The package is built with the CFLAGS/CXXFLAGS from our profiles but it also appends -O3. Since the last specified optimization level is effective, the package compiles with a higher optimization level than expected.

Example (relevant options are bold): /usr/bin/x86_64-pc-linux-gnu-g++ -MMD -MF /var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/build/linux-x86_64-normal-server-release/hotspot/variant-server/libjvm/objs/jvmciEnv.d.tmp -D_STDC_FORMAT_MACROS -DSTDC_LIMIT_MACROS -D_STDC_CONSTANT_MACROS -D_GNU_SOURCE -D_REENTRANT -pipe -fno-rtti -fno-exceptions -fvisibility=hidden -fno-strict-aliasing -fno-omit-frame-pointer -fcheck-new -fstack-protector -std=gnu++98 -DLIBC=gnu -DSUPPORTS_CLOCK_MONOTONIC -DLINUX -Wpointer-arith -Wsign-compare -Wunused-function -Wundef -Wformat=2 -Wunused-value -Woverloaded-virtual -Wreturn-type -fPIC -fmacro-prefix-map=/var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/= -DVM_LITTLE_ENDIAN -D_LP64=1 -fno-delete-null-pointer-checks -fno-lifetime-dse -Wno-format-zero-length -Wtype-limits -Wuninitialized -m64 -march=core2 -O2 -pipe -fcommon -DPRODUCT -DTARGET_ARCH_x86 -DINCLUDE_SUFFIX_OS=_linux -DINCLUDE_SUFFIX_CPU=_x86 -DINCLUDE_SUFFIX_COMPILER=_gcc -DTARGET_COMPILER_gcc -DAMD64 -DHOTSPOT_LIB_ARCH='"amd64"' -DCOMPILER1 -DCOMPILER2 -DINCLUDE_SHENANDOAHGC=0 -I/var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/build/linux-x86_64-normal-server-release/hotspot/variant-server/gensrc/adfiles -I/var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/src/hotspot/share -I/var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/src/hotspot/os/linux -I/var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/src/hotspot/os/posix -I/var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/src/hotspot/cpu/x86 -I/var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/src/hotspot/os_cpu/linux_x86 -I/var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/build/linux-x86_64-normal-server-release/hotspot/variant-server/gensrc -I/var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/src/hotspot/share/precompiled -I/var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/src/hotspot/share/include -I/var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/src/hotspot/os/posix/include -I/var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/build/linux-x86_64-normal-server-release/support/modules_include/java.base -I/var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/build/linux-x86_64-normal-server-release/support/modules_include/java.base/linux -I/var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/src/java.base/share/native/libjimage -m64 -march=core2 -O2 -pipe -fcommon -DDONT_USE_PRECOMPILED_HEADER --sysroot=/ -O3 -c -o /var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/build/linux-x86_64-normal-server-release/hotspot/variant-server/libjvm/objs/jvmciEnv.o /var/tmp/portage/dev-java/openjdk-11.0.16.1_p1/work/jdk-11.0.16.1+1-src/src/hotspot/share/jvmci/jvmciEnv.cpp