1 files changed, 35 insertions, 27 deletions

diff --git a/contrib/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp b/contrib/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp
index b5ba770..c821084 100644
--- a/contrib/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp
+++ b/contrib/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp
@@ -79,8 +79,7 @@ static cl::opt<CompactBranchPolicy> MipsCompactBranchPolicy(
   cl::values(
     clEnumValN(CB_Never, "never", "Do not use compact branches if possible."),
     clEnumValN(CB_Optimal, "optimal", "Use compact branches where appropiate (default)."),
-    clEnumValN(CB_Always, "always", "Always use compact branches if possible."),
-    clEnumValEnd
+    clEnumValN(CB_Always, "always", "Always use compact branches if possible.")
   )
 );
 
@@ -192,9 +191,7 @@ namespace {
     Filler(TargetMachine &tm)
       : MachineFunctionPass(ID), TM(tm) { }
 
-    const char *getPassName() const override {
-      return "Mips Delay Slot Filler";
-    }
+    StringRef getPassName() const override { return "Mips Delay Slot Filler"; }
 
     bool runOnMachineFunction(MachineFunction &F) override {
       bool Changed = false;
@@ -213,7 +210,7 @@ namespace {
 
     MachineFunctionProperties getRequiredProperties() const override {
       return MachineFunctionProperties().set(
-          MachineFunctionProperties::Property::AllVRegsAllocated);
+          MachineFunctionProperties::Property::NoVRegs);
     }
 
     void getAnalysisUsage(AnalysisUsage &AU) const override {
@@ -242,7 +239,7 @@ namespace {
 
     /// This function searches in the backward direction for an instruction that
     /// can be moved to the delay slot. Returns true on success.
-    bool searchBackward(MachineBasicBlock &MBB, Iter Slot) const;
+    bool searchBackward(MachineBasicBlock &MBB, MachineInstr &Slot) const;
 
     /// This function searches MBB in the forward direction for an instruction
     /// that can be moved to the delay slot. Returns true on success.
@@ -543,6 +540,9 @@ Iter Filler::replaceWithCompactBranch(MachineBasicBlock &MBB, Iter Branch,
 
 // For given opcode returns opcode of corresponding instruction with short
 // delay slot.
+// For the pseudo TAILCALL*_MM instrunctions return the short delay slot
+// form. Unfortunately, TAILCALL<->b16 is denied as b16 has a limited range
+// that is too short to make use of for tail calls.
 static int getEquivalentCallShort(int Opcode) {
   switch (Opcode) {
   case Mips::BGEZAL:
@@ -555,6 +555,10 @@ static int getEquivalentCallShort(int Opcode) {
     return Mips::JALRS_MM;
   case Mips::JALR16_MM:
     return Mips::JALRS16_MM;
+  case Mips::TAILCALL_MM:
+    llvm_unreachable("Attempting to shorten the TAILCALL_MM pseudo!");
+  case Mips::TAILCALLREG:
+    return Mips::JR16_MM;
   default:
     llvm_unreachable("Unexpected call instruction for microMIPS.");
   }
@@ -587,7 +591,7 @@ bool Filler::runOnMachineBasicBlock(MachineBasicBlock &MBB) {
 
       if (MipsCompactBranchPolicy.getValue() != CB_Always ||
            !TII->getEquivalentCompactForm(I)) {
-        if (searchBackward(MBB, I)) {
+        if (searchBackward(MBB, *I)) {
           Filled = true;
         } else if (I->isTerminator()) {
           if (searchSuccBBs(MBB, I)) {
@@ -602,10 +606,16 @@ bool Filler::runOnMachineBasicBlock(MachineBasicBlock &MBB) {
         // Get instruction with delay slot.
         MachineBasicBlock::instr_iterator DSI = I.getInstrIterator();
 
-        if (InMicroMipsMode && TII->GetInstSizeInBytes(*std::next(DSI)) == 2 &&
+        if (InMicroMipsMode && TII->getInstSizeInBytes(*std::next(DSI)) == 2 &&
             DSI->isCall()) {
           // If instruction in delay slot is 16b change opcode to
           // corresponding instruction with short delay slot.
+
+          // TODO: Implement an instruction mapping table of 16bit opcodes to
+          // 32bit opcodes so that an instruction can be expanded. This would
+          // save 16 bits as a TAILCALL_MM pseudo requires a fullsized nop.
+          // TODO: Permit b16 when branching backwards to the the same function
+          // if it is in range.
           DSI->setDesc(TII->get(getEquivalentCallShort(DSI->getOpcode())));
         }
         continue;
@@ -646,8 +656,6 @@ template<typename IterTy>
 bool Filler::searchRange(MachineBasicBlock &MBB, IterTy Begin, IterTy End,
                          RegDefsUses &RegDU, InspectMemInstr& IM, Iter Slot,
                          IterTy &Filler) const {
-  bool IsReverseIter = std::is_convertible<IterTy, ReverseIter>::value;
-
   for (IterTy I = Begin; I != End;) {
     IterTy CurrI = I;
     ++I;
@@ -664,12 +672,6 @@ bool Filler::searchRange(MachineBasicBlock &MBB, IterTy Begin, IterTy End,
 
     if (CurrI->isKill()) {
       CurrI->eraseFromParent();
-
-      // This special case is needed for reverse iterators, because when we
-      // erase an instruction, the iterators are updated to point to the next
-      // instruction.
-      if (IsReverseIter && I != End)
-        I = CurrI;
       continue;
     }
 
@@ -692,9 +694,14 @@ bool Filler::searchRange(MachineBasicBlock &MBB, IterTy Begin, IterTy End,
     bool InMicroMipsMode = STI.inMicroMipsMode();
     const MipsInstrInfo *TII = STI.getInstrInfo();
     unsigned Opcode = (*Slot).getOpcode();
-    if (InMicroMipsMode && TII->GetInstSizeInBytes(*CurrI) == 2 &&
+    // This is complicated by the tail call optimization. For non-PIC code
+    // there is only a 32bit sized unconditional branch which can be assumed
+    // to be able to reach the target. b16 only has a range of +/- 1 KB.
+    // It's entirely possible that the target function is reachable with b16
+    // but we don't have enough information to make that decision.
+     if (InMicroMipsMode && TII->getInstSizeInBytes(*CurrI) == 2 &&
         (Opcode == Mips::JR || Opcode == Mips::PseudoIndirectBranch ||
-         Opcode == Mips::PseudoReturn))
+         Opcode == Mips::PseudoReturn || Opcode == Mips::TAILCALL))
       continue;
 
     Filler = CurrI;
@@ -704,23 +711,24 @@ bool Filler::searchRange(MachineBasicBlock &MBB, IterTy Begin, IterTy End,
   return false;
 }
 
-bool Filler::searchBackward(MachineBasicBlock &MBB, Iter Slot) const {
+bool Filler::searchBackward(MachineBasicBlock &MBB, MachineInstr &Slot) const {
   if (DisableBackwardSearch)
     return false;
 
   auto *Fn = MBB.getParent();
   RegDefsUses RegDU(*Fn->getSubtarget().getRegisterInfo());
-  MemDefsUses MemDU(Fn->getDataLayout(), Fn->getFrameInfo());
+  MemDefsUses MemDU(Fn->getDataLayout(), &Fn->getFrameInfo());
   ReverseIter Filler;
 
-  RegDU.init(*Slot);
+  RegDU.init(Slot);
 
-  if (!searchRange(MBB, ReverseIter(Slot), MBB.rend(), RegDU, MemDU, Slot,
+  MachineBasicBlock::iterator SlotI = Slot;
+  if (!searchRange(MBB, ++SlotI.getReverse(), MBB.rend(), RegDU, MemDU, Slot,
                    Filler))
     return false;
 
-  MBB.splice(std::next(Slot), &MBB, std::next(Filler).base());
-  MIBundleBuilder(MBB, Slot, std::next(Slot, 2));
+  MBB.splice(std::next(SlotI), &MBB, Filler.getReverse());
+  MIBundleBuilder(MBB, SlotI, std::next(SlotI, 2));
   ++UsefulSlots;
   return true;
 }
@@ -776,8 +784,8 @@ bool Filler::searchSuccBBs(MachineBasicBlock &MBB, Iter Slot) const {
   if (HasMultipleSuccs) {
     IM.reset(new LoadFromStackOrConst());
   } else {
-    const MachineFrameInfo *MFI = Fn->getFrameInfo();
-    IM.reset(new MemDefsUses(Fn->getDataLayout(), MFI));
+    const MachineFrameInfo &MFI = Fn->getFrameInfo();
+    IM.reset(new MemDefsUses(Fn->getDataLayout(), &MFI));
   }
 
   if (!searchRange(MBB, SuccBB->begin(), SuccBB->end(), RegDU, *IM, Slot,