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Bug ID: 7047954 VM crashes with assert(is_Mem()) failed: invalid node class
7047954 : VM crashes with assert(is_Mem()) failed: invalid node class

Details
Type:
Bug
Submit Date:
2011-05-24
Status:
Closed
Updated Date:
2011-11-25
Project Name:
JDK
Resolved Date:
2011-09-30
Component:
hotspot
OS:
generic
Sub-Component:
compiler
CPU:
generic
Priority:
P3
Resolution:
Fixed
Affected Versions:
hs21
Fixed Versions:
hs22

Related Reports
Backport:
JDK-2212439 - VM crashes with assert(is_Mem()) failed: invalid node class
Backport:
JDK-2213563 - VM crashes with assert(is_Mem()) failed: invalid node class
Relates:
JDK-7041789 - 30% perf regression with c2/arm following 7017732
Relates:
JDK-7048030 - is_scavengable changes causing compiler to embed more constants

Sub Tasks

Description
VM crashes with 
;; Using jvm: "/export/local/common/jdk/baseline/linux-i586/jre/lib/i386/server/libjvm.so"
#
# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (/tmp/jprt/P1/B/122931.et151817/source/src/share/vm/opto/node.hpp:749), pid=1881, tid=2401237872
#  assert(is_Mem()) failed: invalid node class
#
# JRE version: 7.0-b142
# Java VM: Java HotSpot(TM) Server VM (21.0-b14-internal-201105201229.et151817.hs21-b14-snapshot-fastdebug mixed mode linux-x86 )
# Core dump written. Default location: /export/local/50717.HSX.PIT.VM+linux-i586_javase__client_mixed_JT_HS/results/workDir/closed/runtime/4827353/ReadAfterWrite/core or core.1881
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.sun.com/bugreport/crash.jsp
#

---------------  T H R E A D  ---------------

Current thread (0x8f259800):  JavaThread "C2 CompilerThread0" daemon [_thread_in_native, id=1889, stack(0x8f17f000,0x8f200000)]

Stack: [0x8f17f000,0x8f200000],  sp=0x8f1fd0b0,  free space=504k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [libjvm.so+0xab1af1]  VMError::report_and_die()+0x1a1;;  VMError::report_and_die()+0x1a1
V  [libjvm.so+0x4cd1a8]  report_vm_error(char const*, int, char const*, char const*)+0x68;;  report_vm_error(char const*, int, char const*, char const*)+0x68
V  [libjvm.so+0x7e99fe]  Node::as_Mem() const+0x3e;;  Node::as_Mem() const+0x3e
V  [libjvm.so+0xa0843e]  SuperWord::co_locate_pack(Node_List*)+0xce;;  SuperWord::co_locate_pack(Node_List*)+0xce
V  [libjvm.so+0xa0db0b]  SuperWord::SLP_extract()+0x16b;;  SuperWord::SLP_extract()+0x16b
V  [libjvm.so+0x7fc9b1]  PhaseIdealLoop::build_and_optimize(bool)+0x10a1;;  PhaseIdealLoop::build_and_optimize(bool)+0x10a1
V  [libjvm.so+0x45cc4a]  Compile::Optimize()+0xd5a;;  Compile::Optimize()+0xd5a
V  [libjvm.so+0x460444]  Compile::Compile(ciEnv*, C2Compiler*, ciMethod*, int, bool, bool)+0x1114;;  Compile::Compile(ciEnv*, C2Compiler*, ciMethod*, int, bool, bool)+0x1114
V  [libjvm.so+0x374f39]  C2Compiler::compile_method(ciEnv*, ciMethod*, int)+0x229;;  C2Compiler::compile_method(ciEnv*, ciMethod*, int)+0x229
V  [libjvm.so+0x46a3a8]  CompileBroker::invoke_compiler_on_method(CompileTask*)+0x548;;  CompileBroker::invoke_compiler_on_method(CompileTask*)+0x548
V  [libjvm.so+0x46b09b]  CompileBroker::compiler_thread_loop()+0x5bb;;  CompileBroker::compiler_thread_loop()+0x5bb
V  [libjvm.so+0xa4bc6f]  compiler_thread_entry(JavaThread*, Thread*)+0x4f;;  compiler_thread_entry(JavaThread*, Thread*)+0x4f
V  [libjvm.so+0xa5a254]  JavaThread::thread_main_inner()+0xf4;;  JavaThread::thread_main_inner()+0xf4
V  [libjvm.so+0x8e2d61]  java_start(Thread*)+0x111;;  java_start(Thread*)+0x111
C  [libpthread.so.0+0x596e]  start_thread+0xbe


Current CompileTask:
C2:    551    4 %           ReadAfterWrite::main @ 5 (79 bytes)

Comments
EVALUATION

http://hg.openjdk.java.net/hsx/hotspot-rt/hotspot/rev/7889bbcc7f88
2011-07-08 
EVALUATION

http://hg.openjdk.java.net/hsx/hotspot-main/hotspot/rev/7889bbcc7f88
2011-07-07 
EVALUATION

http://hg.openjdk.java.net/hsx/hotspot-comp/hotspot/rev/7889bbcc7f88
2011-07-01 
SUGGESTED FIX

src/share/vm/opto/compile.cpp	Thu May 26 18:19:10 2011 -0700
@@ -1206,11 +1206,7 @@
     // Make sure the Bottom and NotNull variants alias the same.
     // Also, make sure exact and non-exact variants alias the same.
     if( ptr == TypePtr::NotNull || ta->klass_is_exact() ) {
-      if (ta->const_oop()) {
-        tj = ta = TypeAryPtr::make(TypePtr::Constant,ta->const_oop(),ta->ary(),ta->klass(),false,offset);
-      } else {
-        tj = ta = TypeAryPtr::make(TypePtr::BotPTR,ta->ary(),ta->klass(),false,offset);
-      }
+      tj = ta = TypeAryPtr::make(TypePtr::BotPTR,ta->ary(),ta->klass(),false,offset);
     }
   }
2011-05-27 
EVALUATION

The loop has 2 MergeMem nodes. Why?
2011-05-27 
EVALUATION

I traced this problem to the 7041789 push, the same as for 7048030. The test has two static final arrays and the loop which initialize them:

public class ReadAfterWrite {

    static final int n = 1000000;
    static final int[] AA = new int[n];
    static final int[] BB = new int[n];

        for(int i = 0; i < n; i++) {
            AA[i] = 0;
            BB[i] = 0;
        }

And we totally lost memory Phi in the loop so the stores only depend on nonmutable memory. After 16 unrolls instead of 32 stores the loop has only 4 stores.

I was able to reproduce the problem on Solaris after I set -Xms10m so the arrays are allocated in Old gen. With 7048030 fix the test passed.
2011-05-25


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