buggy behavior in AMD64NodeLIRBuilder.emitCompareBranchMemory

Thu May 15 04:12:51 UTC 2014

I think this is actually a bug in tail duplication.  I’ve been chasing my tail a bit on this because the code that reports the error is only compiled when exercising the matching code, so I assumed they were causally connected.  I just added logic that allows the matching logic to run but never installs the match result, so the code is exercised but doesn’t actually change code generation and it still shows up.  Looking at the graph I can see if the isInt guard disappear during tail duplication which causes the problem I’m seeing.  https://lafo.ssw.uni-linz.ac.at/jira/browse/GRAAL-791 has a patch that makes it easy to reproduce.  Hopefully Lukas can get to the bottom of it.

tom

On May 14, 2014, at 11:01 AM, Tom Rodriguez <tom.rodriguez at oracle.com> wrote:

> Thanks for the test case.  I’ve been narrowing it down in between a few other things but I was seeing an issue with a mirrored unsigned compare.  It generates bad code in the compiler itself and then fails much later.  It’s possible there are multiple things going on.  Anyway, I hope to have it resolved today.
> 
> tom
> 
> On May 14, 2014, at 10:56 AM, Yudi Zheng <yudi.zheng at usi.ch> wrote:
> 
>> In case you might need it, please find attached the simplified test case.
>> During the TailDuplicationPhase when compiling TailDuplicatoinTest.bar,
>> some ObjectEqualsNode is evaluated to false..
>> (com.oracle.graal.nodes.calc.ObjectEqualsNode.java#64)
>> 
>> - Yudi
>> 
>> 
>> On 13 May 2014, at 00:40, Tom Rodriguez <tom.rodriguez at oracle.com<mailto:tom.rodriguez at oracle.com>> wrote:
>> 
>> Thanks for the report.  I’m looking into it.
>> 
>> tom
>> 
>> On May 12, 2014, at 1:10 PM, Yudi Zheng <yudi.zheng at usi.ch<mailto:yudi.zheng at usi.ch>> wrote:
>> 
>> Hi,
>> 
>> 1. A minor problem is that the default TypeProfileWidth is 2, resulting in lots of megamorphic-inlining with a probability of 60~70% in many cases,
>> instead of polymorphic-inlining.
>> 
>> 2. When running with -XX:TypeProfileWidth=8, I observed buggy behavior:
>> 
>> mx vm -XX:+BootstrapGraal -XX:TypeProfileWidth=8 -version
>> Bootstrapping Graal.......................com.oracle.graal.compiler.common.GraalInternalError: should not reach here
>> at lir instruction: B192 at 1350 LCMP (address: [rax|j + 24], y: long[33286881400|0x7c00d8078]{HotSpotType<Lcom/oracle/graal/nodes/DeoptimizingNode$DeoptBefore;, resolved>}) kind: long
>> [B0, B2, B3, B5, B6, B8, B416, B419, B9, B11, B12, B14, B16, B17, B19, B21, B413, B23, B25, B26, B28, B29, B31, B409, B412, B32, B33, B35, B36, B38, B39, B41, B42, B44, B45, B47, B49, B50, B52, B54, B53, B55, B56, B57, B59, B61, B63, B65, B66, B67, B69, B70, B72, B74, B77, B79, B80, B94, B96, B98, B99, B101, B102, B103, B104, B107, B108, B109, B110, B113, B114, B115, B117, B118, B120, B122, B125, B127, B128, B129, B143, B145, B147, B148, B160, B126, B119, B149, B116, B130, B132, B153, B133, B136, B138, B139, B141, B142, B137, B140, B150, B134, B168, B105, B166, B171, B180, B181, B183, B186, B188, B190, B192, B194, B196, B198, B200, B197, B161, B170, B179, B177, B178, B184, B403, B78, B193, B202, B203, B204, B209, B211, B212, B214, B399, B401, B215, B216, B218, B220, B222, B397, B71, B208, B205, B206, B100, B195, B201, B187, B189, B68, B191, B199, B219, B224, B226, B228, B229, B231, B233, B394, B395, B221, B223, B82, B84, B173, B174, B154, B155, B51, B48, B232, B235, B239, B393, B236, B238, B234, B85, B87, B89, B90, B92, B93, B88, B240, B242, B284, B286, B288, B289, B291, B294, B296, B297, B299, B300, B302, B304, B307, B308, B310, B311, B313, B315, B317, B318, B320, B322, B323, B325, B326, B327, B343, B345, B346, B348, B349, B351, B354, B356, B357, B358, B360, B362, B364, B365, B367, B369, B372, B368, B373, B83, B371, B46, B352, B237, B287, B316, B330, B332, B333, B335, B336, B337, B244, B246, B247, B249, B250, B252, B254, B257, B258, B260, B261, B263, B265, B267, B268, B270, B273, B275, B276, B370, B266, B207, B285, B314, B264, B91, B355, B295, B245, B339, B384, B301, B306, B251, B256, B390, B391, B281, B283, B167, B282, B347, B382, B344, B30, B27, B378, B379, B175, B385, B388, B324, B386, B34, B407, B259, B280, B402, B312, B387, B309, B62, B389, B24, B410, B210, B392, B165, B230, B278, B159, B415, B396, B135, B404, B262, B169, B157, B10, B381, B15, B331, B376, B277, B405, B414, B37, B1, B213, B398, B417, B279, B418, B408, B400, B176, B338, B58, B40, B151, B274, B411, B380, B375, B334, B7, B340, B64, B4, B377, B406, B60, B13, B172, B163, B106, B86, B217, B18, B112, B383]
>> at com.oracle.graal.compiler.common.GraalInternalError.shouldNotReachHere(GraalInternalError.java:44)
>> at com.oracle.graal.lir.amd64.AMD64Compare$CompareMemoryOp.emitMemAccess(AMD64Compare.java:129)
>> at com.oracle.graal.lir.amd64.AMD64Move$MemOp.emitCode(AMD64Move.java:129)
>> at com.oracle.graal.lir.amd64.AMD64LIRInstruction.emitCode(AMD64LIRInstruction.java:36)
>> at com.oracle.graal.lir.asm.CompilationResultBuilder.emitOp(CompilationResultBuilder.java:350)
>> at com.oracle.graal.lir.asm.CompilationResultBuilder.emitBlock(CompilationResultBuilder.java:341)
>> at com.oracle.graal.lir.asm.CompilationResultBuilder.emit(CompilationResultBuilder.java:323)
>> at com.oracle.graal.hotspot.amd64.AMD64HotSpotBackend.emitCodeBody(AMD64HotSpotBackend.java:301)
>> at com.oracle.graal.hotspot.amd64.AMD64HotSpotBackend.emitCode(AMD64HotSpotBackend.java:254)
>> at com.oracle.graal.compiler.GraalCompiler.emitCode(GraalCompiler.java:288)
>> at com.oracle.graal.compiler.GraalCompiler.emitBackEnd(GraalCompiler.java:200)
>> at com.oracle.graal.compiler.GraalCompiler.compileGraph(GraalCompiler.java:141)
>> at com.oracle.graal.hotspot.CompilationTask.runCompilation(CompilationTask.java:302)
>> at com.oracle.graal.hotspot.CompilationTask.run(CompilationTask.java:159)
>> at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
>> at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
>> at java.lang.Thread.run(Thread.java:745)
>> at com.oracle.graal.compiler.CompilerThread.run(CompilerThread.java:48)
>> 
>> 
>> The potential bug can be tracked in com.oracle.graal.compiler.amd64.AMD64NodeLIRBuilder.emitCompareBranchMemory
>> (-G:Dump= -G:MethodFilter=com.oracle.graal.compiler.amd64.AMD64NodeLIRBuilder.emitCompareBranchMemory),
>> and can be bypassed either by not inlining com.oracle.graal.compiler.amd64.AMD64NodeLIRBuilder.getMemoryKind,
>> or by skipping the TailDuplicationPhase.
>> 
>> I guess that the TailDuplicationPhase dropped some of the IfNode. Could be verified using the following code:
>> 
>> protected ComplexMatchResult emitCompareBranchMemory(IfNode ifNode, CompareNode compare, ValueNode value, Access access) {
>>     Condition cond = compare.condition();
>>     Kind kind = getMemoryKind(access);
>> 
>>     if (kind != Kind.Long) {
>>         notInlinedMethodPlaceHolder(kind);
>>     }
>> 
>> After tail duplication at some merge node, the IfNode<if (kind != Kind.Long)> disappeared..
>> 
>> - Yudi
>> 
>> 
>> 
>> 
>> <TailDuplicationTest.java>
> 