[MC] Ensure all new sections have a MCDataFragment

MCAssembler::layout ensures that every section has at least one
fragment, which simplifies MCAsmLayout::getSectionAddressSize (see
e73353c7201a3080851d99a16f5fe2c17f7697c6 from 2010). It's better to
ensure the condition is satisfied at create time (COFF, GOFF, Mach-O) to
simplify more fragment processing.

1 files changed, 2 insertions, 10 deletions

diff --git a/llvm/lib/MC/MCAssembler.cpp b/llvm/lib/MC/MCAssembler.cpp
index fe0419b..f8b7e4b 100644
--- a/llvm/lib/MC/MCAssembler.cpp
+++ b/llvm/lib/MC/MCAssembler.cpp
@@ -126,6 +126,7 @@ void MCAssembler::reset() {
 bool MCAssembler::registerSection(MCSection &Section) {
   if (Section.isRegistered())
     return false;
+  assert(Section.curFragList()->Head && "allocInitialFragment not called");
   Sections.push_back(&Section);
   Section.setIsRegistered(true);
   return true;
@@ -856,17 +857,8 @@ void MCAssembler::layout(MCAsmLayout &Layout) {
 
   // Create dummy fragments and assign section ordinals.
   unsigned SectionIndex = 0;
-  for (MCSection &Sec : *this) {
-    // Create dummy fragments to eliminate any empty sections, this simplifies
-    // layout.
-    if (Sec.empty()) {
-      auto *F = getContext().allocFragment<MCDataFragment>();
-      F->setParent(&Sec);
-      Sec.addFragment(*F);
-    }
-
+  for (MCSection &Sec : *this)
     Sec.setOrdinal(SectionIndex++);
-  }
 
   // Assign layout order indices to sections and fragments.
   for (unsigned i = 0, e = Layout.getSectionOrder().size(); i != e; ++i) {