Clean up in rangecheck

[EgorBo]

Minor cleanup in rangecheck.cpp:

• Range Check was trying to do what assertionprop already did - handle constant indices. Removed with zero diffs.
• The previous code had a correctness issue - it called a slow SSA-based GetRangeWorker for Array's length but didn't use DoesOverflow that must be called for GetRangeWorker. Instead, I just call the VN-based GetRangeFromAssertions (that plays nicely with overflows) and it seems to be enough, a few minor regression, a minor TP improvement.

Note

This PR was generated with the assistance of GitHub Copilot.

Diffs (from an incorrect call to GetRangeWorker without DoesOverflow)

[Copilot]

Pull request overview

This PR refactors CoreCLR JIT bounds-check range analysis in rangecheck.cpp by removing a now-redundant constant-index fast path and a helper (optIsTreeKnownIntValue) in favor of using conservative VNs plus the existing assertion-based range machinery.

Changes:

• Simplifies RangeCheck::OptimizeRangeCheck by dropping the dedicated constant-index / arrSize computation path and relying on TryGetRange + BetweenBounds.
• Extends assertion-based range recovery for VNF_ARR_LENGTH to tighten to an exact length for new T[cns].Length via TryGetNewArrSize.
• Removes Compiler::optIsTreeKnownIntValue declaration and definition.

Reviewed changes

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

File	Description
src/coreclr/jit/rangecheck.cpp	Refactors bounds-check removal to rely on VN + assertion-based range info; enhances VNF_ARR_LENGTH assertion-range inference.
src/coreclr/jit/compiler.h	Removes the optIsTreeKnownIntValue declaration.
src/coreclr/jit/assertionprop.cpp	Removes the optIsTreeKnownIntValue implementation.

Comments suppressed due to low confidence (1)

src/coreclr/jit/rangecheck.cpp:806

• GetRangeFromAssertionsWorker returns early for GC VN types (varTypeIsGC(vnType)), so VNF_StrFastAllocate (which represents a string ref VN) is effectively unreachable here. Leaving it in the int-range switch adds dead code and can mislead readers into thinking StrFastAllocate is an int-producing VN.

            case VNF_GT:
            case VNF_GT_UN:
            case VNF_GE:
            case VNF_GE_UN:
            case VNF_LT:
            case VNF_LT_UN:

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.