From ca80a0a39a30ccff27f0a71a7117f0376255cbdf Mon Sep 17 00:00:00 2001
From: klzgrad <kizdiv@gmail.com>
Date: Tue, 19 May 2020 23:42:14 +0800
Subject: [PATCH] build: Support -mcpu= on ARM and ARM64

---
 src/build/config/arm.gni           |  5 +++++
 src/build/config/compiler/BUILD.gn | 16 ++++++++++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/build/config/arm.gni b/src/build/config/arm.gni
index b50fd629ff..7760e829f2 100644
--- a/src/build/config/arm.gni
+++ b/src/build/config/arm.gni
@@ -37,6 +37,8 @@ if (current_cpu == "arm" || v8_current_cpu == "arm") {
     # Thumb is a reduced instruction set available on some ARM processors that
     # has increased code density.
     arm_use_thumb = true
+
+    arm_cpu = ""
   }
 
   # For lacros build, we use ARM v8 by default.
@@ -128,6 +130,9 @@ if (current_cpu == "arm" || v8_current_cpu == "arm") {
   # arm64 supports only "hard".
   arm_float_abi = "hard"
   arm_use_neon = true
+  declare_args() {
+    arm_cpu = ""
+  }
   declare_args() {
     # Enables the new Armv8 branch protection features. Valid strings are:
     # - "pac": Enables Pointer Authentication Code (PAC, featured in Armv8.3)
diff --git a/src/build/config/compiler/BUILD.gn b/src/build/config/compiler/BUILD.gn
index ebe4a1fe06..a56fe6eefa 100644
--- a/src/build/config/compiler/BUILD.gn
+++ b/src/build/config/compiler/BUILD.gn
@@ -720,7 +720,11 @@ config("compiler") {
     # TODO(pcc): The contents of .ARM.attributes should be based on the
     # -march flag passed at compile time (see llvm.org/pr36291).
     if (current_cpu == "arm") {
-      ldflags += [ "-march=$arm_arch" ]
+      if (arm_cpu != "") {
+        ldflags += [ "-mcpu=$arm_cpu" ]
+      } else {
+        ldflags += [ "-march=$arm_arch" ]
+      }
     }
   }
 
@@ -931,9 +935,14 @@ config("compiler_cpu_abi") {
       }
       if (!is_nacl) {
         cflags += [
-          "-march=$arm_arch",
           "-mfloat-abi=$arm_float_abi",
         ]
+        if (arm_cpu != "") {
+          cflags += [ "-mcpu=$arm_cpu" ]
+        } else {
+          cflags += [ "-march=$arm_arch" ]
+        }
+        ldflags += [ "-mfloat-abi=$arm_float_abi" ]
       }
       if (arm_tune != "") {
         cflags += [ "-mtune=$arm_tune" ]
@@ -948,6 +957,9 @@ config("compiler_cpu_abi") {
         # Outline atomics crash on Exynos 9810. http://crbug.com/1272795
         cflags += [ "-mno-outline-atomics" ]
       }
+      if (arm_cpu != "") {
+        cflags += [ "-mcpu=$arm_cpu" ]
+      }
     } else if (current_cpu == "mipsel" && !is_nacl) {
       ldflags += [ "-Wl,--hash-style=sysv" ]
       if (custom_toolchain == "") {