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39fcec1541
to avoid redundant mov out3=r44 type instructions, we need to tell the register allocator the truth about out? registers. FIXME: unfortunately, since the list of allocatable registers is immutable, we can't simply 'delete r127' from the allocation order, say, if 'out0' is used. The only correct thing we can do is have a linear order of regs: out7, out6 ... out2, out1, out0, r32, r33, r34 ... r126, r127 and slide a 'window' of 96 registers along this line, depending on how many of the out? regs a function actually uses. The only downside of this is that the out? registers will be allocated _first_, which makes the resulting assembly ugly. :( Note this in the README. Hope this gets fixed soon. :) (note the 3rd person speech there) llvm-svn: 21252
103 lines
4.4 KiB
Plaintext
103 lines
4.4 KiB
Plaintext
*** README for the LLVM IA64 Backend "Version 0.01" - March 18, 2005
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*** Quote for this version:
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"Kaori and Hitomi are naughty!!"
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Congratulations, you have found:
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****************************************************************
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* @@@ @@@ @@@ @@@ @@@@@@@@@@ *
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* @@@ @@@ @@@ @@@ @@@@@@@@@@@ *
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* @@! @@! @@! @@@ @@! @@! @@! *
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* !@! !@! !@! @!@ !@! !@! !@! *
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* @!! @!! @!@ !@! @!! !!@ @!@ *
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* !!! !!! !@! !!! !@! ! !@! *
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* !!: !!: :!: !!: !!: !!: *
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* :!: :!: ::!!:! :!: :!: *
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* :: :::: :: :::: :::: ::: :: *
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* : :: : : : :: : : : : : *
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* *
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* *
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* @@@@@@ @@@ @@@ @@@ @@@@@@ @@@@@@ @@@ *
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* @@@@@@@@ @@@@ @@@ @@@ @@@@@@@@ @@@@@@@ @@@@ *
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* @@! @@@ @@!@!@@@ @@! @@! @@@ !@@ @@!@! *
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* !@! @!@ !@!!@!@! !@! !@! @!@ !@! !@!!@! *
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* @!@ !@! @!@ !!@! !!@ @!@!@!@! !!@@!@! @!! @!! *
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* !@! !!! !@! !!! !!! !!!@!!!! @!!@!!!! !!! !@! *
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* !!: !!! !!: !!! !!: !!: !!! !:! !:! :!!:!:!!: *
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* :!: !:! :!: !:! :!: :!: !:! :!: !:! !:::!!::: *
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* ::::: :: :: :: :: :: ::: :::: ::: ::: *
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* : : : :: : : : : : :: : : ::: *
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* *
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****************************************************************
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* Bow down, bow down, before the power of IA64! Or be crushed, *
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* be crushed, by its jolly registers of doom!! *
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****************************************************************
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DEVELOPMENT PLAN:
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_ you are 2005 maybe 2005 2006 2006 and
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/ here | | | beyond
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v v v v |
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v
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CLEAN UP ADD INSTRUCTION ADD PLAY WITH
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INSTRUCTION --> SCHEDULING AND --> JIT --> DYNAMIC --> FUTURE WORK
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SELECTION BUNDLING SUPPORT REOPTIMIZATION
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DISCLAIMER AND PROMISE:
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As of the time of this release, you are probably better off using Intel C/C++
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or GCC. The performance of the code emitted right now is, in a word,
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terrible. Check back in a few months - the story will be different then,
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I guarantee it.
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TODO:
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- clean up and thoroughly test the isel patterns.
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- fix stacked register allocation order: (for readability) we don't want
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the out? registers being the first ones used
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- fix up floating point
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(nb http://gcc.gnu.org/wiki?pagename=ia64%20floating%20point )
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- bundling!
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(we will avoid the mess that is:
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http://gcc.gnu.org/ml/gcc/2003-12/msg00832.html )
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- instruction scheduling (yep)
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- write truly inspirational documentation
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- if-conversion (predicate database/knowledge? etc etc)
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- counted loop support
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- make integer + FP mul/div more clever (we have fixed pseudocode atm)
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- track and use comparison complements
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INFO:
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- we are strictly LP64 here, no support for ILP32 on HP-UX. Linux users
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don't need to worry about this.
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- i have instruction scheduling/bundling pseudocode, that really works
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(has been tested, albeit at the perl-script level).
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so, before you go write your own, send me an email!
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KNOWN DEFECTS AT THE CURRENT TIME:
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- C++ vtables contain naked function pointers, not function descriptors,
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which is bad. see http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=406
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- varargs are broken
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- alloca doesn't work (indeed, stack frame layout is bogus)
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- no support for big-endian environments
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- (not really the backend, but...) the CFE has some issues on IA64.
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these will probably be fixed soon.
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ACKNOWLEDGEMENTS:
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- Chris Lattner (x100)
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- Other LLVM developers ("hey, that looks familiar")
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CONTACT:
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- You can email me at duraid@octopus.com.au. If you find a small bug,
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just email me. If you find a big bug, please file a bug report
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in bugzilla! http://llvm.cs.uiuc.edu is your one stop shop for all
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things LLVM.
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