[X86][GlobalISel] Enable G_LROUND/G_LLROUND with libcall mapping (#125096)

diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index f0b241f..d4cb224 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -411,6 +411,10 @@
   } while (0)
 
   switch (Opcode) {
+  case TargetOpcode::G_LROUND:
+    RTLIBCASE(LROUND_F);
+  case TargetOpcode::G_LLROUND:
+    RTLIBCASE(LLROUND_F);
   case TargetOpcode::G_MUL:
     RTLIBCASE_INT(MUL_I);
   case TargetOpcode::G_SDIV:
@@ -1267,6 +1271,8 @@
       return Status;
     break;
   }
+  case TargetOpcode::G_LROUND:
+  case TargetOpcode::G_LLROUND:
   case TargetOpcode::G_INTRINSIC_LRINT:
   case TargetOpcode::G_INTRINSIC_LLRINT: {
     LLT LLTy = MRI.getType(MI.getOperand(1).getReg());