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| author | Jeff Law <law@gcc.gnu.org> | 1999-06-06 17:30:31 -0600 |
|---|---|---|
| committer | Jeff Law <law@gcc.gnu.org> | 1999-06-06 17:30:31 -0600 |
| commit | bc4a88097bd3bbbc5ef2cf6df4347c12e54f3de1 (patch) | |
| tree | 7abda5b3f104673811b8e999f763c4a5c537a896 | |
| parent | 6570c0bd04ff0b9c4c64263db5b6ee6ae13e8006 (diff) | |
| download | gcc-bc4a88097bd3bbbc5ef2cf6df4347c12e54f3de1.zip gcc-bc4a88097bd3bbbc5ef2cf6df4347c12e54f3de1.tar.gz gcc-bc4a88097bd3bbbc5ef2cf6df4347c12e54f3de1.tar.bz2 | |
Update LCM stuff.
From-SVN: r27386
| -rw-r--r-- | gcc/PROJECTS | 16 |
1 files changed, 6 insertions, 10 deletions
diff --git a/gcc/PROJECTS b/gcc/PROJECTS index 6ff7a05..80f7967 100644 --- a/gcc/PROJECTS +++ b/gcc/PROJECTS @@ -33,16 +33,12 @@ Haifa scheduler (haifa-sched.c, loop.[ch], unroll.[ch], genattrtab.c): Improvements to global cse and partial redundancy elimination: -The current implementation of global cse uses partial redundancy elimination -as described in Chow's thesis. - -Long term we want to use lazy code motion as the basis for partial redundancy -elimination. lcm will find as many (or more) redunancies *and* it will -place the remaining computations at computationally optimal placement points -within the function. This reduces the number of redundant operations performed -as well as reducing register lifetimes. My experiments have shown that the -cases were the current PRE code hurts performance are greatly helped by using -lazy code motion. +The current implementation of global cse uses a lazy code motion algorithm +from Muchnick's "Advanced Compiler Design and Implementation". + +Longer term we want to convert to an edge based LCM algorithm using the +new structures defined by flow.c. This allows for better expression +placement and provides edge splitting "for free". lcm also provides the underlying framework for several additional optimizations such as shrink wrapping, spill code motion, dead store elimination, and generic |