https://llvm.org/bugs/show_bug.cgi?id=27433
Bug ID: 27433
Summary: LVI misses opportunities to conclude overdefined
Product: new-bugs
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: new bugs
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected], [email protected]
Classification: Unclassified
Following each icmp ne + branch, LVI properly concludes that x is not 10 and
20, respectively. However, it should also put these facts together and conclude
that x is overdefined at cont2. Instead of intersecting the incoming dataflow
fact with the new one, it seems to only overwrite it, concluding at cont2 that
x != 20.
define void @foo8(i32 %x) #0 {
entry:
%cmp = icmp ne i32 %x, 10
br i1 %cmp, label %if.end3, label %cont
cont:
%cmp1 = icmp ne i32 %x, 20
br i1 %cmp1, label %if.end3, label %cont2
cont2:
;; LVI should be able to tell we can't get here!
br label %if.end3
if.end3:
ret void
}
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