[ARM] Fix 28282: cost computation for constant hoisting
Summary:
This fixes bug: https://llvm.org/bugs/show_bug.cgi?id=28282
Currently the cost model of constant hoisting checks the bit width of the data type of the constants.
However, the actual immediate value is small enough and not need to be hoisted.
This patch checks for the actual bit width needed for the constant.
Reviewers: t.p.northover, rengolin
Subscribers: aemerson, rengolin, llvm-commits
Differential Revision: http://reviews.llvm.org/D21668
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274073
91177308-0d34-0410-b5e6-
96231b3b80d8
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