[lld] r247097 - Create a dynamic segment.

[Rafael Espindola via llvm-commits]

Author: rafael
Date: Tue Sep  8 17:55:28 2015
New Revision: 247097

URL: http://llvm.org/viewvc/llvm-project?rev=247097&view=rev
Log:
Create a dynamic segment.

It is still empty. I will add content next.

Modified:
    lld/trunk/ELF/Writer.cpp
    lld/trunk/test/elf2/shared.s

Modified: lld/trunk/ELF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=247097&r1=247096&r2=247097&view=diff
==============================================================================
--- lld/trunk/ELF/Writer.cpp (original)
+++ lld/trunk/ELF/Writer.cpp Tue Sep  8 17:55:28 2015
@@ -558,6 +558,17 @@ template <class ELFT> void Writer<ELFT>:
   FileSize = SizeOfHeaders + RoundUpToAlignment(FileOff - SizeOfHeaders, 8);
 }
 
+static uint32_t convertSectionFlagsToSegmentFlags(uint64_t Flags) {
+  uint32_t Ret = PF_R;
+  if (Flags & SHF_WRITE)
+    Ret |= PF_W;
+
+  if (Flags & SHF_EXECINSTR)
+    Ret |= PF_X;
+
+  return Ret;
+}
+
 template <class ELFT> void Writer<ELFT>::writeHeader() {
   uint8_t *Buf = Buffer->getBufferStart();
   auto *EHdr = reinterpret_cast<Elf_Ehdr *>(Buf);
@@ -572,8 +583,17 @@ template <class ELFT> void Writer<ELFT>:
   EHdr->e_ident[EI_VERSION] = EV_CURRENT;
   EHdr->e_ident[EI_OSABI] = ELFOSABI_NONE;
 
-  EHdr->e_type = ET_EXEC;
+  // FIXME: Generalize the segment construction similar to how we create
+  // output sections.
+  unsigned NumSegments = 1;
   const SymbolTable &Symtab = SymTable.getSymTable();
+  const std::vector<std::unique_ptr<SharedFileBase>> &SharedFiles =
+      Symtab.getSharedFiles();
+  bool HasDynamicSegment = !SharedFiles.empty();
+  if (HasDynamicSegment)
+    NumSegments++;
+
+  EHdr->e_type = ET_EXEC;
   auto &FirstObj = cast<ObjectFile<ELFT>>(*Symtab.getFirstELF());
   EHdr->e_machine = FirstObj.getEMachine();
   EHdr->e_version = EV_CURRENT;
@@ -582,7 +602,7 @@ template <class ELFT> void Writer<ELFT>:
   EHdr->e_shoff = SectionHeaderOff;
   EHdr->e_ehsize = sizeof(Elf_Ehdr);
   EHdr->e_phentsize = sizeof(Elf_Phdr);
-  EHdr->e_phnum = 1;
+  EHdr->e_phnum = NumSegments;
   EHdr->e_shentsize = sizeof(Elf_Shdr);
   EHdr->e_shnum = getNumSections();
   EHdr->e_shstrndx = StringTable.getSectionIndex();
@@ -597,6 +617,18 @@ template <class ELFT> void Writer<ELFT>:
   PHdrs->p_memsz = FileSize;
   PHdrs->p_align = 0x4000;
 
+  if (HasDynamicSegment) {
+    PHdrs++;
+    PHdrs->p_type = PT_DYNAMIC;
+    PHdrs->p_flags = convertSectionFlagsToSegmentFlags(DynamicSec.getFlags());
+    PHdrs->p_offset = DynamicSec.getFileOff();
+    PHdrs->p_vaddr = DynamicSec.getVA();
+    PHdrs->p_paddr = PHdrs->p_vaddr;
+    PHdrs->p_filesz = 0;
+    PHdrs->p_memsz = 0;
+    PHdrs->p_align = DynamicSec.getAlign();
+  }
+
   auto SHdrs = reinterpret_cast<Elf_Shdr *>(Buf + EHdr->e_shoff);
   // First entry is null.
   ++SHdrs;

Modified: lld/trunk/test/elf2/shared.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/elf2/shared.s?rev=247097&r1=247096&r2=247097&view=diff
==============================================================================
--- lld/trunk/test/elf2/shared.s (original)
+++ lld/trunk/test/elf2/shared.s Tue Sep  8 17:55:28 2015
@@ -1,6 +1,6 @@
 // RUN: llvm-mc -filetype=obj -triple=i686-unknown-linux %s -o %t.o
 // RUN: lld -flavor gnu2 %t.o %p/Inputs/i686-simple-library.so -o %t
-// RUN: llvm-readobj -t -s %t | FileCheck %s
+// RUN: llvm-readobj --program-headers -t -s %t | FileCheck %s
 // REQUIRES: x86
 
 // CHECK:        Name: .dynamic
@@ -9,16 +9,16 @@
 // CHECK-NEXT:     SHF_ALLOC
 // CHECK-NEXT:     SHF_WRITE
 // CHECK-NEXT:   ]
-// CHECK-NEXT:   Address:
-// CHECK-NEXT:   Offset:
-// CHECK-NEXT:   Size:
-// CHECK-NEXT:   Link: 6
+// CHECK-NEXT:   Address: [[ADDR:.*]]
+// CHECK-NEXT:   Offset: [[OFFSET:.*]]
+// CHECK-NEXT:   Size: 0
+// CHECK-NEXT:   Link: [[STRTAB:.*]]
 // CHECK-NEXT:   Info: 0
-// CHECK-NEXT:   AddressAlignment: 4
+// CHECK-NEXT:   AddressAlignment: [[ALIGN:.*]]
 // CHECK-NEXT:   EntrySize: 8
 // CHECK-NEXT: }
 
-// CHECK:        Index: 6
+// CHECK:        Index: [[STRTAB]]
 // CHECK-NEXT:   Name: .strtab
 // CHECK-NEXT:   Type: SHT_STRTAB
 // CHECK-NEXT:   Flags [
@@ -63,6 +63,21 @@
 // CHECK-NEXT:   }
 // CHECK-NEXT: ]
 
+
+// CHECK:      ProgramHeader {
+// CHECK:        Type: PT_DYNAMIC
+// CHECK-NEXT:   Offset: [[OFFSET]]
+// CHECK-NEXT:   VirtualAddress: [[ADDR]]
+// CHECK-NEXT:   PhysicalAddress: [[ADDR]]
+// CHECK-NEXT:   FileSize: 0
+// CHECK-NEXT:   MemSize: 0
+// CHECK-NEXT:   Flags [
+// CHECK-NEXT:     PF_R
+// CHECK-NEXT:     PF_W
+// CHECK-NEXT:   ]
+// CHECK-NEXT:   Alignment: [[ALIGN]]
+// CHECK-NEXT: }
+
 .global _start
 _start:
 .long bar