Implement ObjectFileELF::GetBaseAddress

Summary:
The concept of a base address was already present in the implementation
(it's needed for computing section load addresses properly), but it was
never exposed through this function. This fixes that.

llvm-svn: 350804

lldb/lit/Modules/ELF/basic-info.yaml

@@ -0,0 +1,27 @@
+# REQUIRES: lld
+
+# RUN: yaml2obj %s > %t.o
+# RUN: ld.lld %t.o -o %t -image-base 0x47000
+# RUN: lldb-test object-file %t | FileCheck %s
+
+# CHECK: Plugin name: elf
+# CHECK: Architecture: x86_64--
+# CHECK: Executable: true
+# CHECK: Stripped: false
+# CHECK: Type: executable
+# CHECK: Strata: user
+# CHECK: Base VM address: 0x47000
+
+--- !ELF
+FileHeader:      
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_X86_64
+Sections:        
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    AddressAlign:    0x0000000000000010
+    Content:         554889E55DC3
+...

lldb/lit/Modules/ELF/compressed-sections.yaml

@@ -19,13 +19,15 @@ Sections:
 
 # CHECK: Name: .hello_elf
 # CHECK-NEXT: Type: regular
-# CHECK: VM size: 0
+# CHECK: VM address: 0
+# CHECK-NEXT: VM size: 0
 # CHECK-NEXT: File size: 28
 # CHECK-NEXT: Data:
 # CHECK-NEXT: 20304050 60708090
 
 # CHECK: Name: .bogus
 # CHECK-NEXT: Type: regular
-# CHECK: VM size: 0
+# CHECK: VM address: 0
+# CHECK-NEXT: VM size: 0
 # CHECK-NEXT: File size: 8
 # CHECK-NEXT: Data: ()

lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp

@@ -806,17 +806,10 @@ bool ObjectFileELF::SetLoadAddress(Target &target, lldb::addr_t value,
     SectionList *section_list = GetSectionList();
     if (section_list) {
       if (!value_is_offset) {
-        bool found_offset = false;
-        for (const ELFProgramHeader &H : ProgramHeaders()) {
-          if (H.p_type != PT_LOAD || H.p_offset != 0)
-            continue;
-
-          value = value - H.p_vaddr;
-          found_offset = true;
-          break;
-        }
-        if (!found_offset)
+        addr_t base = GetBaseAddress().GetFileAddress();
+        if (base == LLDB_INVALID_ADDRESS)
           return false;
+        value -= base;
       }
 
       const size_t num_sections = section_list->GetSize();
@@ -1055,6 +1048,18 @@ lldb_private::Address ObjectFileELF::GetEntryPointAddress() {
   return m_entry_point_address;
 }
 
+Address ObjectFileELF::GetBaseAddress() {
+  for (const auto &EnumPHdr : llvm::enumerate(ProgramHeaders())) {
+    const ELFProgramHeader &H = EnumPHdr.value();
+    if (H.p_type != PT_LOAD || H.p_offset != 0)
+      continue;
+
+    return Address(
+        GetSectionList()->FindSectionByID(SegmentID(EnumPHdr.index())), 0);
+  }
+  return LLDB_INVALID_ADDRESS;
+}
+
 //----------------------------------------------------------------------
 // ParseDependentModules
 //----------------------------------------------------------------------

lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.h

@@ -134,6 +134,8 @@ public:
 
   lldb_private::Address GetEntryPointAddress() override;
 
+  lldb_private::Address GetBaseAddress() override;
+
   ObjectFile::Type CalculateType() override;
 
   ObjectFile::Strata CalculateStrata() override;

lldb/tools/lldb-test/lldb-test.cpp

@@ -785,6 +785,8 @@ static int dumpObjectFiles(Debugger &Dbg) {
     Printer.formatLine("Stripped: {0}", ObjectPtr->IsStripped());
     Printer.formatLine("Type: {0}", ObjectPtr->GetType());
     Printer.formatLine("Strata: {0}", ObjectPtr->GetStrata());
+    Printer.formatLine("Base VM address: {0:x}",
+                       ObjectPtr->GetBaseAddress().GetFileAddress());
 
     dumpSectionList(Printer, *Sections, /*is_subsection*/ false);