Fix possible overflow in optAssertionPropGlobal_RelOp

[EgorBo]

Fixes #122288

We deal with 1 >= (2147483646 + X) expression. Since getting the range of the whole op2 (2147483646 + X) didn't get us anything, we have this hack where we peel the offset (so 2147483646) and try to find the range of X. (I'll move this logic into ryGetRangeFromAssertions itself in the future).

We end up with [0...65535] range of X which clearly may overflow when 2147483646 is added. The previous logic was trying to just move the constant to the left 1 - 2147483646 >= X where Subtract didn't overflow.

I want to do some refactoring around overflow handling. Today, e.g. for range1=[0..int.MaxValue] and range2=[10..20] the RangeOps::Add(range1, range2) returns [10..unknown], I want it to return [unknown..unknown] (or maybe [-2147483639..0] ?). It seems to be not a problem today except for 2 places in global assertion prop.

This fix doesn't contain the refactoring to be backport-friendly.

A few diffs correctness related.

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[Copilot]

Pull request overview

This PR fixes a potential overflow issue in the JIT compiler's assertion propagation optimizer when performing range analysis on relational operators.

Changes:

• Enhanced the Limit::AddConstant method to optionally report overflow conditions via an out parameter
• Updated optAssertionProp_RangeProperties to explicitly check for overflow when adding constants to range bounds
• Fixed optAssertionPropGlobal_RelOp to detect and bail out when adding peeled offsets would overflow range limits
• Added a regression test that reproduces the overflow scenario

Reviewed changes

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

File	Description
src/coreclr/jit/rangecheck.h	Added optional overflows parameter to AddConstant method to report overflow conditions
src/coreclr/jit/assertionprop.cpp	Updated two call sites to use explicit overflow detection instead of relying on return values, improving code clarity and correctness
src/tests/JIT/Regression/JitBlue/Runtime_122288/Runtime_122288.cs	Added regression test for the overflow scenario with a comparison involving large constants

[EgorBo]

PTAL @jakobbotsch @dotnet/jit-contrib

[EgorBo]

Closed in favor of #123233