diff --git a/arm/arm.gni b/arm/arm.gni new file mode 100644 index 00000000..90b03608 --- /dev/null +++ b/arm/arm.gni @@ -0,0 +1,158 @@ +# Copyright 2022 The Chromium Authors and Alex313031. 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/config/chromeos/ui_mode.gni") +import("//build/config/v8_target_cpu.gni") + +# These are primarily relevant in current_cpu == "arm" contexts, where +# ARM code is being compiled. But they can also be relevant in the +# other contexts when the code will change its behavior based on the +# cpu it wants to generate code for. +if (current_cpu == "arm" || v8_current_cpu == "arm") { + declare_args() { + # Version of the ARM processor when compiling on ARM. Ignored on non-ARM + # platforms. + arm_version = 7 + + # The ARM architecture. This will be a string like "armv6" or "armv7-a". + # An empty string means to use the default for the arm_version. + arm_arch = "" + + # The ARM floating point hardware. This will be a string like "neon" or + # "vfpv3". An empty string means to use the default for the arm_version. + arm_fpu = "" + + # The ARM variant-specific tuning mode. This will be a string like "armv6" + # or "cortex-a15". An empty string means to use the default for the + # arm_version. + arm_tune = "" + + # Whether to use the neon FPU instruction set or not. + arm_use_neon = "" + + # Whether to enable optional NEON code paths. + arm_optionally_use_neon = false + + # Thumb is a reduced instruction set available on some ARM processors that + # has increased code density. + arm_use_thumb = true + } + + # For lacros build, we use ARM v8 by default. + if (is_chromeos_lacros && arm_arch == "") { + arm_version = 8 + arm_arch = "armv8-a+crc" + } + + if (current_os == "android" || target_os == "android") { + arm_float_abi = "softfp" + } else { + declare_args() { + # The ARM floating point mode. This is either the string "hard", "soft", + # or "softfp". An empty string means to use the default one for the + # arm_version. + arm_float_abi = "" + } + } + assert(arm_float_abi == "" || arm_float_abi == "hard" || + arm_float_abi == "soft" || arm_float_abi == "softfp") + + if (arm_use_neon == "") { + if (current_os == "linux" && target_cpu != v8_target_cpu) { + # Don't use neon on V8 simulator builds as a default. + arm_use_neon = false + } else { + arm_use_neon = true + } + } + + if (arm_version == 6) { + if (arm_arch == "") { + # v8 can still with version 6 but only with the armv6k extension. + arm_arch = "armv6k" + } + if (arm_tune != "") { + arm_tune = "" + } + if (arm_float_abi == "") { + arm_float_abi = "softfp" + } + if (arm_fpu == "") { + arm_fpu = "vfp" + } + arm_use_thumb = false + arm_use_neon = false + } else if (arm_version == 7) { + if (arm_arch == "") { + arm_arch = "armv7-a" + } + + if (arm_float_abi == "") { + if (current_os == "linux" && target_cpu != v8_target_cpu) { + # Default to the same as Android for V8 simulator builds. + arm_float_abi = "softfp" + } else { + arm_float_abi = "hard" + } + } + + if (arm_fpu == "") { + if (arm_use_neon) { + arm_fpu = "neon" + } else { + arm_fpu = "vfpv3-d16" + } + } + } else if (arm_version == 8) { + if (arm_arch == "") { + arm_arch = "armv8-a" + } + if (arm_tune == "") { + arm_tune = "generic-armv8-a" + } + + if (arm_float_abi == "") { + arm_float_abi = "hard" + } + + if (arm_fpu == "") { + if (arm_use_neon) { + arm_fpu = "neon" + } else { + arm_fpu = "vfpv3-d16" + } + } + } +} else if (current_cpu == "arm64" || v8_current_cpu == "arm64") { + # arm64 supports only "hard". + arm_version = 8 + arm_arch = "armv8-a" + arm_tune = "generic-armv8-a" + arm_float_abi = "hard" + arm_use_thumb = true + arm_use_neon = false + arm_optionally_use_neon = false + arm_fpu = "vfpv3-d16" + declare_args() { + # Enables the new Armv8 branch protection features. Valid strings are: + # - "pac": Enables Pointer Authentication Code (PAC, featured in Armv8.3) + # - "standard": Enables both PAC and Branch Target Identification (Armv8.5). + # - "none": No branch protection. + arm_control_flow_integrity = "standard" + + # TODO(cavalcantii): enable the feature for the following OSes next. + if (is_mac || is_chromeos || is_fuchsia || is_win || + target_cpu != "arm64") { + # target_cpu != "arm64" covers some cases (e.g. the ChromeOS x64 MSAN + # build) where the target platform is x64, but V8 is configured to use + # the arm64 simulator. Pointer authentication doesn't work properly + # in this mode (yet). + arm_control_flow_integrity = "none" + } + } + assert(arm_control_flow_integrity == "none" || + arm_control_flow_integrity == "standard" || + arm_control_flow_integrity == "pac", + "Invalid branch protection option") +}