[llvm] 6ebc423 - MCStreamer: Move fragment-related functions to MCObjectStreamer

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2025-07-20T21:15:34-07:00
New Revision: 6ebc42322ca7bd0261c1faa6e2d785057ab95c5f

URL: https://github.com/llvm/llvm-project/commit/6ebc42322ca7bd0261c1faa6e2d785057ab95c5f
DIFF: https://github.com/llvm/llvm-project/commit/6ebc42322ca7bd0261c1faa6e2d785057ab95c5f.diff

LOG: MCStreamer: Move fragment-related functions to MCObjectStreamer

They are specific to MCObjectStreamer and unneeded by MCAsmStreamer.

Add isObj() so that MCTargetAsmParser can determine whether the streamer
is MCObjectStreamer and conditionally call newFragment.

Added: 
    

Modified: 
    llvm/include/llvm/MC/MCObjectStreamer.h
    llvm/include/llvm/MC/MCStreamer.h
    llvm/lib/MC/MCObjectStreamer.cpp
    llvm/lib/MC/MCParser/MCTargetAsmParser.cpp
    llvm/lib/MC/MCStreamer.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/MC/MCObjectStreamer.h b/llvm/include/llvm/MC/MCObjectStreamer.h
index e06bfb287da0e..c19053fa48e86 100644
--- a/llvm/include/llvm/MC/MCObjectStreamer.h
+++ b/llvm/include/llvm/MC/MCObjectStreamer.h
@@ -80,6 +80,13 @@ class MCObjectStreamer : public MCStreamer {
   /// \name MCStreamer Interface
   /// @{
 
+  // Add a fragment with a variable-size tail and start a new empty fragment.
+  void insert(MCFragment *F);
+
+  void addFixup(const MCExpr *Value, MCFixupKind Kind, uint32_t Offset = 0);
+  // Add a new fragment to the current section without a variable-size tail.
+  void newFragment();
+
   void emitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc()) override;
   virtual void emitLabelAtPos(MCSymbol *Symbol, SMLoc Loc, MCFragment &F,
                               uint64_t Offset);

diff  --git a/llvm/include/llvm/MC/MCStreamer.h b/llvm/include/llvm/MC/MCStreamer.h
index bdee9ea8452e0..ca6166e415a5f 100644
--- a/llvm/include/llvm/MC/MCStreamer.h
+++ b/llvm/include/llvm/MC/MCStreamer.h
@@ -259,6 +259,8 @@ class LLVM_ABI MCStreamer {
   bool AllowAutoPadding = false;
 
 protected:
+  bool IsObj = false;
+
   // Symbol of the current epilog for which we are processing SEH directives.
   WinEH::FrameInfo::Epilog *CurrentWinEpilog = nullptr;
 
@@ -310,6 +312,7 @@ class LLVM_ABI MCStreamer {
   virtual void reset();
 
   MCContext &getContext() const { return Context; }
+  bool isObj() const { return IsObj; }
 
   // MCObjectStreamer has an MCAssembler and allows more expression folding at
   // parse time.
@@ -462,11 +465,6 @@ class LLVM_ABI MCStreamer {
 
   MCSymbol *endSection(MCSection *Section);
 
-  /// Add a new fragment to the current section without a variable-size tail.
-  void newFragment();
-  /// Add a fragment with a variable-size tail and start a new empty fragment.
-  void insert(MCFragment *F);
-
   /// Returns the mnemonic for \p MI, if the streamer has access to a
   /// instruction printer and returns an empty string otherwise.
   virtual StringRef getMnemonic(const MCInst &MI) const { return ""; }

diff  --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp
index bf6ebb4cd660e..7087c95dd04b1 100644
--- a/llvm/lib/MC/MCObjectStreamer.cpp
+++ b/llvm/lib/MC/MCObjectStreamer.cpp
@@ -33,6 +33,7 @@ MCObjectStreamer::MCObjectStreamer(MCContext &Context,
           Context, std::move(TAB), std::move(Emitter), std::move(OW))),
       EmitEHFrame(true), EmitDebugFrame(false) {
   assert(Assembler->getBackendPtr() && Assembler->getEmitterPtr());
+  IsObj = true;
   setAllowAutoPadding(Assembler->getBackend().allowAutoPadding());
   if (Context.getTargetOptions() && Context.getTargetOptions()->MCRelaxAll)
     Assembler->setRelaxAll(true);
@@ -46,6 +47,23 @@ MCAssembler *MCObjectStreamer::getAssemblerPtr() {
   return nullptr;
 }
 
+void MCObjectStreamer::newFragment() {
+  addFragment(getContext().allocFragment<MCFragment>());
+}
+
+void MCObjectStreamer::insert(MCFragment *F) {
+  assert(F->getKind() != MCFragment::FT_Data &&
+         "F should have a variable-size tail");
+  addFragment(F);
+  newFragment();
+}
+
+void MCObjectStreamer::addFixup(const MCExpr *Value, MCFixupKind Kind,
+                                uint32_t Offset) {
+  CurFrag->addFixup(
+      MCFixup::create(CurFrag->getFixedSize() + Offset, Value, Kind));
+}
+
 // As a compile-time optimization, avoid allocating and evaluating an MCExpr
 // tree for (Hi - Lo) when Hi and Lo are offsets into the same fragment's fixed
 // part.

diff  --git a/llvm/lib/MC/MCParser/MCTargetAsmParser.cpp b/llvm/lib/MC/MCParser/MCTargetAsmParser.cpp
index 7f0934971b27c..d7b0546d70558 100644
--- a/llvm/lib/MC/MCParser/MCTargetAsmParser.cpp
+++ b/llvm/lib/MC/MCParser/MCTargetAsmParser.cpp
@@ -8,8 +8,8 @@
 
 #include "llvm/MC/MCParser/MCTargetAsmParser.h"
 #include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCObjectStreamer.h"
 #include "llvm/MC/MCRegister.h"
-#include "llvm/MC/MCStreamer.h"
 
 using namespace llvm;
 
@@ -25,8 +25,9 @@ MCSubtargetInfo &MCTargetAsmParser::copySTI() {
   STI = &STICopy;
   // The returned STI will likely be modified. Create a new fragment to prevent
   // mixing STI values within a fragment.
-  if (getStreamer().getCurrentFragment())
-    getStreamer().newFragment();
+  auto &S = getStreamer();
+  if (S.isObj() && S.getCurrentFragment())
+    static_cast<MCObjectStreamer &>(S).newFragment();
   return STICopy;
 }
 

diff  --git a/llvm/lib/MC/MCStreamer.cpp b/llvm/lib/MC/MCStreamer.cpp
index b0e52bf511ba4..30198c97d8ab9 100644
--- a/llvm/lib/MC/MCStreamer.cpp
+++ b/llvm/lib/MC/MCStreamer.cpp
@@ -1413,17 +1413,6 @@ void MCStreamer::addFragment(MCFragment *F) {
   Sec->curFragList()->Tail = F;
 }
 
-void MCStreamer::newFragment() {
-  addFragment(getContext().allocFragment<MCFragment>());
-}
-
-void MCStreamer::insert(MCFragment *F) {
-  assert(F->getKind() != MCFragment::FT_Data &&
-         "F should have a variable-size tail");
-  addFragment(F);
-  newFragment();
-}
-
 static VersionTuple
 targetVersionOrMinimumSupportedOSVersion(const Triple &Target,
                                          VersionTuple TargetVersion) {