[llvm-branch-commits] [llvm] release/23.x: [SystemZ][z/OS] Implement emitCommonSymbol in MCGOFFStreamer (#210179) (PR #213042)

[via llvm-branch-commits]

https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/213042

Backport 705d0ec6115cef3232eafe6221f42f78e7b884e8

Requested by: @maryammo

>From 4df58feb98c1daabcb637c323148cdd033ecbcfd Mon Sep 17 00:00:00 2001
From: Maryam Moghadas <maryammo at ca.ibm.com>
Date: Wed, 29 Jul 2026 15:58:16 -0400
Subject: [PATCH] [SystemZ][z/OS] Implement emitCommonSymbol in MCGOFFStreamer
 (#210179)

Common globals were not emitted in GOFF object files due to a missing
emitCommonSymbol implementation. This adds the implementation to emit
the required SD/ED/PR ESD records in the GOFF object file.

(cherry picked from commit 705d0ec6115cef3232eafe6221f42f78e7b884e8)
---
 llvm/include/llvm/MC/MCGOFFStreamer.h         |  2 +-
 llvm/lib/MC/MCGOFFStreamer.cpp                | 29 +++++++++++++++++++
 .../test/CodeGen/SystemZ/zos-common-global.ll | 28 ++++++++++++++++++
 3 files changed, 58 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/CodeGen/SystemZ/zos-common-global.ll

diff --git a/llvm/include/llvm/MC/MCGOFFStreamer.h b/llvm/include/llvm/MC/MCGOFFStreamer.h
index 756574d1caaf3..92b37681b1225 100644
--- a/llvm/include/llvm/MC/MCGOFFStreamer.h
+++ b/llvm/include/llvm/MC/MCGOFFStreamer.h
@@ -37,7 +37,7 @@ class LLVM_ABI MCGOFFStreamer : public MCObjectStreamer {
   bool emitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) override;
 
   void emitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
-                        Align ByteAlignment) override {}
+                        Align ByteAlignment) override;
 };
 
 } // end namespace llvm
diff --git a/llvm/lib/MC/MCGOFFStreamer.cpp b/llvm/lib/MC/MCGOFFStreamer.cpp
index 7c99fcbc5451c..ebe8bc0a0207d 100644
--- a/llvm/lib/MC/MCGOFFStreamer.cpp
+++ b/llvm/lib/MC/MCGOFFStreamer.cpp
@@ -73,6 +73,35 @@ bool MCGOFFStreamer::emitSymbolAttribute(MCSymbol *Sym,
   return static_cast<MCSymbolGOFF *>(Sym)->setSymbolAttribute(Attribute);
 }
 
+void MCGOFFStreamer::emitCommonSymbol(MCSymbol *S, uint64_t Size,
+                                      Align ByteAlignment) {
+  auto *Symbol = static_cast<MCSymbolGOFF *>(S);
+
+  MCSectionGOFF *SD = getContext().getGOFFSection(
+      SectionKind::getMetadata(), Symbol->getName(),
+      GOFF::SDAttr{GOFF::ESD_TA_Unspecified, GOFF::ESD_BSC_Unspecified});
+
+  MCSectionGOFF *ED = getContext().getGOFFSection(
+      SectionKind::getMetadata(), GOFF::CLASS_WSA,
+      GOFF::EDAttr{false, GOFF::ESD_RMODE_64, GOFF::ESD_NS_Parts,
+                   GOFF::ESD_TS_ByteOriented, GOFF::ESD_BA_Merge,
+                   GOFF::ESD_LB_Deferred, GOFF::ESD_RQ_0, 0},
+      SD);
+  ED->setAlignment(ByteAlignment);
+
+  MCSectionGOFF *Section = getContext().getGOFFSection(
+      SectionKind::getBSS(), Symbol->getName(),
+      GOFF::PRAttr{false, GOFF::ESD_EXE_DATA, GOFF::ESD_LT_XPLink,
+                   Symbol->getBindingScope(), 0},
+      ED);
+
+  pushSection();
+  switchSection(Section);
+  emitLabel(Symbol);
+  emitZeros(Size);
+  popSection();
+}
+
 MCStreamer *llvm::createGOFFStreamer(MCContext &Context,
                                      std::unique_ptr<MCAsmBackend> &&MAB,
                                      std::unique_ptr<MCObjectWriter> &&OW,
diff --git a/llvm/test/CodeGen/SystemZ/zos-common-global.ll b/llvm/test/CodeGen/SystemZ/zos-common-global.ll
new file mode 100644
index 0000000000000..98d3c357964c5
--- /dev/null
+++ b/llvm/test/CodeGen/SystemZ/zos-common-global.ll
@@ -0,0 +1,28 @@
+; RUN: llc <%s --mtriple s390x-ibm-zos --filetype=obj | \
+; RUN:   od -Ax -tx1 -v | FileCheck --ignore-case %s
+
+ at x = common global i32 0, align 4
+
+; ESD record, type SD.
+; The name is x.
+; CHECK:      0001e0 03 00 00 00 [[X:00 00 00 05]] 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 0001f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 000200 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 000210 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 000220 00 00 00 00 00 00 00 01 a7 00 00 00 00 00 00 00
+
+; ESD record, type ED.
+; The name is C_WSA64.
+; CHECK-NEXT: 000230 03 00 00 01 [[X_WSA:00 00 00 06]] [[X]] 00 00 00 00
+; CHECK-NEXT: 000240 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 000250 00 00 00 00 00 00 00 00 03 80 00 00 00 00 00 00
+; CHECK-NEXT: 000260 00 00 00 00 00 00 00 00 00 00 00 00 00 04 01 00
+; CHECK-NEXT: 000270 00 40 02 00 00 00 00 07 c3 6d e6 e2 c1 f6 f4 00
+
+; ESD record, type PR.
+; The name is x.
+; CHECK-NEXT: 000280 03 00 00 03 [[X_PR:00 00 00 07]] [[X_WSA]] 00 00 00 00
+; CHECK-NEXT: 000290 00 00 00 00 00 00 00 00 00 00 00 04 00 00 00 00
+; CHECK-NEXT: 0002a0 00 00 00 00 00 00 00 00 03 00 00 00 00 00 00 00
+; CHECK-NEXT: 0002b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01
+; CHECK-NEXT: 0002c0 00 04 22 00 00 00 00 01 a7 00 00 00 00 00 00 00