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Add structural analysis by using given CFG and add _hasBackEdges flag…
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… when generating CFG

This is a part of the BenefitInliner contribution.

* Dominators.hpp, Dominators.cpp, StructuralAnalysis.hpp, StructuralAnalysis.cpp: add structural analysis by using given CFG.
* OMRCfg.hpp: add _hasBackEdges flag to mark having loop in the CFG.

Co-authored-by: Cijie Xia <[email protected]>
Signed-off-by: Mingwei Li <[email protected]>
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@mingweiarthurli @xiacijie
mingweiarthurli and xiacijie committed Feb 16, 2024
1 parent 8414472 commit bf109fc
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Showing 5 changed files with 62 additions and 49 deletions.
5 changes: 5 additions & 0 deletions compiler/infra/OMRCfg.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -136,6 +136,7 @@ class CFG
_calledFrequency = 0;
_initialBlockFrequency = -1;
_edgeProbabilities = NULL;
_hasBackEdges = false;
}

TR::CFG * self();
Expand Down Expand Up @@ -357,6 +358,9 @@ class CFG
IsOrphanedRegion
};

void setHasBackEdges() { _hasBackEdges = true; }
bool hasBackEdges() { return _hasBackEdges; }

protected:
TR::Compilation *_compilation;
TR::ResolvedMethodSymbol *_method;
Expand All @@ -376,6 +380,7 @@ class CFG
bool _ignoreUnreachableBlocks;
bool _removingUnreachableBlocks;

bool _hasBackEdges;

TR::CFGNode **_forwardTraversalOrder;
int32_t _forwardTraversalLength;
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29 changes: 22 additions & 7 deletions compiler/optimizer/Dominators.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -44,18 +44,32 @@ TR_Dominators::TR_Dominators(TR::Compilation *c, bool post) :
_info(c->getFlowGraph()->getNextNodeNumber()+1, BBInfo(_region), _region),
_dfNumbers(c->getFlowGraph()->getNextNodeNumber()+1, 0, _region),
_dominators(c->getFlowGraph()->getNextNodeNumber()+1, static_cast<TR::Block *>(NULL), _region)
{
construct(c->getFlowGraph(), post);
}

TR_Dominators::TR_Dominators(TR::Compilation *c, TR::CFG* cfg, bool post) :
_region(c->trMemory()->heapMemoryRegion()),
_compilation(c),
_info(cfg->getNextNodeNumber()+1, BBInfo(_region), _region),
_dfNumbers(cfg->getNextNodeNumber()+1, 0, _region),
_dominators(cfg->getNextNodeNumber()+1, static_cast<TR::Block *>(NULL), _region)
{
construct(cfg, post);
}

void TR_Dominators::construct(TR::CFG* cfg, bool post)
{
LexicalTimer tlex("TR_Dominators::TR_Dominators", _compilation->phaseTimer());

_postDominators = post;
_isValid = true;
_hasUnreachableBlocks = false;
_topDfNum = 0;
_visitCount = c->incOrResetVisitCount();
_visitCount = _compilation->incOrResetVisitCount();
_trace = comp()->getOption(TR_TraceDominators);

TR::CFG *cfg = c->getFlowGraph();

_cfg = c->getFlowGraph();
_cfg = cfg;
_numNodes = cfg->getNumberOfNodes()+1;

if (trace())
Expand All @@ -80,7 +94,7 @@ TR_Dominators::TR_Dominators(TR::Compilation *c, bool post) :
_dominators[dominated->getNumber()] = dominator;
if (trace())
traceMsg(comp(), " %sDominator of block_%d is block_%d\n", _postDominators ? "post-" : "",
dominated->getNumber(), dominator->getNumber());
dominated->getNumber(), dominator->getNumber());
}

// The exit block may not be reachable from the entry node. In this case just
Expand Down Expand Up @@ -111,14 +125,15 @@ TR_Dominators::TR_Dominators(TR::Compilation *c, bool post) :
return;
}
else
_hasUnreachableBlocks = true;
TR_ASSERT(false, "Unreachable block in the CFG %d %d", _topDfNum, _numNodes-1);
}

#if DEBUG
for (auto block = toBlock(cfg->getFirstNode()); block; block = toBlock(block->getNext()))
{
{
TR_ASSERT(_dfNumbers[block->getNumber()] >= 0, "Unreachable block in the CFG");
}
}
#endif

if (trace())
Expand Down
6 changes: 6 additions & 0 deletions compiler/optimizer/Dominators.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -53,11 +53,14 @@ class TR_Dominators
TR_ALLOC(TR_Memory::Dominators)

TR_Dominators(TR::Compilation *, bool post = false);
TR_Dominators(TR::Compilation *, TR::CFG* cfg, bool post = false);
TR::Block *getDominator(TR::Block *);
int dominates(TR::Block *block, TR::Block *other);

TR::Compilation * comp() { return _compilation; }
bool trace() { return _trace; }
bool isValid() { return _isValid; }
bool hasUnreachableBlocks() { return _hasUnreachableBlocks; }

protected:

Expand Down Expand Up @@ -113,6 +116,8 @@ class TR_Dominators
int32_t parent;
};

void construct(TR::CFG* cfg, bool post);

BBInfo& getInfo(int32_t index) {return _info[index];}
int32_t blockNumber(int32_t index) {return _info[index]._block->getNumber();}

Expand All @@ -133,6 +138,7 @@ class TR_Dominators
int32_t _numNodes;
int32_t _topDfNum;
vcount_t _visitCount;
bool _hasUnreachableBlocks;

protected:
TR::CFG * _cfg;
Expand Down
68 changes: 26 additions & 42 deletions compiler/optimizer/StructuralAnalysis.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -171,34 +171,28 @@ void TR_RegionAnalysis::createLeafStructures(TR::CFG *cfg, TR::Region &region)
/**
* Mainline for performing Region Analysis.
*/
TR_Structure *TR_RegionAnalysis::getRegions(TR::Compilation *comp, TR::ResolvedMethodSymbol* methSym)
TR_Structure *TR_RegionAnalysis::getRegionsImpl(TR::Compilation *comp, TR_Dominators& dominators, TR::CFG* cfg)
{
TR::StackMemoryRegion stackMemoryRegion(*comp->trMemory());

// Calculate dominators
// This has the side-effect of renumbering the blocks in depth-first order
//
TR_Dominators dominators = TR_Dominators(comp);

#if DEBUG
if (debug("verifyDominator"))
{
{
TR_DominatorVerifier verifyDominator(dominators);
}
}
#endif

TR::CFG *cfg = methSym->getFlowGraph();
TR_ASSERT(cfg, "cfg is NULL\n");

TR_RegionAnalysis ra(comp, dominators, cfg, stackMemoryRegion);
ra._trace = comp->getOption(TR_TraceSA);

ra._useNew = !comp->getOption(TR_DisableIterativeSA);
if (ra.trace())
{
{
traceMsg(comp, "Blocks before Region Analysis:\n");
comp->getDebug()->print(comp->getOutFile(), cfg);
}
}

ra.createLeafStructures(cfg, stackMemoryRegion);

Expand All @@ -210,48 +204,38 @@ TR_Structure *TR_RegionAnalysis::getRegions(TR::Compilation *comp, TR::ResolvedM
return result;
}

TR_Structure *TR_RegionAnalysis::getRegions(TR::Compilation *comp, TR::CFG* cfg, bool acceptUnreachableBlocks)
{
// Calculate dominators
// This has the side-effect of renumbering the blocks in depth-first order
//
TR_Dominators dominators(comp, cfg);
if (!acceptUnreachableBlocks and dominators.hasUnreachableBlocks())
return NULL;

return getRegionsImpl(comp, dominators, cfg);
}


/**
* Mainline for performing Region Analysis.
*/
TR_Structure *TR_RegionAnalysis::getRegions(TR::Compilation *comp)
TR_Structure *TR_RegionAnalysis::getRegions(TR::Compilation *comp, TR::ResolvedMethodSymbol* methSym)
{
TR::StackMemoryRegion stackMemoryRegion(*comp->trMemory());

// Calculate dominators
// This has the side-effect of renumbering the blocks in depth-first order
//
TR_Dominators dominators(comp);
TR::CFG *cfg = methSym->getFlowGraph();

#if DEBUG
if (debug("verifyDominator"))
{
TR_DominatorVerifier verifyDominator(dominators);
}
#endif

TR::CFG *cfg = comp->getFlowGraph();

TR_RegionAnalysis ra(comp, dominators, cfg, stackMemoryRegion);
ra._trace = comp->getOption(TR_TraceSA);

ra._useNew = !comp->getOption(TR_DisableIterativeSA);
if (ra.trace())
{
traceMsg(comp, "Blocks before Region Analysis:\n");
comp->getDebug()->print(comp->getOutFile(), cfg);
}

ra.createLeafStructures(cfg, stackMemoryRegion);
return getRegionsImpl(comp, dominators, cfg);
}

// Loop through the node set until there is only one node left - this is the
// root of the control tree.
TR_Structure *TR_RegionAnalysis::getRegions(TR::Compilation *comp)
{
// Calculate dominators
// This has the side-effect of renumbering the blocks in depth-first order
//
TR_Structure *result = ra.findRegions(stackMemoryRegion);
TR_Dominators dominators(comp);
TR::CFG *cfg = comp->getFlowGraph();

return result;
return getRegionsImpl(comp, dominators, cfg);
}

/**
Expand Down
3 changes: 3 additions & 0 deletions compiler/optimizer/StructuralAnalysis.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,7 @@ class TR_RegionAnalysis

static TR_Structure *getRegions(TR::Compilation *);
static TR_Structure *getRegions(TR::Compilation *, TR::ResolvedMethodSymbol *);
static TR_Structure *getRegions(TR::Compilation *, TR::CFG *, bool acceptUnreachableBlocks = true);

friend class TR_Debug;

Expand Down Expand Up @@ -122,6 +123,8 @@ class TR_RegionAnalysis
bool _useNew;
void createLeafStructures(TR::CFG *cfg, TR::Region &region);

static TR_Structure *getRegionsImpl(TR::Compilation *comp, TR_Dominators& dominators, TR::CFG* cfg);

TR_Structure *findRegions(TR::Region &region);
TR_RegionStructure *findNaturalLoop(StructInfo &node,
WorkBitVector &regionNodes,
Expand Down

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