Yingwei Zheng 59eae919c9
[ValueTracking] Don't use CondContext in dataflow analysis of phi nodes (#100316)
See the following case:
```
define i16 @pr100298() {
entry:
  br label %for.inc

for.inc:
  %indvar = phi i32 [ -15, %entry ], [ %mask, %for.inc ]
  %add = add nsw i32 %indvar, 9
  %mask = and i32 %add, 65535
  %cmp1 = icmp ugt i32 %mask, 5
  br i1 %cmp1, label %for.inc, label %for.end

for.end:
  %conv = trunc i32 %add to i16
  %cmp2 = icmp ugt i32 %mask, 3
  %shl = shl nuw i16 %conv, 14
  %res = select i1 %cmp2, i16 %conv, i16 %shl
  ret i16 %res
}
```

When computing knownbits of `%shl` with `%cmp2=false`, we cannot use
this condition in the analysis of `%mask (%for.inc -> %for.inc)`.
 
Fixes https://github.com/llvm/llvm-project/issues/100298.
2024-07-24 20:06:36 +08:00
..
2024-07-01 14:52:06 +02:00

This directory contains test cases for the instcombine transformation.  The
dated tests are actual bug tests, whereas the named tests are used to test
for features that the this pass should be capable of performing.