[LLVMbugs] [Bug 5375] New: Too many redundant neon / vfp reg-reg moves are generated

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=5375

           Summary: Too many redundant neon / vfp reg-reg moves are
                    generated
           Product: libraries
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Backend: ARM
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: asl at math.spbu.ru
                CC: llvmbugs at cs.uiuc.edu


Created an attachment (id=3748)
 --> (http://llvm.org/bugs/attachment.cgi?id=3748)
Small testcase

We are generating too much extra reg-reg moves mostly due to weak subreg
lowering - it's not able to fold the stuff.

Consider the attached testcase (I think it's the smalles one possible). We have
the following code generated:

        fldd    d0, .LCPI1_0
        fldd    d2, .LCPI1_1

        vmov    d1, d2
        bl      baz

d2 is killed at vmov, thus vmov should be folded into fldd.


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