JIT: Add morphing to LE_UN/GT_UN(expr, uint.MaxValue) (dotnet#76525)

[shunkino]

Add morphing for comparison between uint.MaxValue and a ulong value.

Contribute to: #76525

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

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[shunkino]

@dotnet-policy-service agree company="Microsoft"

[EgorBo]

the asserts below this change check exactly that - is it needed?

[shunkino]

Yes. The morphing added in this commit is changing gtOp1, so we need to reload ops here just like for fgOptimizeRelationalComparisonWithCasts.

runtime/src/coreclr/jit/morph.cpp

Line 9390 in 63a3a5f

cmp->gtOp1 = shiftNode;

Before this commit, fgOptimizeRelationalComparisonWithConst doesn't update op1 and op2, so there are pair of asserts to check it. Is it better to remove these asserts to clarify this?

                assert(op1 == tree->AsOp()->gtGetOp1());
                assert(op2 == tree->AsOp()->gtGetOp2());

[EgorBo]

Seems like CI failed with

 ISSUE: <ASSERT> #263216 D:\a\_work\1\s\src\coreclr\jit\codegenxarch.cpp (4912) - Assertion failed 'operandReg != REG_RCX' in 'bug.Program:TestEntryPoint():int' during 'Generate code' (IL size 42; hash 0x8feb9733; FullOpts)

[EgorBo]

EQ/NE(RSZ(expr, 32), 0).

I don't see where that 0 is set here, what is cmp->gtOp2 at this point?

[shunkino]

I believe this line sets op2 to 0. All other morphing done in fgOptimizeRelationalComparisonWithConst also don't set 0 explicitly.

runtime/src/coreclr/jit/morph.cpp

Line 9400 in 63a3a5f

op2->SetIntegralValue(0);