This patch intrinsifies `Math.max(long, long)` and `Math.min(long, long)` in
order to help improve vectorization performance.
Currently vectorization does not kick in for loops containing either of these
calls because of the following error:
VLoop::check_preconditions: failed: control flow in loop not allowed
The control flow is due to the java implementation for these methods, e.g.
public static long max(long a, long b) {
return (a >= b) ? a : b;
}
This patch intrinsifies the calls to replace the CmpL + Bool nodes for
MaxL/MinL nodes respectively.
By doing this, vectorization no longer finds the control flow and so it can
carry out the vectorization.
E.g.
SuperWord::transform_loop:
Loop: N518/N126 counted [int,int),+4 (1025 iters) main has_sfpt
strip_mined
518 CountedLoop === 518 246 126 [[ 513 517 518 242 521 522 422 210 ]] inner
stride: 4 main of N518 strip mined !orig=[419],[247],[216],[193] !jvms:
Test::test @ bci:14 (line 21)
Applying the same changes to `ReductionPerf` as in
https://github.com/openjdk/jdk/pull/13056, we can compare the results before
and after. Before the patch, on darwin/aarch64 (M1):
==============================
Test summary
==============================
TEST TOTAL PASS FAIL ERROR
jtreg:test/hotspot/jtreg/compiler/loopopts/superword/ReductionPerf.java
1 1 0 0
==============================
TEST SUCCESS
long min 1155
long max 1173
After the patch, on darwin/aarch64 (M1):
==============================
Test summary
==============================
TEST TOTAL PASS FAIL ERROR
jtreg:test/hotspot/jtreg/compiler/loopopts/superword/ReductionPerf.java
1 1 0 0
==============================
TEST SUCCESS
long min 1042
long max 1042
This patch does not add an platform-specific backend implementations for the
MaxL/MinL nodes.
Therefore, it still relies on the macro expansion to transform those into
CMoveL.
I've run tier1 and hotspot compiler tests on darwin/aarch64 and got these
results:
==============================
Test summary
==============================
TEST TOTAL PASS FAIL ERROR
jtreg:test/hotspot/jtreg:tier1 2500 2500 0 0
>> jtreg:test/jdk:tier1 2413 2412 1 0 <<
jtreg:test/langtools:tier1 4556 4556 0 0
jtreg:test/jaxp:tier1 0 0 0 0
jtreg:test/lib-test:tier1 33 33 0 0
==============================
The failure I got is
[CODETOOLS-7903745](https://bugs.openjdk.org/browse/CODETOOLS-7903745) so
unrelated to these changes.
-------------
Commit messages:
- 8307513: C2: intrinsify Math.max(long,long) and Math.min(long,long)
Changes: https://git.openjdk.org/jdk/pull/20098/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20098&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8307513
Stats: 32 lines in 5 files changed: 32 ins; 0 del; 0 mod
Patch: https://git.openjdk.org/jdk/pull/20098.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/20098/head:pull/20098
PR: https://git.openjdk.org/jdk/pull/20098
