Add support for arm64 QNX toolchains. (flutter#168699)

The pattern is similar to the recently added WASM (and previously NACL)
toolchains.

The major change is the engines use of functions that became constexpr
in C++26 (such as
[sqrt](https://en.cppreference.com/w/cpp/numeric/math/sqrt)) as if they
were already constexpr. I have attempted to keep the linkage the same
and am investigating how to enable this form of checking with our own
toolchain.

Author: chinmaygarde

engine/src/build/config/BUILDCONFIG.gn

@@ -202,6 +202,7 @@ if (current_os == "win") {
   is_posix = false
   is_win = true
   is_wasm = false
+  is_qnx = false
 } else if (current_os == "mac") {
   is_android = false
   is_chromeos = false
@@ -213,6 +214,7 @@ if (current_os == "win") {
   is_posix = true
   is_win = false
   is_wasm = false
+  is_qnx = false
 } else if (current_os == "android") {
   is_android = true
   is_chromeos = false
@@ -224,6 +226,7 @@ if (current_os == "win") {
   is_posix = true
   is_win = false
   is_wasm = false
+  is_qnx = false
 } else if (current_os == "chromeos") {
   is_android = false
   is_chromeos = true
@@ -235,6 +238,7 @@ if (current_os == "win") {
   is_posix = true
   is_win = false
   is_wasm = false
+  is_qnx = false
 } else if (current_os == "nacl") {
   # current_os == "nacl" will be passed by the nacl toolchain definition.
   # It is not set by default or on the command line. We treat is as a
@@ -249,6 +253,7 @@ if (current_os == "win") {
   is_posix = true
   is_win = false
   is_wasm = false
+  is_qnx = false
 } else if (current_os == "ios") {
   is_android = false
   is_chromeos = false
@@ -260,6 +265,7 @@ if (current_os == "win") {
   is_posix = true
   is_win = false
   is_wasm = false
+  is_qnx = false
 } else if (current_os == "linux") {
   is_android = false
   is_chromeos = false
@@ -271,6 +277,7 @@ if (current_os == "win") {
   is_posix = true
   is_win = false
   is_wasm = false
+  is_qnx = false
 } else if (current_os == "fuchsia" || target_os == "fuchsia") {
   is_android = false
   is_chromeos = false
@@ -282,6 +289,7 @@ if (current_os == "win") {
   is_posix = true
   is_win = false
   is_wasm = false
+  is_qnx = false
 } else if (current_os == "wasm") {
   is_android = false
   is_chromeos = false
@@ -293,6 +301,19 @@ if (current_os == "win") {
   is_posix = false
   is_win = false
   is_wasm = true
+  is_qnx = false
+} else if (current_os == "qnx") {
+  is_android = false
+  is_chromeos = false
+  is_fuchsia = false
+  is_fuchsia_host = false
+  is_ios = false
+  is_linux = false
+  is_mac = false
+  is_posix = false
+  is_win = false
+  is_wasm = false
+  is_qnx = true
 }
 
 is_apple = is_ios || is_mac
@@ -598,6 +619,9 @@ if (custom_toolchain != "") {
   clang_win_version = ""
   host_toolchain = "//build/toolchain/wasm"
   set_default_toolchain("//build/toolchain/wasm")
+} else if (is_qnx) {
+  host_toolchain = "//build/toolchain/linux:clang_$host_cpu"
+  set_default_toolchain("//build/toolchain/qnx")
 } else {
   assert(false, "Toolchain not set because of unknown platform.")
 }

engine/src/build/config/compiler/BUILD.gn

@@ -76,6 +76,14 @@ config("compiler") {
     configs += [ "//build/config/darwin:compiler" ]
   }
 
+  if (is_qnx) {
+    defines += [
+      "_XOPEN_SOURCE=700",
+      "_QNX_SOURCE",
+      "SKNX_NO_SIMD",
+    ]
+  }
+
   # In general, Windows is totally different, but all the other builds share
   # some common GCC configuration. This section sets up Windows and the common
   # GCC flags, and then we handle the other non-Windows platforms specifically
@@ -104,7 +112,7 @@ config("compiler") {
     # Stack protection.
     if (is_mac) {
       cflags += [ "-fstack-protector-all" ]
-    } else if (!is_ios && !is_wasm) {
+    } else if (!is_ios && !is_wasm && !is_qnx) {
       cflags += [
         "-fstack-protector",
         # 8 is the default, but make this explicit here so that we don't have to
@@ -346,12 +354,17 @@ config("compiler") {
 
   # Linux/Android common flags setup.
   # ---------------------------------
-  if (is_linux || is_android) {
+  if (is_linux || is_android || is_qnx) {
     cflags += [
       "-fPIC",
-      "-pipe",  # Use pipes for communicating between sub-processes. Faster.
     ]
 
+    if (!is_qnx) {
+      cflags += [
+        "-pipe",  # Use pipes for communicating between sub-processes. Faster.
+      ]
+    }
+
     ldflags += [
       "-fPIC",
       "-Wl,-z,noexecstack",
@@ -363,6 +376,20 @@ config("compiler") {
     }
   }
 
+  if (is_qnx) {
+    qnx_arch_flags = []
+    if (target_cpu == "arm64") {
+      qnx_arch_flags += [
+        "-V",
+        "gcc_ntoaarch64le"
+      ]
+    } else {
+      assert(false, "Unknown QNX architecture")
+    }
+    cflags += qnx_arch_flags
+    ldflags += qnx_arch_flags
+  }
+
   # Linux-specific compiler flags setup.
   # ------------------------------------
   if (is_linux) {
@@ -619,6 +646,9 @@ config("runtime_library") {
 
 default_warning_flags = []
 default_warning_flags_cc = []
+if (is_qnx) {
+  default_warning_flags_cc += [ "-fpermissive" ]
+}
 if (is_win) {
   default_warning_flags += [
     # Permanent.
@@ -659,13 +689,18 @@ if (is_win) {
   default_warning_flags += [
     # Enables.
     "-Wendif-labels",  # Weird old-style text after an #endif.
-    "-Werror",  # Warnings as errors.
 
     # Disables.
     "-Wno-missing-field-initializers",  # "struct foo f = {0};"
     "-Wno-unused-parameter",  # Unused function parameters.
   ]
 
+  if (!is_qnx) {
+    default_warning_flags += [
+      "-Werror",  # Warnings as errors.
+    ]
+  }
+
   if (is_wasm) {
     default_warning_flags += [
       # zlib needs this
@@ -680,27 +715,32 @@ if (is_win) {
   default_warning_flags += [
     "-Wno-unused-but-set-parameter",
     "-Wno-unused-but-set-variable",
-    "-Wno-implicit-int-float-conversion",
-    "-Wno-deprecated-copy",
 
     # Needed for compiling Skia with clang-12
     "-Wno-psabi",
   ]
 
-  if (!is_android) {
+  if (is_clang) {
+    default_warning_flags += [
+      "-Wno-implicit-int-float-conversion",
+      "-Wno-deprecated-copy",
+    ]
+  }
+
+  if (!is_android && is_clang) {
     default_warning_flags += [
       # Needed for nlohmann/json.
       "-Wno-deprecated-literal-operator",
     ]
   }
 
-  if (!is_wasm) {
+  if (!is_wasm && is_clang) {
     default_warning_flags += [
       # Unqualified std::move is pretty common.
       "-Wno-unqualified-std-cast-call",
     ]
   }
-  if (!is_fuchsia) {
+  if (!is_fuchsia && is_clang) {
     default_warning_flags += [
       "-Wno-non-c-typedef-for-linkage",
       "-Wno-range-loop-construct",
@@ -728,10 +768,14 @@ config("chromium_code") {
   if (is_win || is_wasm) {
     cflags = []
   } else {
-    cflags = [
-      "-Wall",
-      "-Wextra",
-    ]
+    cflags = []
+
+    if (!is_qnx) {
+      cflags = [
+        "-Wall",
+        "-Wextra",
+      ]
+    }
 
     # In Chromium code, we define __STDC_foo_MACROS in order to get the
     # C99 macros on Mac and Linux.

engine/src/build/toolchain/qnx/BUILD.gn

@@ -0,0 +1,22 @@
+# Copyright (c) 2013 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import("//build/toolchain/gcc_toolchain.gni")
+
+gcc_toolchain("qnx") {
+  asm = "qcc"
+  cc = "qcc"
+  cxx = "q++"
+
+  readelf = "readelf"
+  nm = "ntoaarch64-nm"
+  ar = "ntoaarch64-ar"
+  ld = "q++"
+  strip = "ntoaarch64-strip"
+
+  toolchain_cpu = "arm64"
+  toolchain_os = "linux"
+  is_clang = false
+}
+

engine/src/flutter/BUILD.gn

@@ -74,11 +74,15 @@ group("flutter") {
   testonly = true
 
   # Compile the engine.
-  public_deps = [
-    ":unittests",
-    "//flutter/shell/platform/embedder:flutter_engine",
-    "//flutter/sky",
-  ]
+  public_deps = []
+
+  if (!is_qnx) {
+    public_deps = [
+      ":unittests",
+      "//flutter/shell/platform/embedder:flutter_engine",
+      "//flutter/sky",
+    ]
+  }
 
   # Ensure the example for a sample embedder compiles.
   if (build_embedder_examples) {
@@ -93,7 +97,7 @@ group("flutter") {
   }
 
   # If enabled, compile the SDK / snapshot.
-  if (!is_fuchsia) {
+  if (!is_fuchsia && !is_qnx) {
     public_deps += [ "//flutter/lib/snapshot:generate_snapshot_bins" ]
 
     if (build_engine_artifacts) {
@@ -154,7 +158,7 @@ group("flutter") {
   }
 
   # Build the standalone Impeller library.
-  if (is_mac || is_linux || is_win || is_android) {
+  if (is_mac || is_linux || is_win || is_android || is_qnx) {
     public_deps += [ "//flutter/impeller/toolkit/interop:sdk" ]
   }
 

engine/src/flutter/ci/licenses_golden/licenses_flutter

@@ -51089,6 +51089,7 @@ ORIGIN: ../../../flutter/fml/platform/posix/native_library_posix.cc + ../../../f
 ORIGIN: ../../../flutter/fml/platform/posix/paths_posix.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/fml/platform/posix/posix_wrappers_posix.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/fml/platform/posix/process_posix.cc + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/fml/platform/qnx/paths_qnx.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/fml/platform/win/command_line_win.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/fml/platform/win/errors_win.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/fml/platform/win/errors_win.h + ../../../flutter/LICENSE
@@ -54109,6 +54110,7 @@ FILE: ../../../flutter/fml/platform/posix/native_library_posix.cc
 FILE: ../../../flutter/fml/platform/posix/paths_posix.cc
 FILE: ../../../flutter/fml/platform/posix/posix_wrappers_posix.cc
 FILE: ../../../flutter/fml/platform/posix/process_posix.cc
+FILE: ../../../flutter/fml/platform/qnx/paths_qnx.cc
 FILE: ../../../flutter/fml/platform/win/command_line_win.cc
 FILE: ../../../flutter/fml/platform/win/errors_win.cc
 FILE: ../../../flutter/fml/platform/win/errors_win.h

engine/src/flutter/display_list/BUILD.gn

@@ -280,36 +280,38 @@ if (enable_unittests) {
   }
 }
 
-source_set("display_list_benchmarks_source") {
-  testonly = true
+if (enable_unittests) {
+  source_set("display_list_benchmarks_source") {
+    testonly = true
 
-  sources = [
-    "benchmarking/dl_benchmarks.cc",
-    "benchmarking/dl_benchmarks.h",
-  ]
+    sources = [
+      "benchmarking/dl_benchmarks.cc",
+      "benchmarking/dl_benchmarks.h",
+    ]
 
-  deps = [
-    ":display_list",
-    ":display_list_fixtures",
-    "$dart_src/runtime:libdart_jit",  # for tracing
-    "//flutter/benchmarking",
-    "//flutter/common/graphics",
-    "//flutter/display_list/testing:display_list_surface_provider",
-    "//flutter/display_list/testing:display_list_testing",
-    "//flutter/fml",
-    "//flutter/skia",
-    "//flutter/testing:skia",
-    "//flutter/testing:testing_lib",
-  ]
-}
+    deps = [
+      ":display_list",
+      ":display_list_fixtures",
+      "$dart_src/runtime:libdart_jit",  # for tracing
+      "//flutter/benchmarking",
+      "//flutter/common/graphics",
+      "//flutter/display_list/testing:display_list_surface_provider",
+      "//flutter/display_list/testing:display_list_testing",
+      "//flutter/fml",
+      "//flutter/skia",
+      "//flutter/testing:skia",
+      "//flutter/testing:testing_lib",
+    ]
+  }
 
-executable("display_list_benchmarks") {
-  testonly = true
+  executable("display_list_benchmarks") {
+    testonly = true
 
-  deps = [ ":display_list_benchmarks_source" ]
+    deps = [ ":display_list_benchmarks_source" ]
+  }
 }
 
-if (is_ios) {
+if (is_ios && enable_unittests) {
   shared_library("ios_display_list_benchmarks") {
     testonly = true
     visibility = [ ":*" ]

engine/src/flutter/display_list/benchmarking/dl_complexity_helper.h

@@ -8,6 +8,7 @@
 #include "flutter/display_list/benchmarking/dl_complexity.h"
 #include "flutter/display_list/dl_blend_mode.h"
 #include "flutter/display_list/dl_op_receiver.h"
+#include "flutter/display_list/geometry/dl_path.h"
 #include "flutter/display_list/utils/dl_receiver_utils.h"
 
 namespace flutter {