RegisterScavenger: Take a reference as enterBasicBlock() argument.

Make it obvious that the argument cannot be nullptr.
Remove an unnecessary nullptr check in initRegState.

llvm-svn: 265511

4 files changed, 8 insertions, 11 deletions

diff --git a/llvm/lib/CodeGen/BranchFolding.cpp b/llvm/lib/CodeGen/BranchFolding.cpp
index 0a6e88ea45b..065bac015c5 100644
--- a/llvm/lib/CodeGen/BranchFolding.cpp
+++ b/llvm/lib/CodeGen/BranchFolding.cpp
@@ -397,7 +397,7 @@ static unsigned ComputeCommonTailLength(MachineBasicBlock *MBB1,
 void BranchFolder::MaintainLiveIns(MachineBasicBlock *CurMBB,
                                    MachineBasicBlock *NewMBB) {
   if (RS) {
-    RS->enterBasicBlock(CurMBB);
+    RS->enterBasicBlock(*CurMBB);
     if (!CurMBB->empty())
       RS->forward(std::prev(CurMBB->end()));
     for (unsigned int i = 1, e = TRI->getNumRegs(); i != e; i++)
diff --git a/llvm/lib/CodeGen/PrologEpilogInserter.cpp b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
index 84b202128e4..7c3fe33cf75 100644
--- a/llvm/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
@@ -880,7 +880,7 @@ void PEI::replaceFrameIndices(MachineBasicBlock *BB, MachineFunction &Fn,
   unsigned FrameSetupOpcode = TII.getCallFrameSetupOpcode();
   unsigned FrameDestroyOpcode = TII.getCallFrameDestroyOpcode();
 
-  if (RS && !FrameIndexVirtualScavenging) RS->enterBasicBlock(BB);
+  if (RS && !FrameIndexVirtualScavenging) RS->enterBasicBlock(*BB);
 
   bool InsideCallSequence = false;
 
@@ -991,7 +991,7 @@ PEI::scavengeFrameVirtualRegs(MachineFunction &Fn) {
   // Run through the instructions and find any virtual registers.
   for (MachineFunction::iterator BB = Fn.begin(),
        E = Fn.end(); BB != E; ++BB) {
-    RS->enterBasicBlock(&*BB);
+    RS->enterBasicBlock(*BB);
 
     int SPAdj = 0;
 
diff --git a/llvm/lib/CodeGen/RegisterScavenging.cpp b/llvm/lib/CodeGen/RegisterScavenging.cpp
index 8fa1bf74b7e..8e002749d3b 100644
--- a/llvm/lib/CodeGen/RegisterScavenging.cpp
+++ b/llvm/lib/CodeGen/RegisterScavenging.cpp
@@ -49,9 +49,6 @@ void RegScavenger::initRegState() {
   // All register units start out unused.
   RegUnitsAvailable.set();
 
-  if (!MBB)
-    return;
-
   // Live-in registers are in use.
   for (const auto &LI : MBB->liveins())
     setRegUsed(LI.PhysReg, LI.LaneMask);
@@ -63,8 +60,8 @@ void RegScavenger::initRegState() {
     setRegUsed(I);
 }
 
-void RegScavenger::enterBasicBlock(MachineBasicBlock *mbb) {
-  MachineFunction &MF = *mbb->getParent();
+void RegScavenger::enterBasicBlock(MachineBasicBlock &MBB) {
+  MachineFunction &MF = *MBB.getParent();
   TII = MF.getSubtarget().getInstrInfo();
   TRI = MF.getSubtarget().getRegisterInfo();
   MRI = &MF.getRegInfo();
@@ -78,15 +75,15 @@ void RegScavenger::enterBasicBlock(MachineBasicBlock *mbb) {
          "Cannot use register scavenger with inaccurate liveness");
 
   // Self-initialize.
-  if (!MBB) {
+  if (!this->MBB) {
     NumRegUnits = TRI->getNumRegUnits();
     RegUnitsAvailable.resize(NumRegUnits);
     KillRegUnits.resize(NumRegUnits);
     DefRegUnits.resize(NumRegUnits);
     TmpRegUnits.resize(NumRegUnits);
   }
+  this->MBB = &MBB;
 
-  MBB = mbb;
   initRegState();
 
   Tracking = false;
diff --git a/llvm/lib/CodeGen/TailDuplication.cpp b/llvm/lib/CodeGen/TailDuplication.cpp
index 2a8431c2bab..7dca17ccd9a 100644
--- a/llvm/lib/CodeGen/TailDuplication.cpp
+++ b/llvm/lib/CodeGen/TailDuplication.cpp
@@ -816,7 +816,7 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB,
 
     if (RS && !TailBB->livein_empty()) {
       // Update PredBB livein.
-      RS->enterBasicBlock(PredBB);
+      RS->enterBasicBlock(*PredBB);
       if (!PredBB->empty())
         RS->forward(std::prev(PredBB->end()));
       for (const auto &LI : TailBB->liveins()) {