : i64}
...

Attributes:

Results:

cir.await (::mlir::cir::AwaitOp)

Wraps C++ co_await implicit logic

Syntax:

operation ::= `cir.await` `(` $kind `,`
              `ready` `:` $ready `,`
              `suspend` `:` $suspend `,`
              `resume` `:` $resume `,`
              `)`
              attr-dict

The under the hood effect of using C++ co_await expr roughly translates to:

// co_await expr;

auto &&x = CommonExpr();
if (!x.await_ready()) {
   ...
   x.await_suspend(...);
   ...
}
x.await_resume();

cir.await represents this logic by using 3 regions:

• ready: covers veto power from x.await_ready()
• suspend: wraps actual x.await_suspend() logic
• resume: handles x.await_resume()

Breaking this up in regions allow individual scrutiny of conditions which might lead to folding some of them out. Lowerings coming out of CIR, e.g. LLVM, should use the suspend region to track more lower level codegen (e.g. intrinsic emission for coro.save/coro.suspend).

There are also 3 flavors of cir.await available:

• init: compiler generated initial suspend via implicit co_await.
• user: also known as normal, representing user written co_await's.
• final: compiler generated final suspend via implicit co_await.

From the C++ snippet we get:

  cir.scope {
    ... // auto &&x = CommonExpr();
    cir.await(user, ready : {
      ... // x.await_ready()
    }, suspend : {
      ... // x.await_suspend()
    }, resume : {
      ... // x.await_resume()
    })
  }

Note that resulution of the common expression is assumed to happen as part of the enclosing await scope.

Traits: NoRegionArguments, RecursivelySpeculatableImplTrait

Interfaces: ConditionallySpeculatable, RegionBranchOpInterface

Attributes:

cir.binop (::mlir::cir::BinOp)

Binary operations (arith and logic)

Syntax:

operation ::= `cir.binop` `(` $kind `,` $lhs `,` $rhs  `)` `:` type($lhs) attr-dict

cir.binop performs the binary operation according to the specified opcode kind: [mul, div, rem, add, sub, shl, shr, and, xor, or].

It requires two input operands and has one result, all types should be the same.

%7 = binop(add, %1, %2) : i32
%7 = binop(mul, %1, %2) : i8

Traits: AlwaysSpeculatableImplTrait, SameOperandsAndResultType, SameTypeOperands

Interfaces: ConditionallySpeculatable, InferTypeOpInterface, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Attributes:

Operands:

Results:

cir.brcond (::mlir::cir::BrCondOp)

Conditional branch

Syntax:

operation ::= `cir.brcond` $cond
              $destTrue (`(` $destOperandsTrue^ `:` type($destOperandsTrue) `)`)?
              `,`
              $destFalse (`(` $destOperandsFalse^ `:` type($destOperandsFalse) `)`)?
              attr-dict

The cir.brcond %cond, ^bb0, ^bb1 branches to ‘bb0' block in case %cond (which must be a !cir.bool type) evaluates to true, otherwise it branches to ‘bb1'.

Example:

  ...
    cir.brcond %a, ^bb3, ^bb4
  ^bb3:
    cir.return
  ^bb4:
    cir.yield

Traits: AlwaysSpeculatableImplTrait, SameVariadicOperandSize, Terminator

Interfaces: BranchOpInterface, ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Operands:

Successors:

cir.br (::mlir::cir::BrOp)

Unconditional branch

Syntax:

operation ::= `cir.br` $dest (`(` $destOperands^ `:` type($destOperands) `)`)? attr-dict

The cir.br branches unconditionally to a block. Used to represent C/C++ goto's and general block branching.

Example:

  ...
    cir.br ^bb3
  ^bb3:
    cir.return

Traits: AlwaysSpeculatableImplTrait, Terminator

Interfaces: BranchOpInterface, ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Operands:

Successors:

cir.call (::mlir::cir::CallOp)

call operation

Syntax:

operation ::= `cir.call` $callee `(` $operands `)` attr-dict `:` functional-type($operands, results)

The call operation represents a direct call to a function that is within the same symbol scope as the call. The operands and result types of the call must match the specified function type. The callee is encoded as a symbol reference attribute named "callee".

Since mlir::func::CallOp requires defining symbols to be tied with a mlir::func::FuncOp, a custom cir.call is needed to interop with cir.func. For now this is basically a simplified mlir::func::CallOp.

Example:

%2 = cir.call @my_add(%0, %1) : (f32, f32) -> f32

Interfaces: CallOpInterface, SymbolUserOpInterface

Attributes:

Operands:

Results:

cir.cast (::mlir::cir::CastOp)

Conversion between values of different types

Syntax:

operation ::= `cir.cast` `(` $kind `,` $src `:` type($src) `)`
              `,` type($result) attr-dict

Apply C/C++ usual conversions rules between values. Currently supported kinds:

• int_to_bool
• array_to_ptrdecay
• integral
• bitcast
• floating

This is effectively a subset of the rules from llvm-project/clang/include/clang/AST/OperationKinds.def; but note that some of the conversions aren't implemented in terms of cir.cast, lvalue-to-rvalue for instance is modeled as a regular cir.load.

%4 = cir.cast (int_to_bool, %3 : i32), !cir.bool
...
%x = cir.cast(array_to_ptrdecay, %0 : !cir.ptr<!cir.array<i32 x 10>>), !cir.ptr<i32>

Traits: AlwaysSpeculatableImplTrait

Interfaces: ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Attributes:

Operands:

Results:

cir.cmp (::mlir::cir::CmpOp)

Compare values two values and produce a boolean result

Syntax:

operation ::= `cir.cmp` `(` $kind `,` $lhs `,` $rhs  `)` `:` type($lhs) `,` type($result) attr-dict

cir.cmp compares two input operands of the same type and produces a cir.bool result. The kinds of comparison available are: [lt,gt,ge,eq,ne]

%7 = cir.cmp(gt, %1, %2) : i32, !cir.bool

Traits: AlwaysSpeculatableImplTrait, SameTypeOperands

Interfaces: ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Attributes:

Operands:

Results:

cir.cst (::mlir::cir::ConstantOp)

Defines a CIR constant

Syntax:

operation ::= `cir.cst` `(` custom<ConstantValue>($value) `)` attr-dict `:` type($res)

The cir.cst operation turns a literal into an SSA value. The data is attached to the operation as an attribute.

  %0 = cir.cst(42 : i32) : i32
  %1 = cir.cst(4.2 : f32) : f32
  %2 = cir.cst(nullptr : !cir.ptr<i32>) : !cir.ptr<i32>

Traits: AlwaysSpeculatableImplTrait, ConstantLike

Interfaces: ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Attributes:

Results:

cir.func (::mlir::cir::FuncOp)

Declare or define a function

Similar to mlir::FuncOp built-in:

Operations within the function cannot implicitly capture values defined outside of the function, i.e. Functions are IsolatedFromAbove. All external references must use function arguments or attributes that establish a symbolic connection (e.g. symbols referenced by name via a string attribute like SymbolRefAttr). An external function declaration (used when referring to a function declared in some other module) has no body. While the MLIR textual form provides a nice inline syntax for function arguments, they are internally represented as "block arguments" to the first block in the region.

Only dialect attribute names may be specified in the attribute dictionaries for function arguments, results, or the function itself.

The function linkage information is specified by linkage, as defined by GlobalLinkageKind attribute.

A compiler builtin function must be marked as builtin for further processing when lowering from CIR.

The coroutine keyword is used to mark coroutine function, which requires at least one cir.await instruction to be used in its body.

Example:

// External function definitions.
cir.func @abort()

// A function with internal linkage.
cir.func internal @count(%x: i64) -> (i64)
  return %x : i64
}

// Linkage information
cir.func linkonce_odr @some_method(...)

// Builtin function
cir.func builtin @__builtin_coro_end(!cir.ptr<i8>, !cir.bool) -> !cir.bool

// Coroutine
cir.func coroutine @_Z10silly_taskv() -> !CoroTask {
  ...
  cir.await(...)
  ...
}

Traits: AutomaticAllocationScope, IsolatedFromAbove

Interfaces: CallableOpInterface, FunctionOpInterface, Symbol

Attributes:

cir.get_global (::mlir::cir::GetGlobalOp)

Get the address of a global variable

Syntax:

operation ::= `cir.get_global` $name `:` `cir.ptr` type($addr) attr-dict

The cir.get_global operation retrieves the address pointing to a named global variable. If the global variable is marked constant, writing to the resulting address (such as through a cir.store operation) is undefined. Resulting type must always be a !cir.ptr<...> type.

Example:

%x = cir.get_global @foo : !cir.ptr<i32>

Traits: AlwaysSpeculatableImplTrait

Interfaces: ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface), SymbolUserOpInterface

Effects: MemoryEffects::Effect{}

Attributes:

Results:

cir.global (::mlir::cir::GlobalOp)

Declares or defines a global variable

Syntax:

operation ::= `cir.global` ($sym_visibility^)?
              (`constant` $constant^)?
              $linkage
              $sym_name
              custom<GlobalOpTypeAndInitialValue>($sym_type, $initial_value)
              attr-dict

The cir.global operation declares or defines a named global variable.

The backing memory for the variable is allocated statically and is described by the type of the variable.

The operation is a declaration if no inital_value is specified, else it is a definition.

The global variable can also be marked constant using the constant unit attribute. Writing to such constant global variables is undefined.

The linkage tracks C/C++ linkage types, currently very similar to LLVM's. Symbol visibility in sym_visibility is defined in terms of MLIR's visibility and verified to be in accordance to linkage.

Example:

// Public and constant variable with initial value.
cir.global public constant @c : i32 = 4;

Interfaces: Symbol

Attributes:

cir.if (::mlir::cir::IfOp)

The if-then-else operation

The cir.if operation represents an if-then-else construct for conditionally executing two regions of code. The operand is a cir.bool type.

Examples:

cir.if %b  {
  ...
} else {
  ...
}

cir.if %c  {
  ...
}

cir.if %c  {
  ...
  cir.br ^a
^a:
  cir.yield
}

cir.if defines no values and the ‘else' can be omitted. cir.yield must explicitly terminate the region if it has more than one block.

Traits: AutomaticAllocationScope, NoRegionArguments, RecursivelySpeculatableImplTrait

Interfaces: ConditionallySpeculatable, RegionBranchOpInterface

Operands:

cir.load (::mlir::cir::LoadOp)

Load value from memory adddress

Syntax:

operation ::= `cir.load` (`deref` $isDeref^)? $addr `:` `cir.ptr` type($addr) `,`
              type($result) attr-dict

cir.load reads a value (lvalue to rvalue conversion) given an address backed up by a cir.ptr type. A unit attribute deref can be used to mark the resulting value as used by another operation to dereference a pointer.

Example:

// Read from local variable, address in %0.
%1 = cir.load %0 : !cir.ptr<i32>, i32

// Load address from memory at address %0. %3 is used by at least one
// operation that dereferences a pointer.
%3 = cir.load deref %0 : cir.ptr <!cir.ptr<i32>>

Interfaces: InferTypeOpInterface

Attributes:

Operands:

Results:

cir.loop (::mlir::cir::LoopOp)

Loop

Syntax:

operation ::= `cir.loop` $kind
              `(`
              `cond` `:` $cond `,`
              `step` `:` $step
              `)`
              $body
              attr-dict

cir.loop represents C/C++ loop forms. It defines 3 blocks:

• cond: region can contain multiple blocks, terminated by regular cir.yield when control should yield back to the parent, and cir.yield continue when execution continues to another region. The region destination depends on the loop form specified.
• step: region with one block, containing code to compute the loop step, must be terminated with cir.yield.
• body: region for the loop's body, can contain an arbitrary number of blocks.

The loop form: for, while and dowhile must also be specified and each implies the loop regions execution order.

  // while (true) {
  //  i = i + 1;
  // }
  cir.loop while(cond :  {
    cir.yield continue
  }, step :  {
    cir.yield
  })  {
    %3 = cir.load %1 : cir.ptr <i32>, i32
    %4 = cir.cst(1 : i32) : i32
    %5 = cir.binop(add, %3, %4) : i32
    cir.store %5, %1 : i32, cir.ptr <i32>
    cir.yield
  }

Traits: NoRegionArguments, RecursivelySpeculatableImplTrait

Interfaces: ConditionallySpeculatable, LoopLikeOpInterface, RegionBranchOpInterface

Attributes:

cir.ptr_stride (::mlir::cir::PtrStrideOp)

Pointer access with stride

Syntax:

operation ::= `cir.ptr_stride` `(` $base `:` type($base) `,` $stride `:` type($stride) `)`
              `,` type($result) attr-dict

Given a base pointer as operand, provides a new pointer after applying a stride. Currently only used for array subscripts.

%3 = cir.cst(0 : i32) : i32
%4 = cir.ptr_stride(%2 : !cir.ptr<i32>, %3 : i32), !cir.ptr<i32>

Traits: AlwaysSpeculatableImplTrait, SameFirstOperandAndResultType

Interfaces: ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Operands:

Results:

cir.return (::mlir::cir::ReturnOp)

Return from function

Syntax:

operation ::= `cir.return` ($input^ `:` type($input))? attr-dict

The "return" operation represents a return operation within a function. The operation takes an optional operand and produces no results. The operand type must match the signature of the function that contains the operation.

  func @foo() -> i32 {
    ...
    cir.return %0 : i32
  }

Traits: HasParent<FuncOp, ScopeOp, IfOp, SwitchOp, LoopOp>, Terminator

Operands:

cir.scope (::mlir::cir::ScopeOp)

Represents a C/C++ scope

cir.scope contains one region and defines a strict "scope" for all new values produced within its blocks.

The region can contain an arbitrary number of blocks but usually defaults to one and can optionally return a value (useful for representing values coming out of C++ full-expressions) via cir.yield:

%rvalue = cir.scope {
  ...
  cir.yield %value
}

If cir.scope yields no value, the cir.yield can be left out, and will be inserted implicitly.

Traits: AutomaticAllocationScope, NoRegionArguments, RecursivelySpeculatableImplTrait

Interfaces: ConditionallySpeculatable, RegionBranchOpInterface

Results:

cir.store (::mlir::cir::StoreOp)

Store value to memory address

Syntax:

operation ::= `cir.store` $value `,` $addr attr-dict `:` type($value) `,` `cir.ptr` type($addr)

cir.store stores a value (first operand) to the memory address specified in the second operand.

Example:

// Store a function argument to local storage, address in %0.
cir.store %arg0, %0 : i32, !cir.ptr<i32>

Operands:

cir.struct_element_addr (::mlir::cir::StructElementAddr)

Get the address of a member of a struct

The cir.struct_element_addr operaration gets the address of a particular named member from the input struct.

Example:

!ty_22struct2EBar22 = type !cir.struct<"struct.Bar", i32, i8>
...
%0 = cir.alloca !ty_22struct2EBar22, cir.ptr <!ty_22struct2EBar22>
...
%1 = cir.struct_element_addr %0, "Bar.a"
%2 = cir.load %1 : cir.ptr <int>, int
...

Attributes:

Operands:

Results:

cir.switch (::mlir::cir::SwitchOp)

Switch operation

Syntax:

operation ::= `cir.switch` custom<SwitchOp>(
              $regions, $cases, $condition, type($condition)
              )
              attr-dict

The cir.switch operation represents C/C++ switch functionality for conditionally executing multiple regions of code. The operand to an switch is an integral condition value.

A variadic list of "case" attribute operands and regions track the possible control flow within cir.switch. A case must be in one of the following forms:

• equal, <constant>: equality of the second case operand against the condition.
• anyof, [constant-list]: equals to any of the values in a subsequent following list.
• default: any other value.

Each case region must be explicitly terminated.

Examples:

cir.switch (%b : i32) [
  case (equal, 20) {
    ...
    cir.yield break
  },
  case (anyof, [1, 2, 3] : i32) {
    ...
    cir.return ...
  }
  case (default) {
    ...
    cir.yield fallthrough
  }
]

Traits: AutomaticAllocationScope, NoRegionArguments, RecursivelySpeculatableImplTrait, SameVariadicOperandSize

Interfaces: ConditionallySpeculatable, RegionBranchOpInterface

Attributes:

Operands:

cir.unary (::mlir::cir::UnaryOp)

Unary operations

Syntax:

operation ::= `cir.unary` `(` $kind `,` $input `)` `:` type($input) `,` type($result) attr-dict

cir.unary performs the unary operation according to the specified opcode kind: [inc, dec, plus, minus].

Note for inc and dec: the operation corresponds only to the addition/subtraction, its input is expect to come from a load and the result to be used by a corresponding store.

It requires one input operand and has one result, both types should be the same.

%7 = cir.unary(inc, %1) : i32 -> i32
%8 = cir.unary(dec, %2) : i32 -> i32

Traits: AlwaysSpeculatableImplTrait, SameOperandsAndResultType

Interfaces: ConditionallySpeculatable, InferTypeOpInterface, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Attributes:

Operands:

Results:

cir.yield (::mlir::cir::YieldOp)

Terminate CIR regions

Syntax:

operation ::= `cir.yield` ($kind^)? ($args^ `:` type($args))? attr-dict

The cir.yield operation terminates regions on different CIR operations: cir.if, cir.scope, cir.switch, cir.loop and cir.await.

Might yield an SSA value and the semantics of how the values are yielded is defined by the parent operation. Note: there are currently no uses of cir.yield with operands - should be helpful to represent lifetime extension out of short lived scopes in the future.

Optionally, cir.yield can be annotated with extra kind specifiers:

• break: breaking out of the innermost cir.switch / cir.loop semantics, cannot be used if not dominated by these parent operations.
• fallthrough: execution falls to the next region in cir.switch case list. Only available inside cir.switch regions.
• continue: only allowed under cir.loop, continue execution to the next loop step.
• nosuspend: specific to the ready region inside cir.await op, it makes control-flow to be transfered back to the parent, preventing suspension.

As a general rule, cir.yield must be explicitly used whenever a region has more than one block and no terminator, or within cir.switch regions not cir.return terminated.

Examples:

cir.if %4 {
  ...
  cir.yield
}

cir.switch (%5) [
  case (equal, 3) {
    ...
    cir.yield fallthrough
  }, ...
]

cir.loop (cond : {...}, step : {...}) {
  ...
  cir.yield continue
}

cir.await(init, ready : {
  // Call std::suspend_always::await_ready
  %18 = cir.call @_ZNSt14suspend_always11await_readyEv(...)
  cir.if %18 {
    // yields back to the parent.
    cir.yield nosuspend
  }
  cir.yield // control-flow to the next region for suspension.
}, ...)

Traits: HasParent<IfOp, ScopeOp, SwitchOp, LoopOp, AwaitOp>, ReturnLike, Terminator

Attributes:

Operands: