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[Jikesrvm-issues] [ jikesrvm-Feature Requests-1616433 ] PPC Baseline compiler: quick-comp style register allocation
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From: SourceForge.net <no...@so...> - 2007-03-27 01:25:37
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Feature Requests item #1616433, was opened at 2006-12-15 09:43 Message generated for change (Comment added) made by dgrove-oss You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=712771&aid=1616433&group_id=128805 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: baseline compiler Group: None Status: Open Resolution: None Priority: 3 Private: No Submitted By: Dave Grove (dgrove-oss) Assigned to: Nobody/Anonymous (nobody) Summary: PPC Baseline compiler: quick-comp style register allocation Initial Comment: On PowerPC we have a large number of registers which the baseline compiler is not efectively exploiting. Furthermore on modern PPC implementations, there is a severe performance penalty when a store and a load to the same memory location occur in close temporal proximity. This causes speculative loads to be trapped/aborted and execution has to roll back. This load/store sequence is exactly what the baseline compiler does _all_ the time when it is pushing/popping values off its representation of the Java expression stack. The quick compiler prototype showed that one could do a very simple register allocation for locals/stack slots with small increase in compile time and get large performance benefits. We don't really want 3 compilers on PPC, so the plan was always to replace the PPC baseline compiler with the quick compiler. However, while the quick compiler was being developed we did the 64 bit port, the PPC baseline compiler changed quite a bit, and the two compilers divereged in structure/functionality. As a result, we moved the quick compiler to the research archive (https://sourceforge.net/tracker/index.php?func=detail&aid=1615435&group_id=128805&atid=723235) with the new plan being to re-implement its core register allocation functionality directly in the baseline compiler instead of trying to finish the quick compiler prototype and remove the baseline compiler. ---------------------------------------------------------------------- >Comment By: Dave Grove (dgrove-oss) Date: 2007-03-26 20:25 Message: Logged In: YES user_id=1215435 Originator: YES Note: PPC baseline compiler now does some register allocation of local variables. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=712771&aid=1616433&group_id=128805 |