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1Date: Wed, 20 Jun 2001 12:32:22 -0500
2From: Vikram Adve <vadve@cs.uiuc.edu>
3To: Chris Lattner <lattner@cs.uiuc.edu>
4Subject: .NET vs. our VM
5
6One significant difference between .NET CLR and our VM is that the CLR
7includes full information about classes and inheritance.  In fact, I just
8sat through the paper on adding templates to .NET CLR, and the speaker
9indicated that the goal seems to be to do simple static compilation (very
10little lowering or optimization).  Also, the templates implementation in CLR
11"relies on dynamic class loading and JIT compilation".
12
13This is an important difference because I think there are some significant
14advantages to have a much lower level VM layer, and do significant static
15analysis and optimization.
16
17I also talked to the lead guy for KAI's C++ compiler (Arch Robison) and he
18said that SGI and other commercial compilers have included options to export
19their *IR* next to the object code (i.e., .il files) and use them for
20link-time code generation.  In fact, he said that the .o file was nearly
21empty and was entirely generated from the .il at link-time.  But he agreed
22that this limited the link-time interprocedural optimization to modules
23compiled by the same compiler, whereas our approach allows us to link and
24optimize modules from multiple different compilers.  (Also, of course, they
25don't do anything for runtime optimization).
26
27All issues to bring up in Related Work.
28
29--Vikram
30
31