https://bugs.llvm.org/show_bug.cgi?id=51668
Bug ID: 51668
Summary: EarlyCSE incorrectly assumes that readonly functions
return
Product: libraries
Version: trunk
Hardware: All
OS: All
Status: NEW
Keywords: miscompilation
Severity: normal
Priority: P
Component: Scalar Optimizations
Assignee: unassignedb...@nondot.org
Reporter: nunoplo...@sapo.pt
CC: alina.sbir...@gmail.com, florian_h...@apple.com,
gbe...@codeaurora.org, llvm-bugs@lists.llvm.org,
llvm-...@redking.me.uk
Test: Transforms/EarlyCSE/globalsaa-memoryssa.ll
define void @f3() {
%call1 = call i16 @f1() nowrite nofree
call void @f2()
%call2 = call i16 @f1() nowrite nofree
ret void
}
=>
define void @f3() {
%call1 = call i16 @f1() nowrite nofree
call void @f2()
ret void
}
The second call to @f1() is incorrectly removed. We don't know if it exits, for
example. Function @f2 may change the state read by @f1 and thus the first call
may return and the second exit.
The optimization should be restricted to functions with the 'willreturn'
attribute.
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