Add a InitSections method to the streamer interface.

The ELF implementation now creates text, data and bss to match the gnu as
behavior.

The text streamer still has the old MachO specific behavior since
the testsuite checks that it will error when a directive is given
before a setting the current section for example.

A nice benefit is that -n is not required anymore when producing
ELF files.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114027 91177308-0d34-0410-b5e6-96231b3b80d8

13 files changed, 116 insertions, 13 deletions

diff --git a/include/llvm/MC/MCStreamer.h b/include/llvm/MC/MCStreamer.h
index f983617a..0e43ce6 100644
--- a/include/llvm/MC/MCStreamer.h
+++ b/include/llvm/MC/MCStreamer.h
@@ -110,6 +110,9 @@ namespace llvm {
     /// This corresponds to assembler directives like .section, .text, etc.
     virtual void SwitchSection(const MCSection *Section) = 0;
 
+    /// InitSections - Create the default sections and set the initial one.
+    virtual void InitSections() = 0;
+
     /// EmitLabel - Emit a label for @p Symbol into the current section.
     ///
     /// This corresponds to an assembler statement such as:
diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index 1cc8fb0..efde8aa 100644
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/lib/MC/MCAsmStreamer.cpp
@@ -100,6 +100,14 @@ public:
 
   virtual void SwitchSection(const MCSection *Section);
 
+  virtual void InitSections() {
+    // FIXME, this is MachO specific, but the testsuite
+    // expects this.
+    SwitchSection(getContext().getMachOSection("__TEXT", "__text",
+                         MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
+                         0, SectionKind::getText()));
+  }
+
   virtual void EmitLabel(MCSymbol *Symbol);
 
   virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
diff --git a/lib/MC/MCAssembler.cpp b/lib/MC/MCAssembler.cpp
index 8db1536..bb12499 100644
--- a/lib/MC/MCAssembler.cpp
+++ b/lib/MC/MCAssembler.cpp
@@ -739,7 +739,7 @@ void MCAssembler::Finish(MCObjectWriter *Writer) {
     // Create dummy fragments to eliminate any empty sections, this simplifies
     // layout.
     if (it->getFragmentList().empty())
-      new MCFillFragment(0, 1, 0, it);
+      new MCDataFragment(it);
 
     it->setOrdinal(SectionIndex++);
   }
diff --git a/lib/MC/MCELFStreamer.cpp b/lib/MC/MCELFStreamer.cpp
index 6490cc7..deb1a0d 100644
--- a/lib/MC/MCELFStreamer.cpp
+++ b/lib/MC/MCELFStreamer.cpp
@@ -46,6 +46,7 @@ public:
   /// @name MCStreamer Interface
   /// @{
 
+  virtual void InitSections();
   virtual void EmitLabel(MCSymbol *Symbol);
   virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
   virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
@@ -109,10 +110,42 @@ public:
   virtual void Finish();
 
   /// @}
+  void SetSection(StringRef Section, unsigned Type, unsigned Flags,
+                  SectionKind Kind) {
+    SwitchSection(getContext().getELFSection(Section, Type, Flags, Kind));
+  }
+
+  void SetSectionData() {
+    SetSection(".data", MCSectionELF::SHT_PROGBITS,
+               MCSectionELF::SHF_WRITE |MCSectionELF::SHF_ALLOC,
+               SectionKind::getDataRel());
+    EmitCodeAlignment(4, 0);
+  }
+  void SetSectionText() {
+    SetSection(".text", MCSectionELF::SHT_PROGBITS,
+               MCSectionELF::SHF_EXECINSTR |
+               MCSectionELF::SHF_ALLOC, SectionKind::getText());
+    EmitCodeAlignment(4, 0);
+  }
+  void SetSectionBss() {
+    SetSection(".bss", MCSectionELF::SHT_NOBITS,
+               MCSectionELF::SHF_WRITE |
+               MCSectionELF::SHF_ALLOC, SectionKind::getBSS());
+    EmitCodeAlignment(4, 0);
+  }
 };
 
 } // end anonymous namespace.
 
+void MCELFStreamer::InitSections() {
+  // This emulates the same behavior of GNU as. This makes it easier
+  // to compare the output as the major sections are in the same order.
+  SetSectionText();
+  SetSectionData();
+  SetSectionBss();
+  SetSectionText();
+}
+
 void MCELFStreamer::EmitLabel(MCSymbol *Symbol) {
   assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
 
diff --git a/lib/MC/MCLoggingStreamer.cpp b/lib/MC/MCLoggingStreamer.cpp
index b96040a..879afa4 100644
--- a/lib/MC/MCLoggingStreamer.cpp
+++ b/lib/MC/MCLoggingStreamer.cpp
@@ -54,6 +54,10 @@ public:
     return Child->SwitchSection(Section);
   }
 
+  virtual void InitSections() {
+    LogCall("InitSections");
+  }
+
   virtual void EmitLabel(MCSymbol *Symbol) {
     LogCall("EmitLabel");
     return Child->EmitLabel(Symbol);
diff --git a/lib/MC/MCMachOStreamer.cpp b/lib/MC/MCMachOStreamer.cpp
index 671874d..cd6fd50 100644
--- a/lib/MC/MCMachOStreamer.cpp
+++ b/lib/MC/MCMachOStreamer.cpp
@@ -46,6 +46,7 @@ public:
   /// @name MCStreamer Interface
   /// @{
 
+  virtual void InitSections();
   virtual void EmitLabel(MCSymbol *Symbol);
   virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
   virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
@@ -110,6 +111,13 @@ public:
 
 } // end anonymous namespace.
 
+void MCMachOStreamer::InitSections() {
+  SwitchSection(getContext().getMachOSection("__TEXT", "__text",
+                                    MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
+                                    0, SectionKind::getText()));
+
+}
+
 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
   // TODO: This is almost exactly the same as WinCOFFStreamer. Consider merging
   // into MCObjectStreamer.
diff --git a/lib/MC/MCNullStreamer.cpp b/lib/MC/MCNullStreamer.cpp
index f7a2f20..b2db410 100644
--- a/lib/MC/MCNullStreamer.cpp
+++ b/lib/MC/MCNullStreamer.cpp
@@ -25,6 +25,9 @@ namespace {
     /// @name MCStreamer Interface
     /// @{
 
+    virtual void InitSections() {
+    }
+
     virtual void SwitchSection(const MCSection *Section) {
       PrevSection = CurSection;
       CurSection = Section;
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index 5ef6f68..b3ffed8 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -365,12 +365,8 @@ const AsmToken &AsmParser::Lex() {
 
 bool AsmParser::Run(bool NoInitialTextSection, bool NoFinalize) {
   // Create the initial section, if requested.
-  //
-  // FIXME: Target hook & command line option for initial section.
   if (!NoInitialTextSection)
-    Out.SwitchSection(Ctx.getMachOSection("__TEXT", "__text",
-                                      MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
-                                      0, SectionKind::getText()));
+    Out.InitSections();
 
   // Prime the lexer.
   Lex();
diff --git a/lib/MC/MCParser/ELFAsmParser.cpp b/lib/MC/MCParser/ELFAsmParser.cpp
index 38288d7..ddf988f 100644
--- a/lib/MC/MCParser/ELFAsmParser.cpp
+++ b/lib/MC/MCParser/ELFAsmParser.cpp
@@ -51,20 +51,28 @@ public:
     AddDirectiveHandler<&ELFAsmParser::ParseDirectivePrevious>(".previous");
   }
 
+  // FIXME: Part of this logic is duplicated in the MCELFStreamer. What is
+  // the best way for us to get access to it?
   bool ParseSectionDirectiveData(StringRef, SMLoc) {
-    return ParseSectionSwitch(".data", MCSectionELF::SHT_PROGBITS,
+    bool ret =  ParseSectionSwitch(".data", MCSectionELF::SHT_PROGBITS,
                               MCSectionELF::SHF_WRITE |MCSectionELF::SHF_ALLOC,
                               SectionKind::getDataRel());
+    getStreamer().EmitCodeAlignment(4, 0);
+    return ret;
   }
   bool ParseSectionDirectiveText(StringRef, SMLoc) {
-    return ParseSectionSwitch(".text", MCSectionELF::SHT_PROGBITS,
+    bool ret = ParseSectionSwitch(".text", MCSectionELF::SHT_PROGBITS,
                               MCSectionELF::SHF_EXECINSTR |
                               MCSectionELF::SHF_ALLOC, SectionKind::getText());
+    getStreamer().EmitCodeAlignment(4, 0);
+    return ret;
   }
   bool ParseSectionDirectiveBSS(StringRef, SMLoc) {
-    return ParseSectionSwitch(".bss", MCSectionELF::SHT_NOBITS,
+    bool ret = ParseSectionSwitch(".bss", MCSectionELF::SHT_NOBITS,
                               MCSectionELF::SHF_WRITE |
                               MCSectionELF::SHF_ALLOC, SectionKind::getBSS());
+    getStreamer().EmitCodeAlignment(4, 0);
+    return ret;
   }
   bool ParseSectionDirectiveRoData(StringRef, SMLoc) {
     return ParseSectionSwitch(".rodata", MCSectionELF::SHT_PROGBITS,
diff --git a/lib/MC/WinCOFFStreamer.cpp b/lib/MC/WinCOFFStreamer.cpp
index 8a194bf..faecfcb 100644
--- a/lib/MC/WinCOFFStreamer.cpp
+++ b/lib/MC/WinCOFFStreamer.cpp
@@ -48,6 +48,7 @@ public:
 
   // MCStreamer interface
 
+  virtual void InitSections();
   virtual void EmitLabel(MCSymbol *Symbol);
   virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
   virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
@@ -126,6 +127,9 @@ void WinCOFFStreamer::AddCommonSymbol(MCSymbol *Symbol, uint64_t Size,
 
 // MCStreamer interface
 
+void WinCOFFStreamer::InitSections() {
+}
+
 void WinCOFFStreamer::EmitLabel(MCSymbol *Symbol) {
   // TODO: This is copied almost exactly from the MachOStreamer. Consider
   // merging into MCObjectStreamer?
diff --git a/test/MC/ELF/empty.s b/test/MC/ELF/empty.s
new file mode 100644
index 0000000..ba98a8c
--- /dev/null
+++ b/test/MC/ELF/empty.s
@@ -0,0 +1,36 @@
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | elf-dump   | FileCheck %s
+
+// Test that like gnu as we create text, data and bss by default.
+
+// CHECK:      ('sh_name', 1) # '.text'
+// CHECK-NEXT: ('sh_type', 1)
+// CHECK-NEXT: ('sh_flags', 6)
+// CHECK-NEXT: ('sh_addr', 0)
+// CHECK-NEXT: ('sh_offset', 64)
+// CHECK-NEXT: ('sh_size', 0)
+// CHECK-NEXT: ('sh_link', 0)
+// CHECK-NEXT: ('sh_info', 0)
+// CHECK-NEXT: ('sh_addralign', 4)
+// CHECK-NEXT: ('sh_entsize', 0)
+
+// CHECK:      ('sh_name', 7) # '.data'
+// CHECK-NEXT: ('sh_type', 1)
+// CHECK-NEXT: ('sh_flags', 3)
+// CHECK-NEXT: ('sh_addr', 0)
+// CHECK-NEXT: ('sh_offset', 64)
+// CHECK-NEXT: ('sh_size', 0)
+// CHECK-NEXT: ('sh_link', 0)
+// CHECK-NEXT: ('sh_info', 0)
+// CHECK-NEXT: ('sh_addralign', 4)
+// CHECK-NEXT: ('sh_entsize', 0)
+
+// CHECK:      ('sh_name', 13) # '.bss'
+// CHECK-NEXT: ('sh_type', 8)
+// CHECK-NEXT: ('sh_flags', 3)
+// CHECK-NEXT: ('sh_addr', 0)
+// CHECK-NEXT: ('sh_offset', 64)
+// CHECK-NEXT: ('sh_size', 0)
+// CHECK-NEXT: ('sh_link', 0)
+// CHECK-NEXT: ('sh_info', 0)
+// CHECK-NEXT: ('sh_addralign', 4)
+// CHECK-NEXT: ('sh_entsize', 0)
diff --git a/test/MC/ELF/sleb.s b/test/MC/ELF/sleb.s
index ed656b6..c3e471f 100644
--- a/test/MC/ELF/sleb.s
+++ b/test/MC/ELF/sleb.s
@@ -1,5 +1,5 @@
-// RUN: llvm-mc -filetype=obj -triple i686-pc-linux-gnu -n %s -o - | elf-dump  --dump-section-data | FileCheck -check-prefix=ELF_32 %s
-// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu -n %s -o - | elf-dump  --dump-section-data | FileCheck -check-prefix=ELF_64 %s
+// RUN: llvm-mc -filetype=obj -triple i686-pc-linux-gnu %s -o - | elf-dump  --dump-section-data | FileCheck -check-prefix=ELF_32 %s
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | elf-dump  --dump-section-data | FileCheck -check-prefix=ELF_64 %s
 // RUN: llvm-mc -filetype=obj -triple i386-apple-darwin9 %s -o - | macho-dump  --dump-section-data | FileCheck -check-prefix=MACHO_32 %s
 // RUN: llvm-mc -filetype=obj -triple x86_64-apple-darwin9 %s -o - | macho-dump  --dump-section-data | FileCheck -check-prefix=MACHO_64 %s
 
diff --git a/test/MC/ELF/uleb.s b/test/MC/ELF/uleb.s
index 1fb2a23..d8d1727 100644
--- a/test/MC/ELF/uleb.s
+++ b/test/MC/ELF/uleb.s
@@ -1,5 +1,5 @@
-// RUN: llvm-mc -filetype=obj -triple i686-pc-linux-gnu -n %s -o - | elf-dump  --dump-section-data | FileCheck -check-prefix=ELF_32 %s
-// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu -n %s -o - | elf-dump  --dump-section-data | FileCheck -check-prefix=ELF_64 %s
+// RUN: llvm-mc -filetype=obj -triple i686-pc-linux-gnu %s -o - | elf-dump  --dump-section-data | FileCheck -check-prefix=ELF_32 %s
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | elf-dump  --dump-section-data | FileCheck -check-prefix=ELF_64 %s
 // RUN: llvm-mc -filetype=obj -triple i386-apple-darwin9 %s -o - | macho-dump  --dump-section-data | FileCheck -check-prefix=MACHO_32 %s
 // RUN: llvm-mc -filetype=obj -triple x86_64-apple-darwin9 %s -o - | macho-dump  --dump-section-data | FileCheck -check-prefix=MACHO_64 %s