Hi, Could I please get a review for this 8u backport related to fdlibm optimization on Linux? The JDK 12 patch doesn't apply as-is as the JDK 8 build system is drastically different from JDK 11+.
Bug: https://bugs.openjdk.java.net/browse/JDK-8210416 webrev: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8210416/jdk8/02/ The main differences to the original fix are: a) optimization level and b) additional hook for older GCC. This backport keeps the optimization level at -O3 (HIGH) over -O2 (LOW) for JDK 8u as this would otherwise regress Linux ppc64{,le} which currently use -O3. As the current code has the implicit assumption of ppc64 being compiled on older GCCs too (JDK-8172053), this backport maintains compatibility in this regard. If -ffp-contract=off is not available, a machine specific set of flags is being used if the compiler supports them (-mno-fused-madd -fno-strict- aliasing). For older GCCs (< 4.6) specific machine flags are being used. That is, for ppc64{,le} and x86{,_64}. ppc64{,le} machine specific flags have already been determined (See JDK-8172053). x86_64 and x86 have the same machine specific flags available, so I've used them there too[1]. Testing: build/test on gcc 8.x Linux x86_64. build/test on gcc 4.4.7 x86_64/ppc64. Manual inspection of build logs for fdlibm files (e.g. w_asin.c). Thoughts? Thanks, Severin [1] https://gcc.gnu.org/onlinedocs/gcc-4.4.7/gcc/i386-and-x86_002d64-Options.html#i386-and-x86_002d64-Options
