[X86] Move the function getOrCreateBoundaryAlignFragment

MCObjectStreamer is more suitable to create fragments than
X86AsmBackend, for example, the function getOrCreateDataFragment is
defined in MCObjectStreamer.

Differential Revision: https://reviews.llvm.org/D75351

include/llvm/MC/MCFragment.h

@@ -533,7 +533,7 @@ class MCBoundaryAlignFragment : public MCFragment {
   uint64_t Size = 0;
 
 public:
-  MCBoundaryAlignFragment(Align AlignBoundary, bool Fused = false,
+  MCBoundaryAlignFragment(Align AlignBoundary = Align(1), bool Fused = false,
                           bool EmitNops = false, MCSection *Sec = nullptr)
       : MCFragment(FT_BoundaryAlign, false, Sec), AlignBoundary(AlignBoundary),
         Fused(Fused), EmitNops(EmitNops) {}
@@ -542,6 +542,7 @@ public:
   void setSize(uint64_t Value) { Size = Value; }
 
   Align getAlignment() const { return AlignBoundary; }
+  void setAlignment(Align Value) { AlignBoundary = Value; }
 
   bool isFused() const { return Fused; }
   void setFused(bool Value) { Fused = Value; }

include/llvm/MC/MCObjectStreamer.h

@@ -87,6 +87,11 @@ public:
   /// if the Subtarget differs from the current fragment.
   MCDataFragment *getOrCreateDataFragment(const MCSubtargetInfo* STI = nullptr);
 
+  /// Get a boundary-align fragment to write into, creating a new one if the
+  /// current fragment is not a boundary-align fragment or has been used to emit
+  /// something.
+  MCBoundaryAlignFragment *getOrCreateBoundaryAlignFragment();
+
 protected:
   bool changeSectionImpl(MCSection *Section, const MCExpr *Subsection);
 

lib/MC/MCObjectStreamer.cpp

@@ -215,6 +215,15 @@ MCObjectStreamer::getOrCreateDataFragment(const MCSubtargetInfo *STI) {
   return F;
 }
 
+MCBoundaryAlignFragment *MCObjectStreamer::getOrCreateBoundaryAlignFragment() {
+  auto *F = dyn_cast_or_null<MCBoundaryAlignFragment>(getCurrentFragment());
+  if (!F || F->canEmitNops()) {
+    F = new MCBoundaryAlignFragment();
+    insert(F);
+  }
+  return F;
+}
+
 void MCObjectStreamer::visitUsedSymbol(const MCSymbol &Sym) {
   Assembler->registerSymbol(Sym);
 }

lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp

@@ -120,8 +120,6 @@ class X86AsmBackend : public MCAsmBackend {
 
   bool needAlign(MCObjectStreamer &OS) const;
   bool needAlignInst(const MCInst &Inst) const;
-  MCBoundaryAlignFragment *
-  getOrCreateBoundaryAlignFragment(MCObjectStreamer &OS) const;
   MCInst PrevInst;
 
 public:
@@ -395,21 +393,6 @@ bool X86AsmBackend::needAlignInst(const MCInst &Inst) const {
           (AlignBranchType & X86::AlignBranchIndirect));
 }
 
-static bool canReuseBoundaryAlignFragment(const MCBoundaryAlignFragment &F) {
-  // If a MCBoundaryAlignFragment has not been used to emit NOP,we can reuse it.
-  return !F.canEmitNops();
-}
-
-MCBoundaryAlignFragment *
-X86AsmBackend::getOrCreateBoundaryAlignFragment(MCObjectStreamer &OS) const {
-  auto *F = dyn_cast_or_null<MCBoundaryAlignFragment>(OS.getCurrentFragment());
-  if (!F || !canReuseBoundaryAlignFragment(*F)) {
-    F = new MCBoundaryAlignFragment(AlignBoundary);
-    OS.insert(F);
-  }
-  return F;
-}
-
 /// Insert MCBoundaryAlignFragment before instructions to align branches.
 void X86AsmBackend::alignBranchesBegin(MCObjectStreamer &OS,
                                        const MCInst &Inst) {
@@ -439,13 +422,15 @@ void X86AsmBackend::alignBranchesBegin(MCObjectStreamer &OS,
     //
     // We will treat the JCC as a unfused branch although it may be fused
     // with the CMP.
-    auto *F = getOrCreateBoundaryAlignFragment(OS);
+    auto *F = OS.getOrCreateBoundaryAlignFragment();
+    F->setAlignment(AlignBoundary);
     F->setEmitNops(true);
     F->setFused(false);
   } else if (NeedAlignFused && isFirstMacroFusibleInst(Inst, *MCII)) {
     // We don't know if macro fusion happens until the reaching the next
     // instruction, so a place holder is put here if necessary.
-    getOrCreateBoundaryAlignFragment(OS);
+    auto *F = OS.getOrCreateBoundaryAlignFragment();
+    F->setAlignment(AlignBoundary);
   }
 
   PrevInst = Inst;