[LLVMbugs] [Bug 11235] New: suboptimal code with load/store vs memcpy

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=11235

           Summary: suboptimal code with load/store vs memcpy
           Product: new-bugs
           Version: trunk
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: s3734770 at mail.zih.tu-dresden.de
                CC: llvmbugs at cs.uiuc.edu


Created an attachment (id=7532)
 --> (http://llvm.org/bugs/attachment.cgi?id=7532)
Test case x.ll

The attached example is a Hello World example.
I'm storing 1 into the reference counter %ref.i.i (line 38), then i'm calling
some memcpy intrinsics and then I read from %ref.i.i again (line 49-51).

The memcpy range did not overlap the value which i loaded/stored, but it loaded
it again.
So the memcpy intrinsic should look at the range which it operates (alias
analysis).

After fixing this issue, `opt -O3 x.ll -S` should return a main function with
only one block.

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