MachineInstr: Don't skip dead reg operands when printing.

[MatzeB]

Summary

Once upon a time there was r86583:

Print "..." instead of all the uninteresting register clobbers on call
instructions. This makes CodeGen dumps significantly less noisy.

Example before:
  BL <ga:@bar>, %R0<imp-def>, %R1<imp-def,dead>, %R2<imp-def,dead>, %R3<imp-def,dead>, %R12<imp-def,dead>, %LR<imp-def,dead>, %D0<imp-def,dead>, %D1<imp-def,dead>, %D2<imp-def,dead>, %D3<imp-def,dead>, %D4<imp-def,dead>, %D5<imp-def,dead>, %D6<imp-def,dead>, %D7<imp-def,dead>, %D16<imp-def,dead>, %D17<imp-def,dead>, %D18<imp-def,dead>, %D19<imp-def,dead>, %D20<imp-def,dead>, %D21<imp-def,dead>, %D22<imp-def,dead>, %D23<imp-def,dead>, %D24<imp-def,dead>, %D25<imp-def,dead>, %D26<imp-def,dead>, %D27<imp-def,dead>, %D28<imp-def,dead>, %D29<imp-def,dead>, %D30<imp-def,dead>, %D31<imp-def,dead>, %CPSR<imp-def,dead>, %FPSCR<imp-def,dead>

Same example after:
  BL <ga:@bar>, %R0<imp-def>, %R1<imp-def,dead>, %LR<imp-def,dead>, %CPSR<imp-def,dead>, ...

Nowadays we have regmask operands on calls and hence don't have dozens of dead defs anymore. Hiding implicit def operands hurts debugging a lot more than it helps today so this reverts that behavior.

[qcolombet]

LGTM

[MatzeB]

Committed as r304254

lib/CodeGen/MachineInstr.cpp

if (TII)
     OS << TII->getName(getOpcode());
   else
     OS << "UNKNOWN";
 
   if (SkipOpers)
     return;
 
   // Print the rest of the operands.
-  bool OmittedAnyCallClobbers = false;
   bool FirstOp = true;
   unsigned AsmDescOp = ~0u;
   unsigned AsmOpCount = 0;
 
   if (isInlineAsm() && e >= InlineAsm::MIOp_FirstOperand) {
     // Print asm string.
     OS << " ";
     getOperand(InlineAsm::MIOp_AsmString).print(OS, MST, TRI);
void MachineInstr::print(raw_ostream &OS, ModuleSlotTracker &MST,
   }
 
   for (unsigned i = StartOp, e = getNumOperands(); i != e; ++i) {
     const MachineOperand &MO = getOperand(i);
 
     if (MO.isReg() && TargetRegisterInfo::isVirtualRegister(MO.getReg()))
       VirtRegs.push_back(MO.getReg());
 
-    // Omit call-clobbered registers which aren't used anywhere. This makes
-    // call instructions much less noisy on targets where calls clobber lots
-    // of registers. Don't rely on MO.isDead() because we may be called before
-    // LiveVariables is run, or we may be looking at a non-allocatable reg.
-    if (MRI && isCall() &&
-        MO.isReg() && MO.isImplicit() && MO.isDef()) {
-      unsigned Reg = MO.getReg();
-      if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
-        if (MRI->use_empty(Reg)) {
-          bool HasAliasLive = false;
-          for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) {
-            unsigned AliasReg = *AI;
-            if (!MRI->use_empty(AliasReg)) {
-              HasAliasLive = true;
-              break;
-            }
-          }
-          if (!HasAliasLive) {
-            OmittedAnyCallClobbers = true;
-            continue;
-          }
-        }
-      }
-    }
-
     if (FirstOp) FirstOp = false; else OS << ",";
     OS << " ";
     if (i < getDesc().NumOperands) {
       const MCOperandInfo &MCOI = getDesc().OpInfo[i];
       if (MCOI.isPredicate())
         OS << "pred:";
       if (MCOI.isOptionalDef())
         OS << "opt:";
if (isDebugValue() && MO.isMetadata()) {
       OS << ']';
 
       // Compute the index of the next operand descriptor.
       AsmDescOp += 1 + InlineAsm::getNumOperandRegisters(Flag);
     } else
       MO.print(OS, MST, TRI);
   }
 
-  // Briefly indicate whether any call clobbers were omitted.
-  if (OmittedAnyCallClobbers) {
-    if (!FirstOp) OS << ",";
-    OS << " ...";
-  }
-
   bool HaveSemi = false;
   const unsigned PrintableFlags = FrameSetup | FrameDestroy;
   if (Flags & PrintableFlags) {
     if (!HaveSemi) {
       OS << ";";
       HaveSemi = true;
     }
     OS << " flags: ";