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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181161 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index 0d1417dd17cbeba02ff777e26a153e9aea501e74..60050542716c23f8766e2f0b9eee54373ae25e80 100644 (file)
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -283,14 +283,20 @@ ARMBaseInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
       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();