Firm Node Types

ASM

executes assembler fragments of the target machine

Inputs
mem
memory dependency
...
additional inputs (oparity_variable)
Attributes
input_constraints
input constraints (ir_asm_constraint*)
n_output_constraints
number of output constraints (size_t)
output_constraints
output constraints (ir_asm_constraint*)
n_clobbers
number of clobbered registers/memory (size_t)
clobbers
list of clobbered registers/memory (ident**)
text
assembler text (ident*)
Flags
keep, uses_memory
API

Add

returns the sum of its operands

Inputs
left
first operand
right
second operand
Flags
commutative
API

Alloc

allocates a block of memory. It can be specified whether the memory should be allocated to the stack or to the heap. Allocates memory for one or more objects (depending on value on count input).

Inputs
mem
memory dependency
count
number of objects to allocate
Outputs
M
memory result
res
pointer to newly allocated memory
X_regular
control flow when no exception occurs
X_except
control flow when exception occured
Attributes
type
type of the objects to allocate (ir_type*)
where
whether to allocate the variable on the stack or heap (ir_where_alloc)
Flags
fragile, uses_memory
API

Anchor

utiliy node used to "hold" nodes in a graph that might possibly not be reachable by other means or which should be reachable immediately without searching through the graph. Each firm-graph contains exactly one anchor node whose address is always known. All other well-known graph-nodes like Start, End, NoMem, Bad, ... are found by looking at the respective Anchor operand.

Inputs
...
additional inputs (oparity_variable)
Flags
dump_noblock
API

And

returns the result of a bitwise and operation of its operands

Inputs
left
first operand
right
second operand
Flags
commutative
API

Bad

Bad nodes indicate invalid input, which is values which should never be computed.

The typical use case for the Bad node is removing unreachable code. Frontends should set the current_block to Bad when it is clear that following code must be unreachable (ie. after a goto or return statement). Optimisations also set block predecessors to Bad when it becomes clear, that a control flow edge can never be executed.

The gigo optimisations ensures that nodes with Bad as their block, get replaced by Bad themselfes. Nodes with at least 1 Bad input get exchanged with Bad too. Exception to this rule are Block, Phi, Tuple and End node; This is because removing inputs from a Block is hairy operation (requiring, Phis to be shortened too for example). So instead of removing block inputs they are set to Bad, and the actual removal is left to the control flow optimisation phase. Block, Phi, Tuple with only Bad inputs however are replaced by Bad right away.

Inputs
Flags
start_block, dump_noblock
API

Block

A basic block

Inputs
...
additional inputs (oparity_variable)
Attributes
entity
entity representing this block (ir_entity*)
Flags
labeled
API

Borrow

Returns the borrow bit from and implied subtractions of its 2 operands

Inputs
left
first operand
right
second operand
Flags
API

Bound

Performs a bounds-check: if lower <= index < upper then return index, otherwise throw an exception.

Inputs
mem
memory dependency
index
value to test
lower
lower bound (inclusive)
upper
upper bound (exclusive)
Outputs
M
memory result
res
the checked index
X_regular
control flow when no exception occurs
X_except
control flow when exception occured
Flags
fragile, highlevel
API

Builtin

performs a backend-specific builtin.

Inputs
mem
memory dependency
...
additional inputs (oparity_variable)
Outputs
M
memory result
Attributes
kind
kind of builtin (ir_builtin_kind)
type
method type for the builtin call (ir_type*)
Flags
uses_memory
API

Call

Calls other code. Control flow is transfered to ptr, additional operands are passed to the called code. Called code usually performs a return operation. The operands of this return operation are the result of the Call node.

Inputs
mem
memory dependency
ptr
pointer to called code
...
additional inputs (oparity_variable)
Outputs
M
memory result
T_result
tuple containing all results
X_regular
control flow when no exception occurs
X_except
control flow when exception occured
Attributes
type
type of the call (usually type of the called procedure) (ir_type*)
Flags
fragile, uses_memory
API

Carry

Computes the value of the carry-bit that would result when adding the 2 operands

Inputs
left
first operand
right
second operand
Flags
commutative
API

Cast

perform a high-level type cast

Inputs
op
operand
Attributes
type
target type of the case (ir_type*)
Flags
highlevel
API

Cmp

Compares its two operands and checks whether a specified relation (like less or equal) is fulfilled.

Inputs
left
first operand
right
second operand
Attributes
relation
Comparison relation (ir_relation)
Flags
API

Cond

Conditionally change control flow.

Inputs
selector
condition parameter
Outputs
false
control flow if operand is "false"
true
control flow if operand is "true"
Attributes
jmp_pred
can indicate the most likely jump (cond_jmp_predicate)
Flags
cfopcode, forking
API

Confirm

Specifies constraints for a value. This allows explicit representation of path-sensitive properties. (Example: This value is always >= 0 on 1 if-branch then all users within that branch are rerouted to a confirm-node specifying this property).

A constraint is specified for the relation between value and bound. value is always returned. Note that this node does NOT check or assert the constraint, it merely specifies it.

Inputs
value
value to express a constraint for
bound
value to compare against
Attributes
relation
relation of value to bound (ir_relation)
Flags
highlevel
API

Const

Returns a constant value.

Inputs
Attributes
tarval
constant value (a tarval object) (ir_tarval*)
Flags
constlike, start_block
API

Conv

Converts values between modes

Inputs
op
operand
Attributes
strict
force floating point to restrict precision even if backend computes in higher precision (deprecated) (int)
Flags
API

CopyB

Copies a block of memory with statically known size/type.

Inputs
mem
memory dependency
dst
destination address
src
source address
Outputs
M
memory result
X_regular
control flow when no exception occurs
X_except
control flow when exception occured
Attributes
type
type of copied data (ir_type*)
Flags
fragile, uses_memory
API

Deleted

Internal node which is temporary set to nodes which are already removed from the graph.

Inputs
Flags
API

Div

returns the quotient of its 2 operands

Inputs
mem
memory dependency
left
first operand
right
second operand
Outputs
M
memory result
res
result of computation
X_regular
control flow when no exception occurs
X_except
control flow when exception occured
Attributes
resmode
mode of the result value (ir_mode*)
no_remainder
(int)
Flags
fragile, uses_memory
API

Dummy

A placeholder value. This is used when constructing cyclic graphs where you have cases where not all predecessors of a phi-node are known. Dummy nodes are used for the unknown predecessors and replaced later.

Inputs
Flags
cfopcode, start_block, constlike, dump_noblock
API

End

Last node of a graph. It references nodes in endless loops (so called keepalive edges)

Inputs
...
inputs dynamically mananged (oparity_dynamic)
Flags
cfopcode
API

Eor

returns the result of a bitwise exclusive or operation of its operands.

This is also known as the Xor operation.

Inputs
left
first operand
right
second operand
Flags
commutative
API

Free

Frees a block of memory previously allocated by an Alloc node

Inputs
mem
memory dependency
ptr
pointer to the object to free
count
number of objects to allocate
Attributes
type
type of the allocated variable (ir_type*)
where
whether allocation was on the stack or heap (ir_where_alloc)
Flags
uses_memory
API

IJmp

Jumps to the code in its argument. The code has to be in the same function and the the destination must be one of the blocks reachable by the tuple results

Inputs
target
target address of the jump
Flags
cfopcode, forking, keep, unknown_jump
API

Id

Returns its operand unchanged.

This is mainly used when exchanging nodes. Usually you shouldn't see Id nodes since the getters/setters for node inputs skip them automatically.

Inputs
pred
the value which is returned unchanged
Flags
API

InstOf

Tests whether an object is an instance of a class-type

Inputs
store
memory dependency
obj
pointer to object being queried
Outputs
M
memory result
res
checked object pointer
X_regular
control flow when no exception occurs
X_except
control flow when exception occured
Attributes
type
type to check ptr for (ir_type*)
Flags
highlevel
API

Jmp

Jumps to the block connected through the out-value

Inputs
Flags
cfopcode
API

Load

Loads a value from memory (heap or stack).

Inputs
mem
memory dependency
ptr
address to load from
Outputs
M
memory result
res
result of load operation
X_regular
control flow when no exception occurs
X_except
control flow when exception occured
Attributes
mode
mode of the value to be loaded (ir_mode*)
volatility
volatile loads are a visible side-effect and may not be optimized (ir_volatility)
unaligned
pointers to unaligned loads don't need to respect the load-mode/type alignments (ir_align)
Flags
fragile, uses_memory
API

Minus

returns the difference between its operands

Inputs
op
operand
Flags
API

Mod

returns the remainder of its operands from an implied division.

Examples:

  • mod(5,3) produces 2
  • mod(5,-3) produces 2
  • mod(-5,3) produces -2
  • mod(-5,-3) produces -2
Inputs
mem
memory dependency
left
first operand
right
second operand
Outputs
M
memory result
res
result of computation
X_regular
control flow when no exception occurs
X_except
control flow when exception occured
Attributes
resmode
mode of the result (ir_mode*)
Flags
fragile, uses_memory
API

Mul

returns the product of its operands

Inputs
left
first operand
right
second operand
Flags
commutative
API

Mulh

returns the upper word of the product of its operands (the part which would not fit into the result mode of a normal Mul anymore)

Inputs
left
first operand
right
second operand
Flags
commutative
API

Mux

returns the false or true operand depending on the value of the sel operand

Inputs
sel
value making the output selection
false
selected if sel input is false
true
selected if sel input is true
Flags
API

NoMem

Placeholder node for cases where you don't need any memory input

Inputs
Flags
dump_noblock, dump_noinput
API

Not

returns the bitwise complement of a value. Works for boolean values, too.

Inputs
op
operand
Flags
API

Or

returns the result of a bitwise or operation of its operands

Inputs
left
first operand
right
second operand
Flags
commutative
API

Phi

Choose a value based on control flow. A phi node has 1 input for each predecessor of its block. If a block is entered from its nth predecessor all phi nodes produce their nth input as result.

Inputs
...
additional inputs (oparity_variable)
Flags
API

Pin

Pin the value of the node node in the current block. No users of the Pin node can float above the Block of the Pin. The node cannot float behind this block. Often used to Pin the NoMem node.

Inputs
op
value which is pinned
Flags
highlevel
API

Proj

returns an entry of a tuple value

Inputs
pred
the tuple value from which a part is extracted
Attributes
proj
number of tuple component to be extracted (long)
Flags
API

Raise

Raises an exception. Unconditional change of control flow. Writes an explicit Except variable to memory to pass it to the exception handler. Must be lowered to a Call to a runtime check function.

Inputs
mem
memory dependency
exo_ptr
pointer to exception object to be thrown
Outputs
M
memory result
X
control flow to exception handler
Flags
highlevel, cfopcode
API

Return

Returns from the current function. Takes memory and return values as operands.

Inputs
mem
memory dependency
...
additional inputs (oparity_variable)
Flags
cfopcode
API

Rotl

Returns its first operand bits rotated left by the amount in the 2nd operand

Inputs
left
first operand
right
second operand
Flags
API

Sel

Computes the address of a entity of a compound type given the base address of an instance of the compound type.

Optimisations assume that a Sel node can only produce a NULL pointer if the ptr input was NULL.

Inputs
mem
memory dependency
ptr
pointer to object to select from
...
additional inputs (oparity_variable)
Attributes
entity
entity which is selected (ir_entity*)
Flags
API

Shl

Returns its first operands bits shifted left by the amount of the 2nd operand

Inputs
left
first operand
right
second operand
Flags
API

Shr

Returns its first operands bits shifted right by the amount of the 2nd operand. No special handling for the sign bit (zero extension)

Inputs
left
first operand
right
second operand
Flags
API

Shrs

Returns its first operands bits shifted right by the amount of the 2nd operand. The leftmost bit (usually the sign bit) stays the same (sign extension)

Inputs
left
first operand
right
second operand
Flags
API

Start

The first node of a graph. Execution starts with this node.

Inputs
Outputs
X_initial_exec
control flow
M
initial memory
P_frame_base
frame base pointer
T_args
function arguments
Flags
cfopcode
API

Store

Stores a value into memory (heap or stack).

Inputs
mem
memory dependency
ptr
address to store to
value
value to store
Outputs
M
memory result
X_regular
control flow when no exception occurs
X_except
control flow when exception occured
Attributes
volatility
volatile stores are a visible side-effect and may not be optimized (ir_volatility)
unaligned
pointers to unaligned stores don't need to respect the load-mode/type alignments (ir_align)
Flags
fragile, uses_memory
API

Sub

returns the difference of its operands

Inputs
left
first operand
right
second operand
Flags
API

Switch

Change control flow. The destination is choosen based on an integer input value which is looked up in a table.

Backends can implement this efficiently using a jump table.

Inputs
selector
input selector
Outputs
default
control flow if no other case matches
Attributes
n_outs
number of outputs (including pn_Switch_default) (unsigned)
table
table describing mapping from input values to Proj numbers (ir_switch_table*)
Flags
cfopcode, forking
API

SymConst

A symbolic constant.

  • symconst_type_size The symbolic constant represents the size of a type.

    The type of which the constant represents the size is given explicitly.

  • symconst_type_align The symbolic constant represents the alignment of a

    type. The type of which the constant represents the size is given explicitly.

  • symconst_addr_ent The symbolic constant represents the address of an

    entity (variable or method). The variable is given explicitly by a firm entity.

  • symconst_ofs_ent The symbolic constant represents the offset of an

    entity in its owner type.

  • symconst_enum_const The symbolic constant is a enumeration constant of

    an enumeration type.

Inputs
Attributes
entity
entity whose address is returned (ir_entity*)
Flags
constlike, start_block
API

Sync

The Sync operation unifies several partial memory blocks. These blocks have to be pairwise disjunct or the values in common locations have to be identical. This operation allows to specify all operations that eventually need several partial memory blocks as input with a single entrance by unifying the memories with a preceding Sync operation.

Inputs
...
inputs dynamically mananged (oparity_dynamic)
Flags
API

Tuple

Builds a Tuple from single values.

This is needed to implement optimizations that remove a node that produced a tuple. The node can be replaced by the Tuple operation so that the following Proj nodes have not to be changed. (They are hard to find due to the implementation with pointers in only one direction.) The Tuple node is smaller than any other node, so that a node can be changed into a Tuple by just changing its opcode and giving it a new in array.

Inputs
...
additional inputs (oparity_variable)
Flags
labeled
API

Unknown

Returns an unknown (at compile- and runtime) value. It is a valid optimisation to replace an Unknown by any other constant value.

Inputs
Flags
start_block, constlike, dump_noblock
API