Assertion failed 'block->bbTryIndex == blockTryIndex[block->bbNum]' in 'System.Collections.Immutable.Tests.ImmutableArrayTest

[jkotas]

  Starting:    System.Collections.Immutable.Tests (parallel test collections = on [2 threads], stop on fail = off)

Assert failure(PID 35 [0x00000023], Thread: 63 [0x003f]): Assertion failed 'block->bbTryIndex == blockTryIndex[block->bbNum]' in 'System.Collections.Immutable.Tests.ImmutableArrayTest+<>c:<RemoveRangeEnumerableInvalid>b__128_15():this' during 'Update flow graph opt pass' (IL size 22; hash 0x56d3b844; Tier1)

    File: /__w/1/s/src/coreclr/jit/jiteh.cpp:3731
    Image: /root/helix/work/correlation/dotnet

Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1091084
Build error leg or test failing: System.Collections.Immutable.Tests.WorkItemExecution
Pull request: #117023

Error Message

Fill the error message using step by step known issues guidance.

{
  "ErrorMessage": "block->bbTryIndex == blockTryIndex[block->bbNum]",
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1091084
Error message validated: [block->bbTryIndex == blockTryIndex[block->bbNum]]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 7/13/2025 9:59:12 AM UTC

Report

Build	Definition	Test	Pull Request
1093412	dotnet/runtime	System.Collections.Immutable.Tests.WorkItemExecution	#117578
1093197	dotnet/runtime	System.Collections.Immutable.Tests.WorkItemExecution	#117584
1092691	dotnet/runtime	System.Collections.Immutable.Tests.WorkItemExecution	#117549
1091084	dotnet/runtime	System.Collections.Immutable.Tests.WorkItemExecution	#117023

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
1	4	4

[jakobbotsch]

cc @dotnet/jit-contrib

[amanasifkhalid]

Ah, yet another arm32 failure. @AndyAyersMS could you please get me a JitDump of this? I can take a look from there.

[AndyAyersMS]

Sure.

[AndyAyersMS]

jit.3e634b59.txt

[amanasifkhalid]

fgUpdateFlowGraph's branch reversal optimization (something I hope to get rid of in .NET 11) isn't sufficiently careful to avoid moving EH region entries:

Moving BB192 after BB08 to enable reversal

Reversing a conditional jump around an unconditional jump (BB33 -> BB192, BB08 -> BB06)

After reversing the jump:

---------------------------------------------------------------------------------------------------------------------------------------------------------------------
BBnum  BBid ref try hnd preds           weight    IBC [IL range]   [jump]                              [EH region]        [flags]
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
BB01  [0000]  1                             1     100 [000..000)                             (throw )                   i IBC gcsafe idxlen newobj nullcheck
BB05  [0005]  1  0    BB79                  5.74  574 [000..000)-> BB29(1),BB32(0)           ( cond ) T0                i IBC internal idxlen bwd bwd-target
BB29  [0041]  1  0    BB05                  5.92  592 [000..000)-> BB06(1)                   (always) T0                i IBC internal idxlen bwd
BB06  [0006]  2  0    BB29,BB33             5.97  597 [000..000)-> BB194(1)                  (always) T0                i IBC internal idxlen bwd bwd-target
BB196 [0260]  1  0    BB50                 18.98 1898 [000..000)-> BB50(0.9),BB49(0.1)       ( cond ) T0                i IBC internal gcsafe idxlen bwd
BB50  [0060]  1  0    BB196                17.08 1708 [000..000)-> BB196(0.9),BB194(0.1)     ( cond ) T0                i IBC internal bwd
BB49  [0059]  1  0    BB196                 1.90  190 [000..000)-> BB33(1)                   (always) T0                i IBC internal bwd
BB194 [0258]  2  0    BB06,BB50             7.51  751 [000..000)-> BB33(1)                   (always) T0                IBC internal bwd
BB33  [0063]  2  0    BB49,BB194            5.63  563 [000..000)-> BB06(0.1),BB192(0.9)      ( cond ) T0                i IBC internal gcsafe idxlen bwd
BB192 [0256]  1  0    BB33                  6.58  658 [000..000)-> BB80(0.0307),BB79(0.969)  ( cond ) T0    try {       IBC keep internal idxlen bwd
BB79  [0096]  1  0    BB192                 6.38  638 [000..000)-> BB05(0.9),BB15(0.1)       ( cond ) T0                i IBC internal bwd
BB80  [0097]  1  0    BB192                 0.20   20 [000..000)-> BB15(1)                   (always) T0                i IBC internal bwd
BB32  [0040]  1  0    BB05                  0       0 [000..000)                             (throw ) T0    }           i IBC rare internal hascall gcsafe newobj bwd

[AndyAyersMS]

@amanasifkhalid do you need an SPMI for that or is the dump enough?

[amanasifkhalid]

@AndyAyersMS I think the dump is enough, thanks for grabbing it. Fix should be pretty targeted.