[llvm] [RISCV][GISel] Add ISel supports for SHXADD from Zba extension (PR #67863)

[Craig Topper via llvm-commits]

================
@@ -235,10 +235,7 @@ def SimmShiftRightBy3XForm : SDNodeXForm<imm, [{
 }]>;
 
 // Pattern to exclude simm12 immediates from matching.
-def non_imm12 : PatLeaf<(XLenVT GPR:$a), [{
-  auto *C = dyn_cast<ConstantSDNode>(N);
-  return !C || !isInt<12>(C->getSExtValue());
-}]>;
+def non_imm12 : ComplexPattern<XLenVT, 1, "selectNonImm12", [], [], 0>;
----------------
topperc wrote:

I used `PredicateCodeUsesOperands` so that I could know which operand wasn't the `shl` since add is commutable and tblgen will generate both patterns.

https://github.com/llvm/llvm-project/pull/67863