Skip branch folding in ilgen if OSR enabled

[a7ehuo]

Do not perform branch folding in ilgen if OSR is enabled. OSR def and liveness analyses rely on dataflow over the IL trees to make conclusions about the bytecode. To ensure correctness, the IL must accurately reflect the bytecode at the time of OSR analysis: It should preserve the same CFG and perform all local variable loads and stores at the same points as in the bytecode. Branch folding will likely be taken care of by later optimizations after OSR analyses such as tree simplification, etc.

[a7ehuo]

A little more information on what the trees will look like with this change if OSR is enabled.

Without this change, ificmpeq is folded away in ILGen before OSR analyses

<optimization id=2 name=osrDefAnalysis method=MyClass4.test()I>
...
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
n30n      BBStart <block_2>                                                                   [0x738a88404430] bci=[-1,0,68] rc=0 vc=0 vn=- li=- udi=- nc=0
n34n      goto --> block_3 BBStart at n2n                                                     [0x738a88404570] bci=[-1,3,68] rc=0 vc=0 vn=- li=- udi=- nc=0
n29n      BBEnd </block_2> =====                                                              [0x738a884043e0] bci=[-1,3,68] rc=0 vc=0 vn=- li=- udi=- nc=0

n2n       BBStart <block_3>                                                                   [0x738a88403b70] bci=[-1,226,113] rc=0 vc=0 vn=- li=- udi=- nc=0
n36n      ireturn                                                                             [0x738a88404610] bci=[-1,227,113] rc=0 vc=0 vn=- li=- udi=- nc=1
n35n        iconst -1 (X!=0 X<=0 )                                                            [0x738a884045c0] bci=[-1,226,113] rc=1 vc=0 vn=- li=- udi=- nc=0 flg=0x204
n1n       BBEnd </block_3>                                                                    [0x738a88403b20] bci=[-1,227,113] rc=0 vc=0 vn=- li=- udi=- nc=0

With this change before osrLiveRangeAnalysis:

<optimization id=1 name=osrLiveRangeAnalysis method=MyClass4.test()I>
...
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
n30n      BBStart <block_2>                                                                   [0x754c8b004430] bci=[-1,0,68] rc=0 vc=0 vn=- li=- udi=- nc=0
n36n      ificmpeq --> block_13 BBStart at n2n (swappedChildren )                             [0x754c8b004610] bci=[-1,3,68] rc=0 vc=0 vn=- li=- udi=- nc=2 flg=0x20020
n33n        iconst 0 (X==0 X>=0 X<=0 )                                                        [0x754c8b004520] bci=[-1,3,68] rc=1 vc=0 vn=- li=- udi=- nc=0 flg=0x302
n31n        iconst 0 (X==0 X>=0 X<=0 )                                                        [0x754c8b004480] bci=[-1,0,68] rc=1 vc=0 vn=- li=- udi=- nc=0 flg=0x302
n29n      BBEnd </block_2> =====                                                              [0x754c8b0043e0] bci=[-1,3,68] rc=0 vc=0 vn=- li=- udi=- nc=0

...
...
n2n       BBStart <block_13>                                                                  [0x754c8b003b70] bci=[-1,226,113] rc=0 vc=0 vn=- li=- udi=- nc=0
n55n      ireturn                                                                             [0x754c8b0900f0] bci=[-1,227,113] rc=0 vc=0 vn=- li=- udi=- nc=1
n54n        iconst -1 (X!=0 X<=0 )                                                            [0x754c8b0900a0] bci=[-1,226,113] rc=1 vc=0 vn=- li=- udi=- nc=0 flg=0x204
n1n       BBEnd </block_13> =====                                                             [0x754c8b003b20] bci=[-1,227,113] rc=0 vc=0 vn=- li=- udi=- nc=0
...

With this change after treeSimplification:

<optimization id=21 name=treeSimplification method=MyClass4.test()I>
...
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
n30n      BBStart <block_2>                                                                   [0x754c8b004430] bci=[-1,226,113] rc=0 vc=81 vn=- li=- udi=- nc=0
n55n      ireturn                                                                             [0x754c8b0900f0] bci=[-1,227,113] rc=0 vc=81 vn=- li=- udi=- nc=1
n54n        iconst -1 (X!=0 X<=0 )                                                            [0x754c8b0900a0] bci=[-1,226,113] rc=1 vc=81 vn=- li=- udi=- nc=0 flg=0x204
n1n       BBEnd </block_2>                                                                    [0x754c8b003b20] bci=[-1,227,113] rc=0 vc=81 vn=- li=- udi=- nc=0

@vijaysun-omr May I ask you to review this change? Thank you!

@jdmpapin Thank you very much for your help in identifying the proper fix!

[vijaysun-omr]

jenkins test sanity all jdk21

[a7ehuo]

Three test failures are all known issues or have been observed in other PR build tests.

(1)
Test_openjdk21_j9_sanity.openjdk_x86-64_mac_Personal failed in jdk_vector_double128_j9_0.
This test failure had been observed in other PR builds as well: #23012 (comment)

12:33:43  java.lang.Exception: failures: 9
12:33:43  	at com.sun.javatest.regtest.agent.TestNGRunner.main(TestNGRunner.java:104)
12:33:43  	at com.sun.javatest.regtest.agent.TestNGRunner.main(TestNGRunner.java:58)
12:33:43  	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
12:33:43  	at java.base/java.lang.reflect.Method.invoke(Method.java:586)
12:33:43  	at com.sun.javatest.regtest.agent.MainWrapper$MainTask.run(MainWrapper.java:138)
12:33:43  	at java.base/java.lang.Thread.run(Thread.java:1595)
12:33:43  
12:33:43  JavaTest Message: Test threw exception: java.lang.Exception: failures: 9
12:33:43  JavaTest Message: shutting down test
12:33:43  
12:33:43  STATUS:Failed.`main' threw exception: java.lang.Exception: failures: 9

(2)
Test_openjdk21_j9_sanity.functional_ppc64_aix_Personal failed in J9vmTest_1.
It is a known issue: #9969. It also failed in night build 599

[2025-12-12T18:05:14.152Z] JVMDUMP055I Processing dump event "systhrow", detail "java/lang/OutOfMemoryError", exception "Java heap space" at 2025/12/12 18:05:19 - please wait.
...
[2025-12-12T18:05:16.962Z] *** Test FAILED *** (j9vm.test.arraylets.ArrayletAllocateTest)

(3)
Test_openjdk21_j9_sanity.functional_x86-64_windows_Personal failed in testSCCMLModularity_3.
It is a known issue: #22758 (comment)

[2025-12-12T18:55:18.102Z] Test result: FAILED
[2025-12-12T18:55:18.102Z]  [ERR] JVMSHRC241E Error: unable to delete shared class cache file
[2025-12-12T18:55:18.102Z]  [ERR] JVMSHRC336E Port layer error code = -102
[2025-12-12T18:55:18.102Z]  [ERR] JVMSHRC337E Platform error message: (5) Access is denied.
[2025-12-12T18:55:18.102Z]  [ERR] JVMSHRC430I Failed to remove current generation of shared class cache "ShareClassesCMLTests"