[MC] Use a stub ctor for MCAsmLayout

and replace MCAssembler::Layout with a bool.
This mostly completes "[MC] Start merging MCAsmLayout into MCAssembler".

Author: MaskRay

llvm/include/llvm/MC/MCAsmLayout.h

@@ -9,21 +9,12 @@
 #ifndef LLVM_MC_MCASMLAYOUT_H
 #define LLVM_MC_MCASMLAYOUT_H
 
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/SmallVector.h"
-
 namespace llvm {
 class MCAssembler;
-class MCSection;
 
 class MCAsmLayout {
-  MCAssembler &Assembler;
-
 public:
-  MCAsmLayout(MCAssembler &Assembler);
-
-  /// Get the assembler object this is a layout for.
-  MCAssembler &getAssembler() const { return Assembler; }
+  MCAsmLayout(MCAssembler &) {}
 };
 
 } // end namespace llvm

llvm/include/llvm/MC/MCAssembler.h

@@ -116,7 +116,7 @@ class MCAssembler {
   std::unique_ptr<MCCodeEmitter> Emitter;
   std::unique_ptr<MCObjectWriter> Writer;
 
-  MCAsmLayout *Layout = nullptr;
+  bool HasLayout = false;
   bool RelaxAll = false;
   bool SubsectionsViaSymbols = false;
   bool IncrementalLinkerCompatible = false;
@@ -354,8 +354,7 @@ class MCAssembler {
     IncrementalLinkerCompatible = Value;
   }
 
-  MCAsmLayout *getLayout() const { return Layout; }
-  bool hasLayout() const { return Layout; }
+  bool hasLayout() const { return HasLayout; }
   bool getRelaxAll() const { return RelaxAll; }
   void setRelaxAll(bool Value) { RelaxAll = Value; }
 

llvm/lib/MC/MCAssembler.cpp

@@ -381,8 +381,6 @@ uint64_t MCAssembler::computeFragmentSize(const MCFragment &F) const {
   llvm_unreachable("invalid fragment kind");
 }
 
-MCAsmLayout::MCAsmLayout(MCAssembler &Asm) : Assembler(Asm) {}
-
 // Compute the amount of padding required before the fragment \p F to
 // obey bundling restrictions, where \p FOffset is the fragment's offset in
 // its section and \p FSize is the fragment's size.
@@ -541,13 +539,14 @@ bool MCAssembler::getSymbolOffset(const MCSymbol &S, uint64_t &Val) const {
 }
 
 uint64_t MCAssembler::getSymbolOffset(const MCSymbol &S) const {
+  assert(HasLayout);
   uint64_t Val;
   getSymbolOffsetImpl(*this, S, true, Val);
   return Val;
 }
 
 const MCSymbol *MCAssembler::getBaseSymbol(const MCSymbol &Symbol) const {
-  assert(Layout);
+  assert(HasLayout);
   if (!Symbol.isVariable())
     return &Symbol;
 
@@ -584,6 +583,7 @@ const MCSymbol *MCAssembler::getBaseSymbol(const MCSymbol &Symbol) const {
 }
 
 uint64_t MCAssembler::getSectionAddressSize(const MCSection &Sec) const {
+  assert(HasLayout);
   // The size is the last fragment's end offset.
   const MCFragment &F = *Sec.curFragList()->Tail;
   return getFragmentOffset(F) + computeFragmentSize(F);
@@ -968,7 +968,7 @@ void MCAssembler::layout(MCAsmLayout &Layout) {
   }
 
   // Layout until everything fits.
-  this->Layout = &Layout;
+  this->HasLayout = true;
   while (layoutOnce()) {
     if (getContext().hadError())
       return;
@@ -1081,7 +1081,7 @@ void MCAssembler::Finish() {
   // Write the object file.
   stats::ObjectBytes += getWriter().writeObject(*this);
 
-  this->Layout = nullptr;
+  HasLayout = false;
 }
 
 bool MCAssembler::fixupNeedsRelaxation(const MCFixup &Fixup,

llvm/lib/MC/MCExpr.cpp

@@ -626,7 +626,7 @@ static void AttemptToFoldSymbolOffsetDifference(
   // separated by a linker-relaxable instruction. If the section contains
   // instructions and InSet is false (not expressions in directive like
   // .size/.fill), disable the fast path.
-  const MCAsmLayout *Layout = Asm->getLayout();
+  bool Layout = Asm->hasLayout();
   if (Layout && (InSet || !SecA.hasInstructions() ||
                  !(Asm->getContext().getTargetTriple().isRISCV() ||
                    Asm->getContext().getTargetTriple().isLoongArch()))) {
@@ -817,7 +817,6 @@ bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
                                        const SectionAddrMap *Addrs,
                                        bool InSet) const {
   ++stats::MCExprEvaluate;
-  MCAsmLayout *Layout = Asm ? Asm->getLayout() : nullptr;
   switch (getKind()) {
   case Target:
     return cast<MCTargetExpr>(this)->evaluateAsRelocatableImpl(Res, Asm, Fixup);
@@ -830,6 +829,7 @@ bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
     const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
     const MCSymbol &Sym = SRE->getSymbol();
     const auto Kind = SRE->getKind();
+    bool Layout = Asm && Asm->hasLayout();
 
     // Evaluate recursively if this is a variable.
     if (Sym.isVariable() && (Kind == MCSymbolRefExpr::VK_None || Layout) &&

llvm/lib/Target/AVR/MCTargetDesc/AVRMCExpr.cpp

@@ -79,7 +79,7 @@ bool AVRMCExpr::evaluateAsRelocatableImpl(MCValue &Result,
   if (Value.isAbsolute()) {
     Result = MCValue::get(evaluateAsInt64(Value.getConstant()));
   } else {
-    if (!Asm || !Asm->getLayout())
+    if (!Asm || !Asm->hasLayout())
       return false;
 
     MCContext &Context = Asm->getContext();

llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCExpr.cpp

@@ -122,7 +122,7 @@ bool PPCMCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
 
     Res = MCValue::get(Result);
   } else {
-    if (!Asm || !Asm->getLayout())
+    if (!Asm || !Asm->hasLayout())
       return false;
 
     MCContext &Context = Asm->getContext();