Handle blocks with 2 unconditional branches in AnalyzeBranch.

llvm-svn: 37571

lib/Target/ARM/ARMInstrInfo.cpp

@@ -345,6 +345,16 @@ bool ARMInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
     return false;
   }
   
+  // If the block ends with two B's or tB's, handle it.  The second one is not
+  // executed, so remove it.
+  if ((SecondLastOpc == ARM::B || SecondLastOpc==ARM::tB) &&
+      (LastOpc == ARM::B || LastOpc == ARM::tB)) {
+    TBB = SecondLastInst->getOperand(0).getMachineBasicBlock();
+    I = LastInst;
+    I->eraseFromParent();
+    return false;
+  }
+
   // Otherwise, can't handle this.
   return true;
 }

lib/Target/Alpha/AlphaInstrInfo.cpp

@@ -200,6 +200,16 @@ bool AlphaInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TB
     return false;
   }
   
+  // If the block ends with two Alpha::BRs, handle it.  The second one is not
+  // executed, so remove it.
+  if (SecondLastInst->getOpcode() == Alpha::BR && 
+      LastInst->getOpcode() == Alpha::BR) {
+    TBB = SecondLastInst->getOperand(0).getMachineBasicBlock();
+    I = LastInst;
+    I->eraseFromParent();
+    return false;
+  }
+
   // Otherwise, can't handle this.
   return true;
 }

lib/Target/PowerPC/PPCInstrInfo.cpp

@@ -220,6 +220,16 @@ bool PPCInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
     return false;
   }
   
+  // If the block ends with two PPC:Bs, handle it.  The second one is not
+  // executed, so remove it.
+  if (SecondLastInst->getOpcode() == PPC::B && 
+      LastInst->getOpcode() == PPC::B) {
+    TBB = SecondLastInst->getOperand(0).getMachineBasicBlock();
+    I = LastInst;
+    I->eraseFromParent();
+    return false;
+  }
+
   // Otherwise, can't handle this.
   return true;
 }

lib/Target/X86/X86InstrInfo.cpp

@@ -427,6 +427,16 @@ bool X86InstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
     return false;
   }
 
+  // If the block ends with two X86::JMPs, handle it.  The second one is not
+  // executed, so remove it.
+  if (SecondLastInst->getOpcode() == X86::JMP && 
+      LastInst->getOpcode() == X86::JMP) {
+    TBB = SecondLastInst->getOperand(0).getMachineBasicBlock();
+    I = LastInst;
+    I->eraseFromParent();
+    return false;
+  }
+
   // Otherwise, can't handle this.
   return true;
 }