Replace PROLOG_LABEL with a new CFI_INSTRUCTION.

The old system was fairly convoluted:
* A temporary label was created.
* A single PROLOG_LABEL was created with it.
* A few MCCFIInstructions were created with the same label.

The semantics were that the cfi instructions were mapped to the PROLOG_LABEL
via the temporary label. The output position was that of the PROLOG_LABEL.
The temporary label itself was used only for doing the mapping.

The new CFI_INSTRUCTION has a 1:1 mapping to MCCFIInstructions and points to
one by holding an index into the CFI instructions of this function.

I did consider removing MMI.getFrameInstructions completelly and having
CFI_INSTRUCTION own a MCCFIInstruction, but MCCFIInstructions have non
trivial constructors and destructors and are somewhat big, so the this setup
is probably better.

The net result is that we don't create temporary labels that are never used.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203204 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 13 insertions, 16 deletions

diff --git a/lib/Target/Sparc/DelaySlotFiller.cpp b/lib/Target/Sparc/DelaySlotFiller.cpp
index 80df99abf2..88fba395c7 100644
--- a/lib/Target/Sparc/DelaySlotFiller.cpp
+++ b/lib/Target/Sparc/DelaySlotFiller.cpp
@@ -211,12 +211,8 @@ Filler::findDelayInstr(MachineBasicBlock &MBB,
     if (I->isDebugValue())
       continue;
 
-
-    if (I->hasUnmodeledSideEffects()
-        || I->isInlineAsm()
-        || I->isLabel()
-        || I->hasDelaySlot()
-        || I->isBundledWithSucc())
+    if (I->hasUnmodeledSideEffects() || I->isInlineAsm() || I->isPosition() ||
+        I->hasDelaySlot() || I->isBundledWithSucc())
       break;
 
     if (delayHasHazard(I, sawLoad, sawStore, RegDefs, RegUses)) {
diff --git a/lib/Target/Sparc/SparcCodeEmitter.cpp b/lib/Target/Sparc/SparcCodeEmitter.cpp
index 97bacf2d31..4f8d4771a1 100644
--- a/lib/Target/Sparc/SparcCodeEmitter.cpp
+++ b/lib/Target/Sparc/SparcCodeEmitter.cpp
@@ -145,7 +145,8 @@ void SparcCodeEmitter::emitInstruction(MachineBasicBlock::instr_iterator MI,
     }
     break;
   }
-  case TargetOpcode::PROLOG_LABEL:
+  case TargetOpcode::CFI_INSTRUCTION:
+    break;
   case TargetOpcode::EH_LABEL: {
     MCE.emitLabel(MI->getOperand(0).getMCSymbol());
     break;
diff --git a/lib/Target/Sparc/SparcFrameLowering.cpp b/lib/Target/Sparc/SparcFrameLowering.cpp
index c75998a36e..d96a4c0649 100644
--- a/lib/Target/Sparc/SparcFrameLowering.cpp
+++ b/lib/Target/Sparc/SparcFrameLowering.cpp
@@ -104,23 +104,23 @@ void SparcFrameLowering::emitPrologue(MachineFunction &MF) const {
 
   MachineModuleInfo &MMI = MF.getMMI();
   const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo();
-  MCSymbol *FrameLabel = MMI.getContext().CreateTempSymbol();
-  BuildMI(MBB, MBBI, dl, TII.get(SP::PROLOG_LABEL)).addSym(FrameLabel);
-
   unsigned regFP = MRI->getDwarfRegNum(SP::I6, true);
 
   // Emit ".cfi_def_cfa_register 30".
-  MMI.addFrameInst(MCCFIInstruction::createDefCfaRegister(FrameLabel,
-                                                          regFP));
+  unsigned CFIIndex =
+      MMI.addFrameInst(MCCFIInstruction::createDefCfaRegister(nullptr, regFP));
+  BuildMI(MBB, MBBI, dl, TII.get(SP::CFI_INSTRUCTION)).addCFIIndex(CFIIndex);
+
   // Emit ".cfi_window_save".
-  MMI.addFrameInst(MCCFIInstruction::createWindowSave(FrameLabel));
+  CFIIndex = MMI.addFrameInst(MCCFIInstruction::createWindowSave(nullptr));
+  BuildMI(MBB, MBBI, dl, TII.get(SP::CFI_INSTRUCTION)).addCFIIndex(CFIIndex);
 
   unsigned regInRA = MRI->getDwarfRegNum(SP::I7, true);
   unsigned regOutRA = MRI->getDwarfRegNum(SP::O7, true);
   // Emit ".cfi_register 15, 31".
-  MMI.addFrameInst(MCCFIInstruction::createRegister(FrameLabel,
-                                                    regOutRA,
-                                                    regInRA));
+  CFIIndex = MMI.addFrameInst(
+      MCCFIInstruction::createRegister(nullptr, regOutRA, regInRA));
+  BuildMI(MBB, MBBI, dl, TII.get(SP::CFI_INSTRUCTION)).addCFIIndex(CFIIndex);
 }
 
 void SparcFrameLowering::