add a crazy idea

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36273 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2007-04-20 20:18:43 +00:00
parent 58d7fbf250
commit 93305bc462

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@ -17,6 +17,18 @@ Reimplement 'select' in terms of 'SEL'.
//===---------------------------------------------------------------------===//
Crazy idea: Consider code that uses lots of 8-bit or 16-bit values. By the
time regalloc happens, these values are now in a 32-bit register, usually with
the top-bits known to be sign or zero extended. If spilled, we should be able
to spill these to a 8-bit or 16-bit stack slot, zero or sign extending as part
of the reload.
Doing this reduces the size of the stack frame (important for thumb etc), and
also increases the likelihood that we will be able to reload multiple values
from the stack with a single load.
//===---------------------------------------------------------------------===//
The constant island pass is in good shape. Some cleanups might be desirable,
but there is unlikely to be much improvement in the generated code.