forked from OSchip/llvm-project
814fb60130
In my previous change to CVP (251606), I made CVP much more aggressive about trying to constant fold comparisons. This patch is a reversal in direction. Rather than being agressive about every compare, we restore the non-block local restriction for most, and then try hard for compares feeding returns. The motivation for this is two fold: * The more I thought about it, the less comfortable I got with the possible compile time impact of the other approach. There have been no reported issues, but after talking to a couple of folks, I've come to the conclusion the time probably isn't justified. * It turns out we need to know the context to leverage the full power of LVI. In particular, asking about something at the end of it's block (the use of a compare in a return) will frequently get more precise results than something in the middle of a block. This is an implementation detail, but it's also hard to get around since mid-block queries have to reason about possible throwing instructions and don't get to use most of LVI's block focused infrastructure. This will become particular important when combined with http://reviews.llvm.org/D14263. Differential Revision: http://reviews.llvm.org/D14271 llvm-svn: 252032 |
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| .. | ||
| 2010-09-02-Trunc.ll | ||
| 2010-09-26-MergeConstantRange.ll | ||
| basic.ll | ||
| crash.ll | ||
| icmp.ll | ||
| non-null.ll | ||
| range.ll | ||
| select.ll | ||