[MC] Remove MCAsmLayout::invalidateFragmentsFrom

The simplification is enabled by
9d0754a ("[MC] Relax fragments eagerly").

Author: MaskRay

llvm/include/llvm/MC/MCAsmLayout.h

@@ -40,11 +40,6 @@ class MCAsmLayout {
   /// Get the assembler object this is a layout for.
   MCAssembler &getAssembler() const { return Assembler; }
 
-  /// Invalidate the fragments starting with F because it has been
-  /// resized. The fragment's size should have already been updated, but
-  /// its bundle padding will be recomputed.
-  void invalidateFragmentsFrom(MCFragment *F);
-
   void layoutBundle(MCFragment *Prev, MCFragment *F);
 
   /// \name Section Access (in layout order)

llvm/lib/MC/MCFragment.cpp

@@ -40,10 +40,6 @@ MCAsmLayout::MCAsmLayout(MCAssembler &Asm) : Assembler(Asm) {
       SectionOrder.push_back(&Sec);
 }
 
-void MCAsmLayout::invalidateFragmentsFrom(MCFragment *F) {
-  F->getParent()->setHasLayout(false);
-}
-
 // Simple getSymbolOffset helper for the non-variable case.
 static bool getLabelOffset(const MCAsmLayout &Layout, const MCSymbol &S,
                            bool ReportError, uint64_t &Val) {

llvm/lib/Target/Hexagon/MCTargetDesc/HexagonAsmBackend.cpp

@@ -756,7 +756,7 @@ class HexagonAsmBackend : public MCAsmBackend {
               //assert(!Error);
               (void)Error;
               ReplaceInstruction(Asm.getEmitter(), RF, Inst);
-              Layout.invalidateFragmentsFrom(&RF);
+              I->setHasLayout(false);
               Size = 0; // Only look back one instruction
               break;
             }

llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp

@@ -925,15 +925,14 @@ void X86AsmBackend::finishLayout(MCAssembler const &Asm,
       // the align directive.  This is purely about human understandability
       // of the resulting code.  If we later find a reason to expand
       // particular instructions over others, we can adjust.
-      MCFragment *FirstChangedFragment = nullptr;
       unsigned RemainingSize = OrigSize;
       while (!Relaxable.empty() && RemainingSize != 0) {
         auto &RF = *Relaxable.pop_back_val();
         // Give the backend a chance to play any tricks it wishes to increase
         // the encoding size of the given instruction.  Target independent code
         // will try further relaxation, but target's may play further tricks.
         if (padInstructionEncoding(RF, Asm.getEmitter(), RemainingSize))
-          FirstChangedFragment = &RF;
+          Sec.setHasLayout(false);
 
         // If we have an instruction which hasn't been fully relaxed, we can't
         // skip past it and insert bytes before it.  Changing its starting
@@ -946,13 +945,6 @@ void X86AsmBackend::finishLayout(MCAssembler const &Asm,
       }
       Relaxable.clear();
 
-      if (FirstChangedFragment) {
-        // Make sure the offsets for any fragments in the effected range get
-        // updated.  Note that this (conservatively) invalidates the offsets of
-        // those following, but this is not required.
-        Layout.invalidateFragmentsFrom(FirstChangedFragment);
-      }
-
       // BoundaryAlign explicitly tracks it's size (unlike align)
       if (F.getKind() == MCFragment::FT_BoundaryAlign)
         cast<MCBoundaryAlignFragment>(F).setSize(RemainingSize);