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