Emit !callback metadata and introduce the callback attribute

  With commit r351627, LLVM gained the ability to apply (existing) IPO
  optimizations on indirections through callbacks, or transitive calls.
  The general idea is that we use an abstraction to hide the middle man
  and represent the callback call in the context of the initial caller.
  It is described in more detail in the commit message of the LLVM patch
  r351627, the llvm::AbstractCallSite class description, and the
  language reference section on callback-metadata.

  This commit enables clang to emit !callback metadata that is
  understood by LLVM. It does so in three different cases:
    1) For known broker functions declarations that are directly
       generated, e.g., __kmpc_fork_call for the OpenMP pragma parallel.
    2) For known broker functions that are identified by their name and
       source location through the builtin detection, e.g.,
       pthread_create from the POSIX thread API.
    3) For user annotated functions that carry the "callback(callee, ...)"
       attribute. The attribute has to include the name, or index, of
       the callback callee and how the passed arguments can be
       identified (as many as the callback callee has). See the callback
       attribute documentation for detailed information.

Differential Revision: https://reviews.llvm.org/D55483

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@351629 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 89 insertions, 0 deletions

diff --git a/test/Sema/attr-callback-broken.c b/test/Sema/attr-callback-broken.c
new file mode 100644
index 0000000000..b9e5f45f40
--- /dev/null
+++ b/test/Sema/attr-callback-broken.c
@@ -0,0 +1,75 @@
+// RUN: %clang_cc1 %s -verify -fsyntax-only
+
+__attribute__((callback())) void no_callee(void (*callback)(void)); // expected-error {{'callback' attribute specifies no callback callee}}
+
+__attribute__((callback(1, 1))) void too_many_args_1(void (*callback)(void)) {}      // expected-error {{'callback' attribute takes one argument}}
+__attribute__((callback(1, -1))) void too_many_args_2(double (*callback)(void));     // expected-error {{'callback' attribute takes one argument}}
+__attribute__((callback(1, 2, 2))) void too_many_args_3(void (*callback)(int), int); // expected-error {{'callback' attribute requires exactly 2 arguments}}
+
+__attribute__((callback(1, 2))) void too_few_args_1(void (*callback)(int, int), int); // expected-error {{'callback' attribute takes one argument}}
+__attribute__((callback(1))) void too_few_args_2(int (*callback)(int));               // expected-error {{'callback' attribute takes no arguments}}
+__attribute__((callback(1, -1))) void too_few_args_3(void (*callback)(int, int)) {}   // expected-error {{'callback' attribute takes one argument}}
+
+__attribute__((callback(-1))) void oob_args_1(void (*callback)(void));         // expected-error {{'callback' attribute specifies invalid callback callee}}
+__attribute__((callback(2))) void oob_args_2(int *(*callback)(void)) {}        // expected-error {{'callback' attribute parameter 1 is out of bounds}}
+__attribute__((callback(1, 3))) void oob_args_3(short (*callback)(int), int);  // expected-error {{'callback' attribute parameter 2 is out of bounds}}
+__attribute__((callback(-2, 2))) void oob_args_4(void *(*callback)(int), int); // expected-error {{'callback' attribute parameter 1 is out of bounds}}
+__attribute__((callback(1, -2))) void oob_args_5(void *(*callback)(int), int); // expected-error {{'callback' attribute parameter 2 is out of bounds}}
+__attribute__((callback(1, 2))) void oob_args_6(void *(*callback)(int), ...);  // expected-error {{'callback' attribute parameter 2 is out of bounds}}
+
+__attribute__((callback(1))) __attribute__((callback(1))) void multiple_cb_1(void (*callback)(void));                           // expected-error {{multiple 'callback' attributes specified}}
+__attribute__((callback(1))) __attribute__((callback(2))) void multiple_cb_2(void (*callback1)(void), void (*callback2)(void)); // expected-error {{multiple 'callback' attributes specified}}
+
+#ifdef HAS_THIS
+__attribute__((callback(0))) void oob_args_0(void (*callback)(void)); // expected-error {{'callback' attribute specifies invalid callback callee}}
+#else
+__attribute__((callback(0))) void oob_args_0(void (*callback)(void));                 // expected-error {{'callback' argument at position 1 references unavailable implicit 'this'}}
+__attribute__((callback(1, 0))) void no_this_1(void *(*callback)(void *));            // expected-error {{'callback' argument at position 2 references unavailable implicit 'this'}}
+__attribute__((callback(1, 0))) void no_this_2(void *(*callback)(int, void *));       // expected-error {{'callback' argument at position 2 references unavailable implicit 'this'}}
+#endif
+
+// We could allow the following declarations if we at some point need to:
+
+__attribute__((callback(1, -1))) void vararg_cb_1(void (*callback)(int, ...)) {}     // expected-error {{'callback' attribute callee may not be variadic}}
+__attribute__((callback(1, 1))) void vararg_cb_2(void (*callback)(int, ...), int a); // expected-error {{'callback' attribute callee may not be variadic}}
+
+__attribute__((callback(1, -1, 1, 2, 3, 4, -1))) void varargs_1(void (*callback)(int, ...), int a, float b, double c) {}               // expected-error {{'callback' attribute requires exactly 6 arguments}}
+__attribute__((callback(1, -1, 4, 2, 3, 4, -1))) void varargs_2(void (*callback)(void *, double, int, ...), int a, float b, double c); // expected-error {{'callback' attribute requires exactly 6 arguments}}
+
+__attribute__((callback(1, -1, 1))) void self_arg_1(void (*callback)(int, ...)) {}          // expected-error {{'callback' attribute requires exactly 2 arguments}}
+__attribute__((callback(1, -1, 1, -1, -1, 1))) void self_arg_2(void (*callback)(int, ...)); // expected-error {{'callback' attribute requires exactly 5 arguments}}
+
+__attribute__((callback(cb))) void unknown_name1(void (*callback)(void)) {}     // expected-error {{'callback' attribute argument 'cb' is not a known function parameter}}
+__attribute__((callback(cb, ab))) void unknown_name2(void (*cb)(int), int a) {} // expected-error {{'callback' attribute argument 'ab' is not a known function parameter}}
+
+__attribute__((callback(callback, 1))) void too_many_args_1b(void (*callback)(void)) {}      // expected-error {{'callback' attribute takes one argument}}
+__attribute__((callback(callback, __))) void too_many_args_2b(double (*callback)(void));     // expected-error {{'callback' attribute takes one argument}}
+__attribute__((callback(callback, 2, 2))) void too_many_args_3b(void (*callback)(int), int); // expected-error {{'callback' attribute requires exactly 2 arguments}}
+
+__attribute__((callback(callback, a))) void too_few_args_1b(void (*callback)(int, int), int a); // expected-error {{'callback' attribute takes one argument}}
+__attribute__((callback(callback))) void too_few_args_2b(int (*callback)(int));                 // expected-error {{'callback' attribute takes no arguments}}
+__attribute__((callback(callback, __))) void too_few_args_3b(void (*callback)(int, int)) {}     // expected-error {{'callback' attribute takes one argument}}
+
+__attribute__((callback(__))) void oob_args_1b(void (*callback)(void)); // expected-error {{'callback' attribute specifies invalid callback callee}}
+
+__attribute__((callback(callback))) __attribute__((callback(callback))) void multiple_cb_1b(void (*callback)(void));                     // expected-error {{multiple 'callback' attributes specified}}
+__attribute__((callback(1))) __attribute__((callback(callback2))) void multiple_cb_2b(void (*callback1)(void), void (*callback2)(void)); // expected-error {{multiple 'callback' attributes specified}}
+
+#ifdef HAS_THIS
+__attribute__((callback(this))) void oob_args_0b(void (*callback)(void)); // expected-error {{'callback' attribute specifies invalid callback callee}}
+#else
+__attribute__((callback(this))) void oob_args_0b(void (*callback)(void));           // expected-error {{'callback' argument at position 1 references unavailable implicit 'this'}}
+__attribute__((callback(1, this))) void no_this_1b(void *(*callback)(void *));      // expected-error {{'callback' argument at position 2 references unavailable implicit 'this'}}
+__attribute__((callback(1, this))) void no_this_2b(void *(*callback)(int, void *)); // expected-error {{'callback' argument at position 2 references unavailable implicit 'this'}}
+#endif
+
+// We could allow the following declarations if we at some point need to:
+
+__attribute__((callback(callback, __))) void vararg_cb_1b(void (*callback)(int, ...)) {} // expected-error {{'callback' attribute callee may not be variadic}}
+__attribute__((callback(1, a))) void vararg_cb_2b(void (*callback)(int, ...), int a);    // expected-error {{'callback' attribute callee may not be variadic}}
+
+__attribute__((callback(callback, __, callback, a, b, c, __))) void varargs_1b(void (*callback)(int, ...), int a, float b, double c) {} // expected-error {{'callback' attribute requires exactly 6 arguments}}
+__attribute__((callback(1, __, c, a, b, c, -1))) void varargs_2b(void (*callback)(void *, double, int, ...), int a, float b, double c); // expected-error {{'callback' attribute requires exactly 6 arguments}}
+
+__attribute__((callback(1, __, callback))) void self_arg_1b(void (*callback)(int, ...)) {}                        // expected-error {{'callback' attribute requires exactly 2 arguments}}
+__attribute__((callback(callback, __, callback, __, __, callback))) void self_arg_2b(void (*callback)(int, ...)); // expected-error {{'callback' attribute requires exactly 5 arguments}}
diff --git a/test/Sema/attr-callback.c b/test/Sema/attr-callback.c
new file mode 100644
index 0000000000..ec12b1650a
--- /dev/null
+++ b/test/Sema/attr-callback.c
@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 %s -verify -fsyntax-only
+
+// expected-no-diagnostics
+
+__attribute__((callback(1))) void no_args(void (*callback)(void));
+__attribute__((callback(1, 2, 3))) void args_1(void (*callback)(int, double), int a, double b);
+__attribute__((callback(2, 3, 3))) void args_2(int a, void (*callback)(double, double), double b);
+__attribute__((callback(2, -1, -1))) void args_3(int a, void (*callback)(double, double), double b);
+
+__attribute__((callback(callback))) void no_argsb(void (*callback)(void));
+__attribute__((callback(callback, a, 3))) void args_1b(void (*callback)(int, double), int a, double b);
+__attribute__((callback(callback, b, b))) void args_2b(int a, void (*callback)(double, double), double b);
+__attribute__((callback(2, __, __))) void args_3b(int a, void (*callback)(double, double), double b);
+__attribute__((callback(callback, -1, __))) void args_3c(int a, void (*callback)(double, double), double b);