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| author | Chad Rosier <mcrosier@codeaurora.org> | 2016-10-12 13:41:38 +0000 |
|---|---|---|
| committer | Chad Rosier <mcrosier@codeaurora.org> | 2016-10-12 13:41:38 +0000 |
| commit | c215c3fd143d11f6fd051b5556b04970f9888381 (patch) | |
| tree | 875b56195be8bda65f81fc56bbb753a4ceb5b785 /llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | |
| parent | b271a58e377f7aeb761945dc02aff7041a1ef44b (diff) | |
| download | bcm5719-llvm-c215c3fd143d11f6fd051b5556b04970f9888381.tar.gz bcm5719-llvm-c215c3fd143d11f6fd051b5556b04970f9888381.zip | |
[CVP] Convert an AShr to a LShr if 1st operand is known to be nonnegative.
An arithmetic shift can be safely changed to a logical shift if the first
operand is known positive. This allows ComputeKnownBits (and similar analysis)
to determine the sign bit of the shifted value in some cases. In turn, this
allows InstCombine to canonicalize a signed comparison (a > 0) into an equality
check (a != 0).
PR30577
Differential Revision: https://reviews.llvm.org/D25119
llvm-svn: 284013
Diffstat (limited to 'llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp')
0 files changed, 0 insertions, 0 deletions
