[llvm] r181161 - ARM AnalyzeBranch should conservatively return true when it sees a predicated

[Evan Cheng]

Author: evancheng
Date: Sun May  5 13:06:32 2013
New Revision: 181161

URL: http://llvm.org/viewvc/llvm-project?rev=181161&view=rev
Log:
ARM AnalyzeBranch should conservatively return true when it sees a predicated
indirect branch at the end of the BB. Otherwise if-converter, branch folding
pass may incorrectly update its successor info if it consider BB as fallthrough
to the next BB.

rdar://13782395

Modified:
    llvm/trunk/lib/Target/ARM/ARMBaseInstrInfo.cpp

Modified: llvm/trunk/lib/Target/ARM/ARMBaseInstrInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMBaseInstrInfo.cpp?rev=181161&r1=181160&r2=181161&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMBaseInstrInfo.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMBaseInstrInfo.cpp Sun May  5 13:06:32 2013
@@ -283,14 +283,20 @@ ARMBaseInstrInfo::AnalyzeBranch(MachineB
       return false;
     --I;
   }
-  if (!isUnpredicatedTerminator(I))
-    return false;
 
   // Get the last instruction in the block.
   MachineInstr *LastInst = I;
+  unsigned LastOpc = LastInst->getOpcode();
+
+  // Check if it's an indirect branch first, this should return 'unanalyzable'
+  // even if it's predicated.
+  if (isIndirectBranchOpcode(LastOpc))
+    return true;
+
+  if (!isUnpredicatedTerminator(I))
+    return false;
 
   // If there is only one terminator instruction, process it.
-  unsigned LastOpc = LastInst->getOpcode();
   if (I == MBB.begin() || !isUnpredicatedTerminator(--I)) {
     if (isUncondBranchOpcode(LastOpc)) {
       TBB = LastInst->getOperand(0).getMBB();