// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

#pragma once
#pragma warning(disable : 4503) // 'identifier' : decorated name length exceeded, name was truncated

#undef SSA_FEATURE_DOMARR

#include "compiler.h"

class SsaRenameState;

typedef int LclVarNum;

// Pair of a local var name eg: V01 and Ssa number; eg: V01_01
typedef jitstd::pair<LclVarNum, int> SsaVarName;

class SsaBuilder
{
private:
    inline void EndPhase(Phases phase)
    {
        m_pCompiler->EndPhase(phase);
    }

    bool IncludeInSsa(unsigned lclNum);

public:
    // Constructor
    SsaBuilder(Compiler* pCompiler);

    // Requires stmt nodes to be already sequenced in evaluation order. Analyzes the graph
    // for introduction of phi-nodes as GT_PHI tree nodes at the beginning of each block.
    // Each GT_LCL_VAR is given its ssa number through its gtSsaNum field in the node.
    // Each GT_PHI node will have gtOp1 set to lhs of the phi node and the gtOp2 to be a
    // GT_LIST of GT_PHI_ARG. Each use or def is denoted by the corresponding GT_LCL_VAR
    // tree. For example, to get all uses of a particular variable fully defined by its
    // lclNum and ssaNum, one would use m_uses and look up all the uses. Similarly, a single
    // def of an SSA variable can be looked up similarly using m_defs member.
    void Build();

    // Requires "bbIDom" of each block to be computed. Requires "domTree" to be allocated
    // and can be updated, i.e., by adding mapping from a block to it's dominated children.
    // Using IDom of each basic block, compute the whole domTree. If a block "b" has IDom "i",
    // then, block "b" is dominated by "i". The mapping then is i -> { ..., b, ... }, in
    // other words, "domTree" is a tree represented by nodes mapped to their children.
    static void ComputeDominators(Compiler* pCompiler, BlkToBlkVectorMap* domTree);

private:
    // Ensures that the basic block graph has a root for the dominator graph, by ensuring
    // that there is a first block that is not in a try region (adding an empty block for that purpose
    // if necessary).  Eventually should move to Compiler.
    void SetupBBRoot();

    // Requires "postOrder" to be an array of size "count". Requires "count" to at least
    // be the size of the flow graph. Sorts the current compiler's flow-graph and places
    // the blocks in post order (i.e., a node's children first) in the array. Returns the
    // number of nodes visited while sorting the graph. In other words, valid entries in
    // the output array.
    int TopologicalSort(BasicBlock** postOrder, int count);

    // Requires "postOrder" to hold the blocks of the flowgraph in topologically sorted
    // order. Requires count to be the valid entries in the "postOrder" array. Computes
    // each block's immediate dominator and records it in the BasicBlock in bbIDom.
    void ComputeImmediateDom(BasicBlock** postOrder, int count);

#ifdef SSA_FEATURE_DOMARR
    // Requires "curBlock" to be the first basic block at the first step of the recursion.
    // Requires "domTree" to be a adjacency list (actually, a set of blocks with a set of blocks
    // as children.) Requires "preIndex" and "postIndex" to be initialized to 0 at entry into recursion.
    // Computes arrays "m_pDomPreOrder" and "m_pDomPostOrder" of block indices such that the blocks of a
    // "domTree" are in pre and postorder respectively.
    void DomTreeWalk(BasicBlock* curBlock, BlkToBlkVectorMap* domTree, int* preIndex, int* postIndex);
#endif

    // Requires all blocks to have computed "bbIDom." Requires "domTree" to be a preallocated BlkToBlkVectorMap.
    // Helper to compute "domTree" from the pre-computed bbIDom of the basic blocks.
    static void ConstructDomTreeForBlock(Compiler* pCompiler, BasicBlock* block, BlkToBlkVectorMap* domTree);

    // Requires "postOrder" to hold the blocks of the flowgraph in topologically sorted order. Requires
    // count to be the valid entries in the "postOrder" array. Computes "domTree" as a adjacency list
    // like object, i.e., a set of blocks with a set of blocks as children defining the DOM relation.
    void ComputeDominators(BasicBlock** postOrder, int count, BlkToBlkVectorMap* domTree);

#ifdef DEBUG
    // Display the dominator tree.
    static void DisplayDominators(BlkToBlkVectorMap* domTree);
#endif // DEBUG

    // Compute flow graph dominance frontiers.
    void ComputeDominanceFrontiers(BasicBlock** postOrder, int count, BlkToBlkVectorMap* mapDF);

    // Compute the iterated dominance frontier for the specified block.
    void ComputeIteratedDominanceFrontier(BasicBlock* b, const BlkToBlkVectorMap* mapDF, BlkVector* bIDF);

    // Requires "postOrder" to hold the blocks of the flowgraph in topologically sorted order. Requires
    // count to be the valid entries in the "postOrder" array. Inserts GT_PHI nodes at the beginning
    // of basic blocks that require them like so:
    // GT_ASG(GT_LCL_VAR, GT_PHI(GT_PHI_ARG(GT_LCL_VAR, Block*), GT_LIST(GT_PHI_ARG(GT_LCL_VAR, Block*), NULL));
    void InsertPhiFunctions(BasicBlock** postOrder, int count);

    // Requires "domTree" to be the dominator tree relation defined by a DOM b.
    // Requires "pRenameState" to have counts and stacks at their initial state.
    // Assigns gtSsaNames to all variables.
    void RenameVariables(BlkToBlkVectorMap* domTree, SsaRenameState* pRenameState);

    // Requires "block" to be non-NULL; and is searched for defs and uses to assign ssa numbers.
    // Requires "pRenameState" to be non-NULL and be currently used for variables renaming.
    void BlockRenameVariables(BasicBlock* block, SsaRenameState* pRenameState);

    // Requires "tree" (assumed to be a statement in "block") to be searched for defs and uses to assign ssa numbers.
    // Requires "pRenameState" to be non-NULL and be currently used for variables renaming.  Assumes that "isPhiDefn"
    // implies that any definition occurring within "tree" is a phi definition.
    void TreeRenameVariables(GenTree* tree, BasicBlock* block, SsaRenameState* pRenameState, bool isPhiDefn);

    // Assumes that "block" contains a definition for local var "lclNum", with SSA number "ssaNum".
    // IF "block" is within one or more try blocks,
    // and the local variable is live at the start of the corresponding handlers,
    // add this SSA number "ssaNum" to the argument list of the phi for the variable in the start
    // block of those handlers.
    void AddDefToHandlerPhis(BasicBlock* block, unsigned lclNum, unsigned ssaNum);

    // Same as above, for memory.
    void AddMemoryDefToHandlerPhis(MemoryKind memoryKind, BasicBlock* block, unsigned ssaNum);

    // Requires "block" to be non-NULL.  Requires "pRenameState" to be non-NULL and be currently used
    // for variables renaming. Assigns the rhs arguments to the phi, i.e., block's phi node arguments.
    void AssignPhiNodeRhsVariables(BasicBlock* block, SsaRenameState* pRenameState);

#ifdef DEBUG
    void Print(BasicBlock** postOrder, int count);
#endif

private:
    Compiler*     m_pCompiler;
    CompAllocator m_allocator;

    // Bit vector used by TopologicalSort and ComputeImmediateDom to track already visited blocks.
    BitVecTraits m_visitedTraits;
    BitVec       m_visited;

#ifdef SSA_FEATURE_DOMARR
    // To answer queries of type a DOM b.
    // Do not move these outside of this class, use accessors/interface methods.
    int* m_pDomPreOrder;
    int* m_pDomPostOrder;
#endif
};