[LLVMbugs] [Bug 9285] New: The LLVM LangRef is unclear regarding shift where the shift size is larger than the word size

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=9285

           Summary: The LLVM LangRef is unclear regarding shift where the
                    shift size is larger than the word size
           Product: libraries
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Backend: MSP430
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: nadav.rotem at intel.com
                CC: llvmbugs at cs.uiuc.edu


Currently, in the x86 backend, scalar shift-left operations use the intel SHL
opcode which only looks at the LSB of the shift word. Starting LLVM 2.8, the
vector-SHL started using the PSLLD shift, which looks at the entire shift value
and zeros the result if the value is greater than the word size. 

The LLVM LangRef does not address the behavior of shift operations where the
shift size is larger than the word size.

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