Aug 23, 2011, 5:40:29 PM (8 years ago)

Use of ccc and Pablo

1 edited


  • docs/HPCA2012/03-research.tex

    r1354 r1355  
    221221Accurate parsing and parallel lexical analysis is done through processor-friendly equations that requires no speculation nor multithreading.
    223 \subsection{Parallel Bit Stream Compilation}
    224 \label {parallel bit stream compilation}
    226 While the description of parallel bit stream parsing in the previous section works conceptually on
    227 infinitely-long bit streams, in practice, the implementation of a Parabix parser must process input streams as bit stream blocks
    228 whose size is equal to the SIMD register width of the target processor.
    229 In our work, we leverage the unbounded integer type of the Python programming language to verify our equations
    230 against unbounded bit streams.
    231 Using a restricted subset of Python, we prototype and validate the functionality of our applications,
    232 such as CSV parsing, XML validation, and UTF-8 to UTF-16 transcoding, etc.
    233 To transform the Python code into the equivalent block-at-a-time C/C++ code,
    234 the key question becomes how to efficiently transfer information from one bit stream block to the next whenever the result of an operation
    235 crosses a block boundary.
    237 The answer lies in carry bit propagation. Since the parallel ScanThru operation relies solely on bit-wise addition and logical operations,
    238 block-to-block information transfer is captured in entirety by the carry bit associated with each underlying addition operation.
    239 Boolean-logical operations do not pass information over block boundaries since each bit value is independent of the state of its surrounding bits.
    240 Properly determining, initializing and inserting carry bits into a block-by-block implementation is tedious and error prone.
    241 Thus we have developed compiler technology to automatically transform parallel bit stream
    242 Python code to block-at-a-time C/C++ implementations. Details are beyond the scope of this paper, but are described in the on-line
    243 source code repository at {\tt http://parabix.costar.sfu.ca}.
    245224\subsection{Parabix Tool Chain}
    268247\begin{tabular}{r l}
    269 \ttfamily{\bfseries INPUT:} & \verb`digit = [<]` \\
     248\ttfamily{\bfseries INPUT:} & \verb`digit = [0-9]` \\
    270249\ttfamily{\bfseries OUTPUT:} & \verb`temp1 = (basis_bits.bit_0 | basis_bits.bit_1)` \\
    271250& \verb`temp2 = (basis_bits.bit_2 & basis_bits.bit_3)` \\
    292271code in C/C++, where the block size is the register
    293272width for SIMD operations on the selected target architecture.
     273The key functionality of Pablo is to arrange for block-to-block
     274carry bit propagation to implement the long bitstream shift
     275and addition operations required by
     276{\tt Advance} and {\tt ScanThru}.
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