[clang] [llvm] [SystemZ][z/OS] This change adds support for the PPA2 section in zOS (PR #68926)

[Ulrich Weigand via cfe-commits]

================
@@ -1026,6 +1030,72 @@ void SystemZAsmPrinter::emitADASection() {
   OutStreamer->popSection();
 }
 
+static std::string getProductID(Module &M) {
+  std::string ProductID;
+  if (auto *MD = M.getModuleFlag("zos_product_id"))
+    ProductID = cast<MDString>(MD)->getString().str();
+  if (ProductID.empty())
+    ProductID = "LLVM";
+  return ProductID;
+}
+
+static uint32_t getProductVersion(Module &M) {
+  if (auto *VersionVal = mdconst::extract_or_null<ConstantInt>(
+          M.getModuleFlag("zos_product_major_version")))
+    return VersionVal->getZExtValue();
+  return LLVM_VERSION_MAJOR;
+}
+
+static uint32_t getProductRelease(Module &M) {
+  if (auto *ReleaseVal = mdconst::extract_or_null<ConstantInt>(
+          M.getModuleFlag("zos_product_minor_version")))
+    return ReleaseVal->getZExtValue();
+  return LLVM_VERSION_MINOR;
+}
+
+static uint32_t getProductPatch(Module &M) {
+  if (auto *PatchVal = mdconst::extract_or_null<ConstantInt>(
+          M.getModuleFlag("zos_product_patchlevel")))
+    return PatchVal->getZExtValue();
+  return LLVM_VERSION_PATCH;
+}
+
+static time_t getTranslationTime(Module &M) {
+  std::time_t Time = 0;
+  if (auto *Val = mdconst::extract_or_null<ConstantInt>(
+          M.getModuleFlag("zos_translation_time"))) {
+    long SecondsSinceEpoch =  Val->getSExtValue();
+    Time = static_cast<time_t>(SecondsSinceEpoch);
+  }
+  return Time;
+}
+
+void SystemZAsmPrinter::emitIDRLSection(Module &M) {
+  OutStreamer->pushSection();
+  OutStreamer->switchSection(getObjFileLowering().getIDRLSection());
+  constexpr unsigned IDRLDataLength = 30;
+  std::time_t Time = getTranslationTime(M);
+
+  uint32_t ProductVersion = getProductVersion(M);
+  uint32_t ProductRelease = getProductRelease(M);
+
+  std::string ProductID = getProductID(M);
+
+  SmallString<IDRLDataLength + 1> TempStr;
+  raw_svector_ostream O(TempStr);
+  O << formatv("{0}{1,0-2:d}{2,0-2:d}{3:%Y-%m-%d %H:%M:%S}",
+               ProductID.substr(0, 10).c_str(), ProductVersion, ProductRelease,
+               llvm::sys::toUtcTime(Time));
+  SmallString<IDRLDataLength> Data;
+  ConverterEBCDIC::convertToEBCDIC(TempStr, Data);
+
+  OutStreamer->emitInt8(0);               // Reserved.
+  OutStreamer->emitInt8(3);               // Format.
+  OutStreamer->emitInt16(IDRLDataLength); // Length.
+  OutStreamer->emitBytes(Data.str());
----------------
uweigand wrote:

One more question about this string - the Length field is hardcoded to 30.  Does that mean that there are exactly 30 bytes supposed to always follow here?   I'm not sure this is guaranteed by the formatv above ...

Also, there doesn't seem to be any test that verifies the layout of this IDRL section, I think we definitely need one.

https://github.com/llvm/llvm-project/pull/68926