TargetInstrInfo: Provide default implementation of isTailCall().

In fact this default implementation should be the only implementation,
keep it virtual for now to accomodate targets that don't model flags
correctly.

Differential Revision: https://reviews.llvm.org/D30747

llvm-svn: 297980

include/llvm/Target/TargetInstrInfo.h

@@ -1503,9 +1503,11 @@ public:
     return None;
   }
 
-  /// Determines whether |Inst| is a tail call instruction.
+  /// Determines whether \p Inst is a tail call instruction. Override this
+  /// method on targets that do not properly set MCID::Return and MCID::Call on
+  /// tail call instructions."
   virtual bool isTailCall(const MachineInstr &Inst) const {
-    return false;
+    return Inst.isReturn() && Inst.isCall();
   }
 
   /// True if the instruction is bound to the top of its basic block and no

lib/Target/AArch64/AArch64InstrInfo.cpp

@@ -1619,17 +1619,6 @@ bool AArch64InstrInfo::isUnscaledLdSt(MachineInstr &MI) const {
   return isUnscaledLdSt(MI.getOpcode());
 }
 
-bool AArch64InstrInfo::isTailCall(const MachineInstr &Inst) const
-{
-  switch (Inst.getOpcode()) {
-  case AArch64::TCRETURNdi:
-  case AArch64::TCRETURNri:
-    return true;
-  default:
-    return false;
-  }
-}
-
 // Is this a candidate for ld/st merging or pairing?  For example, we don't
 // touch volatiles or load/stores that have a hint to avoid pair formation.
 bool AArch64InstrInfo::isCandidateToMergeOrPair(MachineInstr &MI) const {

lib/Target/AArch64/AArch64InstrInfo.h

@@ -87,8 +87,6 @@ public:
   /// Return true if this is an unscaled load/store.
   bool isUnscaledLdSt(MachineInstr &MI) const;
 
-  bool isTailCall(const MachineInstr &Inst) const override;
-
   static bool isPairableLdStInst(const MachineInstr &MI) {
     switch (MI.getOpcode()) {
     default:

lib/Target/ARM/ARMBaseInstrInfo.cpp

@@ -4711,19 +4711,6 @@ bool ARMBaseInstrInfo::hasNOP() const {
   return Subtarget.getFeatureBits()[ARM::HasV6KOps];
 }
 
-bool ARMBaseInstrInfo::isTailCall(const MachineInstr &Inst) const
-{
-  switch (Inst.getOpcode()) {
-  case ARM::TAILJMPd:
-  case ARM::TAILJMPr:
-  case ARM::TCRETURNdi:
-  case ARM::TCRETURNri:
-    return true;
-  default:
-    return false;
-  }
-}
-
 bool ARMBaseInstrInfo::isSwiftFastImmShift(const MachineInstr *MI) const {
   if (MI->getNumOperands() < 4)
     return true;

lib/Target/ARM/ARMBaseInstrInfo.h

@@ -109,8 +109,6 @@ public:
     getNoopForMachoTarget(NopInst);
   }
 
-  bool isTailCall(const MachineInstr &Inst) const override;
-
   // Return the non-pre/post incrementing version of 'Opc'. Return 0
   // if there is not such an opcode.
   virtual unsigned getUnindexedOpcode(unsigned Opc) const = 0;

lib/Target/X86/X86InstrInfo.cpp

@@ -10177,28 +10177,6 @@ X86InstrInfo::getSerializableDirectMachineOperandTargetFlags() const {
   return makeArrayRef(TargetFlags);
 }
 
-bool X86InstrInfo::isTailCall(const MachineInstr &Inst) const {
-  switch (Inst.getOpcode()) {
-    case X86::TCRETURNdi:
-    case X86::TCRETURNmi:
-    case X86::TCRETURNri:
-    case X86::TCRETURNdi64:
-    case X86::TCRETURNmi64:
-    case X86::TCRETURNri64:
-    case X86::TAILJMPd:
-    case X86::TAILJMPm:
-    case X86::TAILJMPr:
-    case X86::TAILJMPd64:
-    case X86::TAILJMPm64:
-    case X86::TAILJMPr64:
-    case X86::TAILJMPm64_REX:
-    case X86::TAILJMPr64_REX:
-      return true;
-    default:
-      return false;
-  }
-}
-
 namespace {
   /// Create Global Base Reg pass. This initializes the PIC
   /// global base register for x86-32.

lib/Target/X86/X86InstrInfo.h

@@ -543,8 +543,6 @@ public:
   ArrayRef<std::pair<unsigned, const char *>>
   getSerializableDirectMachineOperandTargetFlags() const override;
 
-  bool isTailCall(const MachineInstr &Inst) const override;
-
   unsigned getOutliningBenefit(size_t SequenceSize,
                                size_t Occurrences,
                                bool CanBeTailCall) const override;