Add codegen test ensuring always-inline closures don't bypass target features

tests/codegen/target-feature-inline-closure.rs

@@ -0,0 +1,33 @@
+// only-x86_64
+// compile-flags: -Copt-level=3
+
+#![crate_type = "lib"]
+#![feature(target_feature_11)]
+
+#[cfg(target_arch = "x86_64")]
+use std::arch::x86_64::*;
+
+// CHECK-LABEL: @with_avx
+#[no_mangle]
+#[cfg(target_arch = "x86_64")]
+#[target_feature(enable = "avx")]
+fn with_avx(x: __m256) -> __m256 {
+    // CHECK: fadd
+    let add = {
+        #[inline(always)]
+        |x, y| unsafe { _mm256_add_ps(x, y) }
+    };
+    add(x, x)
+}
+
+// CHECK-LABEL: @without_avx
+#[no_mangle]
+#[cfg(target_arch = "x86_64")]
+unsafe fn without_avx(x: __m256) -> __m256 {
+    // CHECK-NOT: fadd
+    let add = {
+        #[inline(always)]
+        |x, y| unsafe { _mm256_add_ps(x, y) }
+    };
+    add(x, x)
+}