[ARM] Fix entry point for Thumb code

Test cases for both entry functions in ARM and Thumb
code are added.

llvm-svn: 232942

2 files changed, 97 insertions, 0 deletions

diff --git a/lld/lib/ReaderWriter/ELF/ARM/ARMExecutableWriter.h b/lld/lib/ReaderWriter/ELF/ARM/ARMExecutableWriter.h
index 4e475e50bcd..19311d516e4 100644
--- a/lld/lib/ReaderWriter/ELF/ARM/ARMExecutableWriter.h
+++ b/lld/lib/ReaderWriter/ELF/ARM/ARMExecutableWriter.h
@@ -42,6 +42,10 @@ protected:
 
   void processUndefinedSymbol(StringRef symName,
                               RuntimeFile<ELFT> &file) const override;
+
+  // Setup the ELF header.
+  std::error_code setELFHeader() override;
+
 private:
   ARMLinkingContext &_context;
   ARMTargetLayout<ELFT> &_armLayout;
@@ -95,6 +99,22 @@ void ARMExecutableWriter<ELFT>::processUndefinedSymbol(
   }
 }
 
+template <class ELFT>
+std::error_code ARMExecutableWriter<ELFT>::setELFHeader() {
+  if (std::error_code ec = ExecutableWriter<ELFT>::setELFHeader())
+    return ec;
+
+  // Fixup entry point for Thumb code.
+  StringRef entryName = _context.entrySymbolName();
+  if (const AtomLayout *al = _armLayout.findAtomLayoutByName(entryName)) {
+    const auto *ea = dyn_cast<DefinedAtom>(al->_atom);
+    if (ea && ea->codeModel() == DefinedAtom::codeARMThumb)
+      this->_elfHeader->e_entry(al->_virtualAddr | 0x1);
+  }
+
+  return std::error_code();
+}
+
 } // namespace elf
 } // namespace lld
 
diff --git a/lld/test/elf/ARM/entry-point.test b/lld/test/elf/ARM/entry-point.test
new file mode 100644
index 00000000000..d168bb6463c
--- /dev/null
+++ b/lld/test/elf/ARM/entry-point.test
@@ -0,0 +1,77 @@
+# 1. Check entry point address for ARM code - should be even.
+# RUN: yaml2obj -format=elf -docnum 1 %s > %t-arm.o
+# RUN: lld -flavor gnu -target arm -m armelf_linux_eabi -Bstatic \
+# RUN: --noinhibit-exec %t-arm.o -o %t-arm
+# RUN: llvm-readobj -file-headers %t-arm | FileCheck -check-prefix=ARM-ENTRY %s
+#
+# ARM-ENTRY: Entry: 0x400074
+
+# 2. Check entry point address for Thumb code - should be odd.
+# RUN: yaml2obj -format=elf -docnum 2 %s > %t-thm.o
+# RUN: lld -flavor gnu -target arm -m armelf_linux_eabi -Bstatic \
+# RUN: --noinhibit-exec %t-thm.o -o %t-thm
+# RUN: llvm-readobj -file-headers %t-thm | FileCheck -check-prefix=THM-ENTRY %s
+#
+# THM-ENTRY: Entry: 0x400075
+
+# arm.o
+---
+FileHeader:
+  Class:           ELFCLASS32
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_ARM
+  Flags:           [ EF_ARM_EABI_VER5 ]
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    AddressAlign:    0x0000000000000004
+    Content:         04B02DE500B08DE20030A0E30300A0E100D04BE204B09DE41EFF2FE1
+  - Name:            .data
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_WRITE, SHF_ALLOC ]
+    AddressAlign:    0x0000000000000001
+    Content:         ''
+  - Name:            .bss
+    Type:            SHT_NOBITS
+    Flags:           [ SHF_WRITE, SHF_ALLOC ]
+    AddressAlign:    0x0000000000000001
+    Content:         ''
+Symbols:
+  Global:
+    - Name:            _start
+      Type:            STT_FUNC
+      Section:         .text
+
+# thm.o
+---
+FileHeader:
+  Class:           ELFCLASS32
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_ARM
+  Flags:           [ EF_ARM_EABI_VER5 ]
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    AddressAlign:    0x0000000000000004
+    Content:         80B400AF00231846BD465DF8047B7047
+  - Name:            .data
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_WRITE, SHF_ALLOC ]
+    AddressAlign:    0x0000000000000001
+    Content:         ''
+  - Name:            .bss
+    Type:            SHT_NOBITS
+    Flags:           [ SHF_WRITE, SHF_ALLOC ]
+    AddressAlign:    0x0000000000000001
+    Content:         ''
+Symbols:
+  Global:
+    - Name:            _start
+      Type:            STT_FUNC
+      Section:         .text
+      Value:           0x0000000000000001
+...