[llvm-commits] CVS: llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Utils:

PromoteMemoryToRegister.cpp updated: 1.37 -> 1.38

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Log message:

Fix bug: Mem2reg/2003-04-18-DeadBlockProblem.ll


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Diffs of the changes:

Index: llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
diff -u llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp:1.37 llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp:1.38
--- llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp:1.37	Thu Apr 10 14:41:13 2003
+++ llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp	Fri Apr 18 14:25:22 2003
@@ -24,6 +24,7 @@
 #include "llvm/Function.h"
 #include "llvm/Constant.h"
 #include "llvm/Type.h"
+#include "llvm/Support/CFG.h"
 #include "Support/StringExtras.h"
 
 /// isAllocaPromotable - Return true if this alloca is legal for promotion.
@@ -187,11 +188,20 @@
   if (BBPNs[AllocaNo]) return false;
 
   // Create a PhiNode using the dereferenced type... and add the phi-node to the
-  // BasicBlock
+  // BasicBlock.
   PHINode *PN = new PHINode(Allocas[AllocaNo]->getAllocatedType(),
                             Allocas[AllocaNo]->getName() + "." +
                                       utostr(VersionNumbers[AllocaNo]++),
                             BB->begin());
+
+  // Add null incoming values for all predecessors.  This ensures that if one of
+  // the predecessors is not found in the depth-first traversal of the CFG (ie,
+  // because it is an unreachable predecessor), that all PHI nodes will have the
+  // correct number of entries for their predecessors.
+  Value *NullVal = Constant::getNullValue(PN->getType());
+  for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI)
+    PN->addIncoming(NullVal, *PI);
+
   BBPNs[AllocaNo] = PN;
   PhiNodes[AllocaNo].push_back(BB);
   return true;
@@ -205,9 +215,12 @@
   std::vector<PHINode *> &BBPNs = NewPhiNodes[BB];
   for (unsigned k = 0; k != BBPNs.size(); ++k)
     if (PHINode *PN = BBPNs[k]) {
-      // at this point we can assume that the array has phi nodes.. let's add
-      // the incoming data
-      PN->addIncoming(IncomingVals[k], Pred);
+      int BBI = PN->getBasicBlockIndex(Pred);
+      assert(BBI >= 0 && "Predecessor not in basic block yet!");
+
+      // At this point we can assume that the array has phi nodes.. let's update
+      // the incoming data.
+      PN->setIncomingValue(BBI, IncomingVals[k]);
 
       // also note that the active variable IS designated by the phi node
       IncomingVals[k] = PN;