[llvm] [InstCombine] fold icmp of select with invertible shl (PR #147182)

[via llvm-commits]

actinks wrote:

> Miscompilation reproducer: https://alive2.llvm.org/ce/z/-TagCh
> 
Is this patch causing this error? My compilation result is  https://alive2.llvm.org/ce/z/enaJTE  @dtcxzyw 

```
define i1 @src(i64 %indvars.iv.i, i32 %conv161.i.i.i) {
entry:
  %cmp104.i.i.i = icmp slt i64 %indvars.iv.i, 1
  br i1 %cmp104.i.i.i, label %lor.end157.i.i.i, label %lor.rhs106.i.i.i

lor.rhs106.i.i.i:
  br label %lor.end157.i.i.i

lor.end157.i.i.i:
  %conv159.i.i.i = zext i1 %cmp104.i.i.i to i16
  %sub.i122.i.i.i = sub i16 0, %conv159.i.i.i
  %conv161.i.i.i2 = zext i16 %sub.i122.i.i.i to i32
  %shl.i.i.i.i = shl nuw i32 %conv161.i.i.i, 31
  %cond.i124.i.i.i = select i1 %cmp104.i.i.i, i32 %conv161.i.i.i2, i32 %shl.i.i.i.i
  %conv163.i.i.i = zext i32 %cond.i124.i.i.i to i64
  %tobool166.not.i.i.i = icmp eq i64 %conv163.i.i.i, 0
  ret i1 %tobool166.not.i.i.i
}

define i1 @tgt(i64 %indvars.iv.i, i32 %conv161.i.i.i) {
entry:
  %cmp104.i.i.i = icmp sgt i64 %indvars.iv.i, 0
  br i1 %cmp104.i.i.i, label %lor.rhs106.i.i.i, label %lor.end157.i.i.i

lor.rhs106.i.i.i:                                 ; preds = %entry
  br label %lor.end157.i.i.i

lor.end157.i.i.i:                                 ; preds = %lor.rhs106.i.i.i, %entry
  %tobool166.not.i.i.i1 = icmp eq i32 %conv161.i.i.i, 0
  %tobool166.not.i.i.i = select i1 %cmp104.i.i.i, i1 %tobool166.not.i.i.i1, i1 false
  ret i1 %tobool166.not.i.i.i
}
```



https://github.com/llvm/llvm-project/pull/147182