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b2322561cb
subtracts. This is a very rough and nasty implementation of Lefevre's
"pattern finding" algorithm. With a few small changes though, it should
end up beating most other methods in common use, regardless of the size
of the constant (currently, it's often one or two shifts worse)
TODO: rewrite it so it's not hideously ugly (this is a translation from
perl, which doesn't help ;)
bypass most of it for multiplies by 2^n+1
(eventually) teach it that some combinations of shift+add are
cheaper than others (e.g. shladd on ia64, scaled adds on alpha)
get it to try multiple booth encodings in search of the cheapest
routine
make it work for negative constants
This is hacked up as a DAG->DAG transform, so once I clean it up I hope
it'll be pulled out of here and put somewhere else. The only thing backends
should really have to worry about for now is where to draw the line
between using this code vs. going ahead and doing an integer multiply
anyway.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21560 91177308-0d34-0410-b5e6-96231b3b80d8
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|---|---|---|
| .. | ||
| IA64.h | ||
| IA64.td | ||
| IA64AsmPrinter.cpp | ||
| IA64InstrBuilder.h | ||
| IA64InstrFormats.td | ||
| IA64InstrInfo.cpp | ||
| IA64InstrInfo.h | ||
| IA64InstrInfo.td | ||
| IA64ISelPattern.cpp | ||
| IA64MachineFunctionInfo.h | ||
| IA64RegisterInfo.cpp | ||
| IA64RegisterInfo.h | ||
| IA64RegisterInfo.td | ||
| IA64TargetMachine.cpp | ||
| IA64TargetMachine.h | ||
| Makefile | ||
| README | ||
*** README for the LLVM IA64 Backend "Version 0.01" - March 18, 2005
*** Quote for this version:
"Kaori and Hitomi are naughty!!"
Congratulations, you have found:
****************************************************************
* @@@ @@@ @@@ @@@ @@@@@@@@@@ *
* @@@ @@@ @@@ @@@ @@@@@@@@@@@ *
* @@! @@! @@! @@@ @@! @@! @@! *
* !@! !@! !@! @!@ !@! !@! !@! *
* @!! @!! @!@ !@! @!! !!@ @!@ *
* !!! !!! !@! !!! !@! ! !@! *
* !!: !!: :!: !!: !!: !!: *
* :!: :!: ::!!:! :!: :!: *
* :: :::: :: :::: :::: ::: :: *
* : :: : : : :: : : : : : *
* *
* *
* @@@@@@ @@@ @@@ @@@ @@@@@@ @@@@@@ @@@ *
* @@@@@@@@ @@@@ @@@ @@@ @@@@@@@@ @@@@@@@ @@@@ *
* @@! @@@ @@!@!@@@ @@! @@! @@@ !@@ @@!@! *
* !@! @!@ !@!!@!@! !@! !@! @!@ !@! !@!!@! *
* @!@ !@! @!@ !!@! !!@ @!@!@!@! !!@@!@! @!! @!! *
* !@! !!! !@! !!! !!! !!!@!!!! @!!@!!!! !!! !@! *
* !!: !!! !!: !!! !!: !!: !!! !:! !:! :!!:!:!!: *
* :!: !:! :!: !:! :!: :!: !:! :!: !:! !:::!!::: *
* ::::: :: :: :: :: :: ::: :::: ::: ::: *
* : : : :: : : : : : :: : : ::: *
* *
****************************************************************
* Bow down, bow down, before the power of IA64! Or be crushed, *
* be crushed, by its jolly registers of doom!! *
****************************************************************
DEVELOPMENT PLAN:
_ you are 2005 maybe 2005 2006 2006 and
/ here | | | beyond
v v v v |
v
CLEAN UP ADD INSTRUCTION ADD PLAY WITH
INSTRUCTION --> SCHEDULING AND --> JIT --> DYNAMIC --> FUTURE WORK
SELECTION BUNDLING SUPPORT REOPTIMIZATION
DISCLAIMER AND PROMISE:
As of the time of this release, you are probably better off using Intel C/C++
or GCC. The performance of the code emitted right now is, in a word,
terrible. Check back in a few months - the story will be different then,
I guarantee it.
TODO:
- clean up and thoroughly test the isel patterns.
- fix stacked register allocation order: (for readability) we don't want
the out? registers being the first ones used
- fix up floating point
(nb http://gcc.gnu.org/wiki?pagename=ia64%20floating%20point )
- bundling!
(we will avoid the mess that is:
http://gcc.gnu.org/ml/gcc/2003-12/msg00832.html )
- instruction scheduling (yep)
- write truly inspirational documentation
- if-conversion (predicate database/knowledge? etc etc)
- counted loop support
- make integer + FP mul/div more clever (we have fixed pseudocode atm)
- track and use comparison complements
INFO:
- we are strictly LP64 here, no support for ILP32 on HP-UX. Linux users
don't need to worry about this.
- i have instruction scheduling/bundling pseudocode, that really works
(has been tested, albeit at the perl-script level).
so, before you go write your own, send me an email!
KNOWN DEFECTS AT THE CURRENT TIME:
- C++ vtables contain naked function pointers, not function descriptors,
which is bad. see http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=406
- varargs are broken
- alloca doesn't work (indeed, stack frame layout is bogus)
- no support for big-endian environments
- (not really the backend, but...) the CFE has some issues on IA64.
these will probably be fixed soon.
ACKNOWLEDGEMENTS:
- Chris Lattner (x100)
- Other LLVM developers ("hey, that looks familiar")
CONTACT:
- You can email me at duraid@octopus.com.au. If you find a small bug,
just email me. If you find a big bug, please file a bug report
in bugzilla! http://llvm.cs.uiuc.edu is your one stop shop for all
things LLVM.