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JIT: Add a head merging transformation alongside the tail merging transformation #90468

Merged
merged 12 commits into from
Aug 18, 2023
5 changes: 5 additions & 0 deletions src/coreclr/jit/block.h
Original file line number Diff line number Diff line change
Expand Up @@ -722,6 +722,11 @@ struct BasicBlock : private LIR::Range
return KindIs(kind) || KindIs(rest...);
}

bool HasTerminator()
{
return KindIs(BBJ_EHFINALLYRET, BBJ_EHFAULTRET, BBJ_EHFILTERRET, BBJ_COND, BBJ_SWITCH, BBJ_RETURN);
}

// NumSucc() gives the number of successors, and GetSucc() returns a given numbered successor.
//
// There are two versions of these functions: ones that take a Compiler* and ones that don't. You must
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4 changes: 2 additions & 2 deletions src/coreclr/jit/compiler.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -4718,7 +4718,7 @@ void Compiler::compCompile(void** methodCodePtr, uint32_t* methodCodeSize, JitFl
{
// Tail merge
//
DoPhase(this, PHASE_TAIL_MERGE, &Compiler::fgTailMerge);
DoPhase(this, PHASE_HEAD_TAIL_MERGE, [this]() { return fgHeadTailMerge(true); });

// Merge common throw blocks
//
Expand Down Expand Up @@ -4835,7 +4835,7 @@ void Compiler::compCompile(void** methodCodePtr, uint32_t* methodCodeSize, JitFl

// Second pass of tail merge
//
DoPhase(this, PHASE_TAIL_MERGE2, &Compiler::fgTailMerge);
DoPhase(this, PHASE_HEAD_TAIL_MERGE2, [this]() { return fgHeadTailMerge(false); });

// Compute reachability sets and dominators.
//
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6 changes: 5 additions & 1 deletion src/coreclr/jit/compiler.h
Original file line number Diff line number Diff line change
Expand Up @@ -5519,7 +5519,11 @@ class Compiler

void fgMoveBlocksAfter(BasicBlock* bStart, BasicBlock* bEnd, BasicBlock* insertAfterBlk);

PhaseStatus fgTailMerge();
PhaseStatus fgHeadTailMerge(bool early);
bool fgHeadMerge(BasicBlock* block, bool early);
bool fgTryOneHeadMerge(BasicBlock* block, bool early);
bool gtTreeContainsTailCall(GenTree* tree);
bool fgCanMoveFirstStatementIntoPred(bool early, Statement* firstStmt, BasicBlock* pred);

enum FG_RELOCATE_TYPE
{
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2 changes: 2 additions & 0 deletions src/coreclr/jit/compiler.hpp
Original file line number Diff line number Diff line change
Expand Up @@ -676,6 +676,8 @@ inline bool BasicBlock::HasPotentialEHSuccs(Compiler* comp)
return false;
}

// Throwing in a filter is the same as returning "continue search", which
// causes enclosed finally/fault handlers to be executed.
return hndDesc->InFilterRegionBBRange(this);
}

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4 changes: 2 additions & 2 deletions src/coreclr/jit/compphases.h
Original file line number Diff line number Diff line change
Expand Up @@ -55,10 +55,10 @@ CompPhaseNameMacro(PHASE_COMPUTE_EDGE_WEIGHTS, "Compute edge weights (1, f
#if defined(FEATURE_EH_FUNCLETS)
CompPhaseNameMacro(PHASE_CREATE_FUNCLETS, "Create EH funclets", false, -1, false)
#endif // FEATURE_EH_FUNCLETS
CompPhaseNameMacro(PHASE_TAIL_MERGE, "Tail merge", false, -1, false)
CompPhaseNameMacro(PHASE_HEAD_TAIL_MERGE, "Head and tail merge", false, -1, false)
CompPhaseNameMacro(PHASE_MERGE_THROWS, "Merge throw blocks", false, -1, false)
CompPhaseNameMacro(PHASE_INVERT_LOOPS, "Invert loops", false, -1, false)
CompPhaseNameMacro(PHASE_TAIL_MERGE2, "Post-morph tail merge", false, -1, false)
CompPhaseNameMacro(PHASE_HEAD_TAIL_MERGE2, "Post-morph head and tail merge", false, -1, false)
CompPhaseNameMacro(PHASE_OPTIMIZE_FLOW, "Optimize control flow", false, -1, false)
CompPhaseNameMacro(PHASE_OPTIMIZE_LAYOUT, "Optimize layout", false, -1, false)
CompPhaseNameMacro(PHASE_COMPUTE_REACHABILITY, "Compute blocks reachability", false, -1, false)
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