[SystemZ][z/OS] Add entry point marker to PPA

[uweigand]

LGTM, but should be merged after https://reviews.llvm.org/D114457 (see inline comment).

llvm/lib/Target/SystemZ/SystemZAsmPrinter.cpp

807

Neumann's patch https://reviews.llvm.org/D114457 is now approved, so as soon as this is merged, you should remove the +128 and the FIXME here.

[yusra.syeda]

Removed the FIXME

[uweigand]

LGTM.

[yusra.syeda]

Rebasing on latest main

[dyung]

The test added in this change fails on build bots that do not build the s390x target. Can you please take a look?

https://lab.llvm.org/buildbot/#/builders/139/builds/15573

******************** TEST 'LLVM :: MC/GOFF/ppa1.ll' FAILED ********************
Script:
--
: 'RUN: at line 1';   /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/llc -mtriple s390x-ibm-zos < /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/test/MC/GOFF/ppa1.ll | /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/FileCheck /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/test/MC/GOFF/ppa1.ll
--
Exit Code: 2
Command Output (stderr):
--
/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/llc: error: : error: unable to get target for 's390x-ibm-zos', see --version and --triple.
FileCheck error: '<stdin>' is empty.
FileCheck command line:  /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/FileCheck /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/test/MC/GOFF/ppa1.ll
--

[foad]

In D115269#3226623, @dyung wrote:

The test added in this change fails on build bots that do not build the s390x target. Can you please take a look?

https://lab.llvm.org/buildbot/#/builders/139/builds/15573

******************** TEST 'LLVM :: MC/GOFF/ppa1.ll' FAILED ********************
Script:
--
: 'RUN: at line 1';   /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/llc -mtriple s390x-ibm-zos < /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/test/MC/GOFF/ppa1.ll | /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/FileCheck /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/test/MC/GOFF/ppa1.ll
--
Exit Code: 2
Command Output (stderr):
--
/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/llc: error: : error: unable to get target for 's390x-ibm-zos', see --version and --triple.
FileCheck error: '<stdin>' is empty.
FileCheck command line:  /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/FileCheck /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/test/MC/GOFF/ppa1.ll
--

Should be fixed by 080f372ad36483b7d413e98c3bef5170bdb97631.

llvm/lib/Target/SystemZ/SystemZAsmPrinter.h

bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                        const char *ExtraCode, raw_ostream &OS) override;
   bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
                              const char *ExtraCode, raw_ostream &OS) override;
 
   bool doInitialization(Module &M) override {
     SM.reset();
     return AsmPrinter::doInitialization(M);
   }
+  void emitFunctionEntryLabel() override;
 
 private:
   void LowerFENTRY_CALL(const MachineInstr &MI, SystemZMCInstLower &MCIL);
   void LowerSTACKMAP(const MachineInstr &MI);
   void LowerPATCHPOINT(const MachineInstr &MI, SystemZMCInstLower &Lower);
 };
 } // end namespace llvm
 
 #endif

llvm/lib/Target/SystemZ/SystemZAsmPrinter.cpp

printAddress(MAI, MI->getOperand(OpNo).getReg(),
                  MI->getOperand(OpNo + 2).getReg(), OS);
   return false;
 }
 
 void SystemZAsmPrinter::emitEndOfAsmFile(Module &M) {
   emitStackMaps(SM);
 }
 
+void SystemZAsmPrinter::emitFunctionEntryLabel() {
+  const SystemZSubtarget &Subtarget =
+      static_cast<const SystemZSubtarget &>(MF->getSubtarget());
+
+  if (Subtarget.getTargetTriple().isOSzOS()) {
+    MCContext &OutContext = OutStreamer->getContext();
+    MCSymbol *EPMarkerSym = OutContext.createTempSymbol("CM_", true);
+
+    // EntryPoint Marker
+    const MachineFrameInfo &MFFrame = MF->getFrameInfo();
+    bool IsUsingAlloca = MFFrame.hasVarSizedObjects();
+
+    // Set Flags
+    uint8_t Flags = 0;
+    if (IsUsingAlloca)
+      Flags |= 0x04;
+
+    uint32_t DSASize = MFFrame.getStackSize();
+
+    // Combine into top 27 bits of DSASize and bottom 5 bits of Flags.
+    uint32_t DSAAndFlags = DSASize & 0xFFFFFFE0; // (x/32) << 5
+    DSAAndFlags |= Flags;
+
+    // Emit entry point marker section.
+    OutStreamer->AddComment("XPLINK Routine Layout Entry");
+    OutStreamer->emitLabel(EPMarkerSym);
+    OutStreamer->AddComment("Eyecatcher 0x00C300C500C500");
+    OutStreamer->emitIntValueInHex(0x00C300C500C500, 7); // Eyecatcher.
+    OutStreamer->AddComment("Mark Type C'1'");
+    OutStreamer->emitInt8(0xF1); // Mark Type.
+    if (OutStreamer->isVerboseAsm()) {
+      OutStreamer->AddComment("DSA Size 0x" + Twine::utohexstr(DSASize));
+      OutStreamer->AddComment("Entry Flags");
+      if (Flags & 0x04)
+        OutStreamer->AddComment("  Bit 2: 1 = Uses alloca");
+      else
+        OutStreamer->AddComment("  Bit 2: 0 = Does not use alloca");
+    }
+    OutStreamer->emitInt32(DSAAndFlags);
+  }
+
+  AsmPrinter::emitFunctionEntryLabel();
+}
+
 // Force static initialization.
 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeSystemZAsmPrinter() {
   RegisterAsmPrinter<SystemZAsmPrinter> X(getTheSystemZTarget());
 }

llvm/test/MC/GOFF/ppa1.ll

+; RUN: llc -mtriple s390x-ibm-zos < %s | FileCheck %s
+
+; CHECK: @@CM_0: * @void_test
+; CHECK: * XPLINK Routine Layout Entry
+; CHECK: .long   12779717 * Eyecatcher 0x00C300C500C500
+; CHECK: .short  197
+; CHECK: .byte   0
+; CHECK: .byte   241 * Mark Type C'1'
+; CHECK: .long   128 * DSA Size 0x80
+; CHECK: * Entry Flags
+; CHECK: *   Bit 2: 0 = Does not use alloca
+define void @void_test() {
+entry:
+  ret void
+}