Refactor: Simplify boolean conditional return statements in lib/Target/SystemZ

[LegalizeAdulthood]

Summary

Use clang-tidy to simplify conditonal return statements

[craig.topper]

lib/Target/SystemZ/SystemZInstrInfo.cpp

510

Can this just be on the previous line and still fit 80 columns?

[LegalizeAdulthood]

lib/Target/SystemZ/SystemZInstrInfo.cpp

510

Fixed.

[LegalizeAdulthood]

clang-format

[uweigand]

Some of these changes make sense to me, but a number of others don't appear to make the code more readable.

The latter are typically of the form:

if (cond1)
  return false;
if (cond2)
  return false;
...
if (condN)
  return false;

return true;

In a sequence like this (which is written this way to be able to easily add/remove further conditions as appropriate, it doesn't really improve maintainability to just transform the *last* condition.

[LegalizeAdulthood]

Update from latest.
Update from comments.
I do not have commit access.

[LegalizeAdulthood]

In D9986#201999, @uweigand wrote:

Some of these changes make sense to me, but a number of others don't appear to make the code more readable.

The latter are typically of the form:

if (cond1)
  return false;
if (cond2)
  return false;
...
if (condN)
  return false;

return true;

In a sequence like this (which is written this way to be able to easily add/remove further conditions as appropriate, it doesn't really improve maintainability to just transform the *last* condition.

This should not be a problem anymore.

[uweigand]

LGTM.

lib/Target/SystemZ/SystemZISelLowering.cpp

 #include "SystemZGenCallingConv.inc"
 
 bool SystemZTargetLowering::allowTruncateForTailCall(Type *FromType,
                                                      Type *ToType) const {
   return isTruncateFree(FromType, ToType);
 }
 
 bool SystemZTargetLowering::mayBeEmittedAsTailCall(CallInst *CI) const {
-  if (!CI->isTailCall())
-    return false;
-  return true;
+  return CI->isTailCall();
 }
 
 // We do not yet support 128-bit single-element vector types.  If the user
 // attempts to use such types as function argument or return type, prefer
 // to error out instead of emitting code violating the ABI.
 static void VerifyVectorType(MVT VT, EVT ArgVT) {
   if (ArgVT.isVector() && !VT.isVector())
     report_fatal_error("Unsupported vector argument or return type");

lib/Target/SystemZ/SystemZInstrInfo.cpp

 
 bool
 SystemZInstrInfo::optimizeCompareInstr(MachineInstr *Compare,
                                        unsigned SrcReg, unsigned SrcReg2,
                                        int Mask, int Value,
                                        const MachineRegisterInfo *MRI) const {
   assert(!SrcReg2 && "Only optimizing constant comparisons so far");
   bool IsLogical = (Compare->getDesc().TSFlags & SystemZII::IsLogical) != 0;
-  if (Value == 0 &&
-      !IsLogical &&
-      removeIPMBasedCompare(Compare, SrcReg, MRI, &RI))
-    return true;
-  return false;
+  return Value == 0 && !IsLogical &&
+         removeIPMBasedCompare(Compare, SrcReg, MRI, &RI);
 }
 
 // If Opcode is a move that has a conditional variant, return that variant,
 // otherwise return 0.
 static unsigned getConditionalMove(unsigned Opcode) {
   switch (Opcode) {
   case SystemZ::LR:  return SystemZ::LOCR;
   case SystemZ::LGR: return SystemZ::LOCGR;
   default:           return 0;
   }
 }
 
 bool SystemZInstrInfo::isPredicable(MachineInstr *MI) const {
   unsigned Opcode = MI->getOpcode();
-  if (STI.hasLoadStoreOnCond() &&
-      getConditionalMove(Opcode))
-    return true;
-  return false;
+  return STI.hasLoadStoreOnCond() && getConditionalMove(Opcode);
 }
 
 bool SystemZInstrInfo::
 isProfitableToIfCvt(MachineBasicBlock &MBB,
                     unsigned NumCycles, unsigned ExtraPredCycles,
                     BranchProbability Probability) const {
   // For now only convert single instructions.
   return NumCycles == 1;
 }