implement and document a new __has_feature and __has_builtin magic

builtin preprocessor macro.  This appears to work with two caveats:
1) builtins are registered in -E mode, and 2) target-specific builtins
are unconditionally registered even if they aren't supported by the
target (e.g. SSE4 builtin when only SSE1 is enabled).

llvm-svn: 73289

1 files changed, 30 insertions, 0 deletions

diff --git a/clang/test/Preprocessor/feature_tests.c b/clang/test/Preprocessor/feature_tests.c
new file mode 100644
index 00000000000..edca1781922
--- /dev/null
+++ b/clang/test/Preprocessor/feature_tests.c
@@ -0,0 +1,30 @@
+// RUN: clang-cc %s --triple=i686-apple-darwin9
+#ifndef __has_feature
+#error Should have __has_feature
+#endif
+
+
+#if __has_feature(something_we_dont_have)
+#error Bad
+#endif
+
+#if  !__has_builtin(__builtin_huge_val) || \
+     !__has_builtin(__builtin_shufflevector) || \
+     !__has_builtin(__builtin_trap) || \
+     !__has_feature(attribute_analyzer_noreturn) || \
+     !__has_feature(attribute_overloadable)
+#error Clang should have these
+#endif
+
+#if __has_builtin(__builtin_insanity)
+#error Clang should not have this
+#endif
+
+
+
+// Make sure we have x86 builtins only (forced with target triple).
+
+#if !__has_builtin(__builtin_ia32_emms) || \
+    __has_builtin(__builtin_altivec_abs_v4sf)
+#error Broken handling of target-specific builtins
+#endif