# Copyright 2019 The Fuchsia 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("//zircon/public/gn/prebuilt.gni")
import("//zircon/public/gn/toolchain/clang.gni")

# All the $current_cpu values that `current_os == "fuchsia"` supports.
standard_fuchsia_cpus = [
  "arm64",
  "x64",
]

# All the {cpu, os} combinations supported as build or SDK hosts.  The
# build will define toolchains for all of these.  Successful
# cross-compilation may require that a sysroot be installed and configured.
standard_build_hosts = [
  {
    cpu = "arm64"
    os = "linux"
  },
  {
    cpu = "x64"
    os = "linux"
  },
]

# Default value for $sysroot build argument.
standard_sysroot = []
foreach(host, standard_build_hosts) {
  standard_sysroot += [
    {
      cpu = host.cpu
      os = host.os
      sysroot = "$prebuilt_dir/third_party/sysroot/linux"
    },
  ]
}

declare_args() {
  # Path to Mac SDK.
  mac_sdk_path = ""
}

# Cross-compiling to Mac isn't possible because of the Mach-O linker.
if (host_os == "mac") {
  standard_build_hosts += [
    {
      cpu = host_cpu
      os = "mac"
    },
  ]
  if (mac_sdk_path == "") {
    mac_sdk_path = exec_script("/usr/bin/xcrun",
                               [
                                 "--sdk",
                                 "macosx",
                                 "--show-sdk-path",
                               ],
                               "trim string")
  }
  if (mac_sdk_path != "") {
    standard_sysroot += [
      {
        cpu = host_cpu
        os = "mac"
        sysroot = mac_sdk_path
      },
    ]
  }
}

# Universal configs that apply to all code in the build.
standard_configs = [
  "//build/config/zircon:compiler",
  "//build/config/zircon:language",
  "//build/config/zircon:machine",
  "//build/config/zircon:relative_paths",
  "//build/config/zircon:assert_level",
  "//build/config/zircon:default_optimize",
  "//build/config/zircon:default_debuginfo",
  "//build/config/zircon:default_warnings",
  "//build/config/zircon:default_icf",
  "//build/config/zircon:default_include_dirs",
  "//build/config/zircon:default_frame_pointers",
  "//build/config/zircon:default_linker_gc",
  "//build/config/zircon:default_template_backtrace_limit",
  "//build/config/zircon:no_exceptions",
  "//build/config/zircon:no_rtti",
  "//build/config/zircon:thread_safety_annotations",
  "//build/config/zircon:warn-implicit-fallthrough",
  "//build/config/zircon:visibility_hidden",
  "//build/config/zircon:auto_var_init",
  "//build/config/zircon:werror",

  {
    # Additional configs apply only to code built into shared libraries.
    # This means everything in a ${toolchain.shlib} toolchain, not just code
    # directly in the `sources` of a shared_library() or library() target.
    shlib = true
    add = [
      "//build/config/zircon:shared_library_config",
      "//build/config/zircon:no_undefined_symbols",
    ]
  },
]

# Additional configs apply to code built for Fuchsia but not to host code.
standard_fuchsia_configs = []

# See environment().  These are the environments that are
# vanilla bases to make derived environments from.
standard_environments = [
  {
    name = "host"
    targets = standard_build_hosts
    globals = {
      is_host = true
    }

    # Ensure that host binaries have __zx_panic.
    implicit_deps = [ "//zircon/system/ulib/zx-panic-libc" ]
    strip = true
  },
  {
    name = "user"
    targets = []
    foreach(cpu, standard_fuchsia_cpus) {
      targets += [
        {
          cpu = cpu
        },
      ]
    }
    configs = standard_fuchsia_configs
    configs += [
      "//build/config/zircon:user",
      {
        shlib = false
        add = [ "//build/config/zircon:user_executable" ]
      },
      {
        # All drivers use hidden visibility and the static standard C++ library.
        types = [
          "driver",
          "test_driver",
        ]
        add = [ "//build/config/zircon:static-libc++" ]
      },
    ]
    implicit_deps = [
      "//zircon/system/ulib/c",
      {
        types = [
          "executable",
          "host_tool",
          "test",
        ]
        add = [
          "//zircon/system/ulib/c:crt1",
          "//build/config/zircon:maybe_scudo_default_options",
        ]
      },
    ]
    shlib = true
    strip = "--strip-sections"
  },
]

# These `standard*variants` lists have the same structure as $variants (see
# //zircon/public/gn/toolchain/environment.gni) but it just supply definitions
# of variants with standard names.  The $variants list can refer to
# variants defined here by name, but these are not otherwise involved in
# variant selection.
standard_variants = []

# These are the baseline variants.  $default_variants refers only to things
# defined here.
standard_base_variants = [
  {
    variant = {
      name = "clang"
    }
  },
  {
    variant = {
      name = "gcc"
      tags = [ "gcc" ]
      globals = {
        is_gcc = true
      }
    }
  },
]
standard_variants += standard_base_variants

if (clang_tool_dir == "") {
  _llvm_symbolizer_path = "llvm-symbolizer"
} else {
  _llvm_symbolizer_path =
      rebase_path("$clang_tool_dir/llvm-symbolizer", root_build_dir)
}

# These are variants that use "sanitizer" instrumentation.
# They are interesting for e.g. fuzzer environments.
standard_sanitizer_variants = [
  {
    variant = {
      name = "asan"
      configs = [
        # ASan wants frame pointers because it captures stack traces
        # on allocations and such, not just on errors.
        {
          # First add and then remove both in case either is already there.
          add = [
            "//build/config/zircon:frame_pointers",
            "//build/config/zircon:default_frame_pointers",
          ]
          remove = add
        },

        # Now add frame_pointers back, only one and no default_frame_pointers.
        "//build/config/zircon:frame_pointers",
        "//zircon/public/gn/config/instrumentation:asan",
      ]
      toolchain_vars = {
        # This is the key for toolchain_runtime_deps() to find the right
        # shared library dependencies for the instrumentation.  Note that
        # the asan runtime includes ubsan but not vice versa, so this set
        # must be used in preference to ubsan when both are enabled.
        runtime_deps_cflags = [ "-fsanitize=address" ]

        # This is picked up by the runtime for host_tool_action() runs.
        host_run_env = [
          "/usr/bin/env",
          "ASAN_SYMBOLIZER_PATH=$_llvm_symbolizer_path",
        ]
      }
      implicit_deps = [
        {
          types = [
            "executable",
            "host_tool",
            "test",
          ]
          add = [
            "//zircon/public/gn/config/instrumentation:asan_default_options",
          ]
        },
      ]
      tags = [
        "asan",
        "instrumentation-runtime",
        "instrumented",
        "lsan",
        "replaces-allocator",
        "useronly",
      ]
    }
  },
  {
    variant = {
      name = "ubsan"
      configs = [
        {
          add = [ "//zircon/public/gn/config/instrumentation:ubsan" ]

          # The vptr instrumentation requires RTTI.  If -fno-rtti is passed
          # then this checking is implicitly disabled.  However, another
          # translation unit built without -fno-rtti will have the checking
          # enabled.  The -fno-rtti vtables are not compatible with the
          # checking at runtime, so a vtable from a -fno-rtti TU used by code
          # from a -frtti TU gets false positive failures.  Since the vtables
          # are emitted in multiple TUs in COMDAT and one implementation chosen
          # randomly at link time, there's no way to be sure the checking code
          # requiring RTTI uses its own RTTI-enabled vtables rather than other
          # non-RTTI vtables.  So just let RTTI be enabled everywhere, and then
          # get the vptr checking everywhere too.
          remove = [ "//zircon/public/gn/config:no_rtti" ]
        },
      ]
      toolchain_vars = {
        # This is the key for toolchain_runtime_deps() to find the right
        # shared library dependencies for the instrumentation.  Note that
        # the asan runtime includes ubsan but not vice versa, so this set
        # should be ignored and the asan set used instead.
        runtime_deps_cflags = [ "-fsanitize=undefined" ]

        # This is picked up by the runtime for host_tool_action() runs.
        # Note this is replaced with asan's setting as mentioned above.
        host_run_env = [
          "/usr/bin/env",
          "UBSAN_SYMBOLIZER_PATH=$_llvm_symbolizer_path",
        ]
      }
      implicit_deps = [
        {
          types = [
            "executable",
            "host_tool",
            "test",
          ]
          add = [
            "//zircon/public/gn/config/instrumentation:ubsan_default_options",
          ]

          # The asan runtime trumps the standalone ubsan runtime and the
          # `__ubsan_default_options()` would go unused.
          unless_configs = [ "//zircon/public/gn/config/instrumentation:asan" ]
        },
      ]
      tags = [
        "instrumentation-runtime",
        "instrumented",
        "useronly",
      ]
    }
  },
  {
    variant = {
      name = "asan-ubsan"
      bases = [
        # Note ubsan comes first so that asan's runtime_deps_cflags setting
        # can override it.  Later bases append to configs and
        # implicit_deps, but each toolchain_vars field just replaces any
        # value set by the earlier base.
        "ubsan",
        "asan",
      ]
    }
  },
]
standard_variants += standard_sanitizer_variants

# These are additional standard variants that are not likely to
# be interesting for special-purpose environments like fuzzers.
standard_variants += [
  {
    # TODO(fxbug.dev/30033): This is identical to "asan" except for having "kernel"
    # and not "useronly" in tags.  When kernel ASan is ready for prime
    # time, this will be removed and the "useronly" tag dropped from "asan"
    # so that a simple "asan" selector will enable it for kernel too.  For
    # now, it's easier to let a simple "kasan" selector enable kernel ASan
    # and not user ASan, and "asan" vice versa.
    variant = {
      name = "kasan"
      configs = [
        # ASan wants frame pointers because it captures stack traces
        # on allocations and such, not just on errors.
        {
          # First add and then remove both in case either is already there.
          add = [
            "//build/config/zircon:frame_pointers",
            "//build/config/zircon:default_frame_pointers",
          ]
          remove = add
        },

        # Now add frame_pointers back, only one and no default_frame_pointers.
        "//build/config/zircon:frame_pointers",

        # kasan disables safestack for all files built with instrumentation, so
        # we need to ensure that files built without instrumentation have a
        # consistent no_safestack setting.
        "//build/config/zircon:no_safestack",

        "//zircon/public/gn/config/instrumentation:asan",
      ]
      toolchain_vars = {
        # This is the key for toolchain_runtime_deps() to find the right
        # shared library dependencies for the instrumentation.  Note that
        # the asan runtime includes ubsan but not vice versa, so this set
        # must be used in preference to ubsan when both are enabled.
        runtime_deps_cflags = [ "-fsanitize=address" ]
      }
      implicit_deps = [
        {
          types = [
            "executable",
            "host_tool",
            "test",
          ]
          add = [
            "//zircon/public/gn/config/instrumentation:asan_default_options",
          ]
        },
      ]
      tags = [
        "instrumentation-runtime",
        "instrumented",
        "kernel",
      ]
    }
  },

  # TODO(fxbug.dev/30033): see above
  {
    variant = {
      name = "kasan-sancov"
      bases = [
        "kasan",
        "sancov",
      ]
    }
  },
  {
    variant = {
      name = "lto"
      configs = [ "//zircon/public/gn/config/lto" ]
      tags = [ "lto" ]
    }
  },
  {
    variant = {
      name = "thinlto"
      configs = [ "//zircon/public/gn/config/lto:thinlto" ]
      tags = [ "lto" ]
    }
  },
  {
    variant = {
      name = "profile"
      configs = [ "//zircon/public/gn/config/instrumentation:profile" ]
      implicit_deps =
          [ "//zircon/public/gn/config/instrumentation:profile_deps" ]
      tags = [
        "instrumented",

        # TODO(fxbug.dev/27321): The instrumentation metadata sections are not put
        # into section groups properly under -ffunction-sections.  This
        # means that links (like the x86 kernel's) that rely for their
        # correctness on --gc-sections pruning dead code with dangling
        # references won't work.
        "breaks-gc-sections",
      ]
    }
  },
  {
    variant = {
      name = "sancov"
      configs = [ "//zircon/public/gn/config/instrumentation:sancov" ]

      # The "sancov" tag is important: see //zircon/system/ulib/c/sanitizers.
      tags = [
        "instrumentation-runtime",
        "instrumented",
        "sancov",
      ]

      # When no other sanitizer is enabled, clang links in the ubsan
      # runtime to provide the sancov runtime.
      toolchain_vars = {
        runtime_deps_cflags = [ "-fsanitize=undefined" ]
      }
    }
  },
  {
    variant = {
      name = "ubsan-sancov"
      bases = [
        "ubsan",
        "sancov",
      ]
    }
  },
  {
    variant = {
      name = "ubsan-sancov-full"
      bases = [
        "ubsan",
        "sancov",
      ]
      configs = [ "//zircon/public/gn/config/instrumentation:sancov-full" ]

      # The kernel provides runtime for sancov but not for sancov-full.
      tags = [ "useronly" ]
    }
  },
]

# This list is appended to the $variants list for the build.  It provides
# default selectors that match if nothing else does.  The first catch-all
# selector must be compatible with all environments used in
# environment_redirect(),
default_variants = [
  # Use Clang as default for both host and the target.
  "clang",
]

# default_variants only refers to variants in standard_base_variants.
foreach(default, default_variants) {
  if (default == "$default") {
    _default = default
  } else {
    _default = default.variant
  }
  assert(_default == "$_default")
  foreach(selector, standard_base_variants) {
    _variant = {
      # Clear from last iteration.
    }
    _variant = selector.variant
    if (_default == _variant.name) {
      _default = true
    }
  }
  assert(_default == true)
}

# Define shorthand selectors that can be used in $variants, which see.
# This is a list of scopes.  Each scope defines one shorthand.
#
#   name
#     Required: The name that matches a string element of $variants (or the
#     part of an element before the slash).
#     Type: string
#
#   selectors
#     Required: The expansion, a list of selectors.  An element of $variants
#     that matches $name is removed and the $selectors list is spliced into the
#     list in its place.  An element that matches "$name/something" is instead
#     replaced by this $selectors list with `output_name = "something"` added
#     to each element.
#     Type: See $variants.
#
variant_shorthands = [
  {
    name = "host_gcc"
    selectors = [
      {
        variant = "gcc"
        host = true
      },
    ]
  },
  {
    name = "host_asan"
    selectors = [
      {
        variant = "asan"
        host = true
      },
    ]
  },
  {
    name = "host_asan-ubsan"
    selectors = [
      {
        variant = "asan-ubsan"
        host = true
      },
    ]
  },
  {
    name = "host_profile"
    selectors = [
      {
        variant = "profile"
        host = true
      },
    ]
  },
  {
    name = "asan_drivers"
    selectors = [
      {
        variant = "asan"
        target_type = [ "driver" ]
      },
    ]
  },
]