[llvm-commits] [llvm] r86147 - /llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp

[Dan Gohman]

Author: djg
Date: Thu Nov  5 12:25:44 2009
New Revision: 86147

URL: http://llvm.org/viewvc/llvm-project?rev=86147&view=rev
Log:
Add an assertion to catch indirectbr in SplitBlockPredecessors. This
makes several optimization passes abort in cases where they're currently
silently miscompiling code.

Remove the indirectbr assertion from SplitEdge. Indirectbr is only
a problem for critical edges, and SplitEdge defers to SplitCriticalEdge
to handle those, and SplitCriticalEdge has its own assertion for
indirectbr.

Modified:
    llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp

Modified: llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp?rev=86147&r1=86146&r2=86147&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp Thu Nov  5 12:25:44 2009
@@ -275,8 +275,6 @@
 /// SplitEdge -  Split the edge connecting specified block. Pass P must 
 /// not be NULL. 
 BasicBlock *llvm::SplitEdge(BasicBlock *BB, BasicBlock *Succ, Pass *P) {
-  assert(!isa<IndirectBrInst>(BB->getTerminator()) &&
-         "Cannot split an edge from an IndirectBrInst");
   TerminatorInst *LatchTerm = BB->getTerminator();
   unsigned SuccNum = 0;
 #ifndef NDEBUG
@@ -386,6 +384,12 @@
   bool IsLoopEntry = !!L;
   bool SplitMakesNewLoopHeader = false;
   for (unsigned i = 0; i != NumPreds; ++i) {
+    // This is slightly more strict than necessary; the minimum requirement
+    // is that there be no more than one indirectbr branching to BB. And
+    // all BlockAddress uses would need to be updated.
+    assert(!isa<IndirectBrInst>(Preds[i]->getTerminator()) &&
+           "Cannot split an edge from an IndirectBrInst");
+
     Preds[i]->getTerminator()->replaceUsesOfWith(BB, NewBB);
 
     if (LI) {