# HG changeset patch
# User manc
# Date 1552098112 28800
#      Fri Mar 08 18:21:52 2019 -0800
# Node ID 8083ba97fe291c38be4dd17eda4dd6ef862562c8
# Parent  687e10fefa11b715d9f9cdf6ae6ddde954cf6b50
8220388: Increase -inlinehint-threshold for Clang to avoid G1 pause time regression
Summary: Make Clang inline more aggressively for functions with inline keyword
Reviewed-by:

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
@@ -535,6 +535,13 @@
     # works for all platforms.
     TOOLCHAIN_CFLAGS_JVM="$TOOLCHAIN_CFLAGS_JVM -mno-omit-leaf-frame-pointer -mstack-alignment=16"
 
+    if test "x$DEBUG_LEVEL" = xrelease; then
+      # Clang does not inline as much as GCC does for functions with "inline" keyword by default.
+      # This causes noticeable slowdown in pause time for G1, and possibly in other areas.
+      # Increasing the inline hint threshold avoids the slowdown for Clang-built JVM.
+      TOOLCHAIN_CFLAGS_JVM="$TOOLCHAIN_CFLAGS_JVM -mllvm -inlinehint-threshold=100000"
+    fi
+
     if test "x$OPENJDK_TARGET_OS" = xlinux; then
       TOOLCHAIN_CFLAGS_JDK="-pipe"
       TOOLCHAIN_CFLAGS_JDK_CONLY="-fno-strict-aliasing" # technically NOT for CXX