[mlir] Fix CMulOp lowering

[PavelKopyl]

Avoid undefined behavior when checking for multiplication overflow.

solx-llvm

[Copilot]

Pull request overview

Updates MLIR/EVM codegen test expectations to match the new CMulOp overflow-check lowering that avoids division-by-zero/UB, and adds a semantic regression case to ensure ofm(int8) behaves correctly for input 0.

Changes:

• Update EVM MLIR FileCheck expectations to use a guarded divisor (arith.select) before arith.divui/divsi in multiplication overflow checks.
• Refresh variable numbering / block contents in generated MLIR checks (panic/revert sequences, stores) to match updated lowering output.
• Add a semantic test case covering ofm(int8): 0 -> 0.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
test/lit/mlirCodegen/EVM/ctor.sol	Updates FileCheck patterns for constructor codegen to reflect safe mul-overflow checks (guarded division).
test/lit/mlirCodegen/EVM/arith.sol	Updates FileCheck patterns for arithmetic codegen; introduces guarded division in mul-overflow checks and adjusts expected IR accordingly.
test/libsolidity/semanticTests/mlir/arith.sol	Adds a semantic regression expectation for ofm(int8) with input 0.

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[abinavpp]

Thank you!