Bob Wilson cc80df92c1 Overhaul the TwoAddressInstructionPass to simplify the logic, especially
for the complicated case where one register is tied to multiple destinations.
This avoids the extra scan of instruction operands that was introduced by
my recent change.  I also pulled some code out into a separate
TryInstructionTransform method, added more comments, and renamed some
variables.

Besides all those changes, this takes care of a FIXME in the code regarding
an assumption about there being a single tied use of a register when
converting to a 3-address form.  I'm not aware of cases where that assumption
is violated, but the code now only attempts to transform an instruction,
either by commuting its operands or by converting to a 3-address form,
for the simple case where there is a single pair of tied operands.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80945 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-03 20:58:42 +00:00
2009-08-20 15:20:15 +00:00

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

This directory and its subdirectories contain source code for the Low Level 
Virtual Machine, a toolkit for the construction of highly optimized compilers,
optimizers, and runtime environments. 

LLVM is open source software. You may freely distribute it under the terms of
the license agreement found in LICENSE.txt.

Please see the HTML documentation provided in docs/index.html for further
assistance with LLVM.

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LLVM backend for 6502
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