[lworld] RFR: 8267791: [lworld][lw3] Support compiler blackholes for inline types
Aleksey Shipilev
shade at openjdk.java.net
Wed May 26 12:46:44 UTC 2021
JDK-8259316 added the support for compiler blackholes. We need to check and implement the support for inline type arguments for them. I am sure we would find more wrinkles with nano-benchmarks, but insofar sample benchmark work as they should:
public class PrimitiveClasses {
static primitive class Value {
long x;
long y;
public Value(long x, long y) {
this.x = x;
this.y = y;
}
}
[volatile] Value v = Value.default;
@Benchmark
public Value test() {
return v;
}
}
Before: crash on assert, `assert(vt->fast_out(i)->is_InlineTypeBase(), "Unexpected inline type user");`
After, generated code in non-`volatile` case shows blackhole of individual components:
$ java -Djmh.blackhole.mode=COMPILER -jar target/benchmarks.jar PrimitiveClasses -prof perfasm
...
....[Hottest Region 1]..............................................................................
c2, level 4, org.openjdk.jmh_generated.PrimitiveClasses_test_jmhTest::test_avgt_jmhStub, version 641 (39 bytes)
...
↗ 0x00007f67bcc8eee0: mov 0x18(%r8),%r10 ; read and blackhole MyValue.x
0.02% │ 0x00007f67bcc8eee4: mov 0x10(%r8),%r11 ; read and blackhole MyValue.y
0.10% │ 0x00007f67bcc8eee8: movzbl 0x94(%r14),%r11d ; read isDone
0.10% │ 0x00007f67bcc8eef0: mov 0x3b0(%r15),%r10 ; TL handshake
2.79% │ 0x00007f67bcc8eef7: add $0x1,%rbp ; ops++
│ 0x00007f67bcc8eefb: test %eax,(%r10) ; TL handshake
86.74% │ 0x00007f67bcc8eefe: test %r11d,%r11d ; isDone?
2.31% ╰ 0x00007f67bcc8ef01: je 0x00007f67bcc8eee0
And generated code in `volatile` case shows blackhole of the box (with the null-check):
↗ 0x00007f3948c8db70: shl $0x3,%r10 ; unpack and blackhole MyValue
0.02% │↗ 0x00007f3948c8db74: movzbl 0x94(%r14),%r8d ; read isDone
0.68% ││ 0x00007f3948c8db7c: mov 0x3b0(%r15),%r9 ; TL handshake
0.72% ││ 0x00007f3948c8db83: add $0x1,%rbp ; ops++
││ 0x00007f3948c8db87: test %eax,(%r9) ; TL handshake
92.30% ││ 0x00007f3948c8db8a: test %r8d,%r8d ; isDone?
╭││ 0x00007f3948c8db8d: jne 0x00007f3948c8dba4
│││ 0x00007f3948c8db8f: mov 0xc(%r11),%r10d ; load "v" (MyValue box)
0.35% │││ 0x00007f3948c8db93: test %r10d,%r10d ; null check it
│╰│ 0x00007f3948c8db96: jne 0x00007f3948c8db70
-------------
Commit messages:
- Comment fixes
- Handle boxed case too
- 8267791: [lworld][lw3] Support compiler blackholes for inline types
Changes: https://git.openjdk.java.net/valhalla/pull/429/files
Webrev: https://webrevs.openjdk.java.net/?repo=valhalla&pr=429&range=00
Issue: https://bugs.openjdk.java.net/browse/JDK-8267791
Stats: 113 lines in 4 files changed: 112 ins; 0 del; 1 mod
Patch: https://git.openjdk.java.net/valhalla/pull/429.diff
Fetch: git fetch https://git.openjdk.java.net/valhalla pull/429/head:pull/429
PR: https://git.openjdk.java.net/valhalla/pull/429
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