Add __builtin_return_address.

Implementation is mostly shared with __builtin_frame_address.
It seems to work on arm64, i386 and x86_64. It may need to be
adapted for other targets.

1 files changed, 13 insertions, 1 deletions

diff --git a/tccgen.c b/tccgen.c
index e86ff4a..3b1336c 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -3874,13 +3874,18 @@ ST_FUNC void unary(void)
         }
         break;
     case TOK_builtin_frame_address:
+    case TOK_builtin_return_address:
         {
+            int tok1 = tok;
             int level;
             CType type;
             next();
             skip('(');
             if (tok != TOK_CINT || tokc.i < 0) {
-                tcc_error("__builtin_frame_address only takes positive integers");
+                tcc_error("%s only takes positive integers",
+                          tok1 == TOK_builtin_return_address ?
+                          "__builtin_return_address" :
+                          "__builtin_frame_address");
             }
             level = tokc.i;
             next();
@@ -3892,6 +3897,13 @@ ST_FUNC void unary(void)
                 mk_pointer(&vtop->type);
                 indir();                    /* -> parent frame */
             }
+            if (tok1 == TOK_builtin_return_address) {
+                // assume return address is just above frame pointer on stack
+                vpushi(PTR_SIZE);
+                gen_op('+');
+                mk_pointer(&vtop->type);
+                indir();
+            }
         }
         break;
 #ifdef TCC_TARGET_X86_64