[llvm-commits] [llvm] r71744 - /llvm/trunk/lib/CodeGen/IfConversion.cpp

[Bob Wilson]

Author: bwilson
Date: Wed May 13 18:54:13 2009
New Revision: 71744

URL: http://llvm.org/viewvc/llvm-project?rev=71744&view=rev
Log:
The IfConverter::MergeBlocks method appears to be used only to merge a basic
block with its unique predecessor.  Change the code to assert if that is not
the case, instead of trying to handle situations where the block has
multiple predecessors.

Modified:
    llvm/trunk/lib/CodeGen/IfConversion.cpp

Modified: llvm/trunk/lib/CodeGen/IfConversion.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/IfConversion.cpp?rev=71744&r1=71743&r2=71744&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/IfConversion.cpp (original)
+++ llvm/trunk/lib/CodeGen/IfConversion.cpp Wed May 13 18:54:13 2009
@@ -1187,15 +1187,10 @@
   ToBBI.BB->splice(ToBBI.BB->end(),
                    FromBBI.BB, FromBBI.BB->begin(), FromBBI.BB->end());
 
-  // Redirect all branches to FromBB to ToBB.
-  std::vector<MachineBasicBlock *> Preds(FromBBI.BB->pred_begin(),
-                                         FromBBI.BB->pred_end());
-  for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
-    MachineBasicBlock *Pred = Preds[i];
-    if (Pred == ToBBI.BB)
-      continue;
-    Pred->ReplaceUsesOfBlockWith(FromBBI.BB, ToBBI.BB);
-  }
+  // This only works when FromBBI has no predecessors except ToBBI.
+  assert(FromBBI.BB->pred_size() == 1 &&
+         *FromBBI.BB->pred_begin() == ToBBI.BB &&
+         "if-converter not merging block into its unique predecessor");
  
   std::vector<MachineBasicBlock *> Succs(FromBBI.BB->succ_begin(),
                                          FromBBI.BB->succ_end());