[release/7.0] Use the register of CAST for contained index operator

[kunalspathak]

Backport of #74275

If index is contained and the underlying operator is GT_CAST we were not handling that case and that led to using REG_COUNT register from index in genScaledAdd() . I have fixed it and also added checks to see if more such cases are missing.

Fixes: #74117

[kunalspathak]

@dotnet/jit-contrib

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Issue Details

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If index is contained and the underlying operator is GT_CAST we were not handling that case and that led to using REG_COUNT register from index in genScaledAdd() . I have fixed it and also added checks to see if more such cases are missing.

Fixes: #74117

Author:	kunalspathak
Assignees:	-
Labels:	area-CodeGen-coreclr
Milestone:	-

[carlossanlop]

@BruceForstall can we get a code review sign off?
@jeffschwMSFT can we get an approval?

[jeffschwMSFT]

approved. once we get a green ci we can merge.

[carlossanlop]

There were a ton of llvmaot failures. Are they related to this change?

All failed with the same error code:

BEGIN : coreclr_initialize failed - error : 0x80004005 [/__w/1/s/src/mono/msbuild/aot-compile.proj]
END : coreclr_initialize failed - error : 0x80004005 [/__w/1/s/src/mono/msbuild/aot-compile.proj]
/__w/1/s/src/mono/msbuild/aot-compile.proj(19,9): error MSB3073: The command "/__w/1/s/artifacts/tests/coreclr/Linux.x64.Release/Tests/Core_Root/corerun /__w/1/s/artifacts/tests/coreclr/Linux.x64.Release/Tests/Core_Root/xunit.runner.utility.netcoreapp10.dll" exited with code 255.
0 Warning(s)
10770 Error(s)

Job results: https://dev.azure.com/dnceng-public/public/_build/results?buildId=5862&view=logs&j=ac444259-14dc-5e9e-4846-f4aabcc22cf0&t=616bd7d0-b458-5b0a-3812-dbea2ad61cca

[kunalspathak]

Original PR didn't had those. The failure seems very fundamental that it failed to initialize coreclr. May be rerun?

[carlossanlop]

@jkotas@MichalStrehovsky do the above llvmaot failures look familiar to you? Should I open an issue? I am unsure if any of the open issues with that error number is the same: https://github.com/dotnet/runtime/issues?q=is%3Aissue+is%3Aopen+0x80004005

[MichalStrehovsky]

@jkotas@MichalStrehovsky do the above llvmaot failures look familiar to you? Should I open an issue?

llvmaot is Mono. Looks like #72114. Cc @lambdageek@SamMonoRT

[carlossanlop]

Approved and signed off.
CI failure determined to be unrelated.
Ready to merge.