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

[Ulrich Weigand via llvm-branch-commits]

================
@@ -2857,3 +2861,45 @@ MCSection *TargetLoweringObjectFileGOFF::SelectSectionForGlobal(
   }
   return TextSection;
 }
+
+static MCSectionGOFF *getStaticStructorSectionGOFF(MCContext &Ctx,
+                                                   const MCSection *TextSection,
+                                                   unsigned Priority) {
+  // xl compilers on z/OS support priorities from min-int to max-int, with
+  // sinit as source priority 0. For clang, sinit has source priority 65535.
+  // For GOFF, the priority sortkey field is an unsigned value. So, we
+  // add min-int to get sorting to work properly but also subtract the
+  // clang sinit (65535) value so internally xl sinit and clang sinit have
+  // the same unsigned GOFF priority sortkey field value (i.e. 0x80000000).
+  static constexpr const uint32_t ClangDefaultSinitPriority = 65535;
+  uint32_t Prio = Priority + (0x80000000 - ClangDefaultSinitPriority);
+
+  std::string Name(".xtor");
+  if (Priority != ClangDefaultSinitPriority)
+    Name = llvm::Twine(Name).concat(".").concat(llvm::utostr(Priority)).str();
+
+  MCSectionGOFF *SInit = Ctx.getGOFFSection(
+      SectionKind::getMetadata(), GOFF::CLASS_SINIT,
+      GOFF::EDAttr{false, GOFF::ESD_RMODE_64, GOFF::ESD_NS_Parts,
+                   GOFF::ESD_TS_ByteOriented, GOFF::ESD_BA_Merge,
+                   GOFF::ESD_LB_Initial, GOFF::ESD_RQ_0,
+                   GOFF::ESD_ALIGN_Doubleword},
+      static_cast<const MCSectionGOFF *>(TextSection)->getParent());
+
+  MCSectionGOFF *Xtor = Ctx.getGOFFSection(
+      SectionKind::getData(), Name,
+      GOFF::PRAttr{true, GOFF::ESD_EXE_DATA, GOFF::ESD_LT_XPLink,
+                   GOFF::ESD_BSC_Section, Prio},
+      SInit);
+  return Xtor;
+}
+
+MCSection *TargetLoweringObjectFileGOFF::getStaticCtorSection(
+    unsigned Priority, const MCSymbol *KeySym) const {
+  return getStaticStructorSectionGOFF(getContext(), TextSection, Priority);
+}
+
+MCSection *TargetLoweringObjectFileGOFF::getStaticDtorSection(
+    unsigned Priority, const MCSymbol *KeySym) const {
+  return getStaticStructorSectionGOFF(getContext(), TextSection, Priority);
+}
----------------
uweigand wrote:

It's still a bit weird to have these two functions that do the same thing.   I understand this is to mirror what other platforms do, but on those the sections are in fact different ...  Maybe it would be better to just have a single `getStaticXtorSection` on GOFF instead, if that matches more directly what GOFF actually does ...

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