[Mips] Emit ELF header for MIPS target. ELF flags set is mostly hardcoded.

Later we need to improve that solution and build a correct set of flags
by merging ELF flags from all input objects.

llvm-svn: 199555

lld/lib/ReaderWriter/ELF/Mips/MipsTargetHandler.cpp

@@ -127,6 +127,27 @@ uint64_t MipsTargetHandler::getGPDispSymAddr() const {
   return _gpDispSymAtom ? _gpDispSymAtom->_virtualAddr : 0;
 }
 
+bool MipsTargetHandler::doesOverrideELFHeader() { return true; }
+
+void MipsTargetHandler::setELFHeader(ELFHeader<Mips32ElELFType> *elfHeader) {
+  elfHeader->e_version(1);
+
+  elfHeader->e_ident(llvm::ELF::EI_VERSION, llvm::ELF::EV_CURRENT);
+  elfHeader->e_ident(llvm::ELF::EI_OSABI, llvm::ELF::ELFOSABI_NONE);
+  if (_targetLayout.findOutputSection(".got.plt"))
+    elfHeader->e_ident(llvm::ELF::EI_ABIVERSION, 1);
+  else
+    elfHeader->e_ident(llvm::ELF::EI_ABIVERSION, 0);
+
+  // FIXME (simon): Read elf flags from all inputs, check compatibility,
+  // merge them and write result here.
+  uint32_t flags = llvm::ELF::EF_MIPS_NOREORDER | llvm::ELF::EF_MIPS_ABI_O32 |
+                   llvm::ELF::EF_MIPS_CPIC | llvm::ELF::EF_MIPS_ARCH_32R2;
+  if (_context.getOutputELFType() == llvm::ELF::ET_DYN)
+    flags |= EF_MIPS_PIC;
+  elfHeader->e_flags(flags);
+}
+
 MipsTargetLayout<Mips32ElELFType> &MipsTargetHandler::targetLayout() {
   return _targetLayout;
 }

lld/lib/ReaderWriter/ELF/Mips/MipsTargetHandler.h

@@ -54,6 +54,8 @@ public:
 
   uint64_t getGPDispSymAddr() const;
 
+  virtual bool doesOverrideELFHeader();
+  virtual void setELFHeader(ELFHeader<Mips32ElELFType> *elfHeader);
   virtual MipsTargetLayout<Mips32ElELFType> &targetLayout();
   virtual const MipsTargetRelocationHandler &getRelocationHandler() const;
   virtual LLD_UNIQUE_BUMP_PTR(DynamicTable<Mips32ElELFType>)

lld/test/elf/Mips/dynlib-fileheader.test

@@ -22,7 +22,13 @@ CHECK:  Version: 1
 CHECK:  Entry: 0x170
 CHECK:  ProgramHeaderOffset: 0x34
 CHECK:  SectionHeaderOffset: 0x21D8
-CHECK:  Flags [ (0x0)
+CHECK:  Flags [ (0x70001007)
+CHECK:    0x1
+CHECK:    0x2
+CHECK:    0x1000
+CHECK:    0x10000000
+CHECK:    0x20000000
+CHECK:    0x40000000
 CHECK:  ]
 CHECK:  HeaderSize: 52
 CHECK:  ProgramHeaderEntrySize: 32

lld/test/elf/Mips/exe-fileheader.test

@@ -0,0 +1,54 @@
+# Check ELF Header for non-pic executable file.
+
+# Build shared library
+# RUN: llvm-mc -triple=mipsel -filetype=obj -relocation-model=pic \
+# RUN:         -o=%t-obj %p/Inputs/ext.s
+# RUN: lld -flavor gnu -target mipsel -shared -o %t-so %t-obj
+
+# Build executable
+# RUN: llvm-mc -triple=mipsel -filetype=obj -o=%t-obj %s
+# RUN: lld -flavor gnu -target mipsel -e glob -o %t-exe %t-obj %t-so
+# RUN: llvm-readobj -file-headers %t-exe | FileCheck %s
+
+# CHECK: Format: ELF32-mips
+# CHECK: Arch: mipsel
+# CHECK: AddressSize: 32bit
+# CHECK: LoadName:
+# CHECK: ElfHeader {
+# CHECK:   Ident {
+# CHECK:     Magic: (7F 45 4C 46)
+# CHECK:     Class: 32-bit (0x1)
+# CHECK:     DataEncoding: LittleEndian (0x1)
+# CHECK:     FileVersion: 1
+# CHECK:     OS/ABI: SystemV (0x0)
+# CHECK:     ABIVersion: 1
+# CHECK:     Unused: (00 00 00 00 00 00 00)
+# CHECK:   }
+# CHECK:   Type: Executable (0x2)
+# CHECK:   Machine: EM_MIPS (0x8)
+# CHECK:   Version: 1
+# CHECK:   Entry: 0x4001B0
+# CHECK:   ProgramHeaderOffset: 0x34
+# CHECK:   SectionHeaderOffset: 0x2268
+# CHECK:   Flags [ (0x70001005)
+# CHECK:     0x1
+# CHECK:     0x4
+# CHECK:     0x1000
+# CHECK:     0x10000000
+# CHECK:     0x20000000
+# CHECK:     0x40000000
+# CHECK:   ]
+# CHECK:   HeaderSize: 52
+# CHECK:   ProgramHeaderEntrySize: 32
+# CHECK:   ProgramHeaderCount: 6
+# CHECK:   SectionHeaderEntrySize: 40
+# CHECK:   SectionHeaderCount: 16
+# CHECK:   StringTableSectionIndex: 13
+# CHECK: }
+
+    .abicalls
+    .global glob
+    .ent    glob
+glob:
+    jal     ext1
+    .end    glob