compiler: compile runtime.getcaller{pc,sp} into builtin functions

    
    The runtime functions runtime.getcallerpc and runtime.getcallersp are
    intended to be efficient ways to get the return and frame address of the
    caller (that is, the caller of runtime.getcallerpc).  In the C code that
    is implemented by simply using C macros:
    
    This patch essentially implements those macros in the Go code.
    
    It would be nice if we could just use //extern for this, but it doesn't
    work because the runtime code passes the right argument.  Of course we
    could change the runtime code, but these are common enough that I'd
    prefer to avoid the difference from the gc version of the runtime code.
    
    This patch corrects the existing declaration of __builtin_return_address
    to use uint32, rather than uint, for the parameter type.  The builtin
    functions take the C type "unsigned int", which for the targets we use
    corresponds to the Go type uint32.  Not that it should matter, really.
    
    Reviewed-on: https://go-review.googlesource.com/29653

From-SVN: r240382

1 files changed, 7 insertions, 6 deletions

diff --git a/gcc/go/go-gcc.cc b/gcc/go/go-gcc.cc
index a332831..f9ba9d5 100644
--- a/gcc/go/go-gcc.cc
+++ b/gcc/go/go-gcc.cc
@@ -818,13 +818,14 @@ Gcc_backend::Gcc_backend()
 		       math_function_type_long, true, false);
 
   // We use __builtin_return_address in the thunk we build for
-  // functions which call recover.
+  // functions which call recover, and for runtime.getcallerpc.
+  t = build_function_type_list(ptr_type_node, unsigned_type_node, NULL_TREE);
   this->define_builtin(BUILT_IN_RETURN_ADDRESS, "__builtin_return_address",
-		       NULL,
-		       build_function_type_list(ptr_type_node,
-						unsigned_type_node,
-						NULL_TREE),
-		       false, false);
+		       NULL, t, false, false);
+
+  // The runtime calls __builtin_frame_address for runtime.getcallersp.
+  this->define_builtin(BUILT_IN_FRAME_ADDRESS, "__builtin_frame_address",
+		       NULL, t, false, false);
 
   // The compiler uses __builtin_trap for some exception handling
   // cases.