GCC Middle and Back End API Reference
immediate_use_iterator_d Struct Reference

#include <ssa-iterators.h>

Collaboration diagram for immediate_use_iterator_d:

Data Fields

ssa_use_operand_t iter_node

Detailed Description

   Immediate use lists are used to directly access all uses for an SSA
   name and get pointers to the statement for each use.

   The structure ssa_use_operand_d consists of PREV and NEXT pointers
   to maintain the list.  A USE pointer, which points to address where
   the use is located and a LOC pointer which can point to the
   statement where the use is located, or, in the case of the root
   node, it points to the SSA name itself.

   The list is anchored by an occurrence of ssa_operand_d *in* the
   ssa_name node itself (named 'imm_uses').  This node is uniquely
   identified by having a NULL USE pointer. and the LOC pointer
   pointing back to the ssa_name node itself.  This node forms the
   base for a circular list, and initially this is the only node in
   the list.

   Fast iteration allows each use to be examined, but does not allow
   any modifications to the uses or stmts.

   Normal iteration allows insertion, deletion, and modification. the
   iterator manages this by inserting a marker node into the list
   immediately before the node currently being examined in the list.
   this marker node is uniquely identified by having null stmt *and* a
   null use pointer.

   When iterating to the next use, the iteration routines check to see
   if the node after the marker has changed. if it has, then the node
   following the marker is now the next one to be visited. if not, the
   marker node is moved past that node in the list (visualize it as
   bumping the marker node through the list).  this continues until
   the marker node is moved to the original anchor position. the
   marker node is then removed from the list.

   If iteration is halted early, the marker node must be removed from
   the list before continuing.  

Field Documentation

ssa_use_operand_t* immediate_use_iterator_d::end_p
     This marks the last use in the list (use node from SSA_NAME)  

Referenced by end_imm_use_stmt_traverse(), relink_imm_use(), and single_phi_def().

ssa_use_operand_t* immediate_use_iterator_d::imm_use
     This is the current use the iterator is processing.  

Referenced by end_imm_use_stmt_traverse(), link_use_stmts_after(), relink_imm_use(), relink_imm_use_stmt(), and single_phi_def().

ssa_use_operand_t immediate_use_iterator_d::iter_node
     This node is inserted and used to mark the end of the uses for a stmt.  

Referenced by end_imm_use_stmt_traverse(), op_iter_init_phiuse(), and relink_imm_use_stmt().

ssa_use_operand_t* immediate_use_iterator_d::next_imm_name
     This is the next ssa_name to visit.  IMM_USE may get removed before
     the next one is traversed to, so it must be cached early.  

Referenced by end_imm_use_stmt_traverse(), and link_use_stmts_after().

The documentation for this struct was generated from the following file: