# HG changeset patch

# User sgehwolf

# Date 1536142767 -7200

#      Wed Sep 05 12:19:27 2018 +0200

# Node ID 7ea57274e55054579d1532e757edb21e67beed83

# Parent  3ee91722550680c18b977f0e00b1013323b5c9ef

8210416: [linux] Poor StrictMath performance due to non-optimized compilation

Summary: Compile fdlibm with -O2 -ffp-contract=off on gcc/clang arches.

Reviewed-by: aph, erikj, dholmes, darcy

diff --git a/make/autoconf/flags-cflags.m4 b/make/autoconf/flags-cflags.m4

--- a/make/autoconf/flags-cflags.m4

+++ b/make/autoconf/flags-cflags.m4

@@ -373,6 +373,18 @@

   FLAGS_SETUP_CFLAGS_CPU_DEP([BUILD], [OPENJDK_BUILD_])

+  COMPILER_FP_CONTRACT_OFF_FLAG="-ffp-contract=off"

+  # Check that the compiler supports -ffp-contract=off flag

+  # Set FDLIBM_CFLAGS to -ffp-contract=off if it does. Empty

+  # otherwise.

+  # These flags are required for GCC-based builds of

+  # fdlibm with optimization without losing precision.

+  # Notably, -ffp-contract=off needs to be added for GCC >= 4.6.

+  FLAGS_COMPILER_CHECK_ARGUMENTS(ARGUMENT: [${COMPILER_FP_CONTRACT_OFF_FLAG}],

+      IF_TRUE: [FDLIBM_CFLAGS=${COMPILER_FP_CONTRACT_OFF_FLAG}],

+      IF_FALSE: [FDLIBM_CFLAGS=""])

+  AC_SUBST(FDLIBM_CFLAGS)

+

   # Tests are only ever compiled for TARGET

   CFLAGS_TESTLIB="$CFLAGS_JDKLIB"

   CXXFLAGS_TESTLIB="$CXXFLAGS_JDKLIB"

diff --git a/make/autoconf/spec.gmk.in b/make/autoconf/spec.gmk.in

--- a/make/autoconf/spec.gmk.in

+++ b/make/autoconf/spec.gmk.in

@@ -450,6 +450,7 @@

 LIBJSIG_HASHSTYLE_LDFLAGS := @LIBJSIG_HASHSTYLE_LDFLAGS@

 LIBJSIG_NOEXECSTACK_LDFLAGS := @LIBJSIG_NOEXECSTACK_LDFLAGS@

+FDLIBM_CFLAGS := @FDLIBM_CFLAGS@

 JVM_CFLAGS := @JVM_CFLAGS@

 JVM_LDFLAGS := @JVM_LDFLAGS@

 JVM_ASFLAGS := @JVM_ASFLAGS@

diff --git a/make/lib/CoreLibraries.gmk b/make/lib/CoreLibraries.gmk

--- a/make/lib/CoreLibraries.gmk

+++ b/make/lib/CoreLibraries.gmk

@@ -39,20 +39,15 @@

   BUILD_LIBFDLIBM_OPTIMIZATION := HIGH

 endif

-ifeq ($(OPENJDK_TARGET_OS), linux)

-  ifeq ($(OPENJDK_TARGET_CPU), ppc64)

-    BUILD_LIBFDLIBM_OPTIMIZATION := HIGH

-  else ifeq ($(OPENJDK_TARGET_CPU), ppc64le)

-    BUILD_LIBFDLIBM_OPTIMIZATION := HIGH

-  else ifeq ($(OPENJDK_TARGET_CPU), s390x)

-    BUILD_LIBFDLIBM_OPTIMIZATION := HIGH

-  else ifeq ($(OPENJDK_TARGET_CPU), aarch64)

-    BUILD_LIBFDLIBM_OPTIMIZATION := HIGH

-  endif

+# If FDLIBM_CFLAGS is non-empty we know that we can optimize

+# fdlibm by adding those extra C flags. Currently GCC,

+# and clang only.

+ifneq ($(FDLIBM_CFLAGS), )

+  BUILD_LIBFDLIBM_OPTIMIZATION := LOW

 endif

 LIBFDLIBM_SRC := $(TOPDIR)/src/java.base/share/native/libfdlibm

-LIBFDLIBM_CFLAGS := -I$(LIBFDLIBM_SRC)

+LIBFDLIBM_CFLAGS := -I$(LIBFDLIBM_SRC) $(FDLIBM_CFLAGS)

 ifneq ($(OPENJDK_TARGET_OS), macosx)

   $(eval $(call SetupNativeCompilation, BUILD_LIBFDLIBM, \

@@ -64,10 +59,6 @@

       CFLAGS := $(CFLAGS_JDKLIB) $(LIBFDLIBM_CFLAGS), \

       CFLAGS_windows_debug := -DLOGGING, \

       CFLAGS_aix := -qfloat=nomaf, \

-      CFLAGS_linux_ppc64 := -ffp-contract=off, \

-      CFLAGS_linux_ppc64le := -ffp-contract=off, \

-      CFLAGS_linux_s390x := -ffp-contract=off, \

-      CFLAGS_linux_aarch64 := -ffp-contract=off, \

       DISABLED_WARNINGS_gcc := sign-compare misleading-indentation, \

       DISABLED_WARNINGS_microsoft := 4146 4244 4018, \

       ARFLAGS := $(ARFLAGS), \