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[ConstantRange][LVI] Use overflow flags from `sub` to constrain the range
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Authored by lebedev.ri on Thu, Nov 7, 4:22 AM.

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Summary

This notably improves non-negativity deduction:

| statistic                              |     old |     new | delta | % change |
| correlated-value-propagation.NumAShrs  |     209 |     227 |    18 |  8.6124% |
| correlated-value-propagation.NumAddNSW |    4972 |    4988 |    16 |  0.3218% |
| correlated-value-propagation.NumAddNUW |    7141 |    7148 |     7 |  0.0980% |
| correlated-value-propagation.NumAddNW  |   12113 |   12136 |    23 |  0.1899% |
| correlated-value-propagation.NumAnd    |     442 |     445 |     3 |  0.6787% |
| correlated-value-propagation.NumNSW    |    7160 |    7176 |    16 |  0.2235% |
| correlated-value-propagation.NumNUW    |   13306 |   13316 |    10 |  0.0752% |
| correlated-value-propagation.NumNW     |   20466 |   20492 |    26 |  0.1270% |
| correlated-value-propagation.NumSDivs  |     207 |     212 |     5 |  2.4155% |
| correlated-value-propagation.NumSExt   |    6279 |    6679 |   400 |  6.3704% |
| correlated-value-propagation.NumSRems  |      28 |      29 |     1 |  3.5714% |
| correlated-value-propagation.NumShlNUW |    2793 |    2796 |     3 |  0.1074% |
| correlated-value-propagation.NumShlNW  |    3964 |    3967 |     3 |  0.0757% |
| correlated-value-propagation.NumUDivs  |     353 |     358 |     5 |  1.4164% |
| instcount.NumAShrInst                  |   13763 |   13741 |   -22 | -0.1598% |
| instcount.NumAddInst                   |  277349 |  277348 |    -1 | -0.0004% |
| instcount.NumLShrInst                  |   27437 |   27463 |    26 |  0.0948% |
| instcount.NumOrInst                    |  102677 |  102678 |     1 |  0.0010% |
| instcount.NumSDivInst                  |    8732 |    8727 |    -5 | -0.0573% |
| instcount.NumSExtInst                  |   80872 |   80468 |  -404 | -0.4996% |
| instcount.NumSRemInst                  |    1679 |    1678 |    -1 | -0.0596% |
| instcount.NumTruncInst                 |   62154 |   62153 |    -1 | -0.0016% |
| instcount.NumUDivInst                  |    2526 |    2527 |     1 |  0.0396% |
| instcount.NumURemInst                  |    1589 |    1590 |     1 |  0.0629% |
| instcount.NumZExtInst                  |   69405 |   69809 |   404 |  0.5821% |
| instcount.TotalInsts                   | 7439575 | 7439574 |    -1 |  0.0000% |

Diff Detail

Event Timeline

lebedev.ri created this revision.Thu, Nov 7, 4:22 AM
nikic accepted this revision.Thu, Nov 7, 5:10 AM

LGTM

This revision is now accepted and ready to land.Thu, Nov 7, 5:10 AM

LGTM

Thank you for the review.
Looking into mul/shl, will need to add ConstantRange::[us]{mul,shl}_sat() at the same time.

This revision was automatically updated to reflect the committed changes.