/** !!!
-*** Ideas for improvement:
+*** Ideas for imrovement:
***
Handle construction of exceptions more comfortable:
Add new constructors that pass the exception region (or better the
it is always unambiguous.
**/
-
-/**
-*** IRCONS
-
- This file documents all datatypes and constructors needed to
- build a FIRM representation of a pocedure. The constructors are
- also implemented in this file.
-
- The documentation also gives a short manual how to use the library.
-
- For extensive documentation of FIRM see UKA Techreport 1999-14.
-
- DATATYPES
- =========
-
- The struct ir_graph
- -------------------
-
- This struct contains all information about a procedure.
- It's allocated directly to memory.
-
- The fields of ir_graph:
-
- *ent The entity describing this procedure.
-
- The beginning and end of a graph:
-
- *start_block This ir_node is the block that contains the unique
- start node of the procedure. With it it contains
- the Proj's on starts results.
- Further all Const nodes are placed in the start block.
- *start This ir_node is the unique start node of the procedure.
-
- *end_block This ir_node is the block that contains the unique
- end node of the procedure. This block contains no
- further nodes.
- *end This ir_node is the unique end node of the procedure.
-
- The following nodes are Projs from the start node, held in ir_graph for
- simple access:
-
- *frame The ir_node producing the pointer to the stack frame of the
- procedure as output. This is the Proj node on the third
- output of the start node. This output of the start node
- is tagged as pns_frame_base. In FIRM most lokal
- variables are modeled as data flow edges. Static
- allocated arrays can not be represented as dataflow
- edges. Therefore FIRM has to represent them in the stack
- frame.
-
- *globals This models a pointer to a space in the memory where _all_
- global things are held. Select from this pointer with a Sel
- node the pointer to a global variable / procedure / compiler
- known function... .
-
- *args The ir_node that produces the arguments of the method as it's
- result. This is a Proj node on the fourth output of the start
- node. This output is tagged as pns_args.
-
- *bad The bad node is an auxiliary node. It is needed only once,
- so there is this globally reachable node.
-
- Datastructures that are private to a graph:
-
- *obst An obstack that contains all nodes.
-
- *current_block A pointer to the current block. Any node created with one
- of the node constructors (new_<opcode>) are assigned to this
- block. It can be set with switch_block(block). Only needed
- for ir construction.
-
- params/n_loc An int giving the number of local variables in this procedure.
- This is neede for ir construction. Name will be changed.
-
- *value_table This pset is used for global value numbering for optimizing
- use in iropt.c.
-
- *Phi_in_stack; a stack needed for automatic Phi construction, needed only
- during ir construction.
-
-
- Three kinds of nodes
- --------------------
-
- There are three kinds of nodes known to the ir: enties,
- types, and ir_nodes
-
- + ir_nodes are the actual nodes of the FIRM intermediate representation.
- They represent operations on the data of the program and control flow
- operations.
-
- + entity ==> implemented in entity.h
- Refers to a single entity of the compiled program, e.g. a field of a class or
- a method.
-
- + types ==> implemented in type.h
- With types type information is represented. There are several type nodes.
-
- Implementation of the FIRM operations: ir_node
- ----------------------------------------------
-
- Ir_nodes represent operations on the data of the program and control flow
- operations. Examples of ir_nodes: Add, Jmp, Cmp
-
- FIRM is a dataflow graph. A dataflow graph is a directed graph,
- so that every node has incoming and outgoing edges. A node is
- executable if every input at it's incoming edges is available.
- Execution of the dataflow graph is started at the Start node which
- has no incoming edges and ends when the End node executes, even if
- there are still executable or not executed nodes. (Is this true,
- or must all executable nodes be executed?) (There are exceptions
- to the dataflow paradigma that all inputs have to be available
- before a node can execute: Phi, Block. See UKA Techreport
- 1999-14.)
-
- The implementation of FIRM differs from the view as a dataflow
- graph. To allow fast traversion of the graph edges are
- implemented as C-pointers. Inputs to nodes are not ambiguous, the
- results can be used by several other nodes. Each input can be
- implemented as a single pointer to a predecessor node, outputs
- need to be lists of pointers to successors. Therefore a node
- contains pointers to it's predecessor so that the implementation is a
- dataflow graph with reversed edges. It has to be traversed bottom
- up.
-
- All nodes of the ir have the same basic structure. They are
- distinguished by a field containing the opcode.
-
- The fields of an ir_node:
-
- kind A firm_kind tag containing k_ir_node. This is useful for
- dynamically checking the type of a node.
-
- *op This ir_op gives the opcode as a tag and a string
- and the number of attributes of an ir_node. There is
- one statically allocated struct ir_op for each opcode.
-
- *mode The ir_mode of the operation represented by this firm node.
- The mode of the operation is the mode of it's result. A Firm
- mode is a datatype as known to the target, not a type of the
- source language.
-
- visit A flag for traversing the ir.
-
- **in An array with pointers to the node's predecessors.
-
- *link A pointer to an ir_node. With this pointer all Phi nodes
- are attached to a Block, i.e., a Block points to it's
- first Phi node, this node points to the second Phi node
- in the Block and so fourth. Used in mature_block
- to find all Phi nodes to be matured. It's also used to
- annotate a node with a better, optimized version of it.
-
- attr An attr struct containing the attributes of the nodes. The
- attributes depend on the opcode of the node. The number of
- these attributes is given in op.
-
- The struct ir_op
- ----------------
- Not yet documented. See irop.h.
-
- The struct ir_mode
- ------------------
- Not yet documented. See irmode.h.
-
- GLOBAL VARIABLES
- ================
-
- current_ir_graph Points to the current ir_graph. All constructors for nodes
- add nodes to this graph.
-
- ir_visited A int used as flag to traverse the ir_graph.
-
- block_visited A int used as a flag to traverse block nodes in the graph.
-
- Others not yet documented.
-
-
-
-
- CONSTRUCTOR FOR IR_GRAPH
- ========================
-
- ir_graph *new_ir_graph (entity *ent, int params);
- -------------------------------------------------
-
- This constructor generates the basic infrastructure needed to
- represent a procedure in FIRM.
-
- The parameters of new_ir_graph are:
-
- *ent A pointer to an entity representing the procedure.
-
- params An integer giving the number of local variables in the
- procedure.
-
- It allocates an ir_graph and sets current_ir_graph to point to this
- graph. Further it allocates the following nodes needed for every
- procedure:
-
- * The start block containing a start node and Proj nodes for it's
- four results (X, M, P, T).
- * The end block containing an end node. This block is not matured
- after executing new_ir_graph as predecessors need to be added to it.
- (Maturing a block means fixing it's number of predecessors.)
- * The current block, which is empty and also not matured.
-
- Further it enters the global store into the datastructure of the start
- block that contanis all valid values in this block (set_store()). This
- datastructure is used to build the Phi nodes and removed after completion
- of the graph.
- There is no path from end to start in the graph after calling ir_graph.
-
-
- IR_NODES AND CONSTRUCTORS FOR IR_NODES
- =======================================
-
- All ir_nodes are defined by a common data structure. They are distinguished
- by their opcode and differ in the number of their attributes.
-
- The constructor for the block node sets current_block to itself.
- Const nodes are always added to the start block.
- All other constructors add the created node to the current_block.
- swich_block(block) allows to set the current block to block.
-
- Watch for my inconsistent use of input and predecessor (dataflow view)
- and `the node points to' (implementation view).
-
- The following description of the nodes lists four properties them if these are
- of interest:
- - the parameters to the constructor
- - the inputs of the Firm node
- - the outputs of the Firm node
- - attributes to the node
-
-
- BASIC BLOCKS
- ------------
-
- ir_node *new_Block (void)
- --------------------------
-
- Creates a new block. Sets current_block to itself. When a new block is
- created it cannot be known how many predecessors this block will have in the
- control flow graph. Therefore the list of inputs can not be fixed at
- creation. Predecessors can be added with add_in_edge (block, control flow
- operation). With every added predecessor the number of inputs to Phi nodes
- also changes.
-
- The block can be completed by mature_block(block) if all predecessors are
- known. If several blocks are built at once, mature_block can only be called
- after set_value has been called for all values that are life at the end
- of the block. This is necessary so that Phi nodes created by mature_block
- get the right predecessors in case of cyclic dependencies. If all set_values
- of this block are called after maturing it and before calling get_value
- in some block that is control flow dependent on this block, the construction
- is correct.
- Example for faulty ir construction:
- block_before_loop = new_block();
- set_value(x);
- mature_block(block_before_loop);
- before2header = new_Jmp;
-
- loop_header = new_block ();
- header2body - new_Jmp();
-
- loop_body = new_block ();
- body2header = new_Jmp();
-
- add_in_edge(loop_header, before2header);
- add_in_edge(loop_header, body2header);
- add_in_edge(loop_body, header2body);
-
- mature_block(loop_header);
- mature_block(loop_body);
-
- get_value(loop_body, x); // gets the Phi in loop_header
- set_value(loop_header, x); // sets the value the above get_value should
- // have returned!!!
- Mature_block also fixes the number of inputs to the Phi nodes. Mature_block
- should be called as early as possible, as afterwards the generation of Phi
- nodes is more efficient.
-
- Inputs:
- There is an input for each control flow predecessor of the block.
- The input points to an instruction producing an output of type X.
- Possible predecessors: Start, Jmp, Cond, Raise or Return or any node
- possibly causing an exception. (Often the real predecessors are Projs.)
- Output:
- Mode R, all nodes belonging to this block should consume this output.
- As they are strict (except Block and Phi node) it is a necessary condition
- that the block node executed before any other node in this block
- executes.
- Attributes:
- block.matured Indicates whether the block is mature.
- block.closed ???
- block.**graph_arr
- This attribute contains all local values valid in this
- block. This is needed to build the Phi nodes and removed
- if the graph is complete.
-
-
- CONTROL FLOW OPERATIONS
- -----------------------
-
- In each block there must be exactly one of the control flow
- operations Start, End, Jmp, Cond, Return or Raise. The output of a
- control flow operation points to the block to be executed next.
-
- ir_node *new_Start (void)
- -------------------------
-
- Creates a start node. Not actually needed public. Created
- by new_ir_graph.
-
- Inputs:
- No inputs except the block it belogns to.
- Output:
- A tuple of 4 (5, 6) distinct values. These are labeled by the following
- projection numbers (pns_number):
- * pns_initial_exec
- mode X, points to the first block to be executed.
- * pns_global_store
- mode M, the global store
- * pns_frame_base mode P, a pointer to the base of the procedures stack frame.
- * pns_globals mode P, a pointer to the part of the memory containing _all_
- global things.
- * pns_args mode T, a tuple containing all arguments of the procedure.
-
-
- ir_node *new_End (void)
- -----------------------
-
- Creates an end node. Not actually needed public. Created by
- new_ir_graph.
-
- Inputs:
- No inputs except the block it belogns to.
- Output:
- No output.
-
- ir_node *new_Jmp (void)
- -----------------------
-
- Creates a Jmp node.
-
- Inputs:
- The block the node belongs to
- Output:
- Control flow to the next block.
-
- ir_node *new_Cond (ir_node *c)
- ------------------------------
-
- Creates a Cond node. There are two versions of this node.
-
- The Boolean Cond:
- Input:
- A value of mode b.
- Output:
- A tuple of two control flows. The first is taken if the input is
- false, the second if it is true.
-
- The Switch Cond:
- Input:
- A value of mode I_u. (i)
- Output:
- A tuple of n control flows. If the Cond's input is i, control
- flow will procede along output i. If the input is >= n control
- flow proceeds along output n.
-
- ir_node *new_Return (in_node *store, int arity, ir_node **in)
- -------------------------------------------------------------
-
- The return node has as inputs the results of the procedure. It
- passes the control flow to the end_block.
-
- Inputs:
- The memory state.
- All results.
- Output
- Control flow to the end block.
-
- ir_node *new_Raise (ir_node *store, ir_node *obj)
- -------------------------------------------------
-
- Raises an exception. Unconditional change of control flow. Writes
- an explicit Except variable to memory to pass it to the exception
- handler. See TechReport 1999-14, chapter Exceptions.
-
- Inputs:
- The memory state.
- A pointer to the Except variable.
- Output:
- A tuple of control flow and the changed memory state. The control flow
- points to the exception handler if it is definied in this procedure,
- else it points to the end_block.
-
-
- CONSTANTS
- ---------
-
- ir_node *new_Const (ir_mode *mode, tarval *con)
- -----------------------------------------------
-
- Creates a constant in the constant table and adds a Const node
- returning this value to the start block.
-
- Parameters:
- *mode The mode of the constant.
- *con Points to an entry in the constant table.
- This pointer is added to the attributes of
- the node (self->attr.con)
- Inputs:
- No inputs except the block it belogns to.
- Output:
- The constant value.
- Attribute:
- attr.con A tarval* pointer to the proper entry in the constant
- table.
-
- ir_node *new_SymConst (type *type, symconst_kind kind)
- ------------------------------------------------------------
-
- There are two kinds of symbolic constants:
- type_tag The symbolic constant represents a type tag.
- size The symbolic constant represents the size of a class.
- link_info Information for the linker.
-
- Parameters
- kind The kind of the symbolic constant: type_tag or size.
- *type Points to the type the tag stands for or to the type
- whose size is represented by the constant.
-
- Inputs:
- No inputs except the block it belogns to.
- Output:
- An unsigned integer (I_u) or a pointer (P).
-
- Attributes:
- attr.i.num The symconst_kind, i.e. one of
- - type_tag
- - size
- - linkage_ptr_info
- If the attr.i.num is type_tag of size, the node contains an attribute
- attr.i.*type A pointer to a type_class.
- if it is linkage_ptr_info it contains
- attr.i.*ptrinfo A ident holding information for the linker.
-
- THE SELECT NODE
- ---------------
-
- ir_node *new_simpleSel (ir_node *store, ir_node *frame, entity *sel)
- --------------------------------------------------------------------
-
-
- Selects an entity from a compound type. This entity can be a field or
- a method.
-
- Parameters:
- *store The memory in which the object the entity should be selected from
- is allocated.
- *frame The pointer to the object.
- *sel The entity to select.
-
- Inputs:
- The memory containing the object.
- A pointer to the object.
- An unsigned integer.
- Output:
- A pointer to the selected entity.
- Attributes:
- attr.sel Pointer to the entity
-
-
- ir_node *new_Sel (ir_node *store, ir_node *frame, int arity, ir_node **in,
- --------------------------------------------------------------------------
- entity *sel)
- ------------
-
- Selects a field from an array type. The entity has as owner the array, as
- type the arrays element type. The indexes to access an array element are
- given also.
-
- Parameters:
- *store The memory in which the object the entity should be selected from
- is allocated.
- *frame The pointer to the object.
- *arity number of array indexes.
- *in array with index inputs to the node.
- *sel The entity to select.
-
- Inputs:
- The memory containing the object.
- A pointer to the object.
- As much unsigned integer as there are array expressions.
- Output:
- A pointer to the selected entity.
- Attributes:
- attr.sel Pointer to the entity
-
- The constructors new_Sel and new_simpleSel generate the same ir nodes.
- simpleSel just sets the arity of the index inputs to zero.
-
-
- ARITHMETIC OPERATIONS
- ---------------------
-
- ir_node *new_Call (ir_node *store, ir_node *callee, int arity, ir_node **in,
- ----------------------------------------------------------------------------
- type_method *type)
- ------------------
-
- Creates a procedure call.
-
- Parameters
- *store The actual store. Why not also the stack frame?
- *callee A pointer to the called procedure.
- arity The number of procedure parameters.
- **in An array with the pointers to the parameters.
- This array is copied in the constructor.
- *type Type information of the procedure called.
-
- Inputs:
- The store, the callee and the parameters.
- Output:
- A tuple containing the eventually changed store and the procedure
- results.
- Attributes:
- attr.call Contains the type information for the procedure.
-
- ir_node *new_Add (ir_node *op1, ir_node *op2, ir_mode *mode)
- ------------------------------------------------------------
-
- Trivial.
-
- ir_node *new_Sub (ir_node *op1, ir_node *op2, ir_mode *mode)
- ------------------------------------------------------------
-
- Trivial.
-
- ir_node *new_Minus (ir_node *op, ir_mode *mode)
- -----------------------------------------------
-
- This constructor is for unary Minus operations on floating point
- values. Such a Minus can trap if it is implemented as a Sub from
- zero due to rounding errors.
-
- ir_node *new_Mul (ir_node *op1, ir_node *op2, ir_mode *mode)
- ------------------------------------------------------------
-
- Trivial.
-
- ir_node *new_Quot (ir_node *memop, ir_node *op1, ir_node *op2)
- --------------------------------------------------------------
-
- Quot performs exact division of floating point numbers. It's mode
- is Tuple, the mode of the result must be annotated to the Proj
- that extracts the result of the arithmetic operations.
-
- Inputs:
- The store needed to model exceptions and the two operands.
- Output:
- A tuple contaning a memory and a execution for modeling exceptions
- and the result of the arithmetic operation.
-
- ir_node *new_DivMod (ir_node *memop, ir_node *op1, ir_node *op2)
- ----------------------------------------------------------------
-
- Performs Div and Mod on interger values.
-
- Output:
- A tuple contaning a memory and a execution for modeling exceptions
- and the two result of the arithmetic operations.
-
- ir_node *new_Div (ir_node *memop, ir_node *op1, ir_node *op2)
- -------------------------------------------------------------
-
- Trivial.
-
- ir_node *new_Mod (ir_node *memop, ir_node *op1, ir_node *op2)
- -------------------------------------------------------------
-
- Trivial.
-
- ir_node *new_Abs (ir_node *op, ir_mode *mode)
- ---------------------------------------------
-
- Trivial.
-
- ir_node *new_And (ir_node *op1, ir_node *op2, ir_mode *mode)
- ------------------------------------------------------------
-
- Trivial.
-
- ir_node *new_Or (ir_node *op1, ir_node *op2, ir_mode *mode)
- -----------------------------------------------------------
-
- Trivial.
-
- ir_node *new_Eor (ir_node *op1, ir_node *op2, ir_mode *mode)
- ------------------------------------------------------------
-
- Trivial.
-
- ir_node *new_Not (ir_node *op, ir_mode *mode)
- ---------------------------------------------
-
- This node constructs a constant where all bits are set to one
- and a Eor of this constant and the operator. This simulates a
- Not operation.
-
- ir_node *new_Shl (ir_node *op, ir_node *k, ir_mode *mode)
- ---------------------------------------------------------
-
- Trivial.
-
- ir_node *new_Shr (ir_node *op, ir_node *k, ir_mode *mode)
- ---------------------------------------------------------
-
- Logic shift right, i.e., zero extended.
-
-
- ir_node *new_Shrs (ir_node *op, ir_node *k, ir_mode *mode)
- ----------------------------------------------------------
-
- Arithmetic shift right, i.e., sign extended.
-
- ir_node *new_Rot (ir_node *op, ir_node *k, ir_mode *mode)
- ---------------------------------------------------------
-
- Rotates the operand to the (right??) by k bits.
-
- ir_node *new_Conv (ir_node *op, ir_mode *mode)
- ---------------------------------------------
-
- Mode conversion. For allowed conversions see UKA Tech Report
- 1999-14.
-
- ir_node *new_Cmp (ir_node *op1, ir_node *op2)
- ---------------------------------------------
-
- Input:
- The two values to be compared.
- Output:
- A 16-tuple containing the results of the 16 different comparisons.
- The following is a list giving the comparisons and a projection
- number (pnc_number) to use in Proj nodes to extract the proper result.
- False false
- Eq equal
- Lt less
- Le less or equal
- Gt greater
- Ge greater of equal
- Lg less or greater
- Leg less, equal or greater = ordered
- Uo unordered
- Ue unordered or equal
- Ul unordered or less
- Ule unordered, less or equal
- Ug unordered or greater
- Uge unordered, greater or equal
- Ne unordered, less or greater = not equal
- True true
-
-
-
- THE PHI NODE
- ------------
-
- In general, Phi nodes are automaitcally inserted. In some cases, if
- all predecessors of a block are known, an explicit Phi node constructor
- is needed. E.g., to construct a FIRM graph for a statement as
- a = (b==c) ? 2 : 5;
-
- ir_node *new_Phi (int arity, ir_node **in, ir_mode *mode)
- ---------------------------------------------------------
-
- Creates a Phi node. The in's order has to correspond to the order
- of in's of current_block. This is not checked by the library!
-
- Parameter
- arity number of predecessors
- **in array with predecessors
- *mode The mode of it's inputs and output.
- Inputs:
- A Phi node has as many inputs as the block it belongs to.
- Each input points to a definition of the same value on a
- different path in the control flow.
- Output
- The definition valid in this block.
-
-
- OPERATIONS TO MANAGE MEMORY EXPLICITLY
- --------------------------------------
-
- ir_node *new_Load (ir_node *store, ir_node *addr)
- ----------------------------------------------------------------
-
- The Load operation reads a value from memory.
-
- Parameters:
- *store The current memory.
- *addr A pointer to the variable to be read in this memory.
- *mode The mode of the loaded value.
-
- Inputs:
- The memory and a pointer to a variable in this memory.
- Output:
- A tuple of the memory, a control flow to be taken in case of
- an exception and the loaded value.
-
- ir_node *new_Store (ir_node *store, ir_node *addr, ir_node *val)
- ----------------------------------------------------------------
-
- The Store operation writes a value to a variable in memory.
-
- Inputs:
- The memory, a pointer to a variable in this memory and the value
- to write to this variable.
- Output:
- A tuple of the changed memory and a control flow to be taken in
- case of an exception.
-
- ir_node *new_Alloc (ir_node *store, ir_node *size, type *alloc_type,
- --------------------------------------------------------------------
- where_alloc where)
- ------------------
-
- The Alloc node allocates a new variable. It can be specified whether the
- variable should be allocated to the stack or to the heap.
-
- Parameters:
- *store The memory which shall contain the new variable.
- ** *size The number of bytes to allocate. Old. **
- *size We decided that the size easily can be derived from the type.
- This field is for allocating arrays, i.e., it gives the multiple
- of the size of alloc_type to allocate memory for.
- *alloc_type The type of the allocated variable.
- where Where to allocate the variable, either heap_alloc or stack_alloc.
-
- Inputs:
- A memory and an unsigned integer.
- Output:
- A tuple of the changed memory, a control flow to be taken in
- case of an exception and the pointer to the new variable.
- Attributes:
- a.where Indicates where the variable is allocated.
- a.*type A pointer to the class the allocated data object
- belongs to.
-
- ir_node *new_Free (ir_node *store, ir_node *ptr, type *free_type)
- ------------------------------------------------------------------
-
- The Free node frees memory of the given variable.
-
- Parameters:
- *store The memory which shall contain the new variable.
- *ptr The pointer to the object to free.
- *size The number of objects of type free_type to free in a sequence.
- *free_type The type of the freed variable.
-
- Inputs:
- A memory, a pointer and an unsigned integer.
- Output:
- The changed memory.
- Attributes:
- f.*type A pointer to the type information of the freed data object.
-
- Not Implemented!
-
- ir_node *new_Sync (int arity, ir_node **in)
- -------------------------------------------
-
- 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.
-
- Parameters
- arity The number of memories to syncronize.
- **in An array of pointers to nodes that produce an output of
- type memory.
- Inputs
- Several memories.
- Output
- The unified memory.
-
-
- SPECIAL OPERATIONS
- ------------------
-
- ir_node *new_Bad (void)
- -----------------------
-
- Returns the unique Bad node current_ir_graph->bad.
- This node is used to express results of dead code elimination.
-
- ir_node *new_Proj (ir_node *arg, ir_mode *mode, long proj)
- ----------------------------------------------------------
-
- Selects one entry of a tuple. This is a hidden `fat edge'.
-
- Parameters
- *arg A node producing a tuple.
- *mode The mode of the value to project.
- proj The position of the value in the tuple.
- Input:
- The tuple.
- Output:
- The value.
-
- ir_node *new_Tuple (int arity, ir_node **in)
- --------------------------------------------
-
- 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 it's
- opcode and giving it a new in array.
-
- Parameters
- arity The number of tuple elements.
- **in An array containing pointers to the nodes producing the
- tuple elements.
-
- ir_node *new_Id (ir_node *val, ir_mode *mode)
- ---------------------------------------------
-
- The single output of the Id operation is it's input. Also needed
- for optimizations.
-
-
- COPING WITH DATA OBJECTS
- ========================
-
- Two kinds of data objects have to be distinguished for generating
- FIRM. First there are local variables other than arrays that are
- known to be alias free. Second there are all other data objects.
- For the first a common SSA representation is built, the second
- are modeled by saving them to memory. The memory is treated as
- a single local variable, the alias problem is hidden in the
- content of this variable.
-
- All values known in a Block are listed in the block's attribute,
- block.**graph_arr which is used to automatically insert Phi nodes.
- The following two funcions can be used to add a newly computed value
- to the array, or to get the producer of a value, i.e., the current
- live value.
-
- inline void set_value (int pos, ir_node *value)
- -----------------------------------------------
-
- Has to be called for every assignment to a local variable. It
- adds the value to the array of used values at position pos. Pos
- has to be a unique identifier for an entry in the procedure's
- definition table. It can be used to access the value again.
-
- ir_node *get_value (int pos, ir_mode *mode)
- -------------------------------------------
-
- Returns the node defining the value referred to by pos. If the
- value is not defined in this block a Phi node is generated and
- all definitions reaching this Phi node are collected. It can
- happen that the algorithm allocates an unnecessary Phi node,
- e.g. if there is only one definition of this value, but this
- definition reaches the currend block on several different
- paths. This Phi node will be eliminated if optimizations are
- turned on right after it's creation.
-
-
- There are two special routines for the global store:
-
- inline void set_store (ir_node *store)
- --------------------------------------
-
- Adds the store to the array of known values at a reserved
- position.
-
- inline ir_node *get_store (void)
- --------------------------------
-
- Returns the node defining the actual store.
-
-**/
+/****h* libfirm/ircons
+ *
+ * NAME
+ * file ircons.h
+ *
+ * NOTES
+ * This file documents all datatypes and constructors needed to
+ * build a FIRM representation of a pocedure. The constructors are
+ * also implemented in this file.
+ *
+ * The documentation also gives a short manual how to use the library.
+ *
+ * For extensive documentation of FIRM see UKA Techreport 1999-14.
+ *
+ * DATATYPES
+ * =========
+ *
+ * The struct ir_graph
+ * -------------------
+ *
+ * This struct contains all information about a procedure.
+ * It's allocated directly to memory.
+ *
+ * The fields of ir_graph:
+ *
+ * *ent The entity describing this procedure.
+ *
+ * The beginning and end of a graph:
+ *
+ * *start_block This ir_node is the block that contains the unique
+ * start node of the procedure. With it it contains
+ * the Proj's on starts results.
+ * Further all Const nodes are placed in the start block.
+ * *start This ir_node is the unique start node of the procedure.
+ *
+ * *end_block This ir_node is the block that contains the unique
+ * end node of the procedure. This block contains no
+ * further nodes.
+ * *end This ir_node is the unique end node of the procedure.
+ *
+ * The following nodes are Projs from the start node, held in ir_graph for
+ * simple access:
+ *
+ * *frame The ir_node producing the pointer to the stack frame of
+ * the procedure as output. This is the Proj node on the
+ * third output of the start node. This output of the start
+ * node is tagged as pns_frame_base. In FIRM most lokal
+ * variables are modeled as data flow edges. Static
+ * allocated arrays can not be represented as dataflow
+ * edges. Therefore FIRM has to represent them in the stack
+ * frame.
+ *
+ * *globals This models a pointer to a space in the memory where
+ * _all_ global things are held. Select from this pointer
+ * with a Sel node the pointer to a global variable /
+ * procedure / compiler known function... .
+ *
+ * *args The ir_node that produces the arguments of the method as
+ * it's result. This is a Proj node on the fourth output of
+ * the start node. This output is tagged as pns_args.
+ *
+ * *bad The bad node is an auxiliary node. It is needed only once,
+ * so there is this globally reachable node.
+ *
+ * Datastructures that are private to a graph:
+ *
+ * *obst An obstack that contains all nodes.
+ *
+ * *current_block A pointer to the current block. Any node created with
+ * one of the node constructors (new_<opcode>) are assigned
+ * to this block. It can be set with switch_block(block).
+ * Only needed for ir construction.
+ *
+ * params/n_loc An int giving the number of local variables in this
+ * procedure. This is neede for ir construction. Name will
+ * be changed.
+ *
+ * *value_table This hash table (pset) is used for global value numbering
+ * for optimizing use in iropt.c.
+ *
+ * *Phi_in_stack; a stack needed for automatic Phi construction, needed only
+ * during ir construction.
+ *
+ * visited A int used as flag to traverse the ir_graph.
+ *
+ * block_visited A int used as a flag to traverse block nodes in the graph.
+ *
+ * Three kinds of nodes
+ * --------------------
+ *
+ * There are three kinds of nodes known to the ir: entities,
+ * types, and ir_nodes
+ *
+ * + ir_nodes are the actual nodes of the FIRM intermediate representation.
+ * They represent operations on the data of the program and control flow
+ * operations.
+ *
+ * + entity ==> implemented in entity.h
+ * Refers to a single entity of the compiled program, e.g. a field of a
+ * class or a method. If a method or variable can not be assigned to
+ * a method or class or the like, it is a global object.
+ *
+ * + types ==> implemented in type.h
+ * With types type information is represented. There are several type
+ * nodes.
+ *
+ * Implementation of the FIRM operations: ir_node
+ * ----------------------------------------------
+ *
+ * Ir_nodes represent operations on the data of the program and control flow
+ * operations. Examples of ir_nodes: Add, Jmp, Cmp
+ *
+ * FIRM is a dataflow graph. A dataflow graph is a directed graph,
+ * so that every node has incoming and outgoing edges. A node is
+ * executable if every input at it's incoming edges is available.
+ * Execution of the dataflow graph is started at the Start node which
+ * has no incoming edges and ends when the End node executes, even if
+ * there are still executable or not executed nodes. (Is this true,
+ * or must all executable nodes be executed?) (There are exceptions
+ * to the dataflow paradigma that all inputs have to be available
+ * before a node can execute: Phi, Block. See UKA Techreport
+ * 1999-14.)
+ *
+ * The implementation of FIRM differs from the view as a dataflow
+ * graph. To allow fast traversion of the graph edges are
+ * implemented as C-pointers. Inputs to nodes are not ambiguous, the
+ * results can be used by several other nodes. Each input can be
+ * implemented as a single pointer to a predecessor node, outputs
+ * need to be lists of pointers to successors. Therefore a node
+ * contains pointers to it's predecessor so that the implementation is a
+ * dataflow graph with reversed edges. It has to be traversed bottom
+ * up.
+ *
+ * All nodes of the ir have the same basic structure. They are
+ * distinguished by a field containing the opcode.
+ *
+ * The fields of an ir_node:
+ *
+ * kind A firm_kind tag containing k_ir_node. This is useful for
+ * dynamically checking the type of a node.
+ *
+ * *op This ir_op gives the opcode as a tag and a string
+ * and the number of attributes of an ir_node. There is
+ * one statically allocated struct ir_op for each opcode.
+ *
+ * *mode The ir_mode of the operation represented by this firm
+ * node. The mode of the operation is the mode of it's
+ * result. A Firm mode is a datatype as known to the target,
+ * not a type of the source language.
+ *
+ * visit A flag for traversing the ir.
+ *
+ * **in An array with pointers to the node's predecessors.
+ *
+ * *link A pointer to an ir_node. With this pointer all Phi nodes
+ * are attached to a Block, i.e., a Block points to it's
+ * first Phi node, this node points to the second Phi node
+ * in the Block and so fourth. Used in mature_block
+ * to find all Phi nodes to be matured. It's also used to
+ * annotate a node with a better, optimized version of it.
+ *
+ * attr An attr struct containing the attributes of the nodes. The
+ * attributes depend on the opcode of the node. The number
+ * of these attributes is given in op.
+ *
+ * The struct ir_op
+ * ----------------
+ * Not yet documented. See irop.h.
+ *
+ * The struct ir_mode
+ * ------------------
+ * Not yet documented. See irmode.h.
+ *
+ * GLOBAL VARIABLES
+ * ================
+ *
+ * current_ir_graph Points to the current ir_graph. All constructors for
+ * nodes add nodes to this graph.
+ *
+ * ir_visited An int used as flag to traverse the ir_graph.
+ *
+ * block_visited An int used as a flag to traverse block nodes in the
+ * graph.
+ *
+ * Others not yet documented.
+ *
+ *
+ *
+ * CONSTRUCTOR FOR IR_GRAPH
+ * ========================
+ *
+ * ir_graph *new_ir_graph (entity *ent, int params);
+ * -------------------------------------------------
+ *
+ * This constructor generates the basic infrastructure needed to
+ * represent a procedure in FIRM.
+ *
+ * The parameters of new_ir_graph are:
+ *
+ * *ent A pointer to an entity representing the procedure.
+ *
+ * params An integer giving the number of local variables in the
+ * procedure.
+ *
+ * It allocates an ir_graph and sets current_ir_graph to point to this
+ * graph. Further it allocates the following nodes needed for every
+ * procedure:
+ *
+ * * The start block containing a start node and Proj nodes for it's
+ * five results (X, M, P, P, T).
+ * * The end block containing an end node. This block is not matured
+ * after executing new_ir_graph as predecessors need to be added to it.
+ * (Maturing a block means fixing it's number of predecessors.)
+ * * The current block, which is empty and also not matured.
+ *
+ * Further it enters the global store into the datastructure of the start
+ * block that contanis all valid values in this block (set_store()). This
+ * datastructure is used to build the Phi nodes and removed after completion
+ * of the graph.
+ * There is no path from end to start in the graph after calling ir_graph.
+ *
+ *
+ * PROCEDURE TO CONSTRUCT AN IR GRAPH
+ * ==================================
+ *
+ * This library supplies several interfaces to construct a FIRM graph for
+ * a program:
+ * * A "comfortable" interface generating SSA automatically. Automatically
+ * computed predecessors of nodes need not be specified in the constructors.
+ * (new_<Node> constructurs and a set of additional routines.)
+ * * A less comfortable interface where all predecessors except the block
+ * an operation belongs to need to be specified. SSA must be constructed
+ * by hand. (new_<Node> constructors and switch_block()). This interface
+ * is called "block oriented". It automatically calles the local optimizations
+ * for each new node.
+ * * An even less comfortable interface where the block needs to be specified
+ * explicitly. This is called the "raw" interface. (new_r_<Node>
+ * constructors). These nodes are not optimized.
+ *
+ * To use the functionality of the comfortable interface correctly the Front
+ * End needs to follow certain protocols. This is explained in the following.
+ * To build a correct IR with the other interfaces study the semantics of
+ * the firm node (See tech-reprot UKA 1999-44). For the construction of
+ * types and entities see the documentation in those modules.
+ *
+ * First the Frontend needs to decide which variables and values used in
+ * a procedure can be represented by dataflow edges. These are variables
+ * that need not be saved to memory as they cause no side effects visible
+ * out of the procedure. In general these are all compiler generated
+ * variables and simple local variables of the procedure as integers,
+ * reals and pointers. The frontend has to count and number these variables.
+ *
+ * First an ir_graph needs to be constructed with new_ir_graph. The
+ * constructor gets the number of local variables. The graph is hold in the
+ * global variable irg.
+ *
+ * Now the construction of the procedure can start. Several basic blocks can
+ * be constructed in parallel, but the code within each block needs to
+ * be constructed (almost) in program order.
+ *
+ * A global variable holds the current basic block. All (non block) nodes
+ * generated are added to this block. The current block can be set with
+ * switch_block(block). If several blocks are constructed in parallel block
+ * switches need to be performed constantly.
+ *
+ * To generate a Block node (with the comfortable interface) it's predecessor
+ * control flow nodes need not be known. In case of cyclic control flow these
+ * can not be known when the block is constructed. With add_in_edge(block,
+ * cfnode) predecessors can be added to the block. If all predecessors are
+ * added to the block mature_block(b) needs to be called. Calling mature_block
+ * early improves the efficiency of the Phi node construction algorithm.
+ * But if several blocks are constructed at once, mature_block must only
+ * be called after performing all set_values and set_stores in the block!
+ * (See documentation of new_immBlock constructor.)
+ *
+ * The constructors of arithmetic nodes require that their predecessors
+ * are mentioned. Sometimes these are available in the Frontend as the
+ * predecessors have just been generated by the frontend. If they are local
+ * values the predecessors can be obtained from the library with a call to
+ * get_value(local_val_nr). (local_val_nr needs to be administered by
+ * the Frontend.) A call to get_value triggers the generation of Phi nodes.
+ * If an arithmetic operation produces a local value this value needs to be
+ * passed to the library by set_value(node, local_val_nr).
+ * In straight line code these two operations just remember and return the
+ * pointer to nodes producing the value. If the value passes block boundaries
+ * Phi nodes can be inserted.
+ * Similar routines exist to manage the Memory operands: set_store and
+ * get_store.
+ *
+ * Several nodes produce more than one result. An example is the Div node.
+ * Such nodes return tuples of values. From these individual values can be
+ * extracted by proj nodes.
+ *
+ * The following example illustrates the construction of a simple basic block
+ * with two predecessors stored in variables cf_pred1 and cf_pred2, containing
+ * the code
+ * a = a div a;
+ * and finally jumping to an other block. The variable a got the local_val_nr
+ * 42 by the frontend.
+ *
+ * ir_node *this_block, *cf_pred1, *cf_pred2, *a_val, *mem, *div, *res, *cf_op;
+ *
+ * this_block = new_immBlock();
+ * add_in_edge(this_block, cf_pred1);
+ * add_in_edge(this_block, cf_pred2);
+ * mature_block(this_block);
+ * a_val = get_value(17, mode_I);
+ * mem = get_store();
+ * div = new_Div(mem, a_val, a_val);
+ * mem = new_Proj(div, mode_M, 0); * for the numbers for Proj see docu *
+ * res = new_Proj(div, mode_I, 2);
+ * set_store(mem);
+ * set_value(res, 17);
+ * cf_op = new_Jmp();
+ *
+ * For further information look at the documentation of the nodes and
+ * constructors and at the paragraph COPING WITH DATA OBJECTS at the
+ * end of this documentation.
+ *
+ * The comfortable interface contains the following routines further explained
+ * below:
+ *
+ * ir_node *new_immBlock (void);
+ * ir_node *new_Start (void);
+ * ir_node *new_End (void);
+ * ir_node *new_Jmp (void);
+ * ir_node *new_Cond (ir_node *c);
+ * ir_node *new_Return (ir_node *store, int arity, ir_node **in);
+ * ir_node *new_Raise (ir_node *store, ir_node *obj);
+ * ir_node *new_Const (ir_mode *mode, tarval *con);
+ * ir_node *new_SymConst (type_or_id *value, symconst_kind kind);
+ * ir_node *new_simpleSel (ir_node *store, ir_node *objptr, entity *ent);
+ * ir_node *new_Sel (ir_node *store, ir_node *objptr, int arity,
+ * ir_node **in, entity *ent);
+ * ir_node *new_Call (ir_node *store, ir_node *callee, int arity,
+ * ir_node **in, type_method *type);
+ * ir_node *new_Add (ir_node *op1, ir_node *op2, ir_mode *mode);
+ * ir_node *new_Sub (ir_node *op1, ir_node *op2, ir_mode *mode);
+ * ir_node *new_Minus (ir_node *op, ir_mode *mode);
+ * ir_node *new_Mul (ir_node *op1, ir_node *op2, ir_mode *mode);
+ * ir_node *new_Quot (ir_node *memop, ir_node *op1, ir_node *op2);
+ * ir_node *new_DivMod (ir_node *memop, ir_node *op1, ir_node *op2);
+ * ir_node *new_Div (ir_node *memop, ir_node *op1, ir_node *op2);
+ * ir_node *new_Mod (ir_node *memop, ir_node *op1, ir_node *op2);
+ * ir_node *new_Abs (ir_node *op, ir_mode *mode);
+ * ir_node *new_And (ir_node *op1, ir_node *op2, ir_mode *mode);
+ * ir_node *new_Or (ir_node *op1, ir_node *op2, ir_mode *mode);
+ * ir_node *new_Eor (ir_node *op1, ir_node *op2, ir_mode *mode);
+ * ir_node *new_Not (ir_node *op, ir_mode *mode);
+ * ir_node *new_Shl (ir_node *op, ir_node *k, ir_mode *mode);
+ * ir_node *new_Shr (ir_node *op, ir_node *k, ir_mode *mode);
+ * ir_node *new_Shrs (ir_node *op, ir_node *k, ir_mode *mode);
+ * ir_node *new_Rot (ir_node *op, ir_node *k, ir_mode *mode);
+ * ir_node *new_Cmp (ir_node *op1, ir_node *op2);
+ * ir_node *new_Conv (ir_node *op, ir_mode *mode);
+ * ir_node *new_Load (ir_node *store, ir_node *addr);
+ * ir_node *new_Store (ir_node *store, ir_node *addr, ir_node *val);
+ * ir_node *new_Alloc (ir_node *store, ir_node *size, type *alloc_type,
+ * where_alloc where);
+ * ir_node *new_Free (ir_node *store, ir_node *ptr, ir_node *size,
+ * type *free_type);
+ * ir_node *new_Proj (ir_node *arg, ir_mode *mode, long proj);
+ *
+ * void add_in_edge (ir_node *block, ir_node *jmp);
+ * void mature_block (ir_node *block);
+ * void switch_block (ir_node *target);
+ * ir_node *get_value (int pos, ir_mode *mode);
+ * void set_value (int pos, ir_node *value);
+ * ir_node *get_store (void);
+ * void set_store (ir_node *store);
+ *
+ *
+ * IR_NODES AND CONSTRUCTORS FOR IR_NODES
+ * =======================================
+ *
+ * All ir_nodes are defined by a common data structure. They are distinguished
+ * by their opcode and differ in the number of their attributes.
+ *
+ * The constructor for the block node sets current_block to itself.
+ * Const nodes are always added to the start block.
+ * All other constructors add the created node to the current_block.
+ * swich_block(block) allows to set the current block to block.
+ *
+ * Watch for my inconsistent use of input and predecessor (dataflow view)
+ * and `the node points to' (implementation view).
+ *
+ * The following description of the nodes lists four properties them if these
+ * are of interest:
+ * - the parameters to the constructor
+ * - the inputs of the Firm node
+ * - the outputs of the Firm node
+ * - attributes to the node
+ *
+ * BASIC BLOCKS
+ * ------------
+ *
+ * ir_node *new_immBlock (void)
+ * ----------------------------
+ *
+ * Creates a new block. Sets current_block to itself. When a new block is
+ * created it cannot be known how many predecessors this block will have in the
+ * control flow graph. Therefore the list of inputs can not be fixed at
+ * creation. Predecessors can be added with add_in_edge (block, control flow
+ * operation). With every added predecessor the number of inputs to Phi nodes
+ * also changes.
+ *
+ * The block can be completed by mature_block(block) if all predecessors are
+ * known. If several blocks are built at once, mature_block can only be called
+ * after set_value has been called for all values that are life at the end
+ * of the block. This is necessary so that Phi nodes created by mature_block
+ * get the right predecessors in case of cyclic dependencies. If all set_values
+ * of this block are called after maturing it and before calling get_value
+ * in some block that is control flow dependent on this block, the construction
+ * is correct.
+ *
+ * Example for faulty ir construction: (draw the graph on a paper and you'll
+ * get it ;-)
+ *
+ * block_before_loop = new_block();
+ * set_value(x);
+ * mature_block(block_before_loop);
+ * before2header = new_Jmp;
+ *
+ * loop_header = new_block ();
+ * header2body - new_Jmp();
+ *
+ * loop_body = new_block ();
+ * body2header = new_Jmp();
+ *
+ * add_in_edge(loop_header, before2header);
+ * add_in_edge(loop_header, body2header);
+ * add_in_edge(loop_body, header2body);
+ *
+ * mature_block(loop_header);
+ * mature_block(loop_body);
+ *
+ * get_value(loop_body, x); // gets the Phi in loop_header
+ * set_value(loop_header, x); // sets the value the above get_value should
+ * // have returned!!!
+ *
+ * Mature_block also fixes the number of inputs to the Phi nodes. Mature_block
+ * should be called as early as possible, as afterwards the generation of Phi
+ * nodes is more efficient.
+ *
+ * Inputs:
+ * There is an input for each control flow predecessor of the block.
+ * The input points to an instruction producing an output of type X.
+ * Possible predecessors: Start, Jmp, Cond, Raise or Return or any node
+ * possibly causing an exception. (Often the real predecessors are Projs.)
+ * Output:
+ * Mode BB (R), all nodes belonging to this block should consume this output.
+ * As they are strict (except Block and Phi node) it is a necessary condition
+ * that the block node executed before any other node in this block executes.
+ * Attributes:
+ * block.matured Indicates whether the block is mature.
+ * block.**graph_arr
+ * This attribute contains all local values valid in this
+ * block. This is needed to build the Phi nodes and removed
+ * if the graph is complete. This field is used by the
+ * internal construction algorithm and should not be accessed
+ * from outside.
+ *
+ *
+ * ir_node *new_Block (int arity, ir_node **in)
+ * --------------------------------------------
+ *
+ * Creates a new Block with the given list of predecessors. This block
+ * is mature.
+ *
+ *
+ * CONTROL FLOW OPERATIONS
+ * -----------------------
+ *
+ * In each block there must be exactly one of the control flow
+ * operations Start, End, Jmp, Cond, Return or Raise. The output of a
+ * control flow operation points to the block to be executed next.
+ *
+ * ir_node *new_Start (void)
+ * -------------------------
+ *
+ * Creates a start node. Not actually needed public. There is only one such
+ * node in each procedure which is automatically created by new_ir_graph.
+ *
+ * Inputs:
+ * No inputs except the block it belogns to.
+ * Output:
+ * A tuple of 4 (5, 6) distinct values. These are labeled by the following
+ * projection numbers (pns_number):
+ * * pns_initial_exec
+ * mode X, points to the first block to be executed.
+ * * pns_global_store
+ * mode M, the global store
+ * * pns_frame_base mode P, a pointer to the base of the procedures
+ * stack frame.
+ * * pns_globals mode P, a pointer to the part of the memory containing
+ * _all_ global things.
+ * * pns_args mode T, a tuple containing all arguments of the procedure.
+ *
+ *
+ * ir_node *new_End (void)
+ * -----------------------
+ *
+ * Creates an end node. Not actually needed public. There is only one such
+ * node in each procedure which is automatically created by new_ir_graph.
+ *
+ * Inputs:
+ * No inputs except the block it belongs to.
+ * Output:
+ * No output.
+ *
+ * ir_node *new_Jmp (void)
+ * -----------------------
+ *
+ * Creates a Jmp node.
+ *
+ * Inputs:
+ * The block the node belongs to
+ * Output:
+ * Control flow to the next block.
+ *
+ * ir_node *new_Cond (ir_node *c)
+ * ------------------------------
+ *
+ * Creates a Cond node. There are two versions of this node.
+ *
+ * The Boolean Cond:
+ * Input:
+ * A value of mode b.
+ * Output:
+ * A tuple of two control flows. The first is taken if the input is
+ * false, the second if it is true.
+ *
+ * The Switch Cond:
+ * Input:
+ * A value of mode I_u. (i)
+ * Output:
+ * A tuple of n control flows. If the Cond's input is i, control
+ * flow will procede along output i. If the input is >= n control
+ * flow proceeds along output n.
+ *
+ * ir_node *new_Return (in_node *store, int arity, ir_node **in)
+ * -------------------------------------------------------------
+ *
+ * The return node has as inputs the results of the procedure. It
+ * passes the control flow to the end_block.
+ *
+ * Inputs:
+ * The memory state.
+ * All results.
+ * Output
+ * Control flow to the end block.
+ *
+ * ir_node *new_Raise (ir_node *store, ir_node *obj)
+ * -------------------------------------------------
+ *
+ * Raises an exception. Unconditional change of control flow. Writes
+ * an explicit Except variable to memory to pass it to the exception
+ * handler. See TechReport 1999-14, chapter Exceptions.
+ *
+ * Inputs:
+ * The memory state.
+ * A pointer to the Except variable.
+ * Output:
+ * A tuple of control flow and the changed memory state. The control flow
+ * points to the exception handler if it is definied in this procedure,
+ * else it points to the end_block.
+ *
+ *
+ * CONSTANTS
+ * ---------
+ *
+ * ir_node *new_Const (ir_mode *mode, tarval *con)
+ * -----------------------------------------------
+ *
+ * Creates a constant in the constant table and adds a Const node
+ * returning this value to the start block.
+ *
+ * Parameters:
+ * *mode The mode of the constant.
+ * *con Points to an entry in the constant table.
+ * This pointer is added to the attributes of
+ * the node (self->attr.con)
+ * Inputs:
+ * No inputs except the block it belogns to.
+ * Output:
+ * The constant value.
+ * Attribute:
+ * attr.con A tarval* pointer to the proper entry in the constant
+ * table.
+ *
+ * ir_node *new_SymConst (type *type, symconst_kind kind)
+ * ------------------------------------------------------------
+ *
+ * There are three kinds of symbolic constants:
+ * type_tag The symbolic constant represents a type tag.
+ * size The symbolic constant represents the size of a class.
+ * link_info Information for the linker, e.g. the name of a global
+ * variable.
+ *
+ * Parameters
+ * kind The kind of the symbolic constant: type_tag, size or link_info.
+ * *type_or_id Points to the type the tag stands for or to the type
+ * whose size is represented by the constant or to an ident
+ * representing the linkage info.
+ *
+ * Inputs:
+ * No inputs except the block it belogns to.
+ * Output:
+ * An unsigned integer (I_u) or a pointer (P).
+ *
+ * Attributes:
+ * attr.i.num The symconst_kind, i.e. one of
+ * - type_tag
+ * - size
+ * - linkage_ptr_info
+ * If the attr.i.num is type_tag or size, the node contains an attribute
+ * attr.i.*type, a pointer to a type_class. The mode of the node is mode_i.
+ * if it is linkage_ptr_info it contains
+ * attr.i.*ptrinfo, an ident holding information for the linker. The mode
+ * of the node is mode_p.
+ *
+ * THE SELECT NODE
+ * ---------------
+ *
+ * ir_node *new_simpleSel (ir_node *store, ir_node *frame, entity *sel)
+ * --------------------------------------------------------------------
+ *
+ *
+ * Selects an entity from a compound type. This entity can be a field or
+ * a method.
+ *
+ * Parameters:
+ * *store The memory in which the object the entity should be selected
+ * from is allocated.
+ * *frame The pointer to the object.
+ * *sel The entity to select.
+ *
+ * Inputs:
+ * The memory containing the object.
+ * A pointer to the object.
+ * An unsigned integer.
+ * Output:
+ * A pointer to the selected entity.
+ * Attributes:
+ * attr.sel Pointer to the entity
+ *
+ *
+ * ir_node *new_Sel (ir_node *store, ir_node *frame, int arity, ir_node **in,
+ * --------------------------------------------------------------------------
+ * entity *sel)
+ * ------------
+ *
+ * Selects a field from an array type. The entity has as owner the array, as
+ * type the arrays element type. The indexes to access an array element are
+ * given also.
+ *
+ * Parameters:
+ * *store The memory in which the object the entity should be selected from
+ * is allocated.
+ * *frame The pointer to the object.
+ * *arity number of array indexes.
+ * *in array with index inputs to the node.
+ * *sel The entity to select.
+ *
+ * Inputs:
+ * The memory containing the object.
+ * A pointer to the object.
+ * As much unsigned integer as there are array expressions.
+ * Output:
+ * A pointer to the selected entity.
+ * Attributes:
+ * attr.sel Pointer to the entity
+ *
+ * The constructors new_Sel and new_simpleSel generate the same ir nodes.
+ * simpleSel just sets the arity of the index inputs to zero.
+ *
+ *
+ * ARITHMETIC OPERATIONS
+ * ---------------------
+ *
+ * ir_node *new_Call (ir_node *store, ir_node *callee, int arity, ir_node **in,
+ * ----------------------------------------------------------------------------
+ * type_method *type)
+ * ------------------
+ *
+ * Creates a procedure call.
+ *
+ * Parameters
+ * *store The actual store.
+ * *callee A pointer to the called procedure.
+ * arity The number of procedure parameters.
+ * **in An array with the pointers to the parameters.
+ * The constructor copies this array.
+ * *type Type information of the procedure called.
+ *
+ * Inputs:
+ * The store, the callee and the parameters.
+ * Output:
+ * A tuple containing the eventually changed store and the procedure
+ * results.
+ * Attributes:
+ * attr.call Contains the type information for the procedure.
+ *
+ * ir_node *new_Add (ir_node *op1, ir_node *op2, ir_mode *mode)
+ * ------------------------------------------------------------
+ *
+ * Trivial.
+ *
+ * ir_node *new_Sub (ir_node *op1, ir_node *op2, ir_mode *mode)
+ * ------------------------------------------------------------
+ *
+ * Trivial.
+ *
+ * ir_node *new_Minus (ir_node *op, ir_mode *mode)
+ * -----------------------------------------------
+ *
+ * This constructor is for unary Minus operations on floating point
+ * values. Such a Minus can trap if it is implemented as a Sub from
+ * zero due to rounding errors.
+ *
+ * ir_node *new_Mul (ir_node *op1, ir_node *op2, ir_mode *mode)
+ * ------------------------------------------------------------
+ *
+ * Trivial.
+ *
+ * ir_node *new_Quot (ir_node *memop, ir_node *op1, ir_node *op2)
+ * --------------------------------------------------------------
+ *
+ * Quot performs exact division of floating point numbers. It's mode
+ * is Tuple, the mode of the result must be annotated to the Proj
+ * that extracts the result of the arithmetic operations.
+ *
+ * Inputs:
+ * The store needed to model exceptions and the two operands.
+ * Output:
+ * A tuple contaning a memory and a execution for modeling exceptions
+ * and the result of the arithmetic operation.
+ *
+ * ir_node *new_DivMod (ir_node *memop, ir_node *op1, ir_node *op2)
+ * ----------------------------------------------------------------
+ *
+ * Performs Div and Mod on interger values.
+ *
+ * Output:
+ * A tuple contaning a memory and a execution for modeling exceptions
+ * and the two result of the arithmetic operations.
+ *
+ * ir_node *new_Div (ir_node *memop, ir_node *op1, ir_node *op2)
+ * -------------------------------------------------------------
+ *
+ * Trivial.
+ *
+ * ir_node *new_Mod (ir_node *memop, ir_node *op1, ir_node *op2)
+ * -------------------------------------------------------------
+ *
+ * Trivial.
+ *
+ * ir_node *new_Abs (ir_node *op, ir_mode *mode)
+ * ---------------------------------------------
+ *
+ * Trivial.
+ *
+ * ir_node *new_And (ir_node *op1, ir_node *op2, ir_mode *mode)
+ * ------------------------------------------------------------
+ *
+ * Trivial.
+ *
+ * ir_node *new_Or (ir_node *op1, ir_node *op2, ir_mode *mode)
+ * -----------------------------------------------------------
+ *
+ * Trivial.
+ *
+ * ir_node *new_Eor (ir_node *op1, ir_node *op2, ir_mode *mode)
+ * ------------------------------------------------------------
+ *
+ * Trivial.
+ *
+ * ir_node *new_Not (ir_node *op, ir_mode *mode)
+ * ---------------------------------------------
+ *
+ * This node constructs a constant where all bits are set to one
+ * and a Eor of this constant and the operator. This simulates a
+ * Not operation.
+ *
+ * ir_node *new_Shl (ir_node *op, ir_node *k, ir_mode *mode)
+ * ---------------------------------------------------------
+ *
+ * Trivial.
+ *
+ * ir_node *new_Shr (ir_node *op, ir_node *k, ir_mode *mode)
+ * ---------------------------------------------------------
+ *
+ * Logic shift right, i.e., zero extended.
+ *
+ *
+ * ir_node *new_Shrs (ir_node *op, ir_node *k, ir_mode *mode)
+ * ----------------------------------------------------------
+ *
+ * Arithmetic shift right, i.e., sign extended.
+ *
+ * ir_node *new_Rot (ir_node *op, ir_node *k, ir_mode *mode)
+ * ---------------------------------------------------------
+ *
+ * Rotates the operand to the (right??) by k bits.
+ *
+ * ir_node *new_Conv (ir_node *op, ir_mode *mode)
+ * ---------------------------------------------
+ *
+ * Mode conversion. For allowed conversions see UKA Tech Report
+ * 1999-14.
+ *
+ * ir_node *new_Cmp (ir_node *op1, ir_node *op2)
+ * ---------------------------------------------
+ *
+ * Input:
+ * The two values to be compared.
+ * Output:
+ * A 16-tuple containing the results of the 16 different comparisons.
+ * The following is a list giving the comparisons and a projection
+ * number (pnc_number) to use in Proj nodes to extract the proper result.
+ * False false
+ * Eq equal
+ * Lt less
+ * Le less or equal
+ * Gt greater
+ * Ge greater of equal
+ * Lg less or greater
+ * Leg less, equal or greater = ordered
+ * Uo unordered
+ * Ue unordered or equal
+ * Ul unordered or less
+ * Ule unordered, less or equal
+ * Ug unordered or greater
+ * Uge unordered, greater or equal
+ * Ne unordered, less or greater = not equal
+ * True true
+ *
+ *
+ *
+ * THE PHI NODE
+ * ------------
+ *
+ * In general, Phi nodes are automaitcally inserted. In some cases, if
+ * all predecessors of a block are known, an explicit Phi node constructor
+ * is needed. E.g., to construct a FIRM graph for a statement as
+ * a = (b==c) ? 2 : 5;
+ *
+ * ir_node *new_Phi (int arity, ir_node **in, ir_mode *mode)
+ * ---------------------------------------------------------
+ *
+ * Creates a Phi node. The in's order has to correspond to the order
+ * of in's of current_block. This is not checked by the library!
+ *
+ * Parameter
+ * arity number of predecessors
+ * **in array with predecessors
+ * *mode The mode of it's inputs and output.
+ * Inputs:
+ * A Phi node has as many inputs as the block it belongs to.
+ * Each input points to a definition of the same value on a
+ * different path in the control flow.
+ * Output
+ * The definition valid in this block.
+ *
+ *
+ * OPERATIONS TO MANAGE MEMORY EXPLICITLY
+ * --------------------------------------
+ *
+ * ir_node *new_Load (ir_node *store, ir_node *addr)
+ * ----------------------------------------------------------------
+ *
+ * The Load operation reads a value from memory.
+ *
+ * Parameters:
+ * *store The current memory.
+ * *addr A pointer to the variable to be read in this memory.
+ *
+ * Inputs:
+ * The memory and a pointer to a variable in this memory.
+ * Output:
+ * A tuple of the memory, a control flow to be taken in case of
+ * an exception and the loaded value.
+ *
+ * ir_node *new_Store (ir_node *store, ir_node *addr, ir_node *val)
+ * ----------------------------------------------------------------
+ *
+ * The Store operation writes a value to a variable in memory.
+ *
+ * Inputs:
+ * The memory, a pointer to a variable in this memory and the value
+ * to write to this variable.
+ * Output:
+ * A tuple of the changed memory and a control flow to be taken in
+ * case of an exception.
+ *
+ * ir_node *new_Alloc (ir_node *store, ir_node *size, type *alloc_type,
+ * --------------------------------------------------------------------
+ * where_alloc where)
+ * ------------------
+ *
+ * The Alloc node allocates a new variable. It can be specified whether the
+ * variable should be allocated to the stack or to the heap.
+ *
+ * Parameters:
+ * *store The memory which shall contain the new variable.
+ * ** *size The number of bytes to allocate. Old. **
+ * *size We decided that the size easily can be derived from the type.
+ * This field is for allocating arrays, i.e., it gives the multiple
+ * of the size of alloc_type to allocate memory for.
+ * *alloc_type The type of the allocated variable.
+ * where Where to allocate the variable, either heap_alloc or stack_alloc.
+ *
+ * Inputs:
+ * A memory and an unsigned integer.
+ * Output:
+ * A tuple of the changed memory, a control flow to be taken in
+ * case of an exception and the pointer to the new variable.
+ * Attributes:
+ * a.where Indicates where the variable is allocated.
+ * a.*type A pointer to the class the allocated data object
+ * belongs to.
+ *
+ * ir_node *new_Free (ir_node *store, ir_node *ptr, type *free_type)
+ * ------------------------------------------------------------------
+ *
+ * The Free node frees memory of the given variable.
+ *
+ * Parameters:
+ * *store The memory which shall contain the new variable.
+ * *ptr The pointer to the object to free.
+ * *size The number of objects of type free_type to free in a sequence.
+ * *free_type The type of the freed variable.
+ *
+ * Inputs:
+ * A memory, a pointer and an unsigned integer.
+ * Output:
+ * The changed memory.
+ * Attributes:
+ * f.*type A pointer to the type information of the freed data object.
+ *
+ * Not Implemented!
+ *
+ * ir_node *new_Sync (int arity, ir_node **in)
+ * -------------------------------------------
+ *
+ * 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.
+ *
+ * Parameters
+ * arity The number of memories to syncronize.
+ * **in An array of pointers to nodes that produce an output of
+ * type memory.
+ * Inputs
+ * Several memories.
+ * Output
+ * The unified memory.
+ *
+ *
+ * SPECIAL OPERATIONS
+ * ------------------
+ *
+ * ir_node *new_Bad (void)
+ * -----------------------
+ *
+ * Returns the unique Bad node current_ir_graph->bad.
+ * This node is used to express results of dead code elimination.
+ *
+ * ir_node *new_Proj (ir_node *arg, ir_mode *mode, long proj)
+ * ----------------------------------------------------------
+ *
+ * Selects one entry of a tuple. This is a hidden `fat edge'.
+ *
+ * Parameters
+ * *arg A node producing a tuple.
+ * *mode The mode of the value to project.
+ * proj The position of the value in the tuple.
+ * Input:
+ * The tuple.
+ * Output:
+ * The value.
+ *
+ * ir_node *new_Tuple (int arity, ir_node **in)
+ * --------------------------------------------
+ *
+ * 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 it's
+ * opcode and giving it a new in array.
+ *
+ * Parameters
+ * arity The number of tuple elements.
+ * **in An array containing pointers to the nodes producing the
+ * tuple elements.
+ *
+ * ir_node *new_Id (ir_node *val, ir_mode *mode)
+ * ---------------------------------------------
+ *
+ * The single output of the Id operation is it's input. Also needed
+ * for optimizations.
+ *
+ *
+ * COPING WITH DATA OBJECTS
+ * ========================
+ *
+ * Two kinds of data objects have to be distinguished for generating
+ * FIRM. First there are local variables other than arrays that are
+ * known to be alias free. Second there are all other data objects.
+ * For the first a common SSA representation is built, the second
+ * are modeled by saving them to memory. The memory is treated as
+ * a single local variable, the alias problem is hidden in the
+ * content of this variable.
+ *
+ * All values known in a Block are listed in the block's attribute,
+ * block.**graph_arr which is used to automatically insert Phi nodes.
+ * The following two funcions can be used to add a newly computed value
+ * to the array, or to get the producer of a value, i.e., the current
+ * live value.
+ *
+ * inline void set_value (int pos, ir_node *value)
+ * -----------------------------------------------
+ *
+ * Has to be called for every assignment to a local variable. It
+ * adds the value to the array of used values at position pos. Pos
+ * has to be a unique identifier for an entry in the procedure's
+ * definition table. It can be used to access the value again.
+ *
+ * ir_node *get_value (int pos, ir_mode *mode)
+ * -------------------------------------------
+ *
+ * Returns the node defining the value referred to by pos. If the
+ * value is not defined in this block a Phi node is generated and
+ * all definitions reaching this Phi node are collected. It can
+ * happen that the algorithm allocates an unnecessary Phi node,
+ * e.g. if there is only one definition of this value, but this
+ * definition reaches the currend block on several different
+ * paths. This Phi node will be eliminated if optimizations are
+ * turned on right after it's creation.
+ *
+ *
+ * There are two special routines for the global store:
+ *
+ * inline void set_store (ir_node *store)
+ * --------------------------------------
+ *
+ * Adds the store to the array of known values at a reserved
+ * position.
+ *
+ * inline ir_node *get_store (void)
+ * --------------------------------
+ *
+ * Returns the node defining the actual store.
+ *****
+ */
# ifndef _IRCONS_H_
# define _IRCONS_H_
-# include "irgmod.h"
+# include "common.h"
+# include "irgraph.h"
+# include "irnode.h"
# include "irmode.h"
# include "entity.h"
# include "tv.h"
-# include "common.h"
-# include "irop.h"
-# include "irgraph.h"
# include "type.h"
-# include "pdeq.h"
-# include "irvrfy.h"
-
-/* irnode constructor */
-/* Create a new irnode in irg, with an op, mode, arity and */
-/* some incoming irnodes. */
-/* If arity is negative, a node with a dynamic array is created. */
-/* inline ir_node *new_ir_node (ir_graph *irg, ir_node *block, ir_op *op,
- ir_mode *mode, int arity, ir_node **in);
-*/
-/** These headers need not to be here. They are never used by the
- public.
- That's not completely true. They need not be seen by a frontend,
- but they might be useful for optimizations changing the IR. **/
-#if USE_EXPICIT_PHI_IN_STACK
-/* A stack needed for the automatic Phi node construction in constructor
- Phi_in. */
-typedef struct Phi_in_stack {
- ir_node **stack;
- int pos;
-} Phi_in_stack;
-#endif
-
-/* privat interfaces */
-/* more detailed construction */
+/***************************************************************************/
+/* The raw interface */
+/***************************************************************************/
+/* Constructs a Block with a fixed number of predecessors.
+ Does not set current_block. Can not be used with automatic
+ Phi node construction. */
ir_node *new_r_Block (ir_graph *irg, int arity, ir_node **in);
ir_node *new_r_Start (ir_graph *irg, ir_node *block);
ir_node *new_r_End (ir_graph *irg, ir_node *block);
ir_node *new_r_Const (ir_graph *irg, ir_node *block,
ir_mode *mode, tarval *con);
ir_node *new_r_SymConst (ir_graph *irg, ir_node *block,
- type_or_id *value, symconst_kind symkind);
+ type_or_id_p value, symconst_kind symkind);
ir_node *new_r_Sel (ir_graph *irg, ir_node *block, ir_node *store,
ir_node *objptr, int n_index, ir_node **index,
entity *ent);
ir_node *new_r_Call (ir_graph *irg, ir_node *block, ir_node *store,
- ir_node *callee, int arity, ir_node **in, type_method *type);
+ ir_node *callee, int arity, ir_node **in,
+ type *type);
ir_node *new_r_Add (ir_graph *irg, ir_node *block,
ir_node *op1, ir_node *op2, ir_mode *mode);
ir_node *new_r_Sub (ir_graph *irg, ir_node *block,
ir_mode *mode, long proj);
ir_node *new_r_Tuple (ir_graph *irg, ir_node *block,
int arity, ir_node **in);
-ir_node *new_r_Id (ir_graph *irg, ir_node *block,
- ir_node *val, ir_mode *mode);
-ir_node *new_r_Bad (ir_node *block);
+ir_node *new_r_Id (ir_graph *irg, ir_node *block,
+ ir_node *val, ir_mode *mode);
+ir_node *new_r_Bad ();
+/*************************************************************************/
+/* The block oriented interface */
+/*************************************************************************/
-/* public interfaces */
-/* normal constructors */
+/* Sets the current block in which the following constructors place the
+ nodes they construct. */
+void switch_block (ir_node *target);
-ir_node *new_Block (void);
+/* Constructs a Block with a fixed number of predecessors.
+ Does set current_block. Can be used with automatic Phi
+ node construction. */
+ir_node *new_Block(int arity, ir_node **in);
ir_node *new_Start (void);
ir_node *new_End (void);
ir_node *new_Jmp (void);
ir_node *new_Return (ir_node *store, int arity, ir_node **in);
ir_node *new_Raise (ir_node *store, ir_node *obj);
ir_node *new_Const (ir_mode *mode, tarval *con);
-ir_node *new_SymConst (type_or_id *value, symconst_kind kind);
+ir_node *new_SymConst (type_or_id_p value, symconst_kind kind);
ir_node *new_simpleSel (ir_node *store, ir_node *objptr, entity *ent);
ir_node *new_Sel (ir_node *store, ir_node *objptr, int arity, ir_node **in,
entity *ent);
ir_node *new_Call (ir_node *store, ir_node *callee, int arity, ir_node **in,
- type_method *type);
+ type *type);
ir_node *new_Add (ir_node *op1, ir_node *op2, ir_mode *mode);
ir_node *new_Sub (ir_node *op1, ir_node *op2, ir_mode *mode);
ir_node *new_Minus (ir_node *op, ir_mode *mode);
ir_node *new_Id (ir_node *val, ir_mode *mode);
ir_node *new_Bad (void);
-
-#if USE_EXPICIT_PHI_IN_STACK
-Phi_in_stack *new_Phi_in_stack();
-#endif
-
-/* initialize ir construction */
+/***********************************************************************/
+/* The comfortable interface. */
+/* Supports automatic Phi node construction. */
+/* All routines of the block oriented interface except new_Block are */
+/* needed also. */
+/***********************************************************************/
+
+/** Block construction **/
+/* immature Block without predecessors */
+ir_node *new_immBlock (void);
+
+/* Add a control flow edge to an immature block. */
+void add_in_edge (ir_node *immblock, ir_node *jmp);
+
+/* fixes the number of predecessors of a block. */
+void mature_block (ir_node *block);
+
+/** Parameter administration **/
+/* Read a value from the array with the local variables. Use this
+ function to obtain the last definition of the value associated with
+ pos. Pos may not exceed the value passed as n_loc to new_ir_graph. */
+ir_node *get_value (int pos, ir_mode *mode);
+
+/* Write a value in the array with the local variables. Use this function
+ to remember a new definition of the value associated with pos. Pos may
+ not exceed the value passed as n_loc to new_ir_graph. */
+void set_value (int pos, ir_node *value);
+
+/* Read a store.
+ Use this function to get the most recent version of the store (type M).
+ Internally it does the same as get_value. */
+ir_node *get_store (void);
+
+/* Write a store. */
+void set_store (ir_node *store);
+
+/***********************************************************************/
+/* initialize ir construction */
+/***********************************************************************/
void init_cons (void);
projects / libfirm / blobdiff