[LLVMbugs] [Bug 11241] New: known constant not folded: new() + 4 != 0

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=11241

           Summary: known constant not folded: new() + 4 != 0
           Product: libraries
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Scalar Optimizations
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: richard-llvm at metafoo.co.uk
                CC: llvmbugs at cs.uiuc.edu


Created an attachment (id=7536)
 --> (http://llvm.org/bugs/attachment.cgi?id=7536)
Testcase

This IR:

  %alloc2 = tail call noalias i8* @_Znwm(i64 8) nounwind
  %add = getelementptr inbounds i8* %alloc2, i64 4
  %always_false = icmp eq i8* %add, null
  ret i1 %always_false

... is collapsed to "ret i1 0". However, this IR:

  %alloc2 = tail call noalias i8* @_Znwm(i64 8) nounwind
  %add = getelementptr inbounds i8* %alloc2, i64 4
  %always_false = icmp eq i8* %add, null
  br i1 %always_false, label %skipinit2, label %init2

init2:                                            ; preds = %entry
  store i8 1, i8* %alloc2, align 1
  ret void

skipinit2:                                        ; preds = %entry
  ret void

... is not optimized any further.

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