[ObjC][CodeGen] CodeGen support for @available.

CodeGens uses of @available into calls to the compiler-rt function
__isOSVersionAtLeast.

This commit is part of a feature that I proposed here:
http://lists.llvm.org/pipermail/cfe-dev/2016-July/049851.html

Differential revision: https://reviews.llvm.org/D27827

llvm-svn: 296015

1 files changed, 31 insertions, 0 deletions

diff --git a/clang/test/CodeGenObjC/availability-check.m b/clang/test/CodeGenObjC/availability-check.m
new file mode 100644
index 00000000000..71c5ff77c96
--- /dev/null
+++ b/clang/test/CodeGenObjC/availability-check.m
@@ -0,0 +1,31 @@
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.11 -emit-llvm -o - %s | FileCheck %s
+
+void use_at_available() {
+  // CHECK: call i32 @__isOSVersionAtLeast(i32 10, i32 12, i32 0)
+  // CHECK-NEXT: icmp ne
+  if (__builtin_available(macos 10.12, *))
+    ;
+
+  // CHECK: call i32 @__isOSVersionAtLeast(i32 10, i32 12, i32 0)
+  // CHECK-NEXT: icmp ne
+  if (@available(macos 10.12, *))
+    ;
+
+  // CHECK: call i32 @__isOSVersionAtLeast(i32 10, i32 12, i32 42)
+  // CHECK-NEXT: icmp ne
+  if (__builtin_available(ios 10, macos 10.12.42, *))
+    ;
+
+  // CHECK-NOT: call i32 @__isOSVersionAtLeast
+  // CHECK: br i1 true
+  if (__builtin_available(ios 10, *))
+    ;
+
+  // This check should be folded: our deployment target is 10.11.
+  // CHECK-NOT: call i32 @__isOSVersionAtLeast
+  // CHECK: br i1 true
+  if (__builtin_available(macos 10.11, *))
+    ;
+}
+
+// CHECK: declare i32 @__isOSVersionAtLeast(i32, i32, i32)