Changeset cd7ef0b for src/libcfa/exception.c

Timestamp:

Aug 10, 2017, 3:39:11 PM (8 years ago)

Author:

Aaron Moss <a3moss@…>

Branches:

ADT, aaron-thesis, arm-eh, ast-experimental, cleanup-dtors, deferred_resn, demangler, enum, forall-pointer-decay, jacob/cs343-translation, jenkins-sandbox, master, new-ast, new-ast-unique-expr, new-env, no_list, persistent-indexer, pthread-emulation, qualifiedEnum, resolv-new, with_gc

Children:

38d70ab

Parents:

275f4b4 (diff), e1780a2 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

Merge branch 'master' of plg.uwaterloo.ca:software/cfa/cfa-cc

File:

• src/libcfa/exception.c (modified) (9 diffs)

src/libcfa/exception.c

@@ -9 +9 @@
 // Author           : Andrew Beach
 // Created On       : Mon Jun 26 15:13:00 2017
-// Last Modified By : Peter A. Buhr
-// Last Modified On : Wed Jul 26 10:37:51 2017
-// Update Count     : 2
+// Last Modified By : Andrew Beach
+// Last Modified On : Fri Aug  4 15:20:00 2017
+// Update Count     : 6
 //
+
+#include <stddef.h> // for size_t
 
 #include "exception.h"
@@ -32 +34 @@
 #include "lsda.h"
 
+
+// Base exception vtable is abstract, you should not have base exceptions.
+struct __cfaehm__base_exception_t_vtable
+                ___cfaehm__base_exception_t_vtable_instance = {
+        .parent = NULL,
+        .size = 0,
+        .copy = NULL,
+        .free = NULL,
+        .msg = NULL
+};
+
+
 // Temperary global exception context. Does not work with concurency.
-struct shared_stack_t {
+struct exception_context_t {
     struct __cfaehm__try_resume_node * top_resume;
     struct __cfaehm__try_resume_node * current_resume;
 
-    exception current_exception;
+    exception * current_exception;
     int current_handler_index;
 } shared_stack = {NULL, NULL, 0, 0};
 
+// Get the current exception context.
+// There can be a single global until multithreading occurs, then each stack
+// needs its own. It will have to be updated to handle that.
+struct exception_context_t * this_exception_context() {
+        return &shared_stack;
+}
+//#define SAVE_EXCEPTION_CONTEXT(to_name)
+//struct exception_context_t * to_name = this_exception_context();
+//exception * this_exception() {
+//    return this_exception_context()->current_exception;
+//}
 
 
@@ -55 +80 @@
 
         // DEBUG
-        printf("Throwing resumption exception %d\n", *except);
+        printf("Throwing resumption exception\n");
 
         struct __cfaehm__try_resume_node * original_head = shared_stack.current_resume;
@@ -69 +94 @@
         }
 
-        printf("Unhandled exception %d\n", *except);
+        printf("Unhandled exception\n");
         shared_stack.current_resume = original_head;
 
@@ -94 +119 @@
 // TERMINATION ===============================================================
 
-// Requires -fexceptions to work.
-
-// Global which defines the current exception.  Currently an int just to make matching easier.
-//int this_exception; (became shared_stack.current_exception)
+// MEMORY MANAGEMENT (still for integers)
+// May have to move to cfa for constructors and destructors (references).
+
+struct __cfaehm__node {
+        struct __cfaehm__node * next;
+};
+
+#define NODE_TO_EXCEPT(node) ((exception *)(1 + (node)))
+#define EXCEPT_TO_NODE(except) ((struct __cfaehm__node *)(except) - 1)
+
+// Creates a copy of the indicated exception and sets current_exception to it.
+static void __cfaehm__allocate_exception( exception * except ) {
+        struct exception_context_t * context = this_exception_context();
+
+        // Allocate memory for the exception.
+        struct __cfaehm__node * store = malloc(
+                sizeof( struct __cfaehm__node ) + except->virtual_table->size );
+
+        if ( ! store ) {
+                // Failure: cannot allocate exception. Terminate thread.
+                abort(); // <- Although I think it might be the process.
+        }
+
+        // Add the node to the list:
+        store->next = EXCEPT_TO_NODE(context->current_exception);
+        context->current_exception = NODE_TO_EXCEPT(store);
+
+        // Copy the exception to storage.
+        except->virtual_table->copy( context->current_exception, except );
+}
+
+// Delete the provided exception, unsetting current_exception if relivant.
+static void __cfaehm__delete_exception( exception * except ) {
+        struct exception_context_t * context = this_exception_context();
+
+        // DEBUG
+        printf( "Deleting Exception\n");
+
+        // Remove the exception from the list.
+        struct __cfaehm__node * to_free = EXCEPT_TO_NODE(except);
+        struct __cfaehm__node * node;
+
+        if ( context->current_exception == except ) {
+                node = to_free->next;
+                context->current_exception = (node) ? NODE_TO_EXCEPT(node) : 0;
+        } else {
+                node = EXCEPT_TO_NODE(context->current_exception);
+                // It may always be in the first or second position.
+                while( to_free != node->next ) {
+                        node = node->next;
+                }
+                node->next = to_free->next;
+        }
+
+        // Free the old exception node.
+        except->virtual_table->free( except );
+        free( to_free );
+}
+
+// If this isn't a rethrow (*except==0), delete the provided exception.
+void __cfaehm__cleanup_terminate( void * except ) {
+        if ( *(void**)except ) __cfaehm__delete_exception( *(exception**)except );
+}
+
 
 // We need a piece of storage to raise the exception
@@ -117 +202 @@
 }
 
-void __cfaehm__throw_terminate( exception * val ) {
-        // Store the current exception
-        shared_stack.current_exception = *val;
-
-        // DEBUG
-        printf("Throwing termination exception %d\n", *val);
+// The exception that is being thrown must already be stored.
+__attribute__((noreturn)) void __cfaehm__begin_unwind(void) {
+        if ( ! this_exception_context()->current_exception ) {
+                printf("UNWIND ERROR missing exception in begin unwind\n");
+                abort();
+        }
+
 
         // Call stdlibc to raise the exception
@@ -148 +234 @@
 }
 
-// Nesting this the other way would probably be faster.
+void __cfaehm__throw_terminate( exception * val ) {
+        // DEBUG
+        printf("Throwing termination exception\n");
+
+        __cfaehm__allocate_exception( val );
+        __cfaehm__begin_unwind();
+}
+
 void __cfaehm__rethrow_terminate(void) {
         // DEBUG
         printf("Rethrowing termination exception\n");
 
-        __cfaehm__throw_terminate(&shared_stack.current_exception);
+        __cfaehm__begin_unwind();
 }
 
@@ -263 +356 @@
                                         _Unwind_Reason_Code (*matcher)(exception *) =
                                                 MATCHER_FROM_CONTEXT(context);
-                                        int index = matcher(&shared_stack.current_exception);
+                                        int index = matcher(shared_stack.current_exception);
                                         _Unwind_Reason_Code ret = (0 == index)
                                                 ? _URC_CONTINUE_UNWIND : _URC_HANDLER_FOUND;
@@ -359 +452 @@
         // Exception handler
         catch_block( shared_stack.current_handler_index,
-                    &shared_stack.current_exception );
+                     shared_stack.current_exception );
 }