Changeset 2a3b019

Timestamp:

Mar 25, 2020, 4:36:25 PM (4 years ago)

Author:

Andrew Beach <ajbeach@…>

Branches:

ADT, arm-eh, ast-experimental, enum, forall-pointer-decay, jacob/cs343-translation, master, new-ast, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

9cb89b87

Parents:

44a88528

Message:

Cleaning exception code: no direct access to shared_stack anymore, small reorganization that fixes debug print.

File:

• libcfa/src/exception.c (modified) (13 diffs)

libcfa/src/exception.c

@@ -63 +63 @@
 // 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() {
+inline static 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;
-//}
 
 
@@ -76 +71 @@
 
 void __cfaabi_ehm__throw_resume(exception_t * except) {
+        struct exception_context_t * context = this_exception_context();
 
         __cfaabi_dbg_print_safe("Throwing resumption exception\n");
 
-        struct __cfaabi_ehm__try_resume_node * original_head = shared_stack.current_resume;
+        struct __cfaabi_ehm__try_resume_node * original_head = context->current_resume;
         struct __cfaabi_ehm__try_resume_node * current =
-                (original_head) ? original_head->next : shared_stack.top_resume;
+                (original_head) ? original_head->next : context->top_resume;
 
         for ( ; current ; current = current->next) {
-                shared_stack.current_resume = current;
+                context->current_resume = current;
                 if (current->handler(except)) {
-                        shared_stack.current_resume = original_head;
+                        context->current_resume = original_head;
                         return;
                 }
@@ -92 +88 @@
 
         __cfaabi_dbg_print_safe("Unhandled exception\n");
-        shared_stack.current_resume = original_head;
+        context->current_resume = original_head;
 
         // Fall back to termination:
@@ -105 +101 @@
 void __cfaabi_ehm__try_resume_setup(struct __cfaabi_ehm__try_resume_node * node,
                         _Bool (*handler)(exception_t * except)) {
-        node->next = shared_stack.top_resume;
+        struct exception_context_t * context = this_exception_context();
+        node->next = context->top_resume;
         node->handler = handler;
-        shared_stack.top_resume = node;
+        context->top_resume = node;
 }
 
 void __cfaabi_ehm__try_resume_cleanup(struct __cfaabi_ehm__try_resume_node * node) {
-        shared_stack.top_resume = node->next;
+        struct exception_context_t * context = this_exception_context();
+        context->top_resume = node->next;
 }
 
@@ -191 +189 @@
                 _Unwind_Exception_Class exceptionClass,
                 struct _Unwind_Exception * unwind_exception,
-                struct _Unwind_Context * context,
-                void * some_param) {
+                struct _Unwind_Context * unwind_context,
+                void * stop_param) {
         if( actions & _UA_END_OF_STACK  ) exit(1);
         if( actions & _UA_CLEANUP_PHASE ) return _URC_NO_REASON;
@@ -251 +249 @@
                 int version, _Unwind_Action actions, unsigned long long exceptionClass,
                 struct _Unwind_Exception* unwind_exception,
-                struct _Unwind_Context* context)
+                struct _Unwind_Context* unwind_context)
 {
 
         //__cfaabi_dbg_print_safe("CFA: 0x%lx\n", _Unwind_GetCFA(context));
         __cfaabi_dbg_print_safe("Personality function (%d, %x, %llu, %p, %p):",
-                        version, actions, exceptionClass, unwind_exception, context);
+                        version, actions, exceptionClass, unwind_exception, unwind_context);
 
         // If we've reached the end of the stack then there is nothing much we can do...
@@ -274 +272 @@
 
         // Get a pointer to the language specific data from which we will read what we need
-        const unsigned char * lsd = (const unsigned char*) _Unwind_GetLanguageSpecificData( context );
+        const unsigned char * lsd = (const unsigned char*) _Unwind_GetLanguageSpecificData( unwind_context );
 
         if( !lsd ) {    //Nothing to do, keep unwinding
@@ -283 +281 @@
         // Get the instuction pointer and a reading pointer into the exception table
         lsda_header_info lsd_info;
-        const unsigned char * cur_ptr = parse_lsda_header(context, lsd, &lsd_info);
-        _Unwind_Ptr instruction_ptr = _Unwind_GetIP( context );
+        const unsigned char * cur_ptr = parse_lsda_header(unwind_context, lsd, &lsd_info);
+        _Unwind_Ptr instruction_ptr = _Unwind_GetIP(unwind_context);
+
+        struct exception_context_t * context = this_exception_context();
 
         // Linearly search the table for stuff to do
@@ -321 +321 @@
 
                 // Something to do?
-                if( callsite_landing_pad ) {
+                if ( 0 == callsite_landing_pad ) {
+                        // Nothing to do, move along
+                        __cfaabi_dbg_print_safe(" no landing pad");
+                } else {
                         // Which phase are we in
                         if (actions & _UA_SEARCH_PHASE) {
@@ -348 +351 @@
 
 #                                       if defined( __x86_64 )
-                                        _Unwind_Word match_pos = _Unwind_GetCFA(context) + 8;
+                                        _Unwind_Word match_pos = _Unwind_GetCFA(unwind_context) + 8;
 #                                       elif defined( __i386 )
-                                        _Unwind_Word match_pos = _Unwind_GetCFA(context) + 24;
+                                        _Unwind_Word match_pos = _Unwind_GetCFA(unwind_context) + 24;
 #                                       endif
                                         int (*matcher)(exception_t *) = *(int(**)(exception_t *))match_pos;
 
-                                        int index = matcher(shared_stack.current_exception);
+                                        int index = matcher(context->current_exception);
                                         _Unwind_Reason_Code ret = (0 == index)
                                                 ? _URC_CONTINUE_UNWIND : _URC_HANDLER_FOUND;
-                                        shared_stack.current_handler_index = index;
+                                        context->current_handler_index = index;
 
                                         // Based on the return value, check if we matched the exception
@@ -382 +385 @@
                                 // We need to run some clean-up or a handler
                                 // These statment do the right thing but I don't know any specifics at all
-                                _Unwind_SetGR( context, __builtin_eh_return_data_regno(0), (_Unwind_Ptr) unwind_exception );
-                                _Unwind_SetGR( context, __builtin_eh_return_data_regno(1), 0 );
+                                _Unwind_SetGR( unwind_context, __builtin_eh_return_data_regno(0),
+                                        (_Unwind_Ptr)unwind_exception );
+                                _Unwind_SetGR( unwind_context, __builtin_eh_return_data_regno(1), 0 );
 
                                 // 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( unwind_context, ((lsd_info.LPStart) + (callsite_landing_pad)) );
 
                                 __cfaabi_dbg_print_safe(" action\n");
@@ -395 +399 @@
                         }
                 }
-
-                // Nothing to do, move along
-                __cfaabi_dbg_print_safe(" no landing pad");
         }
         // No handling found
@@ -457 +458 @@
 
         // Exception handler
-        catch_block( shared_stack.current_handler_index,
-                     shared_stack.current_exception );
+        // Note: Saving the exception context on the stack breaks termination exceptions.
+        catch_block( this_exception_context()->current_handler_index,
+                     this_exception_context()->current_exception );
 }