Add ARM32 device Rust toolchain.

Bug: 141207434
Test: build example rust device module.
Change-Id: I2d5b45ba09f386e1c7da7d7cdc58f13f31135863

Android.bp

@@ -333,6 +333,7 @@ bootstrap_go_package {
         "soong-cc-config",
     ],
     srcs: [
+        "rust/config/arm_device.go",
         "rust/config/arm64_device.go",
         "rust/config/global.go",
         "rust/config/toolchain.go",

rust/config/arm_device.go

@@ -0,0 +1,92 @@
+// Copyright 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package config
+
+import (
+	"strings"
+
+	"android/soong/android"
+)
+
+var (
+	ArmRustFlags            = []string{}
+	ArmArchFeatureRustFlags = map[string][]string{}
+	ArmLinkFlags            = []string{
+		"-Wl,--icf=safe",
+		"-Wl,-m,armelf",
+	}
+
+	ArmArchVariantRustFlags = map[string][]string{
+		"armv7-a":      []string{},
+		"armv7-a-neon": []string{},
+		"armv8-a":      []string{},
+		"armv8-2a":     []string{},
+	}
+)
+
+func init() {
+	registerToolchainFactory(android.Android, android.Arm, ArmToolchainFactory)
+
+	pctx.StaticVariable("ArmToolchainRustFlags", strings.Join(ArmRustFlags, " "))
+	pctx.StaticVariable("ArmToolchainLinkFlags", strings.Join(ArmLinkFlags, " "))
+
+	for variant, rustFlags := range ArmArchVariantRustFlags {
+		pctx.StaticVariable("Arm"+variant+"VariantRustFlags",
+			strings.Join(rustFlags, " "))
+	}
+
+}
+
+type toolchainArm struct {
+	toolchain64Bit
+	toolchainRustFlags string
+}
+
+func (t *toolchainArm) RustTriple() string {
+	return "arm-linux-androideabi"
+}
+
+func (t *toolchainArm) ToolchainLinkFlags() string {
+	return "${config.DeviceGlobalLinkFlags} ${config.ArmToolchainLinkFlags}"
+}
+
+func (t *toolchainArm) ToolchainRustFlags() string {
+	return t.toolchainRustFlags
+}
+
+func (t *toolchainArm) RustFlags() string {
+	return "${config.ArmToolchainRustFlags}"
+}
+
+func (t *toolchainArm) Supported() bool {
+	return true
+}
+
+func ArmToolchainFactory(arch android.Arch) Toolchain {
+	toolchainRustFlags := []string{
+		"${config.ArmToolchainRustFlags}",
+		"${config.Arm" + arch.ArchVariant + "VariantRustFlags}",
+	}
+
+	toolchainRustFlags = append(toolchainRustFlags, deviceGlobalRustFlags...)
+
+	for _, feature := range arch.ArchFeatures {
+		toolchainRustFlags = append(toolchainRustFlags, ArmArchFeatureRustFlags[feature]...)
+	}
+
+	return &toolchainArm{
+		toolchainRustFlags: strings.Join(toolchainRustFlags, " "),
+	}
+}