[CIR][CIRGen][builtin] handle _mm_pause (#1493)

Author: shrikardongre

clang/lib/CIR/CodeGen/CIRGenBuiltinX86.cpp

@@ -113,5 +113,14 @@ mlir::Value CIRGenFunction::emitX86BuiltinExpr(unsigned BuiltinID,
             voidTy)
         .getResult();
   }
+
+  case X86::BI_mm_pause: {
+    mlir::Type voidTy = cir::VoidType::get(&getMLIRContext());
+    return builder
+        .create<cir::LLVMIntrinsicCallOp>(
+            getLoc(E->getExprLoc()), builder.getStringAttr("x86.sse2.pause"),
+            voidTy)
+        .getResult();
+  }
   }
 }

clang/test/CIR/CodeGen/X86/builtins-x86.c

@@ -21,3 +21,11 @@ void test_mm_lfence() {
   // CIR: {{%.*}} = cir.llvm.intrinsic "x86.sse2.lfence" : () -> !void
   // LLVM: call void @llvm.x86.sse2.lfence()
 }
+
+void test_mm_pause() {
+  // CIR-LABEL: test_mm_pause
+  // LLVM-LABEL: test_mm_pause
+  _mm_pause();
+  // CIR: {{%.*}} = cir.llvm.intrinsic "x86.sse2.pause" : () -> !void
+  // LLVM: call void @llvm.x86.sse2.pause()
+}