[llvm-commits] CVS: llvm/lib/Transforms/Scalar/ADCE.cpp

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

ADCE.cpp updated: 1.48 -> 1.49

---
Log message:

Fix bug: ADCE/2003-01-22-PredecessorProblem.ll



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Diffs of the changes:

Index: llvm/lib/Transforms/Scalar/ADCE.cpp
diff -u llvm/lib/Transforms/Scalar/ADCE.cpp:1.48 llvm/lib/Transforms/Scalar/ADCE.cpp:1.49
--- llvm/lib/Transforms/Scalar/ADCE.cpp:1.48	Tue Oct  1 17:38:40 2002
+++ llvm/lib/Transforms/Scalar/ADCE.cpp	Wed Jan 22 20:12:18 2003
@@ -331,10 +331,17 @@
       }
   }
 
-  // Loop over all of the basic blocks in the function, dropping references of
-  // the dead basic blocks
+  // We make changes if there are any dead blocks in the function...
+  if (unsigned NumDeadBlocks = Func->size() - AliveBlocks.size()) {
+    MadeChanges = true;
+    NumBlockRemoved += NumDeadBlocks;
+  }
+
+  // Loop over all of the basic blocks in the function, removing control flow
+  // edges to live blocks (also eliminating any entries in PHI functions in
+  // referenced blocks).
   //
-  for (Function::iterator BB = Func->begin(), E = Func->end(); BB != E; ++BB) {
+  for (Function::iterator BB = Func->begin(), E = Func->end(); BB != E; ++BB)
     if (!AliveBlocks.count(BB)) {
       // Remove all outgoing edges from this basic block and convert the
       // terminator into a return instruction.
@@ -354,12 +361,16 @@
         BB->getInstList().push_back(new ReturnInst(RetTy != Type::VoidTy ?
                                            Constant::getNullValue(RetTy) : 0));
       }
+    }
+
 
+  // Loop over all of the basic blocks in the function, dropping references of
+  // the dead basic blocks.  We must do this after the previous step to avoid
+  // dropping references to PHIs which still have entries...
+  //
+  for (Function::iterator BB = Func->begin(), E = Func->end(); BB != E; ++BB)
+    if (!AliveBlocks.count(BB))
       BB->dropAllReferences();
-      ++NumBlockRemoved;
-      MadeChanges = true;
-    }
-  }
 
   // Now loop through all of the blocks and delete the dead ones.  We can safely
   // do this now because we know that there are no references to dead blocks