RFR: 8210703: vmStructs.cpp compiled with -O0 (was: Why is vmStructs.cpp compiled with -O0?

[Severin Gehwolf]

Hi Magnus,

On Thu, 2018-09-13 at 13:52 +0200, Magnus Ihse Bursie wrote:
> Severin,
> 
> Your patch looks good to me. I'm assuming you have tested that nothing breaks. 

Thanks for the review!

Yes, I've tested with run-test-tier1 which seems OK. It includes
serviceability/sa/ClhsdbVmStructsDump. I've also run VMStructs gtest.
I'm currently running this through jdk-submit.

Thanks,
Severin

> /Magnus
> 
> > 13 sep. 2018 kl. 10:43 skrev Severin Gehwolf <sgehwolf at redhat.com>:
> > 
> > Hi Erik,
> > 
> > > On Wed, 2018-09-12 at 10:25 -0700, Erik Joelsson wrote:
> > > Hello,
> > > 
> > > I very much doubt it was included with the new build system. We were 
> > > extremely careful to use the exact same flags then, and did binary 
> > > comparisons of all object files to verify equal builds.
> > > 
> > > Tracing back, it was caused (probably unintentionally) by this change:
> > > 
> > > http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/e796d52ca85b
> > 
> > Thanks for the detective work! This looks very much unintentional to me
> > as JDK-8114853 is about silencing a note.
> > 
> > > In the old build, setting OPT_CFLAGS/<file> overrides the common 
> > > OPT_CFLAGS. In the new build, we have a more general way of adding flags 
> > > for specific files that does not directly override any other flags. To 
> > > get the same behavior for vmStructs.cpp in the new build as in the old 
> > > at the time of the switch, we had to add -O0 explicitly in the new build.
> > 
> > I've filed JDK-8210703 and posting this patch as review for the bug.
> > Note I've changed the subject. Does this look OK?
> > 
> > diff --git a/make/hotspot/lib/JvmOverrideFiles.gmk b/make/hotspot/lib/JvmOverrideFiles.gmk
> > --- a/make/hotspot/lib/JvmOverrideFiles.gmk
> > +++ b/make/hotspot/lib/JvmOverrideFiles.gmk
> > @@ -30,7 +30,7 @@
> > # status for individual files on specific platforms.
> > 
> > ifeq ($(TOOLCHAIN_TYPE), gcc)
> > -  BUILD_LIBJVM_vmStructs.cpp_CXXFLAGS := -fno-var-tracking-assignments -O0
> > +  BUILD_LIBJVM_vmStructs.cpp_CXXFLAGS := -fno-var-tracking-assignments
> >   BUILD_LIBJVM_jvmciCompilerToVM.cpp_CXXFLAGS := -fno-var-tracking-assignments
> >   BUILD_LIBJVM_jvmciCompilerToVMInit.cpp_CXXFLAGS := -fno-var-tracking-assignments
> >   BUILD_LIBJVM_assembler_x86.cpp_CXXFLAGS := -Wno-maybe-uninitialized
> > 
> > Thanks,
> > Severin
> > 
> > On 2018-09-12 09:13, Severin Gehwolf wrote:
> > > > Hi,
> > > > 
> > > > Does anybody know why vmStructs.cpp gets an override in
> > > > JvmOverrideFiles.gmk:
> > > > 
> > > > $ grep -C3 -n vmStructs.cpp make/hotspot/lib/JvmOverrideFiles.gmk
> > > > 30-# status for individual files on specific platforms.
> > > > 31-
> > > > 32-ifeq ($(TOOLCHAIN_TYPE), gcc)
> > > > 33:  BUILD_LIBJVM_vmStructs.cpp_CXXFLAGS := -fno-var-tracking-assignments -O0
> > > > 34-  BUILD_LIBJVM_jvmciCompilerToVM.cpp_CXXFLAGS := -fno-var-tracking-assignments
> > > > 35-  BUILD_LIBJVM_jvmciCompilerToVMInit.cpp_CXXFLAGS := -fno-var-tracking-assignments
> > > > 36-  BUILD_LIBJVM_assembler_x86.cpp_CXXFLAGS := -Wno-maybe-uninitialized
> > > > 
> > > > It seems to have been introduced with the new build system. JDK 8
> > > > doesn't seem to have it. Thoughts?
> > > > 
> > > > Thanks,
> > > > Severin
> 
>