riscv64: hand-code trampoline instructions.

We don't have a macro-assembler for riscv64 yet, but we need to
generate trampolines for boot images and encode them in the .oat files.

Bug: b/271573990
Test: cuttlefish boots and uses dexpreopt artifacts
      $ lunch aosp_cf_riscv64_phone-userdebug && m
      $ launch_cvd --gpu_mode=drm_virgl
      # observe no crashes in zygote
      # observe that.vdex files are used in logcat
Change-Id: I605e93374e70cde29cdf893b14210f0c60d74129

2 files changed, 54 insertions, 6 deletions

diff --git a/compiler/trampolines/trampoline_compiler.cc b/compiler/trampolines/trampoline_compiler.cc
index a122d3c9d3..e542763f82 100644
--- a/compiler/trampolines/trampoline_compiler.cc
+++ b/compiler/trampolines/trampoline_compiler.cc
@@ -127,6 +127,54 @@ static std::unique_ptr<const std::vector<uint8_t>> CreateTrampoline(
 }  // namespace arm64
 #endif  // ART_ENABLE_CODEGEN_arm64
 
+#ifdef ART_ENABLE_CODEGEN_riscv64
+namespace riscv64 {
+static std::unique_ptr<const std::vector<uint8_t>> CreateTrampoline(
+    ArenaAllocator* /*allocator*/, EntryPointCallingConvention abi, ThreadOffset64 offset) {
+  if (abi == kJniAbi) {
+    // TODO(riscv64): implement this properly once we have macro-assembler for RISC-V.
+    std::unique_ptr<std::vector<uint8_t>> entry_stub(new std::vector<uint8_t>(2));
+    uint8_t* bytes = entry_stub->data();
+
+    // 0000    unimp
+    bytes[0] = 0x00;
+    bytes[1] = 0x00;
+
+    return std::move(entry_stub);
+  } else {
+    CHECK_LE(offset.Int32Value(), 0x7ff);
+    uint8_t offset_hi = (offset.Int32Value() & 0x7ff) >> 4;
+    uint8_t offset_lo = (offset.Int32Value() & 0xf) << 4;
+
+    std::unique_ptr<std::vector<uint8_t>> entry_stub(new std::vector<uint8_t>(6));
+    uint8_t* bytes = entry_stub->data();
+
+    if (abi == kInterpreterAbi) {
+      // Thread* is first argument (A0) in interpreter ABI.
+      // xxx53283     ld t0, xxx(a0)
+      bytes[0] = 0x83;
+      bytes[1] = 0x32;
+      bytes[2] = offset_lo | 0x05;
+      bytes[3] = offset_hi;
+    } else {
+      // abi == kQuickAbi: TR holds Thread*.
+      // xxx4b283     ld t0, xxx(s1)
+      bytes[0] = 0x83;
+      bytes[1] = 0xb2;
+      bytes[2] = offset_lo | 0x04;
+      bytes[3] = offset_hi;
+    }
+
+    // 8282    jr t0
+    bytes[4] = 0x82;
+    bytes[5] = 0x82;
+
+    return std::move(entry_stub);
+  }
+}
+}  // namespace riscv64
+#endif  // ART_ENABLE_CODEGEN_riscv64
+
 #ifdef ART_ENABLE_CODEGEN_x86
 namespace x86 {
 static std::unique_ptr<const std::vector<uint8_t>> CreateTrampoline(ArenaAllocator* allocator,
@@ -179,6 +227,10 @@ std::unique_ptr<const std::vector<uint8_t>> CreateTrampoline64(InstructionSet is
     case InstructionSet::kArm64:
       return arm64::CreateTrampoline(&allocator, abi, offset);
 #endif
+#ifdef ART_ENABLE_CODEGEN_riscv64
+    case InstructionSet::kRiscv64:
+      return riscv64::CreateTrampoline(&allocator, abi, offset);
+#endif
 #ifdef ART_ENABLE_CODEGEN_x86_64
     case InstructionSet::kX86_64:
       return x86_64::CreateTrampoline(&allocator, offset);
diff --git a/dex2oat/linker/oat_writer.cc b/dex2oat/linker/oat_writer.cc
index cfba522632..222a5f4a5f 100644
--- a/dex2oat/linker/oat_writer.cc
+++ b/dex2oat/linker/oat_writer.cc
@@ -2260,9 +2260,7 @@ size_t OatWriter::InitOatCode(size_t offset) {
   oat_header_->SetExecutableOffset(offset);
   size_executable_offset_alignment_ = offset - old_offset;
   InstructionSet instruction_set = compiler_options_.GetInstructionSet();
-  if (GetCompilerOptions().IsBootImage() && primary_oat_file_ &&
-      // TODO(riscv64): remove this when we have compiler support for RISC-V.
-      instruction_set != InstructionSet::kRiscv64) {
+  if (GetCompilerOptions().IsBootImage() && primary_oat_file_) {
     const bool generate_debug_info = GetCompilerOptions().GenerateAnyDebugInfo();
     size_t adjusted_offset = offset;
 
@@ -3068,9 +3066,7 @@ size_t OatWriter::WriteBcpBssInfo(OutputStream* out, size_t file_offset, size_t
 
 size_t OatWriter::WriteCode(OutputStream* out, size_t file_offset, size_t relative_offset) {
   InstructionSet instruction_set = compiler_options_.GetInstructionSet();
-  if (GetCompilerOptions().IsBootImage() && primary_oat_file_ &&
-      // TODO(riscv64): remove this when we have compiler support for RISC-V.
-      instruction_set != InstructionSet::kRiscv64) {
+  if (GetCompilerOptions().IsBootImage() && primary_oat_file_) {
     #define DO_TRAMPOLINE(field) \
       do { \
         /* Pad with at least four 0xFFs so we can do DCHECKs in OatQuickMethodHeader */ \