tree ef97ef4805a72a289f3c0b2914e0eb87b06ca915
parent a18ad697a9e41d27fdf86d0c7b0c85758038d549
author Hal Finkel <hfinkel@anl.gov> 1396480734 +0000
committer Hal Finkel <hfinkel@anl.gov> 1396480734 +0000

Fix multi-register costs in BasicTTI::getCastInstrCost

For an cast (extension, etc.), the currently logic predicts a low cost if the
associated operation (keyed on the destination type) is legal (or promoted).
This is not true when the number of values required to legalize the type is
changing. For example, <8 x i16> being sign extended by <8 x i32> is not
generically cheap on PPC with VSX, even though sign extension to v4i32 is
legal, because two output v4i32 values are required compared to the single
v8i16 input value, and without custom logic in the target, this conversion will
scalarize.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205487 91177308-0d34-0410-b5e6-96231b3b80d8