simd example

simd example.ipynb

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            "text/plain": "v\"1.6.0-DEV.1046\""
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      "source": "https://mobile.twitter.com/lpha_z/status/1310221407649816579"
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      "source": "function test()\n    a = fill(1e-10, 1000)\n    s = 0.0\n    for j = 1:10000000\n        for i = 1:1000\n            s += a[i]\n        end \n    end\n    s\nend\n@time test()",
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          "text": "  9.409779 seconds (1 allocation: 7.938 KiB)\n",
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      "cell_type": "code",
      "source": "function test_inbounds_simd()\n    a = fill(1e-10, 1000)\n    s = 0.0\n    for j = 1:10000000\n        @inbounds @simd for i = 1:1000\n            s += a[i]\n        end \n    end\n    s\nend\n@time test_inbounds_simd()",
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      "outputs": [
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          "text": "  0.895148 seconds (1 allocation: 7.938 KiB)\n",
          "name": "stdout"
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        {
          "output_type": "execute_result",
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      "cell_type": "code",
      "source": "function test_builtin_sum()\n    a = fill(1e-10, 1000)\n    s = 0.0\n    for j = 1:10000000\n        s += sum(a)\n    end\n    s\nend\n@time test_builtin_sum()",
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      "cell_type": "code",
      "source": "using BenchmarkTools\nprint(\"test():              \")\n@btime test()\nprint(\"test_inbounds_simd():\")\n@btime test_inbounds_simd()\nprint(\"test_builtin_sum():  \")\n@btime test_builtin_sum()\n;",
      "execution_count": 5,
      "outputs": [
        {
          "output_type": "stream",
          "text": "test():                9.394 s (1 allocation: 7.94 KiB)\ntest_inbounds_simd():  891.354 ms (1 allocation: 7.94 KiB)\ntest_builtin_sum():    1.036 s (1 allocation: 7.94 KiB)\n",
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