Use the register of CAST for contained index operator

[kunalspathak]

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

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Issue Details

---

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:	-

[kunalspathak]

@dotnet/jit-contrib

[SingleAccretion]

What kind of cast gets here? CAST<long>(int)? But then what is doing the sign/zero-extension?

[kunalspathak]

N006 ( 4, 6) [000018] -c--G----U- t18 = * CAST long <- uint $1c0
/--* t19 byref +--* t18 long N007 ( 6, 8) [000020] ----------- t20 = * LEA(b+(i*1)+0) byref 

[SingleAccretion]

Hmm, so it is indeed CAST<long>(int). There is still the question of what is doing the extension (is it perhaps unnecessary)?

[JulieLeeMSFT]

@kunalspathak, @dotnet/jit-contrib, are we going to backport it to 7?

[kunalspathak]

@kunalspathak, @dotnet/jit-contrib, are we going to backport it to 7?

Probably. This issue is around the code that was introduced in .NET 7.

[SingleAccretion]

Code changes LGTM. We may find out the upfront IsSafeToContainMem it too expensive TP-wise and will need to move it down after the other checks, but hopefully not.

I've also filed #74448 to track the complete fix, you could add a link to it from codegen (or not).

Also it would be nice to add a regression test, say:

[MethodImpl(MethodImplOptions.NoInlining)]privatestaticvoidProblem(refbytex,inta){[MethodImpl(MethodImplOptions.NoInlining)]staticbyteGetByte()=>1;JitUse(&a);Unsafe.Add(refx,a)= GetByte();}[MethodImpl(MethodImplOptions.NoInlining)]publicstaticvoidJitUse<T>(T*arg)whereT: unmanaged {}

[kunalspathak]

@dotnet/jit-contrib - can someone review it?

[kunalspathak]

@EgorBo - can you take a look?

[EgorBo]

@EgorBo - can you take a look?

oops, sorry for the delay - didn't notice this mention, something is wrong with my mail filters. LGTM btw

[kunalspathak]

/backport to release/7.0-rc1

[github-actions]

Started backporting to release/7.0-rc1: https://github.com/dotnet/runtime/actions/runs/2995029976

[github-actions]

@kunalspathak backporting to release/7.0-rc1 failed, the patch most likely resulted in conflicts:

$ git am --3way --ignore-whitespace --keep-non-patch changes.patch
Applying: Rename test files
error: mode change forsrc/tests/JIT/Regression/JitBlue/Runtime_74373/Runtime_73821.cs, which is notin current HEAD
error: could not build fake ancestor
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 Rename test files
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".
Error: The process '/usr/bin/git' failed with exit code 128

Please backport manually!

[kunalspathak]

/backport to release/7.0

[github-actions]

Started backporting to release/7.0: https://github.com/dotnet/runtime/actions/runs/3002058907

[github-actions]

@kunalspathak backporting to release/7.0 failed, the patch most likely resulted in conflicts:

$ git am --3way --ignore-whitespace --keep-non-patch changes.patch
Applying: Rename test files
Applying: Fix index scale for cast
Applying: Do not contain index if indir is not containable.
Applying: Revert "Do not contain index if indir is not containable."
Applying: Instead try to contain the LEA
Using index info to reconstruct a base tree...
M	src/coreclr/jit/lower.cpp
Falling back to patching base and 3-way merge...
Auto-merging src/coreclr/jit/lower.cpp
CONFLICT (content): Merge conflict in src/coreclr/jit/lower.cpp
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0005 Instead try to contain the LEA
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".
Error: The process '/usr/bin/git' failed with exit code 128

Please backport manually!