[MC] Remove setUseAssemblerInfoForParsing(false) workarounds

This reverts commit 245491a ("[MC] Disable MCAssembler based constant folding for DwarfDebug")
and cb09b5f ("[MC] Disable MCAssembler based constant folding for compact unwind and emitJumpTableEntry").

Checking the relative order of FA and FB is now faster due to
de19f7b ("[MC] Replace fragment ilist with singly-linked lists").

Author: MaskRay

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -2463,15 +2463,11 @@ bool AsmPrinter::doFinalization(Module &M) {
     emitGlobalIFunc(M, IFunc);
 
   // Finalize debug and EH information.
-  // Defer MCAssembler based constant folding due to a performance issue. The
-  // label differences will be evaluated at write time.
-  OutStreamer->setUseAssemblerInfoForParsing(false);
   for (const HandlerInfo &HI : Handlers) {
     NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
                        HI.TimerGroupDescription, TimePassesIsEnabled);
     HI.Handler->endModule();
   }
-  OutStreamer->setUseAssemblerInfoForParsing(true);
 
   // This deletes all the ephemeral handlers that AsmPrinter added, while
   // keeping all the user-added handlers alive until the AsmPrinter is
@@ -2803,10 +2799,8 @@ void AsmPrinter::emitJumpTableInfo() {
 
     // Defer MCAssembler based constant folding due to a performance issue. The
     // label differences will be evaluated at write time.
-    OutStreamer->setUseAssemblerInfoForParsing(false);
     for (const MachineBasicBlock *MBB : JTBBs)
       emitJumpTableEntry(MJTI, MBB, JTI);
-    OutStreamer->setUseAssemblerInfoForParsing(true);
   }
   if (!JTInDiffSection)
     OutStreamer->emitDataRegion(MCDR_DataRegionEnd);

llvm/lib/MC/MCDwarf.cpp

@@ -1865,14 +1865,6 @@ void MCDwarfFrameEmitter::Emit(MCObjectStreamer &Streamer, MCAsmBackend *MAB,
   FrameEmitterImpl Emitter(IsEH, Streamer);
   ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getDwarfFrameInfos();
 
-  // Disable AttemptToFoldSymbolOffsetDifference folding of EmitCompactUnwind
-  // and fdeStart-cieStart for EmitFDE due to the the performance issue. The
-  // label differences will be evaluate at write time.
-  assert(Streamer.getUseAssemblerInfoForParsing());
-  Streamer.setUseAssemblerInfoForParsing(false);
-  auto Enable = llvm::make_scope_exit(
-      [&]() { Streamer.setUseAssemblerInfoForParsing(true); });
-
   // Emit the compact unwind info if available.
   bool NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame();
   if (IsEH && MOFI->getCompactUnwindSection()) {