[llvm] [RISCV] Emit .note.gnu.property section when Zicfiss-based shadow stack is enabled (PR #127036)

[Fangrui Song via llvm-commits]

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@@ -51,6 +58,67 @@ void RISCVTargetStreamer::emitTextAttribute(unsigned Attribute,
 void RISCVTargetStreamer::emitIntTextAttribute(unsigned Attribute,
                                                unsigned IntValue,
                                                StringRef StringValue) {}
+
+void RISCVTargetStreamer::emitNoteGnuPropertySection(
+    const uint32_t Feature1And) {
+  MCStreamer &OutStreamer = getStreamer();
+  MCContext &Ctx = OutStreamer.getContext();
+
+  const Triple &Triple = Ctx.getTargetTriple();
+  Align NoteAlign;
+  if (Triple.isArch64Bit())
+    NoteAlign = Align(8);
+  else if (Triple.isArch32Bit())
+    NoteAlign = Align(4);
+  else
+    report_fatal_error("unsupported arch bit width");
+
+  MCSection *NoteSection;
+  switch (Ctx.getObjectFileType()) {
+  case MCContext::Environment::IsELF:
+    NoteSection =
+        Ctx.getELFSection(".note.gnu.property", ELF::SHT_NOTE, ELF::SHF_ALLOC);
+    break;
+  case MCContext::Environment::IsMachO:
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MaskRay wrote:

non elf object files are unreachable. delete

https://github.com/llvm/llvm-project/pull/127036