The Tor Browser: js/src/jit/UnreachableCodeElimination.h@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-

     2  * vim: set ts=8 sts=4 et sw=4 tw=99:

     3  * This Source Code Form is subject to the terms of the Mozilla Public

     4  * License, v. 2.0. If a copy of the MPL was not distributed with this

     5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     7 #ifndef jit_UnreachableCodeElimination_h

     8 #define jit_UnreachableCodeElimination_h

    10 #include "jit/MIRGraph.h"

    12 namespace js {

    13 namespace jit {

    15 class MIRGraph;

    17 class UnreachableCodeElimination

    18 {

    19     typedef Vector<MBasicBlock *, 16, SystemAllocPolicy> BlockList;

    21     MIRGenerator *mir_;

    22     MIRGraph &graph_;

    23     uint32_t marked_;

    24     bool redundantPhis_;

    25     bool rerunAliasAnalysis_;

    26     bool disableAliasAnalysis_;

    28     bool prunePointlessBranchesAndMarkReachableBlocks();

    29     void checkDependencyAndRemoveUsesFromUnmarkedBlocks(MDefinition *instr);

    30     bool removeUnmarkedBlocksAndClearDominators();

    31     bool removeUnmarkedBlocksAndCleanup();

    33     bool enqueue(MBasicBlock *block, BlockList &list);

    34     MBasicBlock *optimizableSuccessor(MBasicBlock *block);

    36   public:

    37     UnreachableCodeElimination(MIRGenerator *mir, MIRGraph &graph)

    38       : mir_(mir),

    39         graph_(graph),

    40         marked_(0),

    41         redundantPhis_(false),

    42         rerunAliasAnalysis_(false),

    43         disableAliasAnalysis_(false)

    44     {}

    46     // Walks the graph and discovers what is reachable. Removes everything else.

    47     bool analyze();

    49     // Removes any blocks that are not marked.  Assumes that these blocks are not

    50     // reachable.  The parameter |marked| should be the number of blocks that

    51     // are marked.

    52     bool removeUnmarkedBlocks(size_t marked);

    54     // Call this function to prevent alias analysis to run a second time if we

    55     // do not need it.

    56     void disableAliasAnalysis() {

    57         disableAliasAnalysis_ = true;

    58     }

    59 };

    61 } /* namespace jit */

    62 } /* namespace js */

    64 #endif /* jit_UnreachableCodeElimination_h */

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