[PATCH] D37438: Fix segfault in FlattenCFG

[Daniil Fukalov via Phabricator via llvm-commits]

dfukalov created this revision.
Herald added subscribers: Anastasia, rampitec.

Got segfault on dereferencing nullptr since getTerminator() returned not a BranchInst but a SwitchInst.
Was found in our OpenCL compiler with HSAIL BE, was not able to create regression test for vanilla llvm (
Fixed other similar places in the file.


https://reviews.llvm.org/D37438

Files:
  lib/Transforms/Utils/FlattenCFG.cpp


Index: lib/Transforms/Utils/FlattenCFG.cpp
===================================================================
--- lib/Transforms/Utils/FlattenCFG.cpp
+++ lib/Transforms/Utils/FlattenCFG.cpp
@@ -240,6 +240,8 @@
     for (;CurrBlock != FirstCondBlock;
           CurrBlock = CurrBlock->getSinglePredecessor()) {
       BranchInst *BI = dyn_cast<BranchInst>(CurrBlock->getTerminator());
+      if (!BI)
+        continue;
       CmpInst *CI = dyn_cast<CmpInst>(BI->getCondition());
       if (!CI)
         continue;
@@ -267,6 +269,8 @@
   // Do the transformation.
   BasicBlock *CB;
   BranchInst *PBI = dyn_cast<BranchInst>(FirstCondBlock->getTerminator());
+  if (!PBI)
+    return false;
   bool Iteration = true;
   IRBuilder<>::InsertPointGuard Guard(Builder);
   Value *PC = PBI->getCondition();
@@ -435,6 +439,8 @@
   FirstEntryBlock->getInstList()
       .splice(FirstEntryBlock->end(), SecondEntryBlock->getInstList());
   BranchInst *PBI = dyn_cast<BranchInst>(FirstEntryBlock->getTerminator());
+  if (!PBI)
+    return false;
   Value *CC = PBI->getCondition();
   BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
   BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();


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