[build] Android RISCV64 using a Canary NDK.

Change-Id: I447941fd4eee0c1e4394b3ab5c0b9c36a7b4c257
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/330701
Reviewed-by: Zach Anderson <zra@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>

DEPS

@@ -605,6 +605,17 @@ Var("dart_root") + "/third_party/pkg/tar":
       "dep_type": "cipd",
   },
 
+  Var("dart_root") + "/third_party/canary_ndk": {
+      "packages": [
+          {
+            "package": "flutter/android/ndk/${{os}}-amd64",
+            "version": "version:r27.0.10869015"
+          }
+      ],
+      "condition": "download_android_deps",
+      "dep_type": "cipd",
+  },
+
   Var("dart_root") + "/third_party/android_tools": {
       "packages": [
           {

build/config/android/config.gni

@@ -55,6 +55,9 @@ if (is_android) {
 
   # Path to the Android NDK and SDK.
   android_ndk_root = "//third_party/android_tools/ndk"
+  if (current_cpu == "riscv64") {
+    android_ndk_root = "//third_party/canary_ndk"
+  }
   android_ndk_include_dir = "$android_ndk_root/usr/include"
 
   android_sdk = "${android_sdk_root}/platforms/android-${android_sdk_version}"
@@ -70,7 +73,9 @@ if (is_android) {
 
   # Subdirectories inside android_ndk_root that contain the sysroot for the
   # associated platform.
-  if (current_cpu == "x64" || current_cpu == "arm64") {
+  if (current_cpu == "riscv64") {
+    android_api_level = 35
+  } else if (current_cpu == "x64" || current_cpu == "arm64") {
     android_api_level = 22
   } else {
     android_api_level = 19
@@ -86,11 +91,13 @@ if (is_android) {
   arm_android_toolchain_root = "$android_ndk_root/toolchains/arm-linux-androideabi-${_android_toolchain_version}/prebuilt/${android_host_os}-${android_host_arch}"
   x86_64_android_toolchain_root = "$android_ndk_root/toolchains/x86_64-${_android_toolchain_version}/prebuilt/${android_host_os}-${android_host_arch}"
   arm64_android_toolchain_root = "$android_ndk_root/toolchains/aarch64-linux-android-${_android_toolchain_version}/prebuilt/${android_host_os}-${android_host_arch}"
+  riscv64_android_toolchain_root = "$android_ndk_root/toolchains/llvm/prebuilt/${android_host_os}-${android_host_arch}"
 
   x86_android_lib = "$llvm_android_toolchain_root/sysroot/usr/lib/i686-linux-android/${android_api_level}"
   arm_android_lib = "$llvm_android_toolchain_root/sysroot/usr/lib/arm-linux-androideabi/${android_api_level}"
   x86_64_android_lib = "$llvm_android_toolchain_root/sysroot/usr/lib/x86_64-linux-android/${android_api_level}"
   arm64_android_lib = "$llvm_android_toolchain_root/sysroot/usr/lib/aarch64-linux-android/${android_api_level}"
+  riscv64_android_lib = "$llvm_android_toolchain_root/sysroot/usr/lib/riscv64-linux-android/${android_api_level}"
 
   # Location of libgcc. This is only needed for the current GN toolchain, so we
   # only need to define the current one, rather than one for every platform
@@ -115,6 +122,11 @@ if (is_android) {
     android_target_triple = "aarch64-linux-android"
     android_toolchain_root = "$arm64_android_toolchain_root"
     android_lib = "$arm64_android_lib"
+  } else if (current_cpu == "riscv64") {
+    android_prebuilt_arch = "android-riscv64"
+    android_target_triple = "riscv64-linux-android"
+    android_toolchain_root = "$riscv64_android_toolchain_root"
+    android_lib = "$riscv64_android_lib"
   } else {
     assert(false, "Need android libgcc support for your target arch.")
   }
@@ -157,6 +169,8 @@ if (is_android) {
     android_app_abi = "x86_64"
   } else if (current_cpu == "arm64") {
     android_app_abi = "arm64-v8a"
+  } else if (current_cpu == "riscv64") {
+    android_app_abi = "riscv64"
   } else {
     assert(false, "Unknown Android ABI: " + current_cpu)
   }

build/config/compiler/BUILD.gn

@@ -415,6 +415,9 @@ config("compiler") {
       } else if (current_cpu == "x64") {
         cflags += [ "--target=x86_64-linux-androideabi" ]
         ldflags += [ "--target=x86_64-linux-androideabi" ]
+      } else if (current_cpu == "riscv64") {
+        cflags += [ "--target=riscv64-linux-android" ]
+        ldflags += [ "--target=riscv64-linux-android" ]
       }
     }
   }
@@ -600,11 +603,6 @@ config("runtime_library") {
 
     lib_dirs += [ "$android_libcpp_root/libs/$android_app_abi" ]
 
-    libs += [
-      "$android_libcpp_library",
-      "c++abi",
-    ]
-
     if (android_api_level < 21) {
       libs += [ "android_support" ]
     }
@@ -619,6 +617,11 @@ config("runtime_library") {
       "dl",
       "m",
     ]
+    if (current_cpu == "riscv64") {
+      libs -= [ "gcc" ]
+      lib_dirs += [ "//third_party/canary_ndk/toolchains/llvm/prebuilt/${android_host_os}-${android_host_arch}/lib/clang/17/lib/linux/" ]
+      libs += [ "clang_rt.builtins-riscv64-android" ]
+    }
 
     # Clang with libc++ does not require an explicit atomic library reference.
     if (!is_clang) {

build/toolchain/android/BUILD.gn

@@ -45,6 +45,11 @@ template("android_gcc_toolchain") {
       not_needed([ "tool_prefix" ])
       prefix =
           rebase_path("//buildtools/${host_os}-x64/clang/bin", root_build_dir)
+      if (current_cpu == "riscv64") {
+        prefix = rebase_path(
+                "//third_party/canary_ndk/toolchains/llvm/prebuilt/${android_host_os}-${android_host_arch}/bin",
+                root_build_dir)
+      }
 
       cc = compiler_prefix + prefix + "/clang"
       cxx = compiler_prefix + prefix + "/clang++"
@@ -130,3 +135,10 @@ android_gcc_toolchains_helper("arm64") {
   tool_prefix = "$llvm_android_toolchain_root/bin/aarch64-linux-android-"
   toolchain_cpu = "aarch64"
 }
+
+android_gcc_toolchains_helper("riscv64") {
+  android_ndk_lib_dir = riscv64_android_lib
+
+  tool_prefix = "$llvm_android_toolchain_root/bin/riscv64-linux-android-"
+  toolchain_cpu = "riscv64"
+}

tools/gn.py

@@ -384,6 +384,7 @@ def ProcessOptions(args):
                     'arm64',
                     'x64c',
                     'arm64c',
+                    'riscv64',
             ]:
                 print(
                     "Cross-compilation to %s is not supported for architecture %s."