Add support for attribute 'noescape'.

The attribute informs the compiler that the annotated pointer parameter
of a function cannot escape and enables IRGen to attach attribute
'nocapture' to parameters that are annotated with the attribute. That is
the only optimization that currently takes advantage of 'noescape', but
there are other optimizations that will be added later that improves
IRGen for ObjC blocks.

rdar://problem/19886775

Differential Revision: https://reviews.llvm.org/D32520

llvm-svn: 313720

1 files changed, 25 insertions, 0 deletions

diff --git a/clang/test/Sema/noescape.c b/clang/test/Sema/noescape.c
new file mode 100644
index 00000000000..39f3f6f542a
--- /dev/null
+++ b/clang/test/Sema/noescape.c
@@ -0,0 +1,25 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+void escapefunc(int *);
+void noescapefunc(__attribute__((noescape)) int *);
+void (*escapefuncptr)(int *);
+void (*noescapefuncptr)(__attribute__((noescape)) int *);
+
+void func_ne(__attribute__((noescape)) int *, int *);
+void func_en(int *, __attribute__((noescape)) int *);
+
+void (*funcptr_ee)(int *, int *);
+void (*funcptr_nn)(__attribute__((noescape)) int *, __attribute__((noescape)) int *);
+
+void test0(int c) {
+  escapefuncptr = &escapefunc;
+  escapefuncptr = &noescapefunc;
+  noescapefuncptr = &escapefunc; // expected-warning {{incompatible function pointer types assigning to 'void (*)(__attribute__((noescape)) int *)' from 'void (*)(int *)'}}
+  noescapefuncptr = &noescapefunc;
+
+  escapefuncptr = c ? &escapefunc : &noescapefunc;
+  noescapefuncptr = c ? &escapefunc : &noescapefunc; // expected-warning {{incompatible function pointer types assigning to 'void (*)(__attribute__((noescape)) int *)' from 'void (*)(int *)'}}
+
+  funcptr_ee = c ? &func_ne : &func_en;
+  funcptr_nn = c ? &func_ne : &func_en; // expected-warning {{incompatible function pointer types assigning to 'void (*)(__attribute__((noescape)) int *, __attribute__((noescape)) int *)' from 'void (*)(int *, int *)'}}
+}