Go patch committed: Be strict about escape analysis of builtin functions

[Ian Lance Taylor via Gcc-patches]

This Go frontend patch by Cherry Mui makes the escape analysis pass
stricter about builtin functions  In the places where we handle
builtin functions, list all supported ones, and fail if an unexpected
one is seen. So if a new builtin function is added in the future we
can detect it, instead of silently treating it as nonescaping.
Bootstrapped and ran Go testsuite on x86_64-pc-linux-gnu.  Committed
to mainline.

Ian

5b720746d8456986f4bb6b53d30b462f93ff58c4
diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index be1a90f7aa1..394530c1cbc 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-616ee658a6238e7de53592ebda5997f6de6a00de
+b47bcf942daa9a0c252db9b57b8f138adbfcdaa2
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
diff --git a/gcc/go/gofrontend/escape.cc b/gcc/go/gofrontend/escape.cc
index 347ac2534c9..c8978ac9239 100644
--- a/gcc/go/gofrontend/escape.cc
+++ b/gcc/go/gofrontend/escape.cc
@@ -1608,8 +1608,33 @@ Escape_analysis_assign::expression(Expression** pexpr)
                 }
                 break;
 
-              default:
+              case Builtin_call_expression::BUILTIN_CLOSE:
+              case Builtin_call_expression::BUILTIN_DELETE:
+              case Builtin_call_expression::BUILTIN_PRINT:
+              case Builtin_call_expression::BUILTIN_PRINTLN:
+              case Builtin_call_expression::BUILTIN_LEN:
+              case Builtin_call_expression::BUILTIN_CAP:
+              case Builtin_call_expression::BUILTIN_COMPLEX:
+              case Builtin_call_expression::BUILTIN_REAL:
+              case Builtin_call_expression::BUILTIN_IMAG:
+              case Builtin_call_expression::BUILTIN_RECOVER:
+              case Builtin_call_expression::BUILTIN_ALIGNOF:
+              case Builtin_call_expression::BUILTIN_OFFSETOF:
+              case Builtin_call_expression::BUILTIN_SIZEOF:
+                // these do not escape.
+                break;
+
+              case Builtin_call_expression::BUILTIN_ADD:
+              case Builtin_call_expression::BUILTIN_SLICE:
+                // handled in ::assign.
                 break;
+
+              case Builtin_call_expression::BUILTIN_MAKE:
+              case Builtin_call_expression::BUILTIN_NEW:
+                // should have been lowered to runtime calls at this point.
+                // fallthrough
+              default:
+                go_unreachable();
               }
             break;
           }
@@ -2372,8 +2397,35 @@ Escape_analysis_assign::assign(Node* dst, Node* src)
                     }
                     break;
 
-                  default:
+                  case Builtin_call_expression::BUILTIN_LEN:
+                  case Builtin_call_expression::BUILTIN_CAP:
+                  case Builtin_call_expression::BUILTIN_COMPLEX:
+                  case Builtin_call_expression::BUILTIN_REAL:
+                  case Builtin_call_expression::BUILTIN_IMAG:
+                  case Builtin_call_expression::BUILTIN_RECOVER:
+                  case Builtin_call_expression::BUILTIN_ALIGNOF:
+                  case Builtin_call_expression::BUILTIN_OFFSETOF:
+                  case Builtin_call_expression::BUILTIN_SIZEOF:
+                    // these do not escape.
+                    break;
+
+                  case Builtin_call_expression::BUILTIN_COPY:
+                    // handled in ::expression.
                     break;
+
+                  case Builtin_call_expression::BUILTIN_CLOSE:
+                  case Builtin_call_expression::BUILTIN_DELETE:
+                  case Builtin_call_expression::BUILTIN_PRINT:
+                  case Builtin_call_expression::BUILTIN_PRINTLN:
+                  case Builtin_call_expression::BUILTIN_PANIC:
+                    // these do not have result.
+                    // fallthrough
+                  case Builtin_call_expression::BUILTIN_MAKE:
+                  case Builtin_call_expression::BUILTIN_NEW:
+                    // should have been lowered to runtime calls at this point.
+                    // fallthrough
+                  default:
+                    go_unreachable();
                   }
                 break;
               }