[LLVMbugs] [Bug 13936] New: Lack of hwdiv (SDIV/UDIV) on ARM mode

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=13936

             Bug #: 13936
           Summary: Lack of hwdiv (SDIV/UDIV) on ARM mode
           Product: new-bugs
           Version: trunk
          Platform: Other
        OS/Version: Windows NT
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: weimingz at codeaurora.org
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified


Currently, LLVM supports sdiv/udiv for thumb on  ARMv7-R and ARMv7-M. 

These instructions are optional in ARMv7-A and ARMv7-R on ARM mode. (See ARM
Architecture Reference Manual ARMv7-A and ARMv7-R edition,
https://silver.arm.com/download/ARM_and_AMBA_Architecture/AR570-DA-70000-r0p0-00rel1/DDI0406C_b_arm_architecture_reference_manual.pdf
, Page A8-600)

We should be able to add the instructions and corresponding encoding into
existing td files and use the existing target-feature: hwdiv flag to guard it. 
So, we can avoid calls to RT lib if the hardware supports hw div.

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