Changes

[CVP] Deduce no-wrap on `mul`
Summary:
`ConstantRange::makeGuaranteedNoWrapRegion()` knows how to deal with
`mul` since rL335646, there is exhaustive test coverage. This is already
used by CVP's `processOverflowIntrinsic()`, and by SCEV's
`StrengthenNoWrapFlags()`
That being said, currently, this doesn't help much in the end:
| statistic                              |     old |     new | delta |
percentage |
| correlated-value-propagation.NumMulNSW |       4 |     275 |   271 |  
6775.00% |
| correlated-value-propagation.NumMulNUW |       4 |    1323 |  1319 | 
32975.00% |
| correlated-value-propagation.NumMulNW  |       8 |    1598 |  1590 | 
19875.00% |
| correlated-value-propagation.NumNSW    |    5715 |    5986 |   271 |  
   4.74% |
| correlated-value-propagation.NumNUW    |    9193 |   10512 |  1319 |  
  14.35% |
| correlated-value-propagation.NumNW     |   14908 |   16498 |  1590 |  
  10.67% |
| instcount.NumAddInst                   |  275871 |  275869 |    -2 |  
   0.00% |
| instcount.NumBrInst                    |  708234 |  708232 |    -2 |  
   0.00% |
| instcount.NumMulInst                   |   43812 |   43810 |    -2 |  
   0.00% |
| instcount.NumPHIInst                   |  316786 |  316784 |    -2 |  
   0.00% |
| instcount.NumTruncInst                 |   62165 |   62167 |     2 |  
   0.00% |
| instcount.NumUDivInst                  |    2528 |    2526 |    -2 |  
  -0.08% |
| instcount.TotalBlocks                  |  842995 |  842993 |    -2 |  
   0.00% |
| instcount.TotalInsts                   | 7376486 | 7376478 |    -8 |  
   0.00% |
(^ test-suite plain, tests still pass)
Reviewers: nikic, reames, luqmana, sanjoy, timshen
Reviewed By: reames
Subscribers: hiraditya, javed.absar, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D69203
llvm-svn: 375396

[NFC][InstCombine] Fixup comments
As noted in post-commit review of rL375378375378.
llvm-svn: 375397