test: add more tests for popcount

[axic]

No description provided.

[chfast]

Cases with single bit are missing.
Same cases should be added to TEST(execute_numeric, i{32,64}_popcnt).

[codecov]

Codecov Report

Merging #688 (fc74d4e) into master (bd56198) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #688      +/-   ##
==========================================
- Coverage   99.31%   99.31%   -0.01%     
==========================================
  Files          72       72              
  Lines       10154    10148       -6     
==========================================
- Hits        10084    10078       -6     
  Misses         70       70              

Flag	Coverage Δ
spectests	91.50% <ø> (ø)
unittests	99.31% <100.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
test/unittests/cxx20_bit_test.cpp	100.00% <100.00%> (ø)
test/unittests/execute_numeric_test.cpp	100.00% <100.00%> (ø)

[axic]

Cases with single bit are missing.

Added two single bit cases.

Same cases should be added to TEST(execute_numeric, i{32,64}_popcnt).

At this point though the tests should be changed to a pair then.

[chfast]

At this point though the tests should be changed to a pair then.

Not sure what exactly do you mean, but you can create a new header file with test cases for clz, ctz, popcnt:

struct BitCountTestCase64
{
uint64_t value;
uint32_t expected_clz;
...
};

constexpr BitCountTestCase64 test_cases_64[] = {{0,32,32,0}, ...}; 

[axic]

Any more test cases to be added?

[chfast]

Any more test cases to be added?

Looks ok for now.