[LLVMbugs] [Bug 2059] New: Missed sret memcpy optimization

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=2059

           Summary: Missed sret memcpy optimization
           Product: new-bugs
           Version: unspecified
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: baldrick at free.fr
                CC: llvmbugs at cs.uiuc.edu


Created an attachment (id=1423)
 --> (http://llvm.org/bugs/attachment.cgi?id=1423)
testcase .ll

The recent sret+memcpy simplification assumes that the memcpy is to
a noalias sret parameter.  But there seems to be no real reason for
that, it just needs to be to something that can be proved not to be
accessed by the called function.  For example another temporary.
Here is a testcase: both of the memcpy's could be removed by passing
the destination directly to the called function.


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