Use tablegen generic tables to get the index of image intrinsic
arguments.
Before, the computation of which image intrinsic argument is at which
index was scattered in a few places, tablegen, the SDag instruction
selection and GlobalISel. This patch changes that, so only tablegen
contains code to compute indices and the ImageDimIntrinsicInfo table
provides these information.
Differential Revision: https://reviews.llvm.org/D86270
G_SHUFFLE_VECTOR is legal since it theoretically may help match op_sel
for VOP3P instructions. Expand it in some other way in case it doesn't
fold into the use instructions.
dfukalov