[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.

0 files changed, 0 insertions, 0 deletions