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annotate docs/HistoricalNotes/2001-06-20-.NET-Differences.txt @ 0:95c75e76d11b LLVM3.4

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LLVM 3.4
author Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
date Thu, 12 Dec 2013 13:56:28 +0900
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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1 Date: Wed, 20 Jun 2001 12:32:22 -0500
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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2 From: Vikram Adve <vadve@cs.uiuc.edu>
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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3 To: Chris Lattner <lattner@cs.uiuc.edu>
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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4 Subject: .NET vs. our VM
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5
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6 One significant difference between .NET CLR and our VM is that the CLR
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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7 includes full information about classes and inheritance. In fact, I just
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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8 sat through the paper on adding templates to .NET CLR, and the speaker
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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9 indicated that the goal seems to be to do simple static compilation (very
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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10 little lowering or optimization). Also, the templates implementation in CLR
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11 "relies on dynamic class loading and JIT compilation".
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12
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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13 This is an important difference because I think there are some significant
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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14 advantages to have a much lower level VM layer, and do significant static
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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15 analysis and optimization.
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16
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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17 I also talked to the lead guy for KAI's C++ compiler (Arch Robison) and he
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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18 said that SGI and other commercial compilers have included options to export
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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19 their *IR* next to the object code (i.e., .il files) and use them for
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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20 link-time code generation. In fact, he said that the .o file was nearly
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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21 empty and was entirely generated from the .il at link-time. But he agreed
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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22 that this limited the link-time interprocedural optimization to modules
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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23 compiled by the same compiler, whereas our approach allows us to link and
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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24 optimize modules from multiple different compilers. (Also, of course, they
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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25 don't do anything for runtime optimization).
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26
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27 All issues to bring up in Related Work.
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28
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29 --Vikram
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30