[PATCH] D38223: Make sure the basic block has an insertion point before dereferencing it

[Marco Castelluccio via Phabricator via llvm-commits]

marco-c created this revision.

This patch fixes the crash from https://bugs.llvm.org/show_bug.cgi?id=34659.


Repository:
  rL LLVM

https://reviews.llvm.org/D38223

Files:
  lib/Transforms/Instrumentation/GCOVProfiling.cpp


Index: lib/Transforms/Instrumentation/GCOVProfiling.cpp
===================================================================
--- lib/Transforms/Instrumentation/GCOVProfiling.cpp
+++ lib/Transforms/Instrumentation/GCOVProfiling.cpp
@@ -637,7 +637,12 @@
         int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
         if (Successors) {
           if (Successors == 1) {
-            IRBuilder<> Builder(&*BB.getFirstInsertionPt());
+            BasicBlock::iterator insertPtr = BB.getFirstInsertionPt();
+            if (insertPtr == BB.end()) {
+              continue;
+            }
+
+            IRBuilder<> Builder(&*insertPtr);
             Value *Counter = Builder.CreateConstInBoundsGEP2_64(Counters, 0,
                                                                 Edge);
             Value *Count = Builder.CreateLoad(Counter);
@@ -670,13 +675,24 @@
         GlobalVariable *EdgeState = getEdgeStateValue();

         for (int i = 0, e = ComplexEdgePreds.size(); i != e; ++i) {
-          IRBuilder<> Builder(&*ComplexEdgePreds[i + 1]->getFirstInsertionPt());
+          auto *BB = ComplexEdgePreds[i + 1];
+          BasicBlock::iterator insertPtr = BB->getFirstInsertionPt();
+          if (insertPtr == BB->end()) {
+            continue;
+          }
+          IRBuilder<> Builder(&*insertPtr);
           Builder.CreateStore(Builder.getInt32(i), EdgeState);
         }

         for (int i = 0, e = ComplexEdgeSuccs.size(); i != e; ++i) {
+          auto *BB = ComplexEdgeSuccs[i + 1];
+          BasicBlock::iterator insertPtr = BB->getFirstInsertionPt();
+          if (insertPtr == BB->end()) {
+            continue;
+          }
+
           // Call runtime to perform increment.
-          IRBuilder<> Builder(&*ComplexEdgeSuccs[i + 1]->getFirstInsertionPt());
+          IRBuilder<> Builder(&*insertPtr);
           Value *CounterPtrArray =
             Builder.CreateConstInBoundsGEP2_64(EdgeTable, 0,
                                                i * ComplexEdgePreds.size());


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