1 files changed, 37 insertions, 19 deletions

diff --git a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
index dc99070..01338ab 100644
--- a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
+++ b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
@@ -1684,7 +1684,8 @@ private:
   /// RPOT block ordering.
   void initialSetup(MachineFunction &MF);
 
-  bool ExtendRanges(MachineFunction &MF, TargetPassConfig *TPC) override;
+  bool ExtendRanges(MachineFunction &MF, TargetPassConfig *TPC,
+                    unsigned InputBBLimit, unsigned InputDbgValLimit) override;
 
 public:
   /// Default construct and initialize the pass.
@@ -3523,8 +3524,9 @@ void InstrRefBasedLDV::initialSetup(MachineFunction &MF) {
 
 /// Calculate the liveness information for the given machine function and
 /// extend ranges across basic blocks.
-bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF,
-                                    TargetPassConfig *TPC) {
+bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF, TargetPassConfig *TPC,
+                                    unsigned InputBBLimit,
+                                    unsigned InputDbgValLimit) {
   // No subprogram means this function contains no debuginfo.
   if (!MF.getFunction().getSubprogram())
     return false;
@@ -3626,6 +3628,7 @@ bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF,
 
   // To mirror old LiveDebugValues, enumerate variables in RPOT order. Otherwise
   // the order is unimportant, it just has to be stable.
+  unsigned VarAssignCount = 0;
   for (unsigned int I = 0; I < OrderToBB.size(); ++I) {
     auto *MBB = OrderToBB[I];
     auto *VTracker = &vlocs[MBB->getNumber()];
@@ -3643,24 +3646,42 @@ bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF,
       ScopeToVars[Scope].insert(Var);
       ScopeToBlocks[Scope].insert(VTracker->MBB);
       ScopeToDILocation[Scope] = ScopeLoc;
+      ++VarAssignCount;
     }
   }
 
-  // OK. Iterate over scopes: there might be something to be said for
-  // ordering them by size/locality, but that's for the future. For each scope,
-  // solve the variable value problem, producing a map of variables to values
-  // in SavedLiveIns.
-  for (auto &P : ScopeToVars) {
-    vlocDataflow(P.first, ScopeToDILocation[P.first], P.second,
-                 ScopeToBlocks[P.first], SavedLiveIns, MOutLocs, MInLocs,
-                 vlocs);
-  }
+  bool Changed = false;
+
+  // If we have an extremely large number of variable assignments and blocks,
+  // bail out at this point. We've burnt some time doing analysis already,
+  // however we should cut our losses.
+  if ((unsigned)MaxNumBlocks > InputBBLimit &&
+      VarAssignCount > InputDbgValLimit) {
+    LLVM_DEBUG(dbgs() << "Disabling InstrRefBasedLDV: " << MF.getName()
+                      << " has " << MaxNumBlocks << " basic blocks and "
+                      << VarAssignCount
+                      << " variable assignments, exceeding limits.\n");
+  } else {
+    // Compute the extended ranges, iterating over scopes. There might be
+    // something to be said for ordering them by size/locality, but that's for
+    // the future. For each scope, solve the variable value problem, producing
+    // a map of variables to values in SavedLiveIns.
+    for (auto &P : ScopeToVars) {
+      vlocDataflow(P.first, ScopeToDILocation[P.first], P.second,
+                   ScopeToBlocks[P.first], SavedLiveIns, MOutLocs, MInLocs,
+                   vlocs);
+    }
+
+    // Using the computed value locations and variable values for each block,
+    // create the DBG_VALUE instructions representing the extended variable
+    // locations.
+    emitLocations(MF, SavedLiveIns, MOutLocs, MInLocs, AllVarsNumbering, *TPC);
 
-  // Using the computed value locations and variable values for each block,
-  // create the DBG_VALUE instructions representing the extended variable
-  // locations.
-  emitLocations(MF, SavedLiveIns, MOutLocs, MInLocs, AllVarsNumbering, *TPC);
+    // Did we actually make any changes? If we created any DBG_VALUEs, then yes.
+    Changed = TTracker->Transfers.size() != 0;
+  }
 
+  // Common clean-up of memory.
   for (int Idx = 0; Idx < MaxNumBlocks; ++Idx) {
     delete[] MOutLocs[Idx];
     delete[] MInLocs[Idx];
@@ -3668,9 +3689,6 @@ bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF,
   delete[] MOutLocs;
   delete[] MInLocs;
 
-  // Did we actually make any changes? If we created any DBG_VALUEs, then yes.
-  bool Changed = TTracker->Transfers.size() != 0;
-
   delete MTracker;
   delete TTracker;
   MTracker = nullptr;