ART: Fix 64-bit ELF file support

The API wasn't cross-compile-safe, 32-bit patchoat would fail for
negative delta applied to a 64-bit ELF file.

Add 64-bit ELF file output to the compilers, behind a flag, currently
off by default (preserving current behavior).

Bug: 20095017
Change-Id: I2cde7b4c7cc83413c76692d7b745868d644a604c

3 files changed, 17 insertions, 4 deletions

diff --git a/compiler/compiler.h b/compiler/compiler.h
index 6ec39f9605..a04641e3fa 100644
--- a/compiler/compiler.h
+++ b/compiler/compiler.h
@@ -107,6 +107,9 @@ class Compiler {
     return driver_;
   }
 
+  // Whether to produce 64-bit ELF files for 64-bit targets. Leave this off for now.
+  static constexpr bool kProduce64BitELFFiles = false;
+
  private:
   CompilerDriver* const driver_;
   const uint64_t maximum_compilation_time_before_warning_;
diff --git a/compiler/dex/quick/quick_compiler.cc b/compiler/dex/quick/quick_compiler.cc
index 8baafc7fd2..01652d6560 100644
--- a/compiler/dex/quick/quick_compiler.cc
+++ b/compiler/dex/quick/quick_compiler.cc
@@ -798,8 +798,13 @@ bool QuickCompiler::WriteElf(art::File* file,
                              const std::vector<const art::DexFile*>& dex_files,
                              const std::string& android_root,
                              bool is_host) const {
-  return art::ElfWriterQuick32::Create(file, oat_writer, dex_files, android_root, is_host,
-                                       *GetCompilerDriver());
+  if (kProduce64BitELFFiles && Is64BitInstructionSet(GetCompilerDriver()->GetInstructionSet())) {
+    return art::ElfWriterQuick64::Create(file, oat_writer, dex_files, android_root, is_host,
+                                         *GetCompilerDriver());
+  } else {
+    return art::ElfWriterQuick32::Create(file, oat_writer, dex_files, android_root, is_host,
+                                         *GetCompilerDriver());
+  }
 }
 
 Mir2Lir* QuickCompiler::GetCodeGenerator(CompilationUnit* cu, void* compilation_unit) const {
diff --git a/compiler/optimizing/optimizing_compiler.cc b/compiler/optimizing/optimizing_compiler.cc
index e474c49121..e67bebd5d8 100644
--- a/compiler/optimizing/optimizing_compiler.cc
+++ b/compiler/optimizing/optimizing_compiler.cc
@@ -201,8 +201,13 @@ class OptimizingCompiler FINAL : public Compiler {
                 const std::vector<const art::DexFile*>& dex_files,
                 const std::string& android_root,
                 bool is_host) const OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
-    return art::ElfWriterQuick32::Create(file, oat_writer, dex_files, android_root, is_host,
-                                        *GetCompilerDriver());
+    if (kProduce64BitELFFiles && Is64BitInstructionSet(GetCompilerDriver()->GetInstructionSet())) {
+      return art::ElfWriterQuick64::Create(file, oat_writer, dex_files, android_root, is_host,
+                                           *GetCompilerDriver());
+    } else {
+      return art::ElfWriterQuick32::Create(file, oat_writer, dex_files, android_root, is_host,
+                                           *GetCompilerDriver());
+    }
   }
 
   void InitCompilationUnit(CompilationUnit& cu) const OVERRIDE;