JDK-7169782 : C2: SIGSEGV in LShiftLNode::Ideal(PhaseGVN*, bool)
  • Type: Bug
  • Status: Closed
  • Resolution: Fixed
  • Component: hotspot
  • Sub-Component: compiler
  • Priority: P3
  • Affected Version: hs23
  • OS: generic
  • CPU: generic
  • Submit Date: 2012-05-17
  • Updated Date: 2013-07-31
  • Resolved Date: 2012-06-16
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JDK 7 JDK 8
7u40Fixed 8Resolved
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Description
C2 crashes during compilation of Test::<clinit> in LShiftLNode::Ideal(PhaseGVN*, bool).

Comments
Closed as already verified during 7u40 bug verification process.
2013-07-31

EVALUATION http://hg.openjdk.java.net/lambda/lambda/hotspot/rev/121e5708ae96
2012-06-29

EVALUATION http://hg.openjdk.java.net/hsx/hsx23.2/hotspot/rev/7cfb7d4b1e17
2012-06-20

EVALUATION http://hg.openjdk.java.net/hsx/hotspot-comp/hotspot/rev/121e5708ae96
2012-06-12

EVALUATION The problem is similar to 6732154/6837011: u0 becomes dead during transformation of temp, but then u0 is used for u0v1 construction: src/share/vm/opto/divnode.cpp: 257 static Node* long_by_long_mulhi(PhaseGVN* phase, Node* dividend, jlong magic_const) { ... 288 Node* u0 = phase->transform(new (phase->C, 3) AndLNode(dividend, phase->longcon(0xFFFFFFFF))); ... 296 Node* w0 = phase->transform(new (phase->C, 3) MulLNode(u0, v0)); ... 300 Node* temp = phase->transform(new (phase->C, 3) URShiftLNode(w0, phase->intcon(N / 2))); ... 317 Node* u0v1 = phase->transform(new (phase->C, 3) MulLNode(u0, v1)); During URShiftLNode transformation at divnode.cpp:300, u0 becomes dead, but then at divnode.cpp:317 MulLNode with dependecy on u0 is constructed and it crashes during transformation, trying to traverse u0 users.
2012-05-28

EVALUATION The problematic part of ideal graph is related to AndLNode (idx=97), produced in Node* long_by_long_mulhi(PhaseGVN*, Node*, jlong): src/share/vm/opto/divnode.cpp: 288 Node* u0 = phase->transform(new (phase->C, 3) AndLNode(dividend, phase->longcon(0xFFFFFFFF))); During u0v1 node (MulLNode) transformation, it tries to follow u0's in-edges and hits NULL: 317 Node* u0v1 = phase->transform(new (phase->C, 3) MulLNode(u0, v1)); The following transformation takes place: MulL( AndL( LoadL#24, //dividend ConL(FFFFFFFF))#97, ConL (1>>32)#101 )#112 ==> LShiftL( AndL#97 ConI) and crash occurs during IterGVN transformation of LShiftL. dividend: 24 LoadL === _ 7 23 [[ 72 28 67 99 110 ]] @java/lang/Class:exact+112 *, name=var_8, idx=4; #long !jvms: Test::<clinit> u0 initially looks fine, but got corrupted during temp construction: 300 Node* temp = phase->transform(new (phase->C, 3) URShiftLNode(w0, phase->intcon(N / 2))); Before temp: 97 AndL === _ 24 96 [[]] !orig=[102] After temp construction: 97 AndL === _ _ _ [[]] [4800097] !orig=[102]
2012-05-25

EVALUATION Program received signal SIGSEGV, Segmentation fault. 0xf767d2b0 in LShiftLNode::Ideal (this=0xada10328, phase=0xadbfdb8c, can_reshape=4146260737) at /set/vmsqe/home/vi158347/hotspot-main/src/share/vm/opto/mulnode.cpp:802 802 int add2_op = add2->Opcode(); (gdb) list 799 // Check for "((x>>c0) & Y)<<c0" which just masks off more low bits 800 if( add1_op == Op_AndL ) { 801 Node *add2 = add1->in(1); 802 int add2_op = add2->Opcode(); 803 if( (add2_op == Op_RShiftL || add2_op == Op_URShiftL ) && (gdb) p add2 $1 = (Node *) 0x0 (gdb) where #0 0xf767d2b0 in LShiftLNode::Ideal (this=0xada10328, phase=0xadbfdb8c, can_reshape=4146260737) at /set/vmsqe/home/vi158347/hotspot-main/src/share/vm/opto/mulnode.cpp:802 #1 0xf770c916 in PhaseIterGVN::transform_old (this=0xadbfdb8c, n=0xada10294) at /set/vmsqe/home/vi158347/hotspot-main/src/share/vm/opto/phaseX.cpp:1069 #2 0xf770b3e3 in PhaseIterGVN::transform(Node*) (this=0xadbfdb8c) at /set/vmsqe/home/vi158347/hotspot-main/src/share/vm/opto/phaseX.cpp:1010 #3 0xf7399290 in long_by_long_mulhi (phase=0xadbfdb8c, dividend=0xada0d570, magic_const=1) at /set/vmsqe/home/vi158347/hotspot-main/src/share/vm/opto/divnode.cpp:317 #4 0xf7399b59 in transform_long_divide (phase=0xadbfdb8c, dividend=0xada0d570, divisor=4294967295) at /set/vmsqe/home/vi158347/hotspot-main/src/share/vm/opto/divnode.cpp:411 #5 0xf7399f78 in DivLNode::Ideal(PhaseGVN*, bool) (this=0xada0ed08, phase=0xadbfdb8c, can_reshape=2913143644) at /set/vmsqe/home/vi158347/hotspot-main/src/share/vm/opto/divnode.cpp:574 #6 0xf770c694 in PhaseIterGVN::transform_old (this=0xadbfdb8c, n=0xada0ed08) at /set/vmsqe/home/vi158347/hotspot-main/src/share/vm/opto/phaseX.cpp:1029 #7 0xf770e60b in PhaseIterGVN::optimize (this=0xadbfdb8c) at /set/vmsqe/home/vi158347/hotspot-main/src/share/vm/opto/phaseX.cpp:903 #8 0xf75fd404 in PhaseIdealLoop::build_and_optimize (this=0xadbfdf44, do_split_ifs=2913141505, skip_loop_opts=4141557760) at /set/vmsqe/home/vi158347/hotspot-main/src/share/vm/opto/loopnode.cpp:2181 #9 0xf72cd6f1 in PhaseIdealLoop::PhaseIdealLoop(PhaseIterGVN&, bool, bool) (tag=-1379934396) at /set/vmsqe/home/vi158347/hotspot-main/src/share/vm/gc_implementation/g1/g1ErgoVerbose.hpp:91 #10 0xf72c5138 in Compile::Optimize (this=0xadbfe8d0) at /set/vmsqe/home/vi158347/hotspot-main/src/share/vm/opto/compile.cpp:1797 #11 0xf72c937d in Compile::Compile (this=0xadbfe8d0, ci_env=0xadbfee38, compiler=0xae5f5948, target=0xf6d344f8, osr_bci=-1, subsume_loads=4294967041, do_escape_analysis=4294967041) at /set/vmsqe/home/vi158347/hotspot-main/src/share/vm/opto/compile.cpp:769 #12 0xf720eb24 in C2Compiler::compile_method (this=0xae5f5948, env=<incomplete type>, target=0xf6d344f8, entry_bci=-1) at /set/vmsqe/home/vi158347/hotspot-main/src/share/vm/opto/c2compiler.cpp:130 ...
2012-05-25