RFR(xs): 8210320: PPC64: Fix uninitialized variable in C1 LIR assembler code

[Doerr, Martin]

Hi Gustavo,

it's not a real bug, just a build warning. But it needs to get fixed. Thanks for doing it. Reviewed.

Best regards,
Martin


-----Original Message-----
From: hotspot-compiler-dev <hotspot-compiler-dev-bounces at openjdk.java.net> On Behalf Of Gustavo Romero
Sent: Dienstag, 4. September 2018 15:42
To: hotspot-compiler-dev at openjdk.java.net
Cc: ppc-aix-port-dev at openjdk.java.net
Subject: RFR(xs): 8210320: PPC64: Fix uninitialized variable in C1 LIR assembler code
Importance: High

Hi,

May I please request reviews for this tiny change that fixes two
uninitialized variables in PPC64 C1 LIR code?

Bug   : https://bugs.openjdk.java.net/browse/JDK-8210320
Webrev: http://cr.openjdk.java.net/~gromero/8210320/v1/

GCC 4.8 does not complain about these two uninitialized pointers ('data'
and 'md') but more recent versions, like 5.4.0 and 7.3.1, complain about
it:

In file included from /home/gromero/hg/jdk/jdk/src/hotspot/share/c1/c1_Compilation.hpp:29:0,
                  from /home/gromero/hg/jdk/jdk/src/hotspot/share/precompiled/precompiled.hpp:286:
/home/gromero/hg/jdk/jdk/src/hotspot/share/ci/ciMethodData.hpp: In member function ‘void LIR_Assembler::emit_typecheck_helper(LIR_OpTypeCheck*, Label*, Label*, Label*)’:
/home/gromero/hg/jdk/jdk/src/hotspot/share/ci/ciMethodData.hpp:595:100: warning: ‘data’ may be used uninitialized in this function [-Wmaybe-uninitialized]
    int      byte_offset_of_slot(ciProfileData* data, ByteSize slot_offset_in_data) { return in_bytes(offset_of_slot(data, slot_offset_in_data)); }
                                                                                                     ^
/home/gromero/hg/jdk/jdk/src/hotspot/cpu/ppc/c1_LIRAssembler_ppc.cpp:2400:18: note: ‘data’ was declared here
    ciProfileData* data;
                   ^
/home/gromero/hg/jdk/jdk/src/hotspot/cpu/ppc/c1_LIRAssembler_ppc.cpp:2483:78: warning: ‘md’ may be used uninitialized in this function [-Wmaybe-uninitialized]
      type_profile_helper(mdo, mdo_offset_bias, md, data, recv, Rtmp1, success);
                                                                               ^

Thank you.

Best regards,
Gustavo