[llvm-bugs] [Bug 50818] New: Some tests compare hash values as if they were floating point

via llvm-bugs llvm-bugs at lists.llvm.org
Wed Jun 23 09:28:14 PDT 2021


https://bugs.llvm.org/show_bug.cgi?id=50818

            Bug ID: 50818
           Summary: Some tests compare hash values as if they were
                    floating point
           Product: Test Suite
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Nightly Tester
          Assignee: unassignedbugs at nondot.org
          Reporter: andrew.kaylor at intel.com
                CC: llvm-bugs at lists.llvm.org

Some tests in the test suite (I'm not sure how many) are hashing the test
output but then using fpcmp to compare the hashed result to the expected hash.

For example, I ran the test suite with "-ffp-contract=on" as an extra compile
option (before a recent change which disabled fp contraction in a number of
tests) and observed the following with the Microbenchmarks/ImageProcessing/Blur
test:

Expected hash value: 7f4246596bcfbb5e6e44cd21ddfeaf07
Actual hash value: 6098466d4eeaf5ccd1871870206176c9
Test error message:
fpcmp-target: Compared: 7.000000e+00 and 6.098466e+10
abs. diff = 6.098466e+10 rel.diff = 1.000000e+00
Out of tolerance: rel/abs: 0.000000e+00/0.000000e+00

The error message results from the test calling fpcmp-target, which looks for
the first thing that seems to be a number and converts it to a floating point
value. So, in this case it was comparing “7” to “6098466”. If the first
character of either hash value is non-numeric, it reports a “not a numeric
difference” error.

The comparison works (for the wrong reasons) if the test produces the exact
output that is expected, but there is no way to allow any floating point
tolerance and the error message is incorrect.

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