[HEXAGON] Add AssertSext in sign-extended mpy (#149061)

The pattern i32xi32->i64, should be matched to the sign-extended
multiply op, instead of explicit sign- extension of the operands
followed by non-widening multiply (this takes 4 operations instead of
one). Currently, if one of the operands of multiply inside a loop is a
constant, the sign-extension of this constant is hoisted out of the loop
by LICM pass and this pattern is not matched by the ISEL.

This change handles multiply operand with Opcode of the type AssertSext
which is seen when the sign-extension is hoisted out-of the loop.
Modifies the DetectUseSxtw() to check for this.

1 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/Target/Hexagon/HexagonISelDAGToDAG.cpp b/llvm/lib/Target/Hexagon/HexagonISelDAGToDAG.cpp
index 53943de3..e285e04 100644
--- a/llvm/lib/Target/Hexagon/HexagonISelDAGToDAG.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonISelDAGToDAG.cpp
@@ -1640,6 +1640,15 @@ bool HexagonDAGToDAGISel::DetectUseSxtw(SDValue &N, SDValue &R) {
       R = N;
       break;
     }
+    case ISD::AssertSext: {
+      EVT T = cast<VTSDNode>(N.getOperand(1))->getVT();
+      if (T.getSizeInBits() == 32)
+        R = N.getOperand(0);
+      else
+        return false;
+      break;
+    }
+
     default:
       return false;
   }