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author Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
date Tue, 14 Jan 2014 01:31:42 +0900
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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1 <!DOCTYPE html>
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2 <html>
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3 <head>
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4 <meta charset='utf-8'>
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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6 <script
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7 src='./trunk/slides.js'></script>
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8 </head>
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Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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10 <body style='display: none'>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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11 <section class='slides layout-regular template-default'>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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12
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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13 <article>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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14 <h1>CbCコンパイラのLLVM3.4上での実装</h1>
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15 <p><br>Kaito Tokumori<br>September 17, 2013</p>
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16 </article>
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17
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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18 <article>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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19 <br>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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20 <h3>研究背景と目的</h3>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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21 <p>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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22 比較的歴史の古い言語であるCは普及率が高く多くのシステムに用いられている。そのCの問題のひとつに関数呼び出しの際のオーバーヘッドが大きいというものがある。当研究室ではこの問題をTail Call Eliminationの強制により解決しようと考えており、それを実現すべくCountinuation based C (CbC)という言語の開発を行なっている。CbCはCの関数呼び出しやループ制御の代わりに継続を用いて制御を行うもので、Cの下位言語に当たる。本研究ではmicro-c,GCC版に次ぐLLVMベースのCbCコンパイラ開発を行う。
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23 </p>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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24 </article>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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25
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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26 <article>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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27 <br>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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28 <h3>今日までの</h3>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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29 <ul>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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30 <li>tail call elimination を適用する<ul><li>returnが後ろに来ない問題</li></ul></li>
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31 </ul>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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32 </article>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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33
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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34
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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35 <article>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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36 <br>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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37 <h3>returnの問題</h3>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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38 <ul>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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39 <li>ReturnInstでなくBranchInstで終わっていることがわかった。</li>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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40 <li>llvmアセンブリからも読み取れる。</li>
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41 <li>llvmアセンブリではBranchInstでもllcを通せばReturnInstに変わっている。</li>
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42 <li>どこかにBranchInstをReturnInstに直すような最適化を行っている部分があるのではないか。</li>
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43 </ul>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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44 </article>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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45
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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46 <article>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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47 <br>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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48 <h3>returnの問題</h3>
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49 <ul>
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50 <li>lib/Transforms/Scalar/CodeGenPrepare.cpp L706 DupRetToEnableTailCallOpts()</li>
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51 <li>llcはこいつがはいっていた。</li>
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52 </ul>
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53 </article>
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54
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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55 <article class='smaller'>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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56 <br>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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57 <h3>DupRetToEnableTailCallOpts()</h3>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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58 <section>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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59 <pre>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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60 /// DupRetToEnableTailCallOpts - Look for opportunities to duplicate return
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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61 /// instructions to the predecessor to enable tail call optimizations. The
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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62 /// case it is currently looking for is:
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63 /// bb0:
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64 /// %tmp0 = tail call i32 @f0()
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65 /// br label %return
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66 /// bb1:
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67 /// %tmp1 = tail call i32 @f1()
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68 /// br label %return
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69 /// bb2:
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70 /// %tmp2 = tail call i32 @f2()
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71 /// br label %return
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72 /// return:
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73 /// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]
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74 /// ret i32 %retval
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75 /// =>
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76 /// bb0:
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77 /// %tmp0 = tail call i32 @f0()
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78 /// ret i32 %tmp0
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79 /// bb1:
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80 /// %tmp1 = tail call i32 @f1()
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81 /// ret i32 %tmp1
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82 /// bb2:
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83 /// %tmp2 = tail call i32 @f2()
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84 /// ret i32 %tmp2
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85 </pre>
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86 </section>
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87 </article>
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88
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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89 <article>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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90 <br>
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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91 <h3>returnの問題</h3>
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92 <ul>
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93 <li>HasCodeSegmentというオプションを付加。</li>
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94 <li>code segmentを持っている時にはここを必ず通るように。</li>
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95 <li>returnがきちんと認識された。</li>
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96 <li>O2のときにはどのBasicBlockもReturnInstを持ってない扱いでcallがtailにならない。</li>
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97 <li>O2の時に通るパスの影響？</li>
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98 <li>emit-llvmしてllc通してもダメなのでPassの影響だとしたらCodeGenのPass以外</li>
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99 </ul>
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100 </article>
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101
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
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102 </section>
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103 </body>
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104 </html>