Iterator that enumerates the ProgramDependenceGraph (PDG) for a function,

i.e., enumerates all data and control dependences for the function.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@4958 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 500 insertions, 0 deletions

diff --git a/lib/Analysis/DataStructure/PgmDependenceGraph.cpp b/lib/Analysis/DataStructure/PgmDependenceGraph.cpp
new file mode 100644
index 0000000..63a0cdf
--- /dev/null
+++ b/lib/Analysis/DataStructure/PgmDependenceGraph.cpp
@@ -0,0 +1,250 @@
+//===- PgmDependenceGraph.cpp - Enumerate PDG for a function ----*- C++ -*-===//
+// 
+// The Program Dependence Graph (PDG) for a single function represents all
+// data and control dependences for the function.  This file provides an
+// iterator to enumerate all these dependences.  In particular, it enumerates:
+// 
+// -- Data dependences on memory locations, computed using the
+//    MemoryDepAnalysis pass;
+// -- Data dependences on SSA registers, directly from Def-Use edges of Values;
+// -- Control dependences, computed using postdominance frontiers
+//    (NOT YET IMPLEMENTED).
+// 
+// Note that this file does not create an explicit dependence graph --
+// it only provides an iterator to traverse the PDG conceptually.
+// The MemoryDepAnalysis does build an explicit graph, which is used internally
+// here.  That graph could be augmented with the other dependences above if
+// desired, but for most uses there will be little need to do that.
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/PgmDependenceGraph.h"
+#include "llvm/Analysis/MemoryDepAnalysis.h"
+#include "llvm/Analysis/PostDominators.h"
+#include "llvm/Function.h"
+#include "llvm/BasicBlock.h"
+#include "llvm/Instruction.h"
+
+
+
+//----------------------------------------------------------------------------
+// class DepIterState
+//----------------------------------------------------------------------------
+
+const DepIterState::IterStateFlags DepIterState::NoFlag  = 0x0;
+const DepIterState::IterStateFlags DepIterState::MemDone = 0x1;
+const DepIterState::IterStateFlags DepIterState::SSADone = 0x2;
+const DepIterState::IterStateFlags DepIterState::AllDone = 0x4;
+const DepIterState::IterStateFlags DepIterState::FirstTimeFlag= 0x8;
+
+// Find the first memory dependence for the current Mem In/Out iterators.
+// Find the first memory dependence for the current Mem In/Out iterators.
+// Sets dep to that dependence and returns true if one is found.
+// 
+bool DepIterState::SetFirstMemoryDep()
+{
+  if (! (depFlags & MemoryDeps))
+    return false;
+
+  bool doIncomingDeps = dep.getDepType() & IncomingFlag;
+
+  if (( doIncomingDeps && memDepIter == memDepGraph->inDepEnd( *depNode)) ||
+      (!doIncomingDeps && memDepIter == memDepGraph->outDepEnd(*depNode)))
+    {
+      iterFlags |= MemDone;
+      return false;
+    }
+
+  dep = *memDepIter;     // simple copy from dependence in memory DepGraph
+
+  return true;
+}
+
+
+// Find the first valid data dependence for the current SSA In/Out iterators.
+// A valid data dependence is one that is to/from an Instruction.
+// E.g., an SSA edge from a formal parameter is not a valid dependence.
+// Sets dep to that dependence and returns true if a valid one is found.
+// Returns false and leaves dep unchanged otherwise.
+// 
+bool DepIterState::SetFirstSSADep()
+{
+  if (! (depFlags & SSADeps))
+    return false;
+
+  bool doIncomingDeps = dep.getDepType() & IncomingFlag;
+  Instruction* firstTarget = NULL;
+
+  // Increment the In or Out iterator till it runs out or we find a valid dep
+  if (doIncomingDeps)
+    for (Instruction::op_iterator E = depNode->getInstr().op_end();
+         ssaInEdgeIter != E &&
+           (firstTarget = dyn_cast<Instruction>(ssaInEdgeIter->get()))== NULL; )
+      ++ssaInEdgeIter;
+  else
+    for (Value::use_iterator E = depNode->getInstr().use_end();
+         ssaOutEdgeIter != E &&
+           (firstTarget = dyn_cast<Instruction>(*ssaOutEdgeIter)) == NULL; )
+      ++ssaOutEdgeIter;
+
+  // If the iterator ran out before we found a valid dep, there isn't one.
+  if (!firstTarget)
+    {
+      iterFlags |= SSADone;
+      return false;
+    }
+
+  // Create a simple dependence object to represent this SSA dependence.
+  dep = Dependence(memDepGraph->getNode(*firstTarget, /*create*/ true),
+                   TrueDependence, doIncomingDeps);
+
+  return true;
+}
+
+
+DepIterState::DepIterState(DependenceGraph* _memDepGraph,
+                           Instruction&     I, 
+                           bool             incomingDeps,
+                           PDGIteratorFlags whichDeps)
+  : memDepGraph(_memDepGraph),
+    depFlags(whichDeps),
+    iterFlags(NoFlag)
+{
+  depNode = memDepGraph->getNode(I, /*create*/ true);
+
+  if (incomingDeps)
+    {
+      if (whichDeps & MemoryDeps) memDepIter= memDepGraph->inDepBegin(*depNode);
+      if (whichDeps & SSADeps)    ssaInEdgeIter = I.op_begin();
+      /* Initialize control dependence iterator here. */
+    }
+  else
+    {
+      if (whichDeps & MemoryDeps) memDepIter=memDepGraph->outDepBegin(*depNode);
+      if (whichDeps & SSADeps)    ssaOutEdgeIter = I.use_begin();
+      /* Initialize control dependence iterator here. */
+    }
+
+  // Set the dependence to the first of a memory dep or an SSA dep
+  // and set the done flag if either is found.  Otherwise, set the
+  // init flag to indicate that the iterators have just been initialized.
+  // 
+  if (!SetFirstMemoryDep() && !SetFirstSSADep())
+    iterFlags |= AllDone;
+  else
+    iterFlags |= FirstTimeFlag;
+}
+
+
+// Helper function for ++ operator that bumps iterator by 1 (to next
+// dependence) and resets the dep field to represent the new dependence.
+// 
+void DepIterState::Next()
+{
+  // firstMemDone and firstSsaDone are used to indicate when the memory or
+  // SSA iterators just ran out, or when this is the very first increment.
+  // In either case, the next iterator (if any) should not be incremented.
+  // 
+  bool firstMemDone = iterFlags & FirstTimeFlag;
+  bool firstSsaDone = iterFlags & FirstTimeFlag;
+  bool doIncomingDeps = dep.getDepType() & IncomingFlag;
+
+  if (depFlags & MemoryDeps && ! (iterFlags & MemDone))
+    {
+      iterFlags &= ~FirstTimeFlag;           // clear "firstTime" flag
+      ++memDepIter;
+      if (SetFirstMemoryDep())
+        return;
+      firstMemDone = true;              // flags that we _just_ rolled over
+    }
+
+  if (depFlags & SSADeps && ! (iterFlags & SSADone))
+    {
+      // Don't increment the SSA iterator if we either just rolled over from
+      // the memory dep iterator, or if the SSA iterator is already done.
+      iterFlags &= ~FirstTimeFlag;           // clear "firstTime" flag
+      if (! firstMemDone)
+        if (doIncomingDeps) ++ssaInEdgeIter;
+        else ++ssaOutEdgeIter;
+      if (SetFirstSSADep())
+        return;
+      firstSsaDone = true;                   // flags if we just rolled over
+    } 
+
+  if (depFlags & ControlDeps != 0)
+    {
+      assert(0 && "Cannot handle control deps");
+      // iterFlags &= ~FirstTimeFlag;           // clear "firstTime" flag
+    }
+
+  // This iterator is now complete.
+  iterFlags |= AllDone;
+}
+
+
+//----------------------------------------------------------------------------
+// class PgmDependenceGraph
+//----------------------------------------------------------------------------
+
+
+// MakeIterator -- Create and initialize an iterator as specified.
+// 
+PDGIterator PgmDependenceGraph::MakeIterator(Instruction& I,
+                                             bool incomingDeps,
+                                             PDGIteratorFlags whichDeps)
+{
+  assert(memDepGraph && "Function not initialized!");
+  return PDGIterator(new DepIterState(memDepGraph, I, incomingDeps, whichDeps));
+}
+
+
+void PgmDependenceGraph::printOutgoingSSADeps(Instruction& I,
+                                              std::ostream &O)
+{
+  iterator SI = this->outDepBegin(I, SSADeps);
+  iterator SE = this->outDepEnd(I, SSADeps);
+  if (SI == SE)
+    return;
+
+  O << "\n    Outgoing SSA dependences:\n";
+  for ( ; SI != SE; ++SI)
+    {
+      O << "\t";
+      SI->print(O);
+      O << " to instruction:";
+      O << SI->getSink()->getInstr();
+    }
+}
+
+
+void PgmDependenceGraph::print(std::ostream &O) const
+{
+  MemoryDepAnalysis& graphSet = getAnalysis<MemoryDepAnalysis>();
+
+  // TEMPORARY LOOP
+  for (hash_map<Function*, DependenceGraph*>::iterator
+         I = graphSet.funcMap.begin(), E = graphSet.funcMap.end();
+       I != E; ++I)
+    {
+      Function* func = I->first;
+      DependenceGraph* depGraph = I->second;
+      const_cast<PgmDependenceGraph*>(this)->runOnFunction(*func);
+
+  O << "DEPENDENCE GRAPH FOR FUNCTION " << func->getName() << ":\n";
+  for (Function::iterator BB=func->begin(), FE=func->end(); BB != FE; ++BB)
+    for (BasicBlock::iterator II=BB->begin(), IE=BB->end(); II !=IE; ++II)
+      {
+        DepGraphNode* dgNode = depGraph->getNode(*II, /*create*/ true);
+        dgNode->print(O);
+        const_cast<PgmDependenceGraph*>(this)->printOutgoingSSADeps(*II, O);
+      }
+    } // END TEMPORARY LOOP
+}
+
+
+void PgmDependenceGraph::dump() const
+{
+  this->print(std::cerr);
+}
+
+static RegisterAnalysis<PgmDependenceGraph>
+Z("pgmdep", "Enumerate Program Dependence Graph (data and control)");
diff --git a/lib/Analysis/IPA/PgmDependenceGraph.cpp b/lib/Analysis/IPA/PgmDependenceGraph.cpp
new file mode 100644
index 0000000..63a0cdf
--- /dev/null
+++ b/lib/Analysis/IPA/PgmDependenceGraph.cpp
@@ -0,0 +1,250 @@
+//===- PgmDependenceGraph.cpp - Enumerate PDG for a function ----*- C++ -*-===//
+// 
+// The Program Dependence Graph (PDG) for a single function represents all
+// data and control dependences for the function.  This file provides an
+// iterator to enumerate all these dependences.  In particular, it enumerates:
+// 
+// -- Data dependences on memory locations, computed using the
+//    MemoryDepAnalysis pass;
+// -- Data dependences on SSA registers, directly from Def-Use edges of Values;
+// -- Control dependences, computed using postdominance frontiers
+//    (NOT YET IMPLEMENTED).
+// 
+// Note that this file does not create an explicit dependence graph --
+// it only provides an iterator to traverse the PDG conceptually.
+// The MemoryDepAnalysis does build an explicit graph, which is used internally
+// here.  That graph could be augmented with the other dependences above if
+// desired, but for most uses there will be little need to do that.
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/PgmDependenceGraph.h"
+#include "llvm/Analysis/MemoryDepAnalysis.h"
+#include "llvm/Analysis/PostDominators.h"
+#include "llvm/Function.h"
+#include "llvm/BasicBlock.h"
+#include "llvm/Instruction.h"
+
+
+
+//----------------------------------------------------------------------------
+// class DepIterState
+//----------------------------------------------------------------------------
+
+const DepIterState::IterStateFlags DepIterState::NoFlag  = 0x0;
+const DepIterState::IterStateFlags DepIterState::MemDone = 0x1;
+const DepIterState::IterStateFlags DepIterState::SSADone = 0x2;
+const DepIterState::IterStateFlags DepIterState::AllDone = 0x4;
+const DepIterState::IterStateFlags DepIterState::FirstTimeFlag= 0x8;
+
+// Find the first memory dependence for the current Mem In/Out iterators.
+// Find the first memory dependence for the current Mem In/Out iterators.
+// Sets dep to that dependence and returns true if one is found.
+// 
+bool DepIterState::SetFirstMemoryDep()
+{
+  if (! (depFlags & MemoryDeps))
+    return false;
+
+  bool doIncomingDeps = dep.getDepType() & IncomingFlag;
+
+  if (( doIncomingDeps && memDepIter == memDepGraph->inDepEnd( *depNode)) ||
+      (!doIncomingDeps && memDepIter == memDepGraph->outDepEnd(*depNode)))
+    {
+      iterFlags |= MemDone;
+      return false;
+    }
+
+  dep = *memDepIter;     // simple copy from dependence in memory DepGraph
+
+  return true;
+}
+
+
+// Find the first valid data dependence for the current SSA In/Out iterators.
+// A valid data dependence is one that is to/from an Instruction.
+// E.g., an SSA edge from a formal parameter is not a valid dependence.
+// Sets dep to that dependence and returns true if a valid one is found.
+// Returns false and leaves dep unchanged otherwise.
+// 
+bool DepIterState::SetFirstSSADep()
+{
+  if (! (depFlags & SSADeps))
+    return false;
+
+  bool doIncomingDeps = dep.getDepType() & IncomingFlag;
+  Instruction* firstTarget = NULL;
+
+  // Increment the In or Out iterator till it runs out or we find a valid dep
+  if (doIncomingDeps)
+    for (Instruction::op_iterator E = depNode->getInstr().op_end();
+         ssaInEdgeIter != E &&
+           (firstTarget = dyn_cast<Instruction>(ssaInEdgeIter->get()))== NULL; )
+      ++ssaInEdgeIter;
+  else
+    for (Value::use_iterator E = depNode->getInstr().use_end();
+         ssaOutEdgeIter != E &&
+           (firstTarget = dyn_cast<Instruction>(*ssaOutEdgeIter)) == NULL; )
+      ++ssaOutEdgeIter;
+
+  // If the iterator ran out before we found a valid dep, there isn't one.
+  if (!firstTarget)
+    {
+      iterFlags |= SSADone;
+      return false;
+    }
+
+  // Create a simple dependence object to represent this SSA dependence.
+  dep = Dependence(memDepGraph->getNode(*firstTarget, /*create*/ true),
+                   TrueDependence, doIncomingDeps);
+
+  return true;
+}
+
+
+DepIterState::DepIterState(DependenceGraph* _memDepGraph,
+                           Instruction&     I, 
+                           bool             incomingDeps,
+                           PDGIteratorFlags whichDeps)
+  : memDepGraph(_memDepGraph),
+    depFlags(whichDeps),
+    iterFlags(NoFlag)
+{
+  depNode = memDepGraph->getNode(I, /*create*/ true);
+
+  if (incomingDeps)
+    {
+      if (whichDeps & MemoryDeps) memDepIter= memDepGraph->inDepBegin(*depNode);
+      if (whichDeps & SSADeps)    ssaInEdgeIter = I.op_begin();
+      /* Initialize control dependence iterator here. */
+    }
+  else
+    {
+      if (whichDeps & MemoryDeps) memDepIter=memDepGraph->outDepBegin(*depNode);
+      if (whichDeps & SSADeps)    ssaOutEdgeIter = I.use_begin();
+      /* Initialize control dependence iterator here. */
+    }
+
+  // Set the dependence to the first of a memory dep or an SSA dep
+  // and set the done flag if either is found.  Otherwise, set the
+  // init flag to indicate that the iterators have just been initialized.
+  // 
+  if (!SetFirstMemoryDep() && !SetFirstSSADep())
+    iterFlags |= AllDone;
+  else
+    iterFlags |= FirstTimeFlag;
+}
+
+
+// Helper function for ++ operator that bumps iterator by 1 (to next
+// dependence) and resets the dep field to represent the new dependence.
+// 
+void DepIterState::Next()
+{
+  // firstMemDone and firstSsaDone are used to indicate when the memory or
+  // SSA iterators just ran out, or when this is the very first increment.
+  // In either case, the next iterator (if any) should not be incremented.
+  // 
+  bool firstMemDone = iterFlags & FirstTimeFlag;
+  bool firstSsaDone = iterFlags & FirstTimeFlag;
+  bool doIncomingDeps = dep.getDepType() & IncomingFlag;
+
+  if (depFlags & MemoryDeps && ! (iterFlags & MemDone))
+    {
+      iterFlags &= ~FirstTimeFlag;           // clear "firstTime" flag
+      ++memDepIter;
+      if (SetFirstMemoryDep())
+        return;
+      firstMemDone = true;              // flags that we _just_ rolled over
+    }
+
+  if (depFlags & SSADeps && ! (iterFlags & SSADone))
+    {
+      // Don't increment the SSA iterator if we either just rolled over from
+      // the memory dep iterator, or if the SSA iterator is already done.
+      iterFlags &= ~FirstTimeFlag;           // clear "firstTime" flag
+      if (! firstMemDone)
+        if (doIncomingDeps) ++ssaInEdgeIter;
+        else ++ssaOutEdgeIter;
+      if (SetFirstSSADep())
+        return;
+      firstSsaDone = true;                   // flags if we just rolled over
+    } 
+
+  if (depFlags & ControlDeps != 0)
+    {
+      assert(0 && "Cannot handle control deps");
+      // iterFlags &= ~FirstTimeFlag;           // clear "firstTime" flag
+    }
+
+  // This iterator is now complete.
+  iterFlags |= AllDone;
+}
+
+
+//----------------------------------------------------------------------------
+// class PgmDependenceGraph
+//----------------------------------------------------------------------------
+
+
+// MakeIterator -- Create and initialize an iterator as specified.
+// 
+PDGIterator PgmDependenceGraph::MakeIterator(Instruction& I,
+                                             bool incomingDeps,
+                                             PDGIteratorFlags whichDeps)
+{
+  assert(memDepGraph && "Function not initialized!");
+  return PDGIterator(new DepIterState(memDepGraph, I, incomingDeps, whichDeps));
+}
+
+
+void PgmDependenceGraph::printOutgoingSSADeps(Instruction& I,
+                                              std::ostream &O)
+{
+  iterator SI = this->outDepBegin(I, SSADeps);
+  iterator SE = this->outDepEnd(I, SSADeps);
+  if (SI == SE)
+    return;
+
+  O << "\n    Outgoing SSA dependences:\n";
+  for ( ; SI != SE; ++SI)
+    {
+      O << "\t";
+      SI->print(O);
+      O << " to instruction:";
+      O << SI->getSink()->getInstr();
+    }
+}
+
+
+void PgmDependenceGraph::print(std::ostream &O) const
+{
+  MemoryDepAnalysis& graphSet = getAnalysis<MemoryDepAnalysis>();
+
+  // TEMPORARY LOOP
+  for (hash_map<Function*, DependenceGraph*>::iterator
+         I = graphSet.funcMap.begin(), E = graphSet.funcMap.end();
+       I != E; ++I)
+    {
+      Function* func = I->first;
+      DependenceGraph* depGraph = I->second;
+      const_cast<PgmDependenceGraph*>(this)->runOnFunction(*func);
+
+  O << "DEPENDENCE GRAPH FOR FUNCTION " << func->getName() << ":\n";
+  for (Function::iterator BB=func->begin(), FE=func->end(); BB != FE; ++BB)
+    for (BasicBlock::iterator II=BB->begin(), IE=BB->end(); II !=IE; ++II)
+      {
+        DepGraphNode* dgNode = depGraph->getNode(*II, /*create*/ true);
+        dgNode->print(O);
+        const_cast<PgmDependenceGraph*>(this)->printOutgoingSSADeps(*II, O);
+      }
+    } // END TEMPORARY LOOP
+}
+
+
+void PgmDependenceGraph::dump() const
+{
+  this->print(std::cerr);
+}
+
+static RegisterAnalysis<PgmDependenceGraph>
+Z("pgmdep", "Enumerate Program Dependence Graph (data and control)");