Changes in src/libcfa/exception.c [cbce272:38ac6ec]

File:

• src/libcfa/exception.c (modified) (15 diffs)

src/libcfa/exception.c

@@ -10 +10 @@
 // Created On       : Mon Jun 26 15:13:00 2017
 // Last Modified By : Andrew Beach
-// Last Modified On : Fri Aug  4 15:20:00 2017
-// Update Count     : 6
-//
-
-#include <stddef.h> // for size_t
+// Last Modified On : Tus Jul 11 16:36:00 2017
+// Update Count     : 1
+//
 
 #include "exception.h"
@@ -24 +22 @@
 #include <unwind.h>
 
-// FIX ME: temporary hack to keep ARM build working
-#ifndef _URC_FATAL_PHASE1_ERROR
-#define _URC_FATAL_PHASE1_ERROR 2
-#endif // ! _URC_FATAL_PHASE1_ERROR
-#ifndef _URC_FATAL_PHASE2_ERROR
-#define _URC_FATAL_PHASE2_ERROR 2
-#endif // ! _URC_FATAL_PHASE2_ERROR
-
 #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 exception_context_t {
+struct shared_stack_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;
-//}
-
-
-// This macro should be the only thing that needs to change across machines.  Used in the personality function, way down
-// in termination.
+
+
+// This macro should be the only thing that needs to change across machines.
+// Used in the personality function, way down in termination.
 // struct _Unwind_Context * -> _Unwind_Reason_Code(*)(exception *)
 #define MATCHER_FROM_CONTEXT(ptr_to_context) \
@@ -80 +47 @@
 
         // DEBUG
-        printf("Throwing resumption exception\n");
+        printf("Throwing resumption exception %d\n", *except);
 
         struct __cfaehm__try_resume_node * original_head = shared_stack.current_resume;
@@ -94 +61 @@
         }
 
-        printf("Unhandled exception\n");
+        printf("Unhandled exception %d\n", *except);
         shared_stack.current_resume = original_head;
 
@@ -102 +69 @@
 }
 
-// Do we control where exceptions get thrown even with concurency?  If not these are not quite thread safe, the cleanup
-// hook has to be added after the node is built but before it is made the top node.
-
+/* Do we control where exceptions get thrown even with concurency?
+ * If not these are not quite thread safe, the cleanup hook has to be added
+ * after the node is built but before it is made the top node.
+ */
 void __cfaehm__try_resume_setup(struct __cfaehm__try_resume_node * node,
                         int (*handler)(exception * except)) {
@@ -119 +87 @@
 // TERMINATION ===============================================================
 
-// 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 );
-}
-
+// 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)
 
 // We need a piece of storage to raise the exception
@@ -202 +111 @@
 }
 
-// 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();
-        }
-
+void __cfaehm__throw_terminate( exception * val ) {
+        // Store the current exception
+        shared_stack.current_exception = *val;
+
+        // DEBUG
+        printf("Throwing termination exception %d\n", *val);
 
         // Call stdlibc to raise the exception
         _Unwind_Reason_Code ret = _Unwind_RaiseException( &this_exception_storage );
 
-        // If we reach here it means something happened.  For resumption to work we need to find a way to return back to
-        // here.  Most of them will probably boil down to setting a global flag and making the phase 1 either stop or
-        // fail.  Causing an error on purpose may help avoiding unnecessary work but it might have some weird side
-        // effects.  If we just pretend no handler was found that would work but may be expensive for no reason since we
-        // will always search the whole stack.
+        // If we reach here it means something happened
+        // For resumption to work we need to find a way to return back to here
+        // Most of them will probably boil down to setting a global flag and making the phase 1 either stop or fail.
+        // Causing an error on purpose may help avoiding unnecessary work but it might have some weird side effects.
+        // If we just pretend no handler was found that would work but may be expensive for no reason since we will always
+        // search the whole stack
 
         if( ret == _URC_END_OF_STACK ) {
-                // No proper handler was found.  This can be handled in several way.  C++ calls std::terminate Here we
-                // force unwind the stack, basically raising a cancellation.
+                // No proper handler was found
+                // This can be handled in several way
+                // C++ calls std::terminate
+                // Here we force unwind the stack, basically raising a cancellation
                 printf("Uncaught exception %p\n", &this_exception_storage);
 
@@ -229 +140 @@
         }
 
-        // We did not simply reach the end of the stack without finding a handler.  Something wen't wrong
+        // We did not simply reach the end of the stack without finding a handler,
+        // Something wen't wrong
         printf("UNWIND ERROR %d after raise exception\n", ret);
         abort();
 }
 
-void __cfaehm__throw_terminate( exception * val ) {
-        // DEBUG
-        printf("Throwing termination exception\n");
-
-        __cfaehm__allocate_exception( val );
-        __cfaehm__begin_unwind();
-}
-
+// Nesting this the other way would probably be faster.
 void __cfaehm__rethrow_terminate(void) {
         // DEBUG
         printf("Rethrowing termination exception\n");
 
-        __cfaehm__begin_unwind();
-}
-
-// This is our personality routine.  For every stack frame anotated with ".cfi_personality 0x3,__gcfa_personality_v0".
-// This function will be called twice when unwinding.  Once in the search phased and once in the cleanup phase.
+        __cfaehm__throw_terminate(&shared_stack.current_exception);
+}
+
+// This is our personality routine
+// For every stack frame anotated with ".cfi_personality 0x3,__gcfa_personality_v0"
+// This function will be called twice when unwinding
+// Once in the search phased and once in the cleanup phase
 _Unwind_Reason_Code __gcfa_personality_v0 (
                 int version, _Unwind_Action actions, unsigned long long exceptionClass,
@@ -356 +263 @@
                                         _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;
@@ -386 +293 @@
                                 // I assume this sets the instruction pointer to the adress of the landing pad
                                 // It doesn't actually set it, it only state the value that needs to be set once we return _URC_INSTALL_CONTEXT
-                                _Unwind_SetIP( context, ((lsd_info.LPStart) + (callsite_landing_pad)) );
+                                _Unwind_SetIP( context, lsd_info.LPStart + callsite_landing_pad );
 
                                 // DEBUG
@@ -410 +317 @@
 }
 
-// Try statements are hoisted out see comments for details.  With this could probably be unique and simply linked from
-// libcfa but there is one problem left, see the exception table for details
+// Try statements are hoisted out see comments for details
+// With this could probably be unique and simply linked from
+// libcfa but there is one problem left, see the exception table
+// for details
 __attribute__((noinline))
 void __cfaehm__try_terminate(void (*try_block)(),
@@ -419 +328 @@
         //! printf("%p %p %p %p\n", &try_block, &catch_block, &match_block, &xy);
 
-        // Setup statments: These 2 statments won't actually result in any code, they only setup global tables.
-        // However, they clobber gcc cancellation support from gcc.  We can replace the personality routine but
-        // replacing the exception table gcc generates is not really doable, it generates labels based on how the
-        // assembly works.
-
+        // Setup statments
+        // These 2 statments won't actually result in any code,
+        // they only setup global tables.
+        // However, they clobber gcc cancellation support from gcc.
+        // We can replace the personality routine but replacing the exception
+        // table gcc generates is not really doable, it generates labels based
+        // on how the assembly works.
         // Setup the personality routine
         asm volatile (".cfi_personality 0x3,__gcfa_personality_v0");
@@ -429 +340 @@
         asm volatile (".cfi_lsda 0x3, .LLSDACFA2");
 
-        // Label which defines the start of the area for which the handler is setup.
+        // Label which defines the start of the area for which the handler is setup
         asm volatile (".TRYSTART:");
 
@@ -443 +354 @@
         // Exceptionnal path
         CATCH : __attribute__(( unused ));
-        // Label which defines the end of the area for which the handler is setup.
+        // Label which defines the end of the area for which the handler is setup
         asm volatile (".TRYEND:");
-        // Label which defines the start of the exception landing pad.  Basically what is called when the exception is
-        // caught.  Note, if multiple handlers are given, the multiplexing should be done by the generated code, not the
-        // exception runtime.
+        // Label which defines the start of the exception landing pad
+        // basically what will be called when the exception is caught
+        // Note, if multiple handlers are given, the multiplexing should be done
+        // by the generated code, not the exception runtime
         asm volatile (".CATCH:");
 
         // Exception handler
-        catch_block( shared_stack.current_handler_index,
-                     shared_stack.current_exception );
-}
-
-// Exception table data we need to generate.  While this is almost generic, the custom data refers to foo_try_match try
-// match, which is no way generic.  Some more works need to be done if we want to have a single call to the try routine.
-
-#if defined( __x86_64__ ) || defined( __i386__ )
+        catch_block(shared_stack.current_handler_index,
+                    &shared_stack.current_exception);
+}
+
+// Exception table data we need to generate
+// While this is almost generic, the custom data refers to
+// foo_try_match try match, which is no way generic
+// Some more works need to be done if we want to have a single
+// call to the try routine
 asm (
         //HEADER
@@ -481 +394 @@
 //      "       .section        .note.GNU-stack,\"x\",@progbits\n"
 );
-#endif // __x86_64__ || __i386__