From e1487f130dbadff68fe49077d3b043ad3c59ea43 Mon Sep 17 00:00:00 2001 From: Boris Boesler Date: Tue, 13 Mar 2001 08:50:56 +0000 Subject: [PATCH] better autodocified [r131] --- ir/ir/ircons.h | 2107 ++++++++++++++++++++++++------------------------ 1 file changed, 1053 insertions(+), 1054 deletions(-) diff --git a/ir/ir/ircons.h b/ir/ir/ircons.h index 5409d0d03..42d84304f 100644 --- a/ir/ir/ircons.h +++ b/ir/ir/ircons.h @@ -27,1060 +27,1059 @@ * 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_) 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_ 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_ 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_ - 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. - ***** - */ + * 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_) 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_ 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_ 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_ + * 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_ -- 2.20.1