[RISCV][GISel] Support G_ROTL/G_ROTR with Zbb. (#72825)

diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 56118e5..045fc78 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -2406,6 +2406,16 @@
     Observer.changedInstr(MI);
     return Legalized;
 
+  case TargetOpcode::G_ROTR:
+  case TargetOpcode::G_ROTL:
+    if (TypeIdx != 1)
+      return UnableToLegalize;
+
+    Observer.changingInstr(MI);
+    widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_ZEXT);
+    Observer.changedInstr(MI);
+    return Legalized;
+
   case TargetOpcode::G_SDIV:
   case TargetOpcode::G_SREM:
   case TargetOpcode::G_SMIN: