arm: compile all thumb with -mthumb-interwork and cleanup -O3

To enable this option use ENABLE_ARM_THUMB_INTERWORK := true

This may slightly increase binary size but will include more arm
instructions for increased performance.

https://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html

Change-Id: I0ba0a2d34b84e34309c20ce0cbb85ea3ee6dda15
Signed-off-by: Paul Beeler <pbeeler80@gmail.com>

core/binary.mk

@@ -114,6 +114,13 @@ endif
 
 # Include custom gcc flags.  Seperate them so they can be easily managed.
 
+# arm thumb
+ifeq ($(strip $(ENABLE_ARM_THUMB_INTERWORK)),true)
+  ifneq ($(strip $(LOCAL_IS_HOST_MODULE)),true)
+    include $(BUILD_SYSTEM)/thumb_interwork.mk
+  endif
+endif
+
 # O3
 ifeq ($(strip $(O3_OPTIMIZATIONS)),true)
   include $(BUILD_SYSTEM)/O3.mk

core/thumb_interwork.mk

@@ -0,0 +1,41 @@
+# Copyright (C) 2014-2015 The SaberMod 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.
+#
+
+# Copyright (C) 2014-2015 The SaberMod 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.
+#
+
+ifeq ($(strip (TARGET_ARCH)),arm)
+  ifneq (1,$(words $(filter $(LOCAL_DISABLE_THUMB_INTERWORK),$(LOCAL_MODULE))))
+    ifdef LOCAL_CFLAGS
+      LOCAL_CFLAGS += \
+        -mthumb-interwork
+    else
+      LOCAL_CFLAGS := \
+        -mthumb-interwork
+    endif
+  endif
+endif