Add the PPCCTRLoops pass: a PPC machine-code-level optimization pass to form CTR-based loop branching code.

This pass is derived from the Hexagon HardwareLoops pass. The only significant enhancement over the Hexagon
pass is that PPCCTRLoops will also attempt to delete the replaced add and compare operations if they are
no longer otherwise used. Also, invalid preheader DebugLoc is not used.

llvm-svn: 158204

1 files changed, 24 insertions, 12 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCBranchSelector.cpp b/llvm/lib/Target/PowerPC/PPCBranchSelector.cpp
index 5f775e1..21a0fb2 100644
--- a/llvm/lib/Target/PowerPC/PPCBranchSelector.cpp
+++ b/llvm/lib/Target/PowerPC/PPCBranchSelector.cpp
@@ -135,21 +135,33 @@ bool PPCBSel::runOnMachineFunction(MachineFunction &Fn) {
           MBBStartOffset += 4;
           continue;
         }
-        
+
         // Otherwise, we have to expand it to a long branch.
-        // The BCC operands are:
-        // 0. PPC branch predicate
-        // 1. CR register
-        // 2. Target MBB
-        PPC::Predicate Pred = (PPC::Predicate)I->getOperand(0).getImm();
-        unsigned CRReg = I->getOperand(1).getReg();
-        
         MachineInstr *OldBranch = I;
         DebugLoc dl = OldBranch->getDebugLoc();
-        
-        // Jump over the uncond branch inst (i.e. $PC+8) on opposite condition.
-        BuildMI(MBB, I, dl, TII->get(PPC::BCC))
-          .addImm(PPC::InvertPredicate(Pred)).addReg(CRReg).addImm(2);
+ 
+        if (I->getOpcode() == PPC::BCC) {
+          // The BCC operands are:
+          // 0. PPC branch predicate
+          // 1. CR register
+          // 2. Target MBB
+          PPC::Predicate Pred = (PPC::Predicate)I->getOperand(0).getImm();
+          unsigned CRReg = I->getOperand(1).getReg();
+       
+          // Jump over the uncond branch inst (i.e. $PC+8) on opposite condition.
+          BuildMI(MBB, I, dl, TII->get(PPC::BCC))
+            .addImm(PPC::InvertPredicate(Pred)).addReg(CRReg).addImm(2);
+        } else if (I->getOpcode() == PPC::BDNZ) {
+          BuildMI(MBB, I, dl, TII->get(PPC::BDZ)).addImm(2);
+        } else if (I->getOpcode() == PPC::BDNZ8) {
+          BuildMI(MBB, I, dl, TII->get(PPC::BDZ8)).addImm(2);
+        } else if (I->getOpcode() == PPC::BDZ) {
+          BuildMI(MBB, I, dl, TII->get(PPC::BDNZ)).addImm(2);
+        } else if (I->getOpcode() == PPC::BDZ8) {
+          BuildMI(MBB, I, dl, TII->get(PPC::BDNZ8)).addImm(2);
+        } else {
+           llvm_unreachable("Unhandled branch type!");
+        }
         
         // Uncond branch to the real destination.
         I = BuildMI(MBB, I, dl, TII->get(PPC::B)).addMBB(Dest);