Warnings Cleanup in Hotspot
Calvin Cheung
calvin.cheung at oracle.com
Thu May 16 11:55:21 PDT 2013
Jeremy,
It seems your suggested patch is incomplete as the build on linux was
failing.
Recall that warnings are treated as errors as in gcc.make:
# Compiler warnings are treated as errors
WARNINGS_ARE_ERRORS = -Werror
Below is the list of files I needed to change for the build to go
through on linux:
make/linux/makefiles/gcc.make
src/share/vm/c1/c1_IR.cpp
src/share/vm/ci/ciUtilities.hpp
src/share/vm/classfile/genericSignatures.cpp
src/share/vm/classfile/verifier.hpp
src/share/vm/code/nmethod.cpp
src/share/vm/memory/cardTableModRefBS.cpp
src/share/vm/memory/universe.cpp
src/share/vm/oops/constantPool.cpp
src/share/vm/prims/forte.cpp
src/share/vm/runtime/perfData.hpp
src/share/vm/runtime/sharedRuntime.cpp
src/share/vm/services/diagnosticArgument.cpp
src/share/vm/utilities/exceptions.hpp
src/share/vm/utilities/taskqueue.hpp
Most of the warnings are related to: "statement has no effect"
e.g. in exceptions.hpp, I needed to change
#define CHECK THREAD); if
(HAS_PENDING_EXCEPTION) return ; (0
to
#define CHECK THREAD); if
(HAS_PENDING_EXCEPTION) return ; (void)(0
I don't want to share webrev yet since I haven't built on other
platforms and haven't done any testing on the change.
2 ways I'm thinking of fixing it:
1) include the -Wunused-value warning flag
this means changes are required on the files listed above
2) not include the -Wunused-value warning flag but only fixing the
potential coding errors which would impact functionality as you pointed
out in your email. This should result in a smaller changeset.
Calvin
On 5/16/2013 10:55 AM, Jeremy Manson wrote:
> Okay. Is there anything you want me to do?
>
> Jeremy
>
>
> On Wed, May 15, 2013 at 2:37 PM, Calvin Cheung
> <calvin.cheung at oracle.com <mailto:calvin.cheung at oracle.com>> wrote:
>
> Jeremy,
>
> We'll fix it in hs25 first and then backport it to hs24 if the fix
> is applicable there.
>
> Calvin
>
>
> On 5/15/2013 2:14 PM, Jeremy Manson wrote:
>> Thanks, Calvin. What does followup look like?
>>
>> Jeremy
>>
>>
>> On Mon, May 13, 2013 at 9:59 AM, Calvin Cheung
>> <calvin.cheung at oracle.com <mailto:calvin.cheung at oracle.com>> wrote:
>>
>> Hi Jeremy,
>>
>> I've created 8014431 (cleanup warnings indicated by the
>> -Wunused-value compiler option on linux) to track this. It'll
>> take a few hours for it to show up in the bugs.sun.com
>> <http://bugs.sun.com>
>> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8014431
>>
>> Calvin
>>
>>
>> On 5/10/2013 11:38 AM, Jeremy Manson wrote:
>>
>> Okay, I turned on -Wunused-value in the gcc makefile for
>> Linux. I also ran this on a more recent build of HS (I
>> was using something very, very old), and I got a few more
>> warnings (including a couple that actually looked as if
>> they would impact functionality). Thoughts on this?
>>
>> diff --git a/make/linux/makefiles/gcc.make
>> b/make/linux/makefiles/gcc.make
>> --- a/make/linux/makefiles/gcc.make
>> +++ b/make/linux/makefiles/gcc.make
>> @@ -126,7 +126,7 @@
>> # Compiler warnings are treated as errors
>> WARNINGS_ARE_ERRORS = -Werror
>> -WARNING_FLAGS = -Wpointer-arith -Wsign-compare -Wundef
>> -Wunused-function
>> +WARNING_FLAGS = -Wpointer-arith -Wsign-compare -Wundef
>> -Wunused-function -Wunused-value
>> # Since GCC 4.3, -Wconversion has changed its meanings
>> to warn these implicit
>> # conversions which might affect the values. Only enable
>> it in earlier versions.
>> diff --git a/src/share/vm/c1/c1_IR.cpp
>> b/src/share/vm/c1/c1_IR.cpp
>> --- a/src/share/vm/c1/c1_IR.cpp
>> +++ b/src/share/vm/c1/c1_IR.cpp
>> @@ -506,7 +506,7 @@
>> _loop_map(0, 0), // initialized later with
>> correct size
>> _compilation(c)
>> {
>> - TRACE_LINEAR_SCAN(2, "***** computing linear-scan
>> block order");
>> + TRACE_LINEAR_SCAN(2, tty->print_cr("***** computing
>> linear-scan block order"));
>> init_visited();
>> count_edges(start_block, NULL);
>> @@ -683,7 +683,7 @@
>> }
>> void
>> ComputeLinearScanOrder::assign_loop_depth(BlockBegin*
>> start_block) {
>> - TRACE_LINEAR_SCAN(3, "----- computing loop-depth and
>> weight");
>> + TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing
>> loop-depth and weight"));
>> init_visited();
>> assert(_work_list.is_empty(), "work list must be empty
>> before processing");
>> @@ -868,7 +868,7 @@
>> }
>> void ComputeLinearScanOrder::compute_order(BlockBegin*
>> start_block) {
>> - TRACE_LINEAR_SCAN(3, "----- computing final block order");
>> + TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing
>> final block order"));
>> // the start block is always the first block in the
>> linear scan order
>> _linear_scan_order = new BlockList(_num_blocks);
>> diff --git a/src/share/vm/code/nmethod.cpp
>> b/src/share/vm/code/nmethod.cpp
>> --- a/src/share/vm/code/nmethod.cpp
>> +++ b/src/share/vm/code/nmethod.cpp
>> @@ -2602,7 +2602,8 @@
>> relocation_begin()-1+ip[1]);
>> for (; ip < index_end; ip++)
>> tty->print_cr(" (%d ?)", ip[0]);
>> - tty->print_cr(" @" INTPTR_FORMAT ":
>> index_size=%d", ip, *ip++);
>> + tty->print_cr(" @" INTPTR_FORMAT ":
>> index_size=%d", ip, *ip);
>> + ip++;
>> tty->print_cr("reloc_end @" INTPTR_FORMAT ":", ip);
>> }
>> }
>> diff --git a/src/share/vm/memory/cardTableModRefBS.cpp
>> b/src/share/vm/memory/cardTableModRefBS.cpp
>> --- a/src/share/vm/memory/cardTableModRefBS.cpp
>> +++ b/src/share/vm/memory/cardTableModRefBS.cpp
>> @@ -395,7 +395,7 @@
>> }
>> // Touch the last card of the covered region to show
>> that it
>> // is committed (or SEGV).
>> - debug_only(*byte_for(_covered[ind].last());)
>> + debug_only((void) (*byte_for(_covered[ind].last()));)
>> debug_only(verify_guard();)
>> }
>> diff --git a/src/share/vm/memory/universe.cpp
>> b/src/share/vm/memory/universe.cpp
>> --- a/src/share/vm/memory/universe.cpp
>> +++ b/src/share/vm/memory/universe.cpp
>> @@ -532,7 +532,9 @@
>> if (vt) vt->initialize_vtable(false, CHECK);
>> if (ko->oop_is_instance()) {
>> InstanceKlass* ik = (InstanceKlass*)ko;
>> - for (KlassHandle s_h(THREAD, ik->subklass()); s_h()
>> != NULL; s_h = (THREAD, s_h()->next_sibling())) {
>> + for (KlassHandle s_h(THREAD, ik->subklass());
>> + s_h() != NULL;
>> + s_h = KlassHandle(THREAD, s_h()->next_sibling())) {
>> reinitialize_vtable_of(s_h, CHECK);
>> }
>> }
>> diff --git a/src/share/vm/runtime/sharedRuntime.cpp
>> b/src/share/vm/runtime/sharedRuntime.cpp
>> --- a/src/share/vm/runtime/sharedRuntime.cpp
>> +++ b/src/share/vm/runtime/sharedRuntime.cpp
>> @@ -2733,7 +2733,7 @@
>> // ResourceObject, so do not put any ResourceMarks in
>> here.
>> char *s = sig->as_C_string();
>> int len = (int)strlen(s);
>> - *s++; len--; // Skip opening paren
>> + s++; len--; // Skip opening paren
>> char *t = s+len;
>> while( *(--t) != ')' ) ; // Find close paren
>> diff --git a/src/share/vm/services/diagnosticArgument.cpp
>> b/src/share/vm/services/diagnosticArgument.cpp
>> --- a/src/share/vm/services/diagnosticArgument.cpp
>> +++ b/src/share/vm/services/diagnosticArgument.cpp
>> @@ -232,7 +232,7 @@
>> } else {
>> _value._time = 0;
>> _value._nanotime = 0;
>> - strcmp(_value._unit, "ns");
>> + strcpy(_value._unit, "ns");
>> }
>> }
>> diff --git a/src/share/vm/utilities/taskqueue.hpp
>> b/src/share/vm/utilities/taskqueue.hpp
>> --- a/src/share/vm/utilities/taskqueue.hpp
>> +++ b/src/share/vm/utilities/taskqueue.hpp
>> @@ -340,8 +340,12 @@
>> if (dirty_n_elems == N - 1) {
>> // Actually means 0, so do the push.
>> uint localBot = _bottom;
>> - // g++ complains if the volatile result of the
>> assignment is unused.
>> - const_cast<E&>(_elems[localBot] = t);
>> + // g++ complains if the volatile result of the
>> assignment is
>> + // unused, so we cast the volatile away. We cannot
>> cast directly
>> + // to void, because gcc treats that as not using the
>> result of the
>> + // assignment. However, casting to E& means that we
>> trigger an
>> + // unused-value warning. So, we cast the E& to void.
>> + (void) const_cast<E&>(_elems[localBot] = t);
>> OrderAccess::release_store(&_bottom,
>> increment_index(localBot));
>> TASKQUEUE_STATS_ONLY(stats.record_push());
>> return true;
>> @@ -397,7 +401,12 @@
>> return false;
>> }
>> - const_cast<E&>(t = _elems[oldAge.top()]);
>> + // g++ complains if the volatile result of the
>> assignment is
>> + // unused, so we cast the volatile away. We cannot
>> cast directly
>> + // to void, because gcc treats that as not using the
>> result of the
>> + // assignment. However, casting to E& means that we
>> trigger an
>> + // unused-value warning. So, we cast the E& to void.
>> + (void) const_cast<E&>(t = _elems[oldAge.top()]);
>> Age newAge(oldAge);
>> newAge.increment();
>> Age resAge = _age.cmpxchg(newAge, oldAge);
>> @@ -640,8 +649,12 @@
>> uint dirty_n_elems = dirty_size(localBot, top);
>> assert(dirty_n_elems < N, "n_elems out of range.");
>> if (dirty_n_elems < max_elems()) {
>> - // g++ complains if the volatile result of the
>> assignment is unused.
>> - const_cast<E&>(_elems[localBot] = t);
>> + // g++ complains if the volatile result of the
>> assignment is
>> + // unused, so we cast the volatile away. We cannot
>> cast directly
>> + // to void, because gcc treats that as not using the
>> result of the
>> + // assignment. However, casting to E& means that we
>> trigger an
>> + // unused-value warning. So, we cast the E& to void.
>> + (void) const_cast<E&>(_elems[localBot] = t);
>> OrderAccess::release_store(&_bottom,
>> increment_index(localBot));
>> TASKQUEUE_STATS_ONLY(stats.record_push());
>> return true;
>> @@ -665,7 +678,12 @@
>> // This is necessary to prevent any read below from
>> being reordered
>> // before the store just above.
>> OrderAccess::fence();
>> - const_cast<E&>(t = _elems[localBot]);
>> + // g++ complains if the volatile result of the
>> assignment is
>> + // unused, so we cast the volatile away. We cannot
>> cast directly
>> + // to void, because gcc treats that as not using the
>> result of the
>> + // assignment. However, casting to E& means that we
>> trigger an
>> + // unused-value warning. So, we cast the E& to void.
>> + (void) const_cast<E&>(t = _elems[localBot]);
>> // This is a second read of "age"; the "size()" above
>> is the first.
>> // If there's still at least one element in the queue,
>> based on the
>> // "_bottom" and "age" we've read, then there can be
>> no interference with
>>
>>
>>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/attachments/20130516/edf09483/attachment-0001.html
More information about the hotspot-runtime-dev
mailing list