[llvm-branch-commits] [llvm] [SystemZ] Implement ctor/dtor emission via @@SQINIT and .xtor sections (PR #171476)

[Amy Kwan via llvm-branch-commits]

================
@@ -1012,6 +1021,59 @@ void SystemZAsmPrinter::emitMachineConstantPoolValue(
   OutStreamer->emitValue(Expr, Size);
 }
 
+// Emit the ctor or dtor list taking into account the init priority.
+void SystemZAsmPrinter::emitXXStructorList(const DataLayout &DL,
+                                           const Constant *List, bool IsCtor) {
+  if (TM.getTargetTriple().isOSBinFormatGOFF())
+    AsmPrinter::emitXXStructorList(DL, List, IsCtor);
+
+  SmallVector<Structor, 8> Structors;
+  preprocessXXStructorList(DL, List, Structors);
+  if (Structors.empty())
+    return;
+
+  const Align Align = llvm::Align(4);
+  const TargetLoweringObjectFile &Obj = getObjFileLowering();
+  for (Structor &S : Structors) {
+    MCSection *OutputSection =
+        (IsCtor ? Obj.getStaticCtorSection(S.Priority, nullptr)
+                : Obj.getStaticDtorSection(S.Priority, nullptr));
+    OutStreamer->switchSection(OutputSection);
+    if (OutStreamer->getCurrentSection() != OutStreamer->getPreviousSection())
+      emitAlignment(Align);
+
+    const MCSectionGOFF *Section =
+        static_cast<const MCSectionGOFF *>(getCurrentSection());
+    uint32_t XtorPriority = Section->getPRAttributes().SortKey;
+
+    const GlobalValue *GV = dyn_cast<GlobalValue>(S.Func->stripPointerCasts());
+    assert(GV && "C++ xxtor pointer was not a GlobalValue!");
+    MCSymbolGOFF *Symbol = static_cast<MCSymbolGOFF *>(getSymbol(GV));
+
+    // @@SQINIT entry: { unsigned prio; void (*ctor)();  void (*dtor)(); }
+
+    unsigned PointerSizeInBytes = DL.getPointerSize();
+
+    auto &Ctx = OutStreamer->getContext();
+    const MCExpr *ADAFuncRefExpr;
+    unsigned SlotKind = SystemZII::MO_ADA_DIRECT_FUNC_DESC;
+    ADAFuncRefExpr = MCBinaryExpr::createAdd(
+        MCSpecifierExpr::create(MCSymbolRefExpr::create(ADASym, OutContext),
+                                SystemZ::S_QCon, OutContext),
+        MCConstantExpr::create(ADATable.insert(Symbol, SlotKind).second, Ctx),
+        Ctx);
+
+    emitInt32(XtorPriority);
----------------
amy-kwan wrote:

Yes, it is required by LE.
In 32-bit, the pointers are aligned but in 64-bit, the pointers are unaligned. I believe @redstar may have some documentation regarding this.

https://github.com/llvm/llvm-project/pull/171476