James Molloy c0c824e64b [ValueTracking] Understand more select patterns in ComputeKnownBits ...

Some patterns of select+compare allow us to know exactly the value of the uppermost bits in the select result. For example:

  %b = icmp ugt i32 %a, 5
  %c = select i1 %b, i32 2, i32 %a

Here we know that %c is bounded by 5, and therefore KnownZero = ~APInt(5).getActiveBits() = ~7.

There are several such patterns, and this patch attempts to understand a reasonable subset of them - namely when the base values are the same (as above), and when they are related by a simple (add nsw), for example (add nsw %a, 4) and %a.

llvm-svn: 257769

2016-01-14 15:23:19 +00:00

..

assume.ll

[ValueTracking] do not overwrite analysis results already computed

2015-06-15 05:46:29 +00:00

dom-cond.ll

[ValueTracking] do not overwrite analysis results already computed

2015-06-15 05:46:29 +00:00

known-bits-from-range-md.ll

[ValueTracking] Use !range metadata more aggressively in KnownBits

2015-10-28 03:20:15 +00:00

known-non-equal.ll

[ValueTracking] Add a new predicate: isKnownNonEqual()

2015-10-22 13:18:42 +00:00

known-power-of-two.ll

[ValueTracking] fix bug computing isKnownToBeAPowerOfTwo() with arithmetic shift right (PR25900)

2015-12-30 22:40:52 +00:00

knownnonzero-shift.ll

[ValueTracking] Extend r251146 to catch a fairly common case

2015-10-26 14:10:46 +00:00

knownzero-shift.ll

[ValueTracking] Teach isKnownNonZero a new trick

2015-09-24 16:06:32 +00:00

memory-dereferenceable.ll

[gc.statepoint] Change gc.statepoint intrinsic's return type to token type instead of i32 type

2015-12-26 07:54:32 +00:00

monotonic-phi.ll

[ValueTracking] Teach isKnownNonZero about monotonically increasing PHIs

2015-09-29 14:08:45 +00:00

pr23011.ll

[ValueTracking] Fix PR23011.

2015-03-25 22:33:53 +00:00

pr24866.ll

Fix for pr24866

2015-09-21 22:04:10 +00:00

select-maxbits.ll

[ValueTracking] Understand more select patterns in ComputeKnownBits

2016-01-14 15:23:19 +00:00