ObjectFile: parse EABI Attributes

This adds basic parsing of the EABI attributes section.  This section contains
additional information about the target for which the file was built.  Attempt
to infer additional architecture information from that section.

llvm-svn: 267291

1 files changed, 100 insertions, 0 deletions

diff --git a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
index bb388d45e36..76416843fd5 100644
--- a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
+++ b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
@@ -31,6 +31,7 @@
 
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Support/ARMBuildAttributes.h"
 #include "llvm/Support/MathExtras.h"
 
 #define CASE_AND_STREAM(s, def, width)                  \
@@ -1516,6 +1517,93 @@ ObjectFileELF::RefineModuleDetailsFromNote (lldb_private::DataExtractor &data, l
     return error;
 }
 
+void
+ObjectFileELF::ParseARMAttributes(DataExtractor &data, uint64_t length, ArchSpec &arch_spec)
+{
+    lldb::offset_t Offset = 0;
+
+    uint8_t FormatVersion = data.GetU8(&Offset);
+    if (FormatVersion != llvm::ARMBuildAttrs::Format_Version)
+      return;
+
+    Offset = Offset + sizeof(uint32_t); // Section Length
+    llvm::StringRef VendorName = data.GetCStr(&Offset);
+
+    if (VendorName != "aeabi")
+      return;
+
+    if (arch_spec.GetTriple().getEnvironment() == llvm::Triple::UnknownEnvironment)
+        arch_spec.GetTriple().setEnvironment(llvm::Triple::EABI);
+
+    while (Offset < length)
+    {
+        uint8_t Tag = data.GetU8(&Offset);
+        uint32_t Size = data.GetU32(&Offset);
+
+        if (Tag != llvm::ARMBuildAttrs::File || Size == 0)
+            continue;
+
+        while (Offset < length)
+        {
+            uint64_t Tag = data.GetULEB128(&Offset);
+            switch (Tag)
+            {
+                default:
+                    if (Tag < 32)
+                        data.GetULEB128(&Offset);
+                    else if (Tag % 2 == 0)
+                        data.GetULEB128(&Offset);
+                    else
+                        data.GetCStr(&Offset);
+
+                    break;
+
+                case llvm::ARMBuildAttrs::CPU_raw_name:
+                case llvm::ARMBuildAttrs::CPU_name:
+                    data.GetCStr(&Offset);
+
+                    break;
+
+                case llvm::ARMBuildAttrs::THUMB_ISA_use:
+                {
+                    uint64_t ThumbISA = data.GetULEB128(&Offset);
+
+                    // NOTE: ignore ThumbISA == llvm::ARMBuildAttrs::AllowThumbDerived
+                    // since that derives it based on the architecutre/profile
+                    if (ThumbISA == llvm::ARMBuildAttrs::AllowThumb32)
+                        if (arch_spec.GetTriple().getArch() == llvm::Triple::UnknownArch ||
+                            arch_spec.GetTriple().getArch() == llvm::Triple::arm)
+                            arch_spec.GetTriple().setArch(llvm::Triple::thumb);
+
+                    break;
+                }
+                case llvm::ARMBuildAttrs::ABI_VFP_args:
+                {
+                    uint64_t VFPArgs = data.GetULEB128(&Offset);
+
+                    if (VFPArgs == llvm::ARMBuildAttrs::BaseAAPCS)
+                    {
+                        if (arch_spec.GetTriple().getEnvironment() == llvm::Triple::UnknownEnvironment ||
+                            arch_spec.GetTriple().getEnvironment() == llvm::Triple::EABIHF)
+                            arch_spec.GetTriple().setEnvironment(llvm::Triple::EABI);
+
+                        arch_spec.SetFlags(ArchSpec::eARM_abi_soft_float);
+                    }
+                    else if (VFPArgs == llvm::ARMBuildAttrs::HardFPAAPCS)
+                    {
+                        if (arch_spec.GetTriple().getEnvironment() == llvm::Triple::UnknownEnvironment ||
+                            arch_spec.GetTriple().getEnvironment() == llvm::Triple::EABI)
+                            arch_spec.GetTriple().setEnvironment(llvm::Triple::EABIHF);
+
+                        arch_spec.SetFlags(ArchSpec::eARM_abi_hard_float);
+                    }
+
+                    break;
+                }
+            }
+        }
+    }
+}
 
 //----------------------------------------------------------------------
 // GetSectionHeaderInfo
@@ -1648,6 +1736,18 @@ ObjectFileELF::GetSectionHeaderInfo(SectionHeaderColl &section_headers,
                     arch_spec.SetFlags (arch_flags);
                 }
 
+                if (arch_spec.GetMachine() == llvm::Triple::arm || arch_spec.GetMachine() == llvm::Triple::thumb)
+                {
+                    DataExtractor data;
+
+                    if (sheader.sh_type != SHT_ARM_ATTRIBUTES)
+                        continue;
+                    if (section_size == 0 || set_data(data, sheader.sh_offset, section_size) != section_size)
+                        continue;
+
+                    ParseARMAttributes(data, section_size, arch_spec);
+                }
+
                 if (name == g_sect_name_gnu_debuglink)
                 {
                     DataExtractor data;