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

[Magnus Ihse Bursie]

Severin,

Your patch looks good to me. I'm assuming you have tested that nothing breaks. 

/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
>