tree 89948dd244c9a2036818021d65bd1d202ccc5dd1
parent 653997ebc2faf89d9af220279347c3f913c03ec9
author James Molloy <james.molloy@arm.com> 1425657047 +0000
committer James Molloy <james.molloy@arm.com> 1425657047 +0000

[ConstantRange] Teach multiply to be cleverer about signed ranges.

Multiplication is not dependent on signedness, so just treating
all input ranges as unsigned is not incorrect. However it will cause
overly pessimistic ranges (such as full-set) when used with signed
negative values.

Teach multiply to try to interpret its inputs as both signed and
unsigned, and then to take the most specific (smallest population)
as its result.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231483 91177308-0d34-0410-b5e6-96231b3b80d8