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Annotation of OpenXM_contrib/gmp/mpn/hppa/README, Revision 1.1

1.1     ! maekawa     1: This directory contains mpn functions for various HP PA-RISC chips.  Code
        !             2: that runs faster on the PA7100 and later implementations, is in the pa7100
        !             3: directory.
        !             4:
        !             5: RELEVANT OPTIMIZATION ISSUES
        !             6:
        !             7:   Load and Store timing
        !             8:
        !             9: On the PA7000 no memory instructions can issue the two cycles after a store.
        !            10: For the PA7100, this is reduced to one cycle.
        !            11:
        !            12: The PA7100 has a lookup-free cache, so it helps to schedule loads and the
        !            13: dependent instruction really far from each other.
        !            14:
        !            15: STATUS
        !            16:
        !            17: 1. mpn_mul_1 could be improved to 6.5 cycles/limb on the PA7100, using the
        !            18:    instructions bwlow (but some sw pipelining is needed to avoid the
        !            19:    xmpyu-fstds delay):
        !            20:
        !            21:        fldds   s1_ptr
        !            22:
        !            23:        xmpyu
        !            24:        fstds   N(%r30)
        !            25:        xmpyu
        !            26:        fstds   N(%r30)
        !            27:
        !            28:        ldws    N(%r30)
        !            29:        ldws    N(%r30)
        !            30:        ldws    N(%r30)
        !            31:        ldws    N(%r30)
        !            32:
        !            33:        addc
        !            34:        stws    res_ptr
        !            35:        addc
        !            36:        stws    res_ptr
        !            37:
        !            38:        addib   Loop
        !            39:
        !            40: 2. mpn_addmul_1 could be improved from the current 10 to 7.5 cycles/limb
        !            41:    (asymptotically) on the PA7100, using the instructions below.  With proper
        !            42:    sw pipelining and the unrolling level below, the speed becomes 8
        !            43:    cycles/limb.
        !            44:
        !            45:        fldds   s1_ptr
        !            46:        fldds   s1_ptr
        !            47:
        !            48:        xmpyu
        !            49:        fstds   N(%r30)
        !            50:        xmpyu
        !            51:        fstds   N(%r30)
        !            52:        xmpyu
        !            53:        fstds   N(%r30)
        !            54:        xmpyu
        !            55:        fstds   N(%r30)
        !            56:
        !            57:        ldws    N(%r30)
        !            58:        ldws    N(%r30)
        !            59:        ldws    N(%r30)
        !            60:        ldws    N(%r30)
        !            61:        ldws    N(%r30)
        !            62:        ldws    N(%r30)
        !            63:        ldws    N(%r30)
        !            64:        ldws    N(%r30)
        !            65:        addc
        !            66:        addc
        !            67:        addc
        !            68:        addc
        !            69:        addc    %r0,%r0,cy-limb
        !            70:
        !            71:        ldws    res_ptr
        !            72:        ldws    res_ptr
        !            73:        ldws    res_ptr
        !            74:        ldws    res_ptr
        !            75:        add
        !            76:        stws    res_ptr
        !            77:        addc
        !            78:        stws    res_ptr
        !            79:        addc
        !            80:        stws    res_ptr
        !            81:        addc
        !            82:        stws    res_ptr
        !            83:
        !            84:        addib