[SystemZ] Tweak SystemZInstrInfo::isBranch() interface

This is needed for the upcoming compare-and-branch patch.  No functional
change intended.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182762 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/SystemZ/SystemZInstrInfo.cpp

@@ -124,19 +124,18 @@ bool SystemZInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
 
     // A terminator that isn't a branch can't easily be handled by this
     // analysis.
-    unsigned ThisCond;
-    const MachineOperand *ThisTarget;
-    if (!isBranch(I, ThisCond, ThisTarget))
+    if (!I->isBranch())
       return true;
 
     // Can't handle indirect branches.
-    if (!ThisTarget->isMBB())
+    SystemZII::Branch Branch(getBranchInfo(I));
+    if (!Branch.Target->isMBB())
       return true;
 
-    if (ThisCond == SystemZ::CCMASK_ANY) {
+    if (Branch.CCMask == SystemZ::CCMASK_ANY) {
       // Handle unconditional branches.
       if (!AllowModify) {
-        TBB = ThisTarget->getMBB();
+        TBB = Branch.Target->getMBB();
         continue;
       }
 
@@ -148,7 +147,7 @@ bool SystemZInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
       FBB = 0;
 
       // Delete the JMP if it's equivalent to a fall-through.
-      if (MBB.isLayoutSuccessor(ThisTarget->getMBB())) {
+      if (MBB.isLayoutSuccessor(Branch.Target->getMBB())) {
         TBB = 0;
         I->eraseFromParent();
         I = MBB.end();
@@ -156,7 +155,7 @@ bool SystemZInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
       }
 
       // TBB is used to indicate the unconditinal destination.
-      TBB = ThisTarget->getMBB();
+      TBB = Branch.Target->getMBB();
       continue;
     }
 
@@ -164,8 +163,8 @@ bool SystemZInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
     if (Cond.empty()) {
       // FIXME: add X86-style branch swap
       FBB = TBB;
-      TBB = ThisTarget->getMBB();
-      Cond.push_back(MachineOperand::CreateImm(ThisCond));
+      TBB = Branch.Target->getMBB();
+      Cond.push_back(MachineOperand::CreateImm(Branch.CCMask));
       continue;
     }
 
@@ -175,12 +174,12 @@ bool SystemZInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
 
     // Only handle the case where all conditional branches branch to the same
     // destination.
-    if (TBB != ThisTarget->getMBB())
+    if (TBB != Branch.Target->getMBB())
       return true;
 
     // If the conditions are the same, we can leave them alone.
     unsigned OldCond = Cond[0].getImm();
-    if (OldCond == ThisCond)
+    if (OldCond == Branch.CCMask)
       continue;
 
     // FIXME: Try combining conditions like X86 does.  Should be easy on Z!
@@ -198,11 +197,9 @@ unsigned SystemZInstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
     --I;
     if (I->isDebugValue())
       continue;
-    unsigned Cond;
-    const MachineOperand *Target;
-    if (!isBranch(I, Cond, Target))
+    if (!I->isBranch())
       break;
-    if (!Target->isMBB())
+    if (!getBranchInfo(I).Target->isMBB())
       break;
     // Remove the branch.
     I->eraseFromParent();
@@ -358,25 +355,20 @@ uint64_t SystemZInstrInfo::getInstSizeInBytes(const MachineInstr *MI) const {
   return MI->getDesc().getSize();
 }
 
-bool SystemZInstrInfo::isBranch(const MachineInstr *MI, unsigned &Cond,
-                                const MachineOperand *&Target) const {
+SystemZII::Branch
+SystemZInstrInfo::getBranchInfo(const MachineInstr *MI) const {
   switch (MI->getOpcode()) {
   case SystemZ::BR:
   case SystemZ::J:
   case SystemZ::JG:
-    Cond = SystemZ::CCMASK_ANY;
-    Target = &MI->getOperand(0);
-    return true;
+    return SystemZII::Branch(SystemZ::CCMASK_ANY, &MI->getOperand(0));
 
   case SystemZ::BRC:
   case SystemZ::BRCL:
-    Cond = MI->getOperand(0).getImm();
-    Target = &MI->getOperand(1);
-    return true;
+    return SystemZII::Branch(MI->getOperand(0).getImm(), &MI->getOperand(1));
 
   default:
-    assert(!MI->getDesc().isBranch() && "Unknown branch opcode");
-    return false;
+    llvm_unreachable("Unrecognized branch opcode");
   }
 }
 

lib/Target/SystemZ/SystemZInstrInfo.h

@@ -42,6 +42,17 @@ namespace SystemZII {
     // @GOT (aka @GOTENT)
     MO_GOT = (1 << 0)
   };
+  // Information about a branch instruction.
+  struct Branch {
+    // CCMASK_<N> is set if the branch should be taken when CC == N.
+    unsigned CCMask;
+
+    // The target of the branch.
+    const MachineOperand *Target;
+
+    Branch(unsigned ccMask, const MachineOperand *target)
+      : CCMask(ccMask), Target(target) {}
+  };
 }
 
 class SystemZInstrInfo : public SystemZGenInstrInfo {
@@ -101,8 +112,7 @@ public:
   // values on which the instruction will branch, and set Target
   // to the operand that contains the branch target.  This target
   // can be a register or a basic block.
-  bool isBranch(const MachineInstr *MI, unsigned &Cond,
-                const MachineOperand *&Target) const;
+  SystemZII::Branch getBranchInfo(const MachineInstr *MI) const;
 
   // Get the load and store opcodes for a given register class.
   void getLoadStoreOpcodes(const TargetRegisterClass *RC,

lib/Target/SystemZ/SystemZLongBranch.cpp

@@ -211,22 +211,21 @@ TerminatorInfo SystemZLongBranch::describeTerminator(MachineInstr *MI) {
   TerminatorInfo Terminator;
   Terminator.Size = TII->getInstSizeInBytes(MI);
   if (MI->isConditionalBranch() || MI->isUnconditionalBranch()) {
-    Terminator.Branch = MI;
     switch (MI->getOpcode()) {
     case SystemZ::J:
       // Relaxes to JG, which is 2 bytes longer.
-      Terminator.TargetBlock = MI->getOperand(0).getMBB()->getNumber();
       Terminator.ExtraRelaxSize = 2;
       break;
     case SystemZ::BRC:
-      // Relaxes to BRCL, which is 2 bytes longer.  Operand 0 is the
-      // condition code mask.
-      Terminator.TargetBlock = MI->getOperand(1).getMBB()->getNumber();
+      // Relaxes to BRCL, which is 2 bytes longer.
       Terminator.ExtraRelaxSize = 2;
       break;
     default:
       llvm_unreachable("Unrecognized branch instruction");
     }
+    Terminator.Branch = MI;
+    Terminator.TargetBlock =
+      TII->getBranchInfo(MI).Target->getMBB()->getNumber();
   }
   return Terminator;
 }