Jakob Stoklund Olesen 6bfba2e5af Prefer cheap registers for busy live ranges.
On the x86-64 and thumb2 targets, some registers are more expensive to encode
than others in the same register class.

Add a CostPerUse field to the TableGen register description, and make it
available from TRI->getCostPerUse. This represents the cost of a REX prefix or a
32-bit instruction encoding required by choosing a high register.

Teach the greedy register allocator to prefer cheap registers for busy live
ranges (as indicated by spill weight).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129864 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-20 18:19:48 +00:00
2011-02-11 19:11:57 +00:00

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

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LLVM backend for 6502
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