[LLVMbugs] [Bug 10581] New: [AVX] vector shifts are scalarized

bugzilla-daemon at llvm.org bugzilla-daemon at llvm.org
Wed Aug 3 16:27:57 PDT 2011


           Summary: [AVX] vector shifts are scalarized
           Product: new-bugs
           Version: trunk
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: matt at pharr.org
                CC: llvmbugs at cs.uiuc.edu


define <8 x i32> @foo___ff(<8 x i32> %a, <8 x i32> %b) nounwind readnone {
  %s = shl <8 x i32> %a, <i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32
  ret <8 x i32> %s

llc -mattr=+avx deconstructs the vector into elements, shifts each one
individually, and reconstructs the vector.  It'd be nice if it just used the
corresponding AVX vector shift instruction for this.

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