False positive for the same GEP pointer after unrolling the loop

[XChy]

https://alive2.llvm.org/ce/z/c8xStZ

In this example, I think %arrayidx104 should be equivalent to %arrayidx84. But it reported target is more poisonous after unrolling the loop.

[nunoplopes]

So this doesn't get lost; a reduced version:

define ptr @src(ptr noundef %a, i32 noundef %b, i1 noundef %cmp86) {
lr.ph:
  br label %for.body
for.body:
  %indvars.iv = phi i32 [ 0, %lr.ph ], [ 8, %for.inc93 ]
  %arrayidx84 = getelementptr inbounds ptr, ptr %a, i32 %indvars.iv
  br i1 %cmp86, label %if.end98, label %for.inc93

for.inc93:
  %indvars.iv.next = add i32 %indvars.iv, 8
  %exitcond.not = icmp ugt i32 %indvars.iv.next, %b
  br i1 %exitcond.not, label %cleanup, label %for.body

if.end98:
  %arrayidx104 = getelementptr inbounds ptr, ptr %a, i32 %indvars.iv
  ret ptr %arrayidx104

cleanup:
  ret ptr null
}

define ptr @tgt(ptr noundef %a, i32 noundef %b, i1 noundef %cmp86) {
lr.ph:
  br label %for.body
for.body:
  %indvars.iv = phi i32 [ 0, %lr.ph ], [ 8, %for.inc93 ]
  %arrayidx84 = getelementptr inbounds ptr, ptr %a, i32 %indvars.iv
  br i1 %cmp86, label %if.end98, label %for.inc93

for.inc93:
  %indvars.iv.next = add i32 %indvars.iv, 8
  %exitcond.not = icmp ugt i32 %indvars.iv.next, %b
  br i1 %exitcond.not, label %cleanup, label %for.body

if.end98:
  ret ptr %arrayidx84

cleanup:
  ret ptr null
}