[PATCH PR87022]Check all bits in dist-vector rather than the fisrt in loop distribution

Sun, 14 Oct 2018 04:10:46 -0700 

Hi,
This patch fixes PR87022.  The root cause is the original code checks the first 
bit
in dist vector for zero and we still do that after enabling loop nest 
distribution. 
For the test case, the first bit is for outer loop while the dependence happens 
in
the inner loop, as a result, the direction of dependence is not correctly 
reverted.
This patch fixes the issue by checking all bits in dist vector.

Bootstrap and test on x86_64, is it OK?

Thanks,
bin

2018-10-14  Bin Cheng  <bin.ch...@linux.alibaba.com>

        PR tree-optimization/87022
        * tree-loop-distribution.c (pg_add_dependence_edges): Check all
        bits in dist vector rather than the first one.

2018-10-14  Bin Cheng  <bin.ch...@linux.alibaba.com>

        PR tree-optimization/87022
        * gcc.dg/tree-ssa/pr87022.c: New test.

Attachment: pr87022.txt
Description: Binary data

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