[RyuJIT/x86/Checked] ngen dump assert

[sandreenko]

On the last build when I try to execute coreclr\bin\tests\Windows_NT.x86.Checked\Tests\Core_Root>crossgen.exe System.Private.CoreLib.dll with complus_ngendump=*
I see:

RESOLVING BB BOUNDARIES
-----------------------
Resolution Candidates:
Assert failure(PID 14924 [0x00003a4c], Thread: 17084 [0x42bc]): Assertion failed 'varNum < comp->lvaCount' in 'SR:get_ArgumentOutOfRange_Enum():ref' (IL size 11)

    File: c:\git\coreclr\src\jit\compiler.cpp Line: 8106
    Image: C:\git\coreclr\bin\tests\Windows_NT.x86.Checked\Tests\Core_Root\crossgen.exe

x64 works fine. Looks like it is a fresh problem.

[mikedn]

Likely broken by dotnet/coreclr#8207. identifyCandidates is supposed to initialize resolutionCandidateVars but it doesn't do so if lvaCount is 0. When dumpConvertedVarSet tries to enumerate it the set sometimes happen to have set bits (0xFFFFFFFF usually) but there are no lclvars so the assert fires. As far as I can tell there may be other code (buildIntervals at least) that uses the set even if lvaCount is 0 so there may be other issues in addition to that dump assert.

cc @CarolEidt

[michellemcdaniel]

Confirmed that @CarolEidt's change introduced this.

[CarolEidt]

Yes, sorry - I noticed this working on another change, and put a fix in with that change, but as that's not yet ready I will make this change separately.