LLVM backend for 6502
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Reed Kotler 74adad6de8 This is for an experimental option -mips-os16. The idea is to compile all
Mips32 code as Mips16 unless it can't be compiled as Mips 16. For now this
would happen as long as floating point instructions are not needed.
Probably it would also make sense to compile as mips32 if atomic operations
are needed too. There may be other cases too.

A module pass prescans the IR and adds the mips16 or nomips16 attribute
to functions depending on the functions needs.

Mips 16 mode can result in a 40% code compression by utililizing 16 bit
encoding of many instructions.

The hope is for this to replace the traditional gcc way of dealing with
Mips16 code using floating point which involves essentially using soft float
but with a library implemented using mips32 floating point. This gcc 
method also requires creating stubs so that Mips32 code can interact with
these Mips 16 functions that have floating point needs. My conjecture is
that in reality this traditional gcc method would never win over this
new method.

I will be implementing the traditional gcc method also. Some of it is already
done but I needed to do the stubs to finish the work and those required
this mips16/32 mixed mode capability.

I have more ideas for to make this new method much better and I think the old
method will just live in llvm for anyone that needs the backward compatibility
but I don't for what reason that would be needed.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179185 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-10 16:58:04 +00:00
autoconf Refine fenv.h handling: check if the desired macros exist, before using 2013-03-25 13:13:33 +00:00
bindings [python] Add markup option to disassembler 2012-12-01 21:57:30 +00:00
cmake [cmake] Avoid rel+asserts warnings when passing -UNDEBUG 2013-04-07 01:45:01 +00:00
docs Remove the confusing sentence. 2013-04-09 04:48:40 +00:00
examples Update links to "Itanium C++ ABI: Exception Handling" document 2013-01-13 15:53:09 +00:00
include Template MachOObjectFile over endianness too. 2013-04-10 15:33:44 +00:00
lib This is for an experimental option -mips-os16. The idea is to compile all 2013-04-10 16:58:04 +00:00
projects Print a warning message if compiler-rt can't be built because of old CMake version to make this requirement more visible to users 2013-03-05 14:43:07 +00:00
runtime Remove GCDAProfiling.c. This copy is old, the copy in compiler-rt is newer and 2013-03-07 02:03:08 +00:00
test This is for an experimental option -mips-os16. The idea is to compile all 2013-04-10 16:58:04 +00:00
tools Template MachOObjectFile over endianness too. 2013-04-10 15:33:44 +00:00
unittests Change CloneFunctionInto to always clone Argument attributes induvidually, 2013-04-10 10:37:38 +00:00
utils Move yaml2obj to tools too. 2013-04-05 20:00:35 +00:00
.arcconfig Add .arcconfig to the repository. Useful if someone wants to use phabricator's command line tool. 2012-12-01 12:07:58 +00:00
.gitignore Add extra vim swap file pattern 2012-10-09 23:48:34 +00:00
CMakeLists.txt Revert "TMP" 2013-04-10 12:08:57 +00:00
CODE_OWNERS.TXT Update 2013-03-18 17:47:33 +00:00
configure Refine fenv.h handling: check if the desired macros exist, before using 2013-03-25 13:13:33 +00:00
CREDITS.TXT Update 2013-03-18 17:47:33 +00:00
LICENSE.TXT Add LICENSE.TXT covering contributions made by ARM. 2013-01-07 10:04:49 +00:00
llvm.spec.in Tidy up. s/Low Level Virtual Machine/LLVM/. 2012-01-25 22:00:23 +00:00
LLVMBuild.txt LLVMBuild: Introduce a common section which currently has a list of the 2011-12-12 22:45:54 +00:00
Makefile Improved svn repo searching for 'make update' 2013-01-28 03:19:57 +00:00
Makefile.common Makefile.common: Update a description, s/Source/SOURCES/ , according to MakefileGuide.html#control-variables . 2012-12-07 01:43:23 +00:00
Makefile.config.in Turn anonymous type in anonymous union warning back on after cleaning up 2013-03-15 00:43:00 +00:00
Makefile.rules Make check depend on all. 2013-04-09 19:42:12 +00:00
README.txt Revert "Test commit" 2013-02-22 19:19:41 +00:00

Low Level Virtual Machine (LLVM)
================================

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