8304893: Link Time Optimization with gcc can be faster

Reviewed-by: dholmes, erikj

Author: TheShermanTanker

make/autoconf/flags-ldflags.m4

@@ -70,7 +70,7 @@ AC_DEFUN([FLAGS_SETUP_LDFLAGS_HELPER],
       fi
     fi
 
-    BASIC_LDFLAGS_JVM_ONLY="-Wl,-O1"
+    BASIC_LDFLAGS_JVM_ONLY=""
 
   elif test "x$TOOLCHAIN_TYPE" = xclang; then
     BASIC_LDFLAGS_JVM_ONLY="-mno-omit-leaf-frame-pointer -mstack-alignment=16 \

make/hotspot/lib/JvmFeatures.gmk

@@ -169,8 +169,12 @@ ifeq ($(call check-jvm-feature, link-time-opt), true)
   # later on if desired
   JVM_OPTIMIZATION := HIGHEST_JVM
   ifeq ($(call isCompiler, gcc), true)
-    JVM_CFLAGS_FEATURES += -flto -fuse-linker-plugin
-    JVM_LDFLAGS_FEATURES += -flto -fuse-linker-plugin -fno-strict-aliasing
+    JVM_CFLAGS_FEATURES += -flto=auto -fuse-linker-plugin -fno-strict-aliasing -fno-fat-lto-objects
+    JVM_LDFLAGS_FEATURES += $(CXX_O_FLAG_HIGHEST_JVM) -flto=auto -fuse-linker-plugin -fno-strict-aliasing
+  endif
+else
+  ifeq ($(call isCompiler, gcc), true)
+    JVM_LDFLAGS_FEATURES += -O1
   endif
 endif