Andrew Trick 2fabd464ae indvars -disable-iv-rewrite: Adds support for eliminating identity
ops.

This is a rewrite of the IV simplification algorithm used by
-disable-iv-rewrite. To avoid perturbing the default mode, I
temporarily split the driver and created SimplifyIVUsersNoRewrite. The
idea is to avoid doing opcode/pattern matching inside
IndVarSimplify. SCEV already does it. We want to optimize with the
full generality of SCEV, but optimize def-use chains top down on-demand rather
than rewriting the entire expression bottom-up. This was easy to do
for operations that SCEV can prove are identity function. So we're now
eliminating bitmasks and zero extends this way.

A result of this rewrite is that indvars -disable-iv-rewrite no longer
requires IVUsers.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133502 91177308-0d34-0410-b5e6-96231b3b80d8
2011-06-21 03:22:38 +00:00
2011-06-16 16:03:13 +00:00
2011-06-09 20:11:46 +00:00
2011-05-31 21:54:28 +00:00
2011-06-16 22:30:41 +00:00
2011-06-12 15:26:54 +00:00
2011-05-12 17:38:08 +00:00

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

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LLVM backend for 6502
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