From 45b392d6cf0e9a7d7401161500d1bce0f05144ae Mon Sep 17 00:00:00 2001
From: Shankar Easwaran <shankare@codeaurora.org>
Date: Sun, 22 Feb 2015 23:32:34 +0000
Subject: [PATCH] [ELF][X86_64] R_X86_64_16 relocation support

llvm-svn: 230189
---
 .../ELF/X86_64/X86_64RelocationHandler.cpp         | 12 +++++
 .../ELF/X86_64/X86_64RelocationPass.cpp            |  1 +
 lld/test/elf/X86_64/reloc_r_x86_64_16.test         | 60 ++++++++++++++++++++++
 3 files changed, 73 insertions(+)
 create mode 100644 lld/test/elf/X86_64/reloc_r_x86_64_16.test

diff --git a/lld/lib/ReaderWriter/ELF/X86_64/X86_64RelocationHandler.cpp b/lld/lib/ReaderWriter/ELF/X86_64/X86_64RelocationHandler.cpp
index 91194c9..e436422 100644
--- a/lld/lib/ReaderWriter/ELF/X86_64/X86_64RelocationHandler.cpp
+++ b/lld/lib/ReaderWriter/ELF/X86_64/X86_64RelocationHandler.cpp
@@ -47,6 +47,15 @@ static void reloc32S(uint8_t *location, uint64_t P, uint64_t S, int64_t A) {
   // TODO: Make sure that the result sign extends to the 64bit value.
 }
 
+/// \brief R_X86_64_16 - word16:  S + A
+static void reloc16(uint8_t *location, uint64_t P, uint64_t S, int64_t A) {
+  uint16_t result = (uint16_t)(S + A);
+  *reinterpret_cast<llvm::support::ulittle16_t *>(location) =
+      result |
+      (uint16_t) * reinterpret_cast<llvm::support::ulittle16_t *>(location);
+  // TODO: Check for overflow.
+}
+
 std::error_code X86_64TargetRelocationHandler::applyRelocation(
     ELFWriter &writer, llvm::FileOutputBuffer &buf, const lld::AtomLayout &atom,
     const Reference &ref) const {
@@ -74,6 +83,9 @@ std::error_code X86_64TargetRelocationHandler::applyRelocation(
   case R_X86_64_32S:
     reloc32S(location, relocVAddress, targetVAddress, ref.addend());
     break;
+  case R_X86_64_16:
+    reloc16(location, relocVAddress, targetVAddress, ref.addend());
+    break;
   case R_X86_64_TPOFF64:
   case R_X86_64_DTPOFF32:
   case R_X86_64_TPOFF32: {
diff --git a/lld/lib/ReaderWriter/ELF/X86_64/X86_64RelocationPass.cpp b/lld/lib/ReaderWriter/ELF/X86_64/X86_64RelocationPass.cpp
index 45bdcad..bf5dbde 100644
--- a/lld/lib/ReaderWriter/ELF/X86_64/X86_64RelocationPass.cpp
+++ b/lld/lib/ReaderWriter/ELF/X86_64/X86_64RelocationPass.cpp
@@ -111,6 +111,7 @@ template <class Derived> class RelocationPass : public Pass {
       return;
     assert(ref.kindArch() == Reference::KindArch::x86_64);
     switch (ref.kindValue()) {
+    case R_X86_64_16:
     case R_X86_64_32:
     case R_X86_64_32S:
     case R_X86_64_64:
diff --git a/lld/test/elf/X86_64/reloc_r_x86_64_16.test b/lld/test/elf/X86_64/reloc_r_x86_64_16.test
new file mode 100644
index 0000000..7cca839
--- /dev/null
+++ b/lld/test/elf/X86_64/reloc_r_x86_64_16.test
@@ -0,0 +1,60 @@
+# Tests that lld can handle relocations of type R_X86_64_16
+#RUN: yaml2obj -format=elf -docnum 1 %s -o %t1.o
+#RUN: lld -flavor gnu -target x86_64 %t1.o --noinhibit-exec -o %t2.out -static
+#RUN: llvm-objdump -s %t2.out | FileCheck %s
+#CHECK: Contents of section .data:
+#CHECK: 401000 0210
+---
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  OSABI:           ELFOSABI_GNU
+  Type:            ET_REL
+  Machine:         EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    AddressAlign:    0x0000000000000004
+    Content:         ''
+  - Name:            .data
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_WRITE, SHF_ALLOC ]
+    AddressAlign:    0x0000000000000008
+    Content:         '0000'
+  - Name:            .rela.data
+    Type:            SHT_RELA
+    Link:            .symtab
+    AddressAlign:    0x0000000000000008
+    Info:            .data
+    Relocations:
+      - Offset:          0x0000000000000000
+        Symbol:          foo
+        Type:            R_X86_64_16
+  - Name:            .bss
+    Type:            SHT_NOBITS
+    Flags:           [ SHF_WRITE, SHF_ALLOC ]
+    AddressAlign:    0x0000000000000004
+    Content:         ''
+Symbols:
+  Local:
+    - Name:            .text
+      Type:            STT_SECTION
+      Section:         .text
+    - Name:            .data
+      Type:            STT_SECTION
+      Section:         .data
+    - Name:            .bss
+      Type:            STT_SECTION
+      Section:         .bss
+  Global:
+    - Name:            bar
+      Type:            STT_OBJECT
+      Section:         .data
+      Size:            0x0000000000000008
+    - Name:            foo
+      Type:            STT_OBJECT
+      Section:         .data
+      Value:           0x0000000000000002
+      Size:            0x0000000000000002
+...
-- 
2.7.4