How to build hotspot jtreg test JNI with specific CFLAGS?

[Severin Gehwolf]

Hi,

I'm trying to get a JNI library used for testing to be compiled with
certain CFLAGS. In particular, I'm trying to get it compiled on a GCC
platform with '-fomit-frame-pointer' and/or '-fomit-frame-pointer -O3'.
The patch currently looks like this:

diff --git a/make/test/JtregNativeHotspot.gmk b/make/test/JtregNativeHotspot.gmk
--- a/make/test/JtregNativeHotspot.gmk
+++ b/make/test/JtregNativeHotspot.gmk
@@ -139,6 +139,13 @@
     -I$(VM_TESTBASE_DIR)/nsk/share/native \
     -I$(VM_TESTBASE_DIR)/nsk/share/jni
 
+NO_FRAMEPOINTER_CFLAGS :=
+ifeq ($(OPENJDK_TARGET_OS),linux)
+   NO_FRAMEPOINTER_CFLAGS := -O3 -fomit-frame-pointer
+endif
+
+BUILD_HOTSPOT_JTREG_LIBRARIES_CFLAGS_libNoFramePointer := $(NO_FRAMEPOINTER_CFLAGS)
+
 BUILD_HOTSPOT_JTREG_LIBRARIES_CFLAGS_libProcessUtils := $(VM_SHARE_INCLUDES)
 
 BUILD_HOTSPOT_JTREG_LIBRARIES_CFLAGS_libThreadController := $(NSK_MONITORING_INCLUDES)

When I look at the compile command line this produces with 'make run-test', I see this:

$ cat ./build/linux-x86_64-normal-server-release/support/test/hotspot/jtreg/native/support/libNoFramePointer/libNoFramePointer.o.cmdline
/usr/bin/gcc -I/disk/openjdk/upstream-sources/openjdk-head/build/linux-x86_64-normal-server-release/support/modules_include/java.base -I/disk/openjdk/upstream-sources/openjdk-head/build/linux-x86_64-normal-server-release/support/modules_include/java.base/linux -I/disk/openjdk/upstream-sources/openjdk-head/src/java.base/share/native/libjava -I/disk/openjdk/upstream-sources/openjdk-head/src/java.base/unix/native/libjava -I/disk/openjdk/upstream-sources/openjdk-head/src/hotspot/share/include -I/disk/openjdk/upstream-sources/openjdk-head/src/hotspot/os/posix/include -pipe -D_GNU_SOURCE -D_REENTRANT -D_LARGEFILE64_SOURCE -DLINUX -DNDEBUG -Wall -Wextra -Wno-unused -Wno-unused-parameter -Wformat=2 -fno-strict-aliasing -m64 -D_LITTLE_ENDIAN -DARCH='"amd64"' -Damd64 -D_LP64=1 -fno-omit-frame-pointer -fno-delete-null-pointer-checks -fno-lifetime-dse -fPIC -O3 -fomit-frame-pointer -g -O2 -DTHIS_FILE='""' -c -MMD -MF /disk/openjdk/upstream-sources/openjdk-head/build/linux-x86_64-normal-server-release/support/test/hotspot/jtreg/native/support/libNoFramePointer/libNoFramePointer.d -o /disk/openjdk/upstream-sources/openjdk-head/build/linux-x86_64-normal-server-release/support/test/hotspot/jtreg/native/support/libNoFramePointer/libNoFramePointer.o /disk/openjdk/upstream-sources/openjdk-head/test/hotspot/jtreg/serviceability/sa/libNoFramePointer.c

The command line has '-O3 -fomit-frame-pointer -g -O2' in that order.
This screws things up since -O2 seems to override -fomit-frame-pointer. 
My guess is that -O2 is from OPTIMIZATION == LOW, but not sure. How can
I get this -O2 flag removed which apparently gets added later?

Thanks,
Severin