RFR: JDK-8272570: C2: crash in PhaseCFG::global_code_motion [v4]

[王超]

> In PhaseCFG::global_code_motion, it allocate recalc_pressure_nodes array. condition is at least one block has more than 10 nodes:
> 
>   if (OptoRegScheduling) {
>     for (uint i = 0; i < number_of_blocks(); i++) {
>       Block* block = get_block(i);
>       if (block->number_of_nodes() > 10) {
>         block_size_threshold_ok = true;
>         break;
>       }
>     }
>   }
> 
> 
> In PhaseCFG::select, it uses recalc_pressure_nodes array, if block's node exceed 10:
> 
> bool block_size_threshold_ok = (block->number_of_nodes() > 10) ? true : false;
> 
> 
> In this case, block#4's node size is 10 at GCM begin, but increased to 11 later. PhaseCFG::select use null recalc_pressure_nodes array, this leads to crash.
> 
> # --- schedule_local B4, before: ---
> #   31: Region              31    6
> #   22: MergeMem          NULL    0   17    0   23   25 NULL NULL
> #   25: storeImmB            3   17   24 NULL
> #   23: storeImmB            3   17   24 NULL
> #    3: MachProj             4
> #    4: CallLeafDirect      31    0   17   18    0   19    0 NULL
> #    5: MachProj             4
> #   19: loadConD          NULL   20 NULL NULL
> #   20: MachConstantBaseNode   11 NULL NULL NULL
> #    2: Ret                  3   21   22   18   26 NULL NULL NULL
> #
> #   ready cnt: -2  latency:  0    31: Region
> #   ready cnt:  2  latency:  0    22: MergeMem
> #   ready cnt:  1  latency:  0    25: storeImmB
> #   ready cnt:  1  latency:  0    23: storeImmB
> #   ready cnt:  1  latency:  0     3: MachProj
> #   ready cnt:  1  latency:  0     4: CallLeafDirect
> #   ready cnt:  1  latency:  0     5: MachProj
> #   ready cnt:  1  latency:  0    19: loadConD
> #   ready cnt:  0  latency:  0    20: MachConstantBaseNode
> #   ready cnt:  0  latency:  0     2: Ret
> #   ready list: 20
> #    select 20: MachConstantBaseNode, latency:0 20  MachConstantBaseNode  ===  11  [[ 19 ]] 
> #   ready list: 19
> #    select 19: loadConD, latency:0 19  loadConD  === _  20  [[ 4 ]] dblcon:1.000000
> #   ready list: 4
> #    select 4: CallLeafDirect, latency:0 4  CallLeafDirect  ===  31  0  17  18  0  19  0  [[ 5  3 ]] dtan # double/half ( double, half ) !jvms: SDD0::foo @ bci:23 (line 10)
> #   ready list: 23 25
> select node_size # B4, 11
> #   31: Region              31    6
> #   20: MachConstantBaseNode   11 NULL NULL NULL
> #   19: loadConD          NULL   20 NULL NULL
> #    4: CallLeafDirect      31    0   17   18    0   19    0 NULL
> #    5: MachProj             4
> #    3: MachProj             4
> #   35: MachProj             4
> #    5: MachProj             4
> #   19: loadConD          NULL   20 NULL NULL
> #   20: MachConstantBaseNode   11 NULL NULL NULL
> #    2: Ret                  3   21   22   18   26 NULL NULL NULL
> #
> #
> # A fatal error has been detected by the Java Runtime Environment:
> #
> #  SIGSEGV (0xb) at pc=0x00007f14bf3ccf81, pid=31936, tid=31949

王超 has updated the pull request incrementally with one additional commit since the last revision:

  Remove othervm to speed up test, and make the loop count larger to let c2 crash

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5140/files
  - new: https://git.openjdk.java.net/jdk/pull/5140/files/8fbadf44..64a11760

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5140&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5140&range=02-03

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5140.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5140/head:pull/5140

PR: https://git.openjdk.java.net/jdk/pull/5140