[MC] Aligned bundling: remove special handling for RelaxAll

When both aligned bundling and RelaxAll are enabled, bundle padding is
directly written into fragments (https://reviews.llvm.org/D8072).
(The original motivation was memory usage, which has been achieved from
different angles with recent assembler improvement).

The code presents challenges with the work to replace fragment
representation (e.g. #94950 #95077). This patch removes the special
handling. RelaxAll still works but the behavior seems slightly different
as revealed by 2 changed tests. However, most `-mc-relax-all` tests are
unchanged.

RelaxAll used to be the default for clang -O0. This mode has significant
code size drawbacks and newer Clang doesn't use it (#90013).

---

flushPendingLabels: The FOffset parameter can be removed: pending labels
will be assigned to the incoming fragment at offset 0.

Pull Request: https://github.com/llvm/llvm-project/pull/95188

1 files changed, 3 insertions, 7 deletions

diff --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp
index 24bed31..35521dd 100644
--- a/llvm/lib/MC/MCObjectStreamer.cpp
+++ b/llvm/lib/MC/MCObjectStreamer.cpp
@@ -81,7 +81,7 @@ void MCObjectStreamer::flushPendingLabels(MCFragment *F, uint64_t FOffset) {
   }
 
   // Associate the labels with F.
-  CurSection->flushPendingLabels(F, FOffset, CurSubsectionIdx);
+  CurSection->flushPendingLabels(F, CurSubsectionIdx);
 }
 
 void MCObjectStreamer::flushPendingLabels() {
@@ -215,7 +215,7 @@ static bool canReuseDataFragment(const MCDataFragment &F,
   // When bundling is enabled, we don't want to add data to a fragment that
   // already has instructions (see MCELFStreamer::emitInstToData for details)
   if (Assembler.isBundlingEnabled())
-    return Assembler.getRelaxAll();
+    return false;
   // If the subtarget is changed mid fragment we start a new fragment to record
   // the new STI.
   return !STI || F.getSubtargetInfo() == STI;
@@ -292,8 +292,7 @@ void MCObjectStreamer::emitLabel(MCSymbol *Symbol, SMLoc Loc) {
   // Otherwise queue the label and set its fragment pointer when we emit the
   // next fragment.
   auto *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
-  if (F && !(getAssembler().isBundlingEnabled() &&
-             getAssembler().getRelaxAll())) {
+  if (F) {
     Symbol->setFragment(F);
     Symbol->setOffset(F->getContents().size());
   } else {
@@ -465,9 +464,6 @@ void MCObjectStreamer::emitInstructionImpl(const MCInst &Inst,
 
 void MCObjectStreamer::emitInstToFragment(const MCInst &Inst,
                                           const MCSubtargetInfo &STI) {
-  if (getAssembler().getRelaxAll() && getAssembler().isBundlingEnabled())
-    llvm_unreachable("All instructions should have already been relaxed");
-
   // Always create a new, separate fragment here, because its size can change
   // during relaxation.
   MCRelaxableFragment *IF =