On Mon, 27 Feb 2023 11:49:27 GMT, Jayathirth D V <j...@openjdk.org> wrote:
> Under https://bugs.openjdk.org/browse/JDK-8264846 we moved to -O3 level of > gcc optimizations from -O1 level for libawt build. This improved our J2DBench > performance numbers in some options considerably. > > Recent changes done under https://bugs.openjdk.org/browse/JDK-8299337 causes > difference in generated code by gcc and this is resulting in performance > regression for bimg_misc-* J2DBench options in our performance servers. Under > https://bugs.openjdk.org/browse/JDK-8299337 we have just removed unused > variables and it is a cleanup task. > > We can force gcc to generate position independent code by using -fpic > option.Also i have removed -fgcse-after-reload option for gcc, because this > is by default covered under -O3 level of optimization introduced under > https://bugs.openjdk.org/browse/JDK-8264846. > > With this change bimg_misc-* J2DBench option performance regression is > resolved and there are no regression in other options of J2DBench or > SwingMark and it is verified in our performance servers. make/modules/java.desktop/lib/Awt2dLibraries.gmk line 132: > 130: # that any cleanup of code related to AWT will not change the > 131: # generated code and cause performance issues in J2DBench > 132: LIBAWT_CFLAGS += -fpic We compile with `-fPIC` as a standard flag for position independent code (I just verified that LIBAWT also gets this flag today). My understanding is that `-fpic` may result in smaller/faster code. Overriding with `-fpic` seems like its helping here, but the comment needs to be fixed to explain the actual difference and reason. ------------- PR: https://git.openjdk.org/jdk/pull/12761
