[llvm] 655d048 - [GOFF] Add writing of text records (#137235)

via llvm-commits llvm-commits at lists.llvm.org
Thu Jun 26 10:50:43 PDT 2025


Author: Kai Nacke
Date: 2025-06-26T13:50:40-04:00
New Revision: 655d04859be6285e05e361044b7d11a5e29040b7

URL: https://github.com/llvm/llvm-project/commit/655d04859be6285e05e361044b7d11a5e29040b7
DIFF: https://github.com/llvm/llvm-project/commit/655d04859be6285e05e361044b7d11a5e29040b7.diff

LOG: [GOFF] Add writing of text records (#137235)

Sections which are not allowed to carry data are marked as virtual. Only
complication when writing out the text is that it must be written in
chunks of 32k-1 bytes, which is done by having a wrapper stream writing
those records.
Data of BSS sections is not written, since the contents is known to be
zero. Instead, the fill byte value is used.

Added: 
    

Modified: 
    llvm/include/llvm/MC/MCContext.h
    llvm/include/llvm/MC/MCSectionGOFF.h
    llvm/lib/MC/GOFFObjectWriter.cpp
    llvm/lib/MC/MCContext.cpp
    llvm/test/CodeGen/SystemZ/zos-section-1.ll
    llvm/test/CodeGen/SystemZ/zos-section-2.ll

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/MC/MCContext.h b/llvm/include/llvm/MC/MCContext.h
index 50085c436c63c..d7b81af4a785a 100644
--- a/llvm/include/llvm/MC/MCContext.h
+++ b/llvm/include/llvm/MC/MCContext.h
@@ -359,7 +359,8 @@ class MCContext {
 
   template <typename TAttr>
   MCSectionGOFF *getGOFFSection(SectionKind Kind, StringRef Name,
-                                TAttr SDAttributes, MCSection *Parent);
+                                TAttr SDAttributes, MCSection *Parent,
+                                bool IsVirtual);
 
   /// Map of currently defined macros.
   StringMap<MCAsmMacro> MacroMap;

diff  --git a/llvm/include/llvm/MC/MCSectionGOFF.h b/llvm/include/llvm/MC/MCSectionGOFF.h
index b8b8cf112a34d..b2ca74c3ba78a 100644
--- a/llvm/include/llvm/MC/MCSectionGOFF.h
+++ b/llvm/include/llvm/MC/MCSectionGOFF.h
@@ -39,6 +39,9 @@ class MCSectionGOFF final : public MCSection {
   // The type of this section.
   GOFF::ESDSymbolType SymbolType;
 
+  // This section is a BSS section.
+  unsigned IsBSS : 1;
+
   // Indicates that the PR symbol needs to set the length of the section to a
   // non-zero value. This is only a problem with the ADA PR - the binder will
   // generate an error in this case.
@@ -50,26 +53,26 @@ class MCSectionGOFF final : public MCSection {
   friend class MCContext;
   friend class MCSymbolGOFF;
 
-  MCSectionGOFF(StringRef Name, SectionKind K, GOFF::SDAttr SDAttributes,
-                MCSectionGOFF *Parent)
-      : MCSection(SV_GOFF, Name, K.isText(), /*IsVirtual=*/false, nullptr),
+  MCSectionGOFF(StringRef Name, SectionKind K, bool IsVirtual,
+                GOFF::SDAttr SDAttributes, MCSectionGOFF *Parent)
+      : MCSection(SV_GOFF, Name, K.isText(), IsVirtual, nullptr),
         Parent(Parent), SDAttributes(SDAttributes),
-        SymbolType(GOFF::ESD_ST_SectionDefinition), RequiresNonZeroLength(0),
-        Emitted(0) {}
+        SymbolType(GOFF::ESD_ST_SectionDefinition), IsBSS(K.isBSS()),
+        RequiresNonZeroLength(0), Emitted(0) {}
 
-  MCSectionGOFF(StringRef Name, SectionKind K, GOFF::EDAttr EDAttributes,
-                MCSectionGOFF *Parent)
-      : MCSection(SV_GOFF, Name, K.isText(), /*IsVirtual=*/false, nullptr),
+  MCSectionGOFF(StringRef Name, SectionKind K, bool IsVirtual,
+                GOFF::EDAttr EDAttributes, MCSectionGOFF *Parent)
+      : MCSection(SV_GOFF, Name, K.isText(), IsVirtual, nullptr),
         Parent(Parent), EDAttributes(EDAttributes),
-        SymbolType(GOFF::ESD_ST_ElementDefinition), RequiresNonZeroLength(0),
-        Emitted(0) {}
+        SymbolType(GOFF::ESD_ST_ElementDefinition), IsBSS(K.isBSS()),
+        RequiresNonZeroLength(0), Emitted(0) {}
 
-  MCSectionGOFF(StringRef Name, SectionKind K, GOFF::PRAttr PRAttributes,
-                MCSectionGOFF *Parent)
-      : MCSection(SV_GOFF, Name, K.isText(), /*IsVirtual=*/false, nullptr),
+  MCSectionGOFF(StringRef Name, SectionKind K, bool IsVirtual,
+                GOFF::PRAttr PRAttributes, MCSectionGOFF *Parent)
+      : MCSection(SV_GOFF, Name, K.isText(), IsVirtual, nullptr),
         Parent(Parent), PRAttributes(PRAttributes),
-        SymbolType(GOFF::ESD_ST_PartReference), RequiresNonZeroLength(0),
-        Emitted(0) {}
+        SymbolType(GOFF::ESD_ST_PartReference), IsBSS(K.isBSS()),
+        RequiresNonZeroLength(0), Emitted(0) {}
 
 public:
   void printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
@@ -81,6 +84,9 @@ class MCSectionGOFF final : public MCSection {
   // Return the parent section.
   MCSectionGOFF *getParent() const { return Parent; }
 
+  // Returns true if this is a BSS section.
+  bool isBSS() const { return IsBSS; }
+
   // Returns the type of this section.
   GOFF::ESDSymbolType getSymbolType() const { return SymbolType; }
 
@@ -102,6 +108,17 @@ class MCSectionGOFF final : public MCSection {
     return PRAttributes;
   }
 
+  // Returns the text style for a section. Only defined for ED and PR sections.
+  GOFF::ESDTextStyle getTextStyle() const {
+    assert(isED() || isPR() || isVirtualSection() && "Expect ED or PR section");
+    if (isED())
+      return EDAttributes.TextStyle;
+    if (isPR())
+      return getParent()->getEDAttributes().TextStyle;
+    // Virtual sections have no data, so byte orientation is fine.
+    return GOFF::ESD_TS_ByteOriented;
+  }
+
   bool requiresNonZeroLength() const { return RequiresNonZeroLength; }
 
   void setName(StringRef SectionName) { Name = SectionName; }

diff  --git a/llvm/lib/MC/GOFFObjectWriter.cpp b/llvm/lib/MC/GOFFObjectWriter.cpp
index 1f3c131289b49..1871f5fe507e2 100644
--- a/llvm/lib/MC/GOFFObjectWriter.cpp
+++ b/llvm/lib/MC/GOFFObjectWriter.cpp
@@ -275,6 +275,7 @@ class GOFFWriter {
 
   void writeHeader();
   void writeSymbol(const GOFFSymbol &Symbol);
+  void writeText(const MCSectionGOFF *MC);
   void writeEnd();
 
   void defineSectionSymbols(const MCSectionGOFF &Section);
@@ -405,6 +406,80 @@ void GOFFWriter::writeSymbol(const GOFFSymbol &Symbol) {
   OS.write(Name.data(), NameLength); // Name
 }
 
+namespace {
+/// Adapter stream to write a text section.
+class TextStream : public raw_ostream {
+  /// The underlying GOFFOstream.
+  GOFFOstream &OS;
+
+  /// The buffer size is the maximum number of bytes in a TXT section.
+  static constexpr size_t BufferSize = GOFF::MaxDataLength;
+
+  /// Static allocated buffer for the stream, used by the raw_ostream class. The
+  /// buffer is sized to hold the payload of a logical TXT record.
+  char Buffer[BufferSize];
+
+  /// The offset for the next TXT record. This is equal to the number of bytes
+  /// written.
+  size_t Offset;
+
+  /// The Esdid of the GOFF section.
+  const uint32_t EsdId;
+
+  /// The record style.
+  const GOFF::ESDTextStyle RecordStyle;
+
+  /// See raw_ostream::write_impl.
+  void write_impl(const char *Ptr, size_t Size) override;
+
+  uint64_t current_pos() const override { return Offset; }
+
+public:
+  explicit TextStream(GOFFOstream &OS, uint32_t EsdId,
+                      GOFF::ESDTextStyle RecordStyle)
+      : OS(OS), Offset(0), EsdId(EsdId), RecordStyle(RecordStyle) {
+    SetBuffer(Buffer, sizeof(Buffer));
+  }
+
+  ~TextStream() { flush(); }
+};
+} // namespace
+
+void TextStream::write_impl(const char *Ptr, size_t Size) {
+  size_t WrittenLength = 0;
+
+  // We only have signed 32bits of offset.
+  if (Offset + Size > std::numeric_limits<int32_t>::max())
+    report_fatal_error("TXT section too large");
+
+  while (WrittenLength < Size) {
+    size_t ToWriteLength =
+        std::min(Size - WrittenLength, size_t(GOFF::MaxDataLength));
+
+    OS.newRecord(GOFF::RT_TXT);
+    OS.writebe<uint8_t>(GOFF::Flags(4, 4, RecordStyle)); // Text Record Style
+    OS.writebe<uint32_t>(EsdId);                         // Element ESDID
+    OS.writebe<uint32_t>(0);                             // Reserved
+    OS.writebe<uint32_t>(static_cast<uint32_t>(Offset)); // Offset
+    OS.writebe<uint32_t>(0);                      // Text Field True Length
+    OS.writebe<uint16_t>(0);                      // Text Encoding
+    OS.writebe<uint16_t>(ToWriteLength);          // Data Length
+    OS.write(Ptr + WrittenLength, ToWriteLength); // Data
+
+    WrittenLength += ToWriteLength;
+    Offset += ToWriteLength;
+  }
+}
+
+void GOFFWriter::writeText(const MCSectionGOFF *Section) {
+  // A BSS section contains only zeros, no need to write this.
+  if (Section->isBSS())
+    return;
+
+  TextStream S(OS, Section->getOrdinal(), Section->getTextStyle());
+  Asm.writeSectionData(S, Section);
+}
+
 void GOFFWriter::writeEnd() {
   uint8_t F = GOFF::END_EPR_None;
   uint8_t AMODE = 0;
@@ -428,6 +503,9 @@ uint64_t GOFFWriter::writeObject() {
 
   defineSymbols();
 
+  for (const MCSection &Section : Asm)
+    writeText(static_cast<const MCSectionGOFF *>(&Section));
+
   writeEnd();
 
   // Make sure all records are written.

diff  --git a/llvm/lib/MC/MCContext.cpp b/llvm/lib/MC/MCContext.cpp
index f3bb5aa88e8fb..3f2f9a756d33b 100644
--- a/llvm/lib/MC/MCContext.cpp
+++ b/llvm/lib/MC/MCContext.cpp
@@ -723,7 +723,8 @@ MCContext::getELFUniqueIDForEntsize(StringRef SectionName, unsigned Flags,
 
 template <typename TAttr>
 MCSectionGOFF *MCContext::getGOFFSection(SectionKind Kind, StringRef Name,
-                                         TAttr Attributes, MCSection *Parent) {
+                                         TAttr Attributes, MCSection *Parent,
+                                         bool IsVirtual) {
   std::string UniqueName(Name);
   if (Parent) {
     UniqueName.append("/").append(Parent->getName());
@@ -737,8 +738,9 @@ MCSectionGOFF *MCContext::getGOFFSection(SectionKind Kind, StringRef Name,
     return Iter->second;
 
   StringRef CachedName = StringRef(Iter->first.c_str(), Name.size());
-  MCSectionGOFF *GOFFSection = new (GOFFAllocator.Allocate()) MCSectionGOFF(
-      CachedName, Kind, Attributes, static_cast<MCSectionGOFF *>(Parent));
+  MCSectionGOFF *GOFFSection = new (GOFFAllocator.Allocate())
+      MCSectionGOFF(CachedName, Kind, IsVirtual, Attributes,
+                    static_cast<MCSectionGOFF *>(Parent));
   Iter->second = GOFFSection;
   allocInitialFragment(*GOFFSection);
   return GOFFSection;
@@ -746,19 +748,23 @@ MCSectionGOFF *MCContext::getGOFFSection(SectionKind Kind, StringRef Name,
 
 MCSectionGOFF *MCContext::getGOFFSection(SectionKind Kind, StringRef Name,
                                          GOFF::SDAttr SDAttributes) {
-  return getGOFFSection<GOFF::SDAttr>(Kind, Name, SDAttributes, nullptr);
+  return getGOFFSection<GOFF::SDAttr>(Kind, Name, SDAttributes, nullptr,
+                                      /*IsVirtual=*/true);
 }
 
 MCSectionGOFF *MCContext::getGOFFSection(SectionKind Kind, StringRef Name,
                                          GOFF::EDAttr EDAttributes,
                                          MCSection *Parent) {
-  return getGOFFSection<GOFF::EDAttr>(Kind, Name, EDAttributes, Parent);
+  return getGOFFSection<GOFF::EDAttr>(
+      Kind, Name, EDAttributes, Parent,
+      /*IsVirtual=*/EDAttributes.BindAlgorithm == GOFF::ESD_BA_Merge);
 }
 
 MCSectionGOFF *MCContext::getGOFFSection(SectionKind Kind, StringRef Name,
                                          GOFF::PRAttr PRAttributes,
                                          MCSection *Parent) {
-  return getGOFFSection<GOFF::PRAttr>(Kind, Name, PRAttributes, Parent);
+  return getGOFFSection<GOFF::PRAttr>(Kind, Name, PRAttributes, Parent,
+                                      /*IsVirtual=*/false);
 }
 
 MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,

diff  --git a/llvm/test/CodeGen/SystemZ/zos-section-1.ll b/llvm/test/CodeGen/SystemZ/zos-section-1.ll
index ea9bc4ce95174..b98584df54d5a 100644
--- a/llvm/test/CodeGen/SystemZ/zos-section-1.ll
+++ b/llvm/test/CodeGen/SystemZ/zos-section-1.ll
@@ -104,9 +104,26 @@ entry:
 ; CHECK-NEXT: 000300 00 00 00 00 00 00 00 00 00 00 00 00 04 00 00 02
 ; CHECK-NEXT: 000310 00 01 20 00 00 00 00 06 a3 85 a2 a3 7b c3 00 00
 
+; Text record for the code section C_CODE64.
+; The regular expression matches the lower byte of the length.
+; CHECK-NEXT: 000320 03 11 00 00 [[C_CODE64]] 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 000330 00 00 00 00 00 00 00 {{..}} 00 c3 00 c5 00 c5 00 f1
+
+; Text record for the section .&ppa2.
+; CHECK:      0003c0 03 10 00 00 [[PPA2]] 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 0003d0 00 00 00 00 00 00 00 {{..}} {{.*}}
+
+; Text record for the ADA section test#S.
+; CHECK:      000410 03 10 00 00 [[TESTS]] 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 000420 00 00 00 00 00 00 00 {{..}} {{.*}}
+
+; Text record for the section B_IDRL.
+; CHECK:      000460 03 10 00 01 [[BIDRL]] 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 000470 00 00 00 00 00 00 00 {{..}} {{.*}}
+
 ; End record.
-; CHECK-NEXT: 000320 03 40 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-; CHECK-NEXT: 000330 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-; CHECK-NEXT: 000340 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-; CHECK-NEXT: 000350 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-; CHECK-NEXT: 000360 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+; CHECK:      0004b0 03 40 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 0004c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 0004d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 0004e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 0004f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

diff  --git a/llvm/test/CodeGen/SystemZ/zos-section-2.ll b/llvm/test/CodeGen/SystemZ/zos-section-2.ll
index 472517acc4a45..0f608c1206b96 100644
--- a/llvm/test/CodeGen/SystemZ/zos-section-2.ll
+++ b/llvm/test/CodeGen/SystemZ/zos-section-2.ll
@@ -147,9 +147,29 @@ source_filename = "test.ll"
 ; CHECK-NEXT: 0004e0 00 00 00 00 00 00 00 00 00 00 00 00 04 00 00 02
 ; CHECK-NEXT: 0004f0 00 01 20 00 00 00 00 06 a3 85 a2 a3 7b c3 00 00
 
+; Text record for the code section C_CODE64.
+; The regular expression matches the lower byte of the length.
+; CHECK-NEXT: 000500 03 10 00 00 [[C_CODE64]] 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 000510 00 00 00 00 00 00 00 {{..}} {{.*}}
+
+; Text record for the section .&ppa2.
+; CHECK:      000550 03 10 00 00 [[PPA2]] 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 000560 00 00 00 00 00 00 00 {{..}} {{.*}}
+
+; Text record for the section data.
+; Length is 4, and the content is 0x2a = 42.
+; CHECK:      0005a0 03 10 00 00 [[DATA_PR]] 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 0005b0 00 00 00 00 00 00 00 04 00 00 00 2a 00 00 00 00
+
+; There is no text record for section bss!
+
+; Text record for the section B_IDRL.
+; CHECK:      0005f0 03 10 00 01 [[BIDRL]] 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 000600 00 00 00 00 00 00 00 {{..}} {{.*}}
+
 ; End record.
-; CHECK-NEXT: 000500 03 40 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-; CHECK-NEXT: 000510 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-; CHECK-NEXT: 000520 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-; CHECK-NEXT: 000530 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-; CHECK-NEXT: 000540 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+; CHECK:      000640 03 40 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 000650 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 000660 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 000670 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+; CHECK-NEXT: 000680 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


        


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