src/intel/compiler/brw_ir_analysis.h

   1 /* -*- c++ -*- */
   2 /*
   3  * Copyright © 2016 Intel Corporation
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the "Software"),
   7  * to deal in the Software without restriction, including without limitation
   8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   9  * and/or sell copies of the Software, and to permit persons to whom the
  10  * Software is furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice (including the next
  13  * paragraph) shall be included in all copies or substantial portions of the
  14  * Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  21  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  22  * IN THE SOFTWARE.
  23  */
  24
  25 #ifndef BRW_IR_ANALYSIS_H
  26 #define BRW_IR_ANALYSIS_H
  27
  28 namespace brw {
  29    /**
  30     * Bitset of state categories that can influence the result of IR analysis
  31     * passes.
  32     */
  33    enum analysis_dependency_class {
  34       /**
  35        * The analysis doesn't depend on the IR, its result is effectively a
  36        * constant during the compilation.
  37        */
  38       DEPENDENCY_NOTHING = 0,
  39       /**
  40        * The analysis depends on the set of instructions in the program and
  41        * their naming.  Note that because instructions are named sequentially
  42        * by IP this implies a dependency on the control flow edges between
  43        * instructions.  This will be signaled whenever instructions are
  44        * inserted, removed or reordered in the program.
  45        */
  46       DEPENDENCY_INSTRUCTION_IDENTITY = 0x1,
  47       /**
  48        * The analysis is sensitive to the detailed semantics of instructions
  49        * in the program, where "detailed" means any change in the instruction
  50        * data structures other than the linked-list pointers (which are
  51        * already covered by DEPENDENCY_INSTRUCTION_IDENTITY).  E.g. changing
  52        * the negate or abs flags of an instruction source would signal this
  53        * flag alone because it would preserve all other instruction dependency
  54        * classes.
  55        */
  56       DEPENDENCY_INSTRUCTION_DETAIL = 0x2,
  57       /**
  58        * The analysis depends on the set of data flow edges between
  59        * instructions.  This will be signaled whenever the dataflow relation
  60        * between instructions has potentially changed, e.g. when the VGRF
  61        * index of an instruction source or destination changes (in which case
  62        * it will appear in combination with DEPENDENCY_INSTRUCTION_DETAIL), or
  63        * when data-dependent instructions are reordered (in which case it will
  64        * appear in combination with DEPENDENCY_INSTRUCTION_IDENTITY).
  65        */
  66       DEPENDENCY_INSTRUCTION_DATA_FLOW = 0x4,
  67       /**
  68        * The analysis depends on all instruction dependency classes.  These
  69        * will typically be signaled simultaneously when inserting or removing
  70        * instructions in the program (or if you're feeling too lazy to read
  71        * through your optimization pass to figure out which of the instruction
  72        * dependency classes above it invalidates).
  73        */
  74       DEPENDENCY_INSTRUCTIONS = 0x7,
  75       /**
  76        * The analysis depends on the set of VGRFs in the program and their
  77        * naming.  This will be signaled when VGRFs are allocated or released.
  78        */
  79       DEPENDENCY_VARIABLES = 0x8,
  80       /**
  81        * The analysis depends on the set of basic blocks in the program, their
  82        * control flow edges and naming.
  83        */
  84       DEPENDENCY_BLOCKS = 0x10,
  85       /**
  86        * The analysis depends on the program being literally the same (good
  87        * luck...), any change in the input invalidates previous analysis
  88        * computations.
  89        */
  90       DEPENDENCY_EVERYTHING = ~0
  91    };
  92
  93    inline analysis_dependency_class
  94    operator|(analysis_dependency_class x, analysis_dependency_class y)
  95    {
  96       return static_cast<analysis_dependency_class>(
  97          static_cast<unsigned>(x) | static_cast<unsigned>(y));
  98    }
  99 }
 100
 101 /**
 102  * Instantiate a program analysis class \p L which can calculate an object of
 103  * type \p T as result.  \p C is a closure that encapsulates whatever
 104  * information is required as argument to run the analysis pass.  The purpose
 105  * of this class is to make sure that:
 106  *
 107  *  - The analysis pass is executed lazily whenever it's needed and multiple
 108  *    executions are optimized out as long as the cached result remains marked
 109  *    up-to-date.
 110  *
 111  *  - There is no way to access the cached analysis result without first
 112  *    calling L::require(), which makes sure that the analysis pass is rerun
 113  *    if necessary.
 114  *
 115  *  - The cached result doesn't become inconsistent with the program for as
 116  *    long as it remains marked up-to-date. (This is only enforced in debug
 117  *    builds for performance reasons)
 118  *
 119  * The requirements on \p T are the following:
 120  *
 121  *  - Constructible with a single argument, as in 'x = T(c)' for \p c of type
 122  *    \p C.
 123  *
 124  *  - 'x.dependency_class()' on const \p x returns a bitset of
 125  *    brw::analysis_dependency_class specifying the set of IR objects that are
 126  *    required to remain invariant for the cached analysis result to be
 127  *    considered valid.
 128  *
 129  *  - 'x.validate(c)' on const \p x returns a boolean result specifying
 130  *    whether the analysis result \p x is consistent with the input IR.  This
 131  *    is currently only used for validation in debug builds.
 132  */
 133 #define BRW_ANALYSIS(L, T, C)                                           \
 134    class L {                                                            \
 135    public:                                                              \
 136       /**                                                               \
 137        * Construct a program analysis.  \p c is an arbitrary object     \
 138        * passed as argument to the constructor of the analysis result   \
 139        * object of type \p T.                                           \
 140        */                                                               \
 141       L(C const &c) : c(c), p(NULL) {}                                  \
 142                                                                         \
 143       /**                                                               \
 144        * Destroy a program analysis.                                    \
 145        */                                                               \
 146       ~L()                                                              \
 147       {                                                                 \
 148          delete p;                                                      \
 149       }                                                                 \
 150                                                                         \
 151       /**                                                               \
 152        * Obtain the result of a program analysis.  This gives a         \
 153        * guaranteed up-to-date result, the analysis pass will be        \
 154        * rerun implicitly if it has become stale.                       \
 155        */                                                               \
 156       T &                                                               \
 157       require()                                                         \
 158       {                                                                 \
 159          if (p)                                                         \
 160             assert(p->validate(c));                                     \
 161          else                                                           \
 162             p = new T(c);                                               \
 163                                                                         \
 164          return *p;                                                     \
 165       }                                                                 \
 166                                                                         \
 167       const T &                                                         \
 168       require() const                                                   \
 169       {                                                                 \
 170          return const_cast<L *>(this)->require();                       \
 171       }                                                                 \
 172                                                                         \
 173       /**                                                               \
 174        * Report that dependencies of the analysis pass may have changed \
 175        * since the last calculation and the cached analysis result may  \
 176        * have to be discarded.                                          \
 177        */                                                               \
 178       void                                                              \
 179       invalidate(brw::analysis_dependency_class c)                      \
 180       {                                                                 \
 181          if (p && c & p->dependency_class()) {                          \
 182             delete p;                                                   \
 183             p = NULL;                                                   \
 184          }                                                              \
 185       }                                                                 \
 186                                                                         \
 187    private:                                                             \
 188       C c;                                                              \
 189       T *p;                                                             \
 190    }
 191
 192 #endif