[llvm] MC: Store fragment content and fixups out-of-line (PR #146307)

[Alexis Engelke via llvm-commits]

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@@ -28,57 +28,90 @@ MCFragment::MCFragment(FragmentType Kind, bool HasInstructions)
     : Kind(Kind), HasInstructions(HasInstructions), AlignToBundleEnd(false),
       LinkerRelaxable(false), AllowAutoPadding(false) {}
 
-void MCFragment::destroy() {
-  switch (Kind) {
-    case FT_Align:
-      cast<MCAlignFragment>(this)->~MCAlignFragment();
-      return;
-    case FT_Data:
-      cast<MCDataFragment>(this)->~MCDataFragment();
-      return;
-    case FT_Fill:
-      cast<MCFillFragment>(this)->~MCFillFragment();
-      return;
-    case FT_Nops:
-      cast<MCNopsFragment>(this)->~MCNopsFragment();
-      return;
-    case FT_Relaxable:
-      cast<MCRelaxableFragment>(this)->~MCRelaxableFragment();
-      return;
-    case FT_Org:
-      cast<MCOrgFragment>(this)->~MCOrgFragment();
-      return;
-    case FT_Dwarf:
-      cast<MCDwarfLineAddrFragment>(this)->~MCDwarfLineAddrFragment();
-      return;
-    case FT_DwarfFrame:
-      cast<MCDwarfCallFrameFragment>(this)->~MCDwarfCallFrameFragment();
-      return;
-    case FT_LEB:
-      cast<MCLEBFragment>(this)->~MCLEBFragment();
-      return;
-    case FT_BoundaryAlign:
-      cast<MCBoundaryAlignFragment>(this)->~MCBoundaryAlignFragment();
-      return;
-    case FT_SymbolId:
-      cast<MCSymbolIdFragment>(this)->~MCSymbolIdFragment();
-      return;
-    case FT_CVInlineLines:
-      cast<MCCVInlineLineTableFragment>(this)->~MCCVInlineLineTableFragment();
-      return;
-    case FT_CVDefRange:
-      cast<MCCVDefRangeFragment>(this)->~MCCVDefRangeFragment();
-      return;
-    case FT_PseudoProbe:
-      cast<MCPseudoProbeAddrFragment>(this)->~MCPseudoProbeAddrFragment();
-      return;
+const MCSymbol *MCFragment::getAtom() const {
+  return cast<MCSectionMachO>(Parent)->getAtom(LayoutOrder);
+}
+
+SmallVectorImpl<char> &MCEncodedFragment::getContentsForAppending() {
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aengelke wrote:

Maybe put an inline implementation of the hot path in MCSection.h? (Single check ContentStart + ContentSize != S.size() should suffice.) Same for doneAppending, I expect these are the most performance-critical functions.

https://github.com/llvm/llvm-project/pull/146307