[LLVMbugs] [Bug 9004] New: GVN correlated expressions handles the hard case but not the easy case!

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=9004

           Summary: GVN correlated expressions handles the hard case but
                    not the easy case!
           Product: new-bugs
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: baldrick at free.fr
                CC: llvmbugs at cs.uiuc.edu


Run "opt -gvn" on the following testcase.  It gets that "ret i1 %cond2" returns
false, but it doesn't see that the a priori easier "ret i1 %cond" returns true!

define i1 @foo(i32 %x) {
  %cond = icmp eq i32 %x, 0
  br i1 %cond, label %iftrue, label %iffalse
iftrue:
  ret i1 %cond
iffalse:
  %cond2 = icmp eq i32 %x, 0
  ret i1 %cond2
}

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