RFR: JDK-8287061: Support for rematerializing scalar replaced objects participating in allocation merges [v14]
Cesar Soares Lucas
cslucas at openjdk.org
Mon Jun 5 19:30:07 UTC 2023
On Mon, 5 Jun 2023 18:05:47 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:
>> Cesar Soares Lucas has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 15 commits:
>>
>> - Catching up with master branch.
>>
>> Merge remote-tracking branch 'origin/master' into rematerialization-of-merges
>> - Address PR review 6: refactoring around rematerialization & improve test cases.
>> - Address PR review 5: refactor on rematerialization & add tests.
>> - Merge remote-tracking branch 'origin/master' into rematerialization-of-merges
>> - Address part of PR review 4 & fix a bug setting only_candidate
>> - Catching up with master
>>
>> Merge remote-tracking branch 'origin/master' into rematerialization-of-merges
>> - Fix tests. Remember previous reducible Phis.
>> - Address PR review 3. Some comments and be able to abort compilation.
>> - Merge with Master
>> - Addressing PR review 2: refactor & reuse MacroExpand::scalar_replacement method.
>> - ... and 5 more: https://git.openjdk.org/jdk/compare/46c4da7f...8f81a7c8
>
> src/hotspot/share/code/debugInfo.cpp line 301:
>
>> 299: void ObjectMergeValue::print_detailed(outputStream* st) const {
>> 300: st->print("merge: ID=%d", _id);
>> 301: #ifndef PRODUCT
>
> Can you post a sample of the output, please?
>
> Why is it limited to non-product builds? It's valuable irrespective of build flavor.
>
> As I see in `ObjectValue::print_on` and `ScopeDesc::print_on`, you mix `print_on` with `print_fields_on`. Any particular reason for that? You could add `is_object_merge` case in ObjectValue::print_on` instead and extend `ObjectValue::print_fields_on` to cover `ObjectMergeValue` case. I find it hard to reason about `ObjectValue::print_on` vs `ObjectMergeValue::print_on` since it's a non-virtual method.
>
>
>
> Also, formatting is broken.
I added a few samples below and there are a few more here: https://gist.github.com/JohnTortugo/913523947e08157def6cfebafa7d5daa
Sample 1:
Compiled method (c2) 415 24 TestTrapAfterMerge::test (57 bytes)
total in heap [0x00007f7b4d03da90,0x00007f7b4d03de18] = 904
relocation [0x00007f7b4d03dc00,0x00007f7b4d03dc18] = 24
main code [0x00007f7b4d03dc20,0x00007f7b4d03dcb8] = 152
stub code [0x00007f7b4d03dcb8,0x00007f7b4d03dcd0] = 24
oops [0x00007f7b4d03dcd0,0x00007f7b4d03dce0] = 16
metadata [0x00007f7b4d03dce0,0x00007f7b4d03dce8] = 8
scopes data [0x00007f7b4d03dce8,0x00007f7b4d03dd50] = 104
scopes pcs [0x00007f7b4d03dd50,0x00007f7b4d03de10] = 192
dependencies [0x00007f7b4d03de10,0x00007f7b4d03de18] = 8
scopes:
ScopeDesc(pc=0x00007f7b4d03dc3a offset=1a):
TestTrapAfterMerge::test at -1 (line 3)
ScopeDesc(pc=0x00007f7b4d03dc41 offset=21):
TestTrapAfterMerge::test at 11 (line 5)
ScopeDesc(pc=0x00007f7b4d03dc44 offset=24):
TestTrapAfterMerge::test at 51 (line 12)
ScopeDesc(pc=0x00007f7b4d03dc4a offset=2a):
TestTrapAfterMerge::test at 46 (line 8)
ScopeDesc(pc=0x00007f7b4d03dc52 offset=32):
TestTrapAfterMerge::test at 37 (line 9)
ScopeDesc(pc=0x00007f7b4d03dc57 offset=37):
TestTrapAfterMerge::test at 43 (line 8)
ScopeDesc(pc=0x00007f7b4d03dc61 offset=41):
TestTrapAfterMerge::test at 46 (line 8) reexecute=true
Locals
- l0: empty
- l1: empty
- l2: reg rbx [6],int
- l3: empty
- l4: merge: ID=26
- l5: reg r11 [22],int
Objects
- 0: merge: ID=26, selector="reg r10 [20],int", merge_pointer="nullptr", candidate objs=[27, 28]
- 1: obj: ID=27, is_root=0, N.Fields=1, klass: Point
Fields: reg r8 [16],int
- 2: obj: ID=28, is_root=0, N.Fields=1, klass: Point
Fields: reg rcx [2],int
ScopeDesc(pc=0x00007f7b4d03dc63 offset=43):
TestTrapAfterMerge::test at 46 (line 8)
ScopeDesc(pc=0x00007f7b4d03dc6c offset=4c):
TestTrapAfterMerge::test at 34 (line 8)
ScopeDesc(pc=0x00007f7b4d03dc71 offset=51):
TestTrapAfterMerge::test at 55 (line 12)
- Sample2:
Compiled method (c2) 443 24 TestManys::test (41 bytes)
total in heap [0x00007f35e9155b90,0x00007f35e9155e78] = 744
relocation [0x00007f35e9155d00,0x00007f35e9155d18] = 24
main code [0x00007f35e9155d20,0x00007f35e9155d88] = 104
stub code [0x00007f35e9155d88,0x00007f35e9155da0] = 24
oops [0x00007f35e9155da0,0x00007f35e9155db0] = 16
metadata [0x00007f35e9155db0,0x00007f35e9155db8] = 8
scopes data [0x00007f35e9155db8,0x00007f35e9155e10] = 88
scopes pcs [0x00007f35e9155e10,0x00007f35e9155e70] = 96
dependencies [0x00007f35e9155e70,0x00007f35e9155e78] = 8
scopes:
ScopeDesc(pc=0x00007f35e9155d3a offset=1a):
TestManys::test at -1 (line 57)
ScopeDesc(pc=0x00007f35e9155d42 offset=22):
TestManys::test at 11 (line 59)
ScopeDesc(pc=0x00007f35e9155d58 offset=38):
TestManys::test at 25 (line 63)
Locals
- l0: empty
- l1: empty
- l2: empty
- l3: empty
- l4: empty
- l5: empty
- l6: empty
- l7: empty
- l8: merge: ID=26
Objects
- 0: merge: ID=26, selector="reg rbp [10],int", merge_pointer="nullptr", candidate objs=[27, 28]
- 1: obj: ID=27, is_root=0, N.Fields=4, klass: Point
Fields: stack[36], stack[36], 0, 0
- 2: obj: ID=28, is_root=0, N.Fields=4, klass: Point
Fields: 2023, 0, 0, 0
ScopeDesc(pc=0x00007f35e9155d74 offset=54):
TestManys::test at 25 (line 63)
- Sample3:
Compiled method (c2) 436 24 TestMultiSFO::test (48 bytes)
total in heap [0x00007f1df5155590,0x00007f1df5155850] = 704
relocation [0x00007f1df5155700,0x00007f1df5155718] = 24
main code [0x00007f1df5155720,0x00007f1df5155788] = 104
stub code [0x00007f1df5155788,0x00007f1df51557a0] = 24
oops [0x00007f1df51557a0,0x00007f1df51557b0] = 16
metadata [0x00007f1df51557b0,0x00007f1df51557b8] = 8
scopes data [0x00007f1df51557b8,0x00007f1df51557f8] = 64
scopes pcs [0x00007f1df51557f8,0x00007f1df5155848] = 80
dependencies [0x00007f1df5155848,0x00007f1df5155850] = 8
scopes:
ScopeDesc(pc=0x00007f1df515573a offset=1a):
TestMultiSFO::test at -1 (line 12)
ScopeDesc(pc=0x00007f1df515575c offset=3c):
TestMultiSFO::test at 28 (line 19)
Locals
- l0: empty
- l1: empty
- l2: empty
- l3: merge: ID=14
- l4: obj: ID=15, is_root=1, N.Fields=2, klass: TestMultiSFO$Point
Fields: stack[12], stack[8]
Objects
- 0: merge: ID=14, selector="reg rbp [10],int", merge_pointer="nullptr", candidate objs=[15, 16]
- 1: obj: ID=15, is_root=1, N.Fields=2, klass: TestMultiSFO$Point
Fields: stack[12], stack[8]
- 2: obj: ID=16, is_root=0, N.Fields=2, klass: TestMultiSFO$Point
Fields: stack[8], stack[12]
ScopeDesc(pc=0x00007f1df5155778 offset=58):
TestMultiSFO::test at 28 (line 19)
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/12897#discussion_r1218500009
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