C++: Remove safeFloor in simple range analysis

[paldepind]

This PR removes the safeFloor predicate from the simple range analysis library. The predicate is a workaround for the fact that QL's floor operates on 32 bit integers. We no longer need this after the recently introduced floorFloat predicate, which operates directly on float without any loss in range.

In addition to getting rid of safeFloor, as the test shows, this also enables correct flooring on fractional numbers greater than 2^32. This problem was pointed out by @geoffw0 back in #3445:

There are some edge cases for int64 types that we don't handle well (because QL floor() fails on large numbers!) so such cases are simply excluded from the analysis.

[Copilot]

Pull request overview

This PR removes the safeFloor predicate from the simple range analysis library, which was a workaround for QL's floor() method operating on 32-bit integers. The new floorFloat predicate directly operates on float values without range limitations, enabling correct handling of fractional numbers greater than 2^32.

Key Changes:

• Removed the safeFloor predicate and its workaround logic
• Replaced safeFloor calls with direct floorFloat() method calls on float expressions
• Added test case demonstrating correct analysis of large numbers (2^53 - 1)

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
cpp/ql/lib/semmle/code/cpp/rangeanalysis/SimpleRangeAnalysis.qll	Removed safeFloor predicate and updated right shift operations to use floorFloat()
cpp/ql/test/library-tests/rangeanalysis/SimpleRangeAnalysis/test.c	Added test case for shift operations on large numbers (2^53)
cpp/ql/test/query-tests/Likely Bugs/Arithmetic/PointlessComparison/PointlessComparison.cpp	Updated comments to reflect corrected analysis (removed "INCORRECT MESSAGE" notes)
cpp/ql/test/query-tests/Likely Bugs/Arithmetic/PointlessComparison/PointlessComparison.expected	Updated expected results with corrected integer bounds (removed .5 fractional values)
cpp/ql/test/library-tests/rangeanalysis/SimpleRangeAnalysis/*.expected	Updated test expectations with new line numbers and corrected bounds for large number handling

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[geoffw0]

LGTM. Glad to see the back of safeFloor. 👍

Please check there are no surprises when the DCA run finishes before merging.

[paldepind]

Please check there are no surprises when the DCA run finishes before merging.

The DCA report seems fine, it shows something about a bad join, but I don't think it's related to the PR?

[geoffw0]

The DCA report seems fine, it shows something about a bad join, but I don't think it's related to the PR?

I don't generally worry about such things unless there's an overall regression to be explained (which I don't see here). And yeah, the predicate its on doesn't seem related to your changes.