FDO: support linux-x86 target

Change-Id: I4a3a1d298176da109df316cf9128f19e77490bc9

core/combo/TARGET_linux-x86.mk

@@ -63,6 +63,8 @@ endif
 ifneq ($(wildcard $(TARGET_CC)),)
 TARGET_LIBGCC := \
 	$(shell $(TARGET_CC) -m32 -print-file-name=libgcc.a)
+target_libgcov := $(shell $(TARGET_CC) $(TARGET_GLOBAL_CFLAGS) \
+	-print-file-name=libgcov.a)
 endif
 
 TARGET_NO_UNDEFINED_LDFLAGS := -Wl,--no-undefined
@@ -72,6 +74,34 @@ libm_root := bionic/libm
 libstdc++_root := bionic/libstdc++
 libthread_db_root := bionic/libthread_db
 
+# Define FDO (Feedback Directed Optimization) options.
+
+TARGET_FDO_CFLAGS:=
+TARGET_FDO_LIB:=
+
+ifneq ($(strip $(BUILD_FDO_INSTRUMENT)),)
+  # Set BUILD_FDO_INSTRUMENT=true to turn on FDO instrumentation.
+  # The profile will be generated on /data/local/tmp/profile on the device.
+  TARGET_FDO_CFLAGS := -fprofile-generate=/data/local/tmp/profile -DANDROID_FDO
+  TARGET_FDO_LIB := $(target_libgcov)
+else
+  # If BUILD_FDO_INSTRUMENT is turned off, then consider doing the FDO optimizations.
+  # Set TARGET_FDO_PROFILE_PATH to set a custom profile directory for your build.
+  ifeq ($(strip $(TARGET_FDO_PROFILE_PATH)),)
+    TARGET_FDO_PROFILE_PATH := fdo/profiles/$(TARGET_ARCH)/$(TARGET_ARCH_VARIANT)
+  else
+    ifeq ($(strip $(wildcard $(TARGET_FDO_PROFILE_PATH))),)
+      $(warning Custom TARGET_FDO_PROFILE_PATH supplied, but directory does not exist. Turn off FDO.)
+    endif
+  endif
+
+  # If the FDO profile directory can't be found, then FDO is off.
+  ifneq ($(strip $(wildcard $(TARGET_FDO_PROFILE_PATH))),)
+    TARGET_FDO_CFLAGS := -fprofile-use=$(TARGET_FDO_PROFILE_PATH) -DANDROID_FDO
+    TARGET_FDO_LIB := $(target_libgcov)
+  endif
+endif
+
 # unless CUSTOM_KERNEL_HEADERS is defined, we're going to use
 # symlinks located in out/ to point to the appropriate kernel
 # headers. see 'config/kernel_headers.make' for more details
@@ -191,6 +221,7 @@ $(hide) $(PRIVATE_CXX) \
 	$(call normalize-target-libraries,$(PRIVATE_ALL_STATIC_LIBRARIES)) \
 	$(if $(PRIVATE_GROUP_STATIC_LIBRARIES),-Wl$(comma)--end-group) \
 	$(PRIVATE_TARGET_LIBGCC) \
+	$(PRIVATE_TARGET_FDO_LIB) \
 	$(call normalize-target-libraries,$(PRIVATE_ALL_SHARED_LIBRARIES)) \
 	-o $@ \
 	$(PRIVATE_LDFLAGS) \
@@ -216,6 +247,7 @@ $(hide) $(PRIVATE_CXX) \
 	$(call normalize-target-libraries,$(PRIVATE_ALL_STATIC_LIBRARIES)) \
 	$(if $(PRIVATE_GROUP_STATIC_LIBRARIES),-Wl$(comma)--end-group) \
 	$(PRIVATE_TARGET_LIBGCC) \
+	$(PRIVATE_TARGET_FDO_LIB) \
 	$(call normalize-target-libraries,$(PRIVATE_ALL_SHARED_LIBRARIES)) \
 	-o $@ \
 	$(PRIVATE_LDFLAGS) \
@@ -237,6 +269,7 @@ $(hide) $(PRIVATE_CXX) \
 	-Wl,--no-whole-archive \
 	-Wl,--start-group \
 	$(call normalize-target-libraries,$(PRIVATE_ALL_STATIC_LIBRARIES)) \
+	$(PRIVATE_TARGET_FDO_LIB) \
 	$(PRIVATE_TARGET_LIBGCC) \
 	-Wl,--end-group \
 	$(if $(filter true,$(PRIVATE_NO_CRT)),,$(PRIVATE_TARGET_CRTEND_O))