RFR: 8316893: Compile without -fno-delete-null-pointer-checks

[Kim Barrett]

On Fri, 29 Sep 2023 10:01:42 GMT, Daniel Jeliński <djelinski at openjdk.org> wrote:

> Please review this patch that reenables `delete-null-pointer-checks` optimization in GCC and Clang.
> 
> It also disables `nonnull-compare` warning that is now triggered in debug builds. The problematic code will be addressed by #15927.
> 
> Mach5 Tier1-5 testing clean.

Changes requested by kbarrett (Reviewer).

make/autoconf/flags-cflags.m4 line 923:

> 921: AC_DEFUN([FLAGS_SETUP_GCC6_COMPILER_FLAGS],
> 922: [
> 923:   # This flags is required for GCC 6 builds as undefined behavior in OpenJDK code

s/flags/flag/

make/hotspot/lib/CompileJvm.gmk line 165:

> 163:     DISABLED_WARNINGS_gcc := $(DISABLED_WARNINGS_gcc), \
> 164:     DISABLED_WARNINGS_gcc_ad_$(HOTSPOT_TARGET_CPU_ARCH).cpp := nonnull, \
> 165:     DISABLED_WARNINGS_gcc_ad_$(HOTSPOT_TARGET_CPU_ARCH)_pipeline.cpp := nonnull-compare, \

How about just waiting for the fix for JDK-8316907 to go in before doing this one, rather than adding these
temporary warning disables.

-------------

PR Review: https://git.openjdk.org/jdk/pull/15982#pullrequestreview-1651834961
PR Review Comment: https://git.openjdk.org/jdk/pull/15982#discussion_r1342076844
PR Review Comment: https://git.openjdk.org/jdk/pull/15982#discussion_r1342077053