Centralized calls for SymSetContext, we only do it when we change the

current stack frame, and no longer every time we look up local symbols
on current stack

programs/winedbg/stack.c

@@ -141,8 +141,6 @@ unsigned stack_fetch_frames(void)
 
     HeapFree(GetProcessHeap(), 0, dbg_curr_thread->frames);
     dbg_curr_thread->frames = NULL;
-    dbg_curr_thread->num_frames = 0;
-    dbg_curr_thread->curr_frame = 0;
 
     memset(&sf, 0, sizeof(sf));
     memory_get_current_frame(&sf.AddrFrame);
@@ -168,7 +166,10 @@ unsigned stack_fetch_frames(void)
         /* we've probably gotten ourselves into an infinite loop so bail */
         if (nf > 200) break;
     }
-    return dbg_curr_thread->num_frames = nf;
+    dbg_curr_thread->curr_frame = -1;
+    dbg_curr_thread->num_frames = nf;
+    stack_set_frame_internal(0);
+    return nf;
 }
 
 struct sym_enum
@@ -215,9 +216,6 @@ static void stack_print_addr_and_args(int nf)
 
     stack_get_frame_internal(nf, &ihsf);
 
-    ihsf.InstructionOffset = (DWORD_PTR)memory_to_linear_addr(&dbg_curr_thread->frames[nf].addr_pc);
-    ihsf.FrameOffset       = (DWORD_PTR)memory_to_linear_addr(&dbg_curr_thread->frames[nf].addr_frame);
-
     /* grab module where symbol is. If we don't have a module, we cannot print more */
     im.SizeOfStruct = sizeof(im);
     if (!SymGetModuleInfo(dbg_curr_process->handle, ihsf.InstructionOffset, &im))
@@ -258,7 +256,8 @@ static void stack_print_addr_and_args(int nf)
  */
 static unsigned backtrace(void)
 {
-    unsigned    nf = 0;
+    unsigned                    nf = 0;
+    IMAGEHLP_STACK_FRAME        ihsf;
 
     dbg_printf("Backtrace:\n");
     for (nf = 0; nf < dbg_curr_thread->num_frames; nf++)
@@ -270,6 +269,9 @@ static unsigned backtrace(void)
         print_bare_address(&dbg_curr_thread->frames[nf].addr_pc);
         dbg_printf(")\n");
     }
+    /* reset context to current stack frame */
+    stack_get_frame_internal(dbg_curr_thread->curr_frame, &ihsf);
+    SymSetContext(dbg_curr_process->handle, &ihsf, NULL);
     return nf;
 }
 

programs/winedbg/symbol.c

@@ -209,8 +209,6 @@ enum sym_get_lval symbol_get_lvalue(const char* name, const int lineno,
 {
     struct sgv_data             sgv;
     int		                i = 0;
-    char                        tmp[sizeof(SYMBOL_INFO) + 256];
-    SYMBOL_INFO*                si = (SYMBOL_INFO*)tmp;
     char                        buffer[512];
     DWORD                       opt;
     IMAGEHLP_STACK_FRAME        ihsf;
@@ -275,13 +273,10 @@ enum sym_get_lval symbol_get_lvalue(const char* name, const int lineno,
     SymSetOptions(opt);
 
     /* now grab local symbols */
-    si->SizeOfStruct = sizeof(*si);
+    if (stack_get_current_frame(&ihsf) && sgv.num < NUMDBGV)
-    si->MaxNameLen = 256;
-    if (stack_get_frame(si, &ihsf) && sgv.num < NUMDBGV)
     {
         sgv.frame_offset = ihsf.FrameOffset;
-        if (SymSetContext(dbg_curr_process->handle, &ihsf, NULL))
+        SymEnumSymbols(dbg_curr_process->handle, 0, name, sgv_cb, (void*)&sgv);
-            SymEnumSymbols(dbg_curr_process->handle, 0, name, sgv_cb, (void*)&sgv);
     }
 
     if (!sgv.num)
@@ -308,7 +303,7 @@ enum sym_get_lval symbol_get_lvalue(const char* name, const int lineno,
                     dbg_printf("%s %sof %s\n",
                                sgv.syms[i].flags & SYMFLAG_PARAMETER ? "Parameter" : "Local variable",
                                sgv.syms[i].flags & (SYMFLAG_REGISTER|SYMFLAG_REGREL) ? "(in a register) " : "",
-                               si->Name);
+                               name);
                 }
                 else if (sgv.syms[i].flags & SYMFLAG_THUNK) 
                 {
@@ -353,8 +348,6 @@ enum sym_get_lval symbol_get_lvalue(const char* name, const int lineno,
 BOOL symbol_is_local(const char* name)
 {
     struct sgv_data             sgv;
-    char                        tmp[sizeof(SYMBOL_INFO) + 256];
-    SYMBOL_INFO*                si = (SYMBOL_INFO*)tmp;
     IMAGEHLP_STACK_FRAME        ihsf;
 
     sgv.num        = 0;
@@ -365,10 +358,7 @@ BOOL symbol_is_local(const char* name)
     sgv.bp_disp    = FALSE;
     sgv.do_thunks  = FALSE;
 
-    si->SizeOfStruct = sizeof(*si);
+    if (stack_get_current_frame(&ihsf))
-    si->MaxNameLen = 256;
-    if (stack_get_frame(si, &ihsf) &&
-        SymSetContext(dbg_curr_process->handle, &ihsf, NULL))
     {
         sgv.frame_offset = ihsf.FrameOffset;
         SymEnumSymbols(dbg_curr_process->handle, 0, name, sgv_cb, (void*)&sgv);
@@ -613,8 +603,7 @@ int symbol_info_locals(void)
     if (stack_get_frame(si, &ihsf))
     {
         dbg_printf("%s:\n", si->Name);
-        if (SymSetContext(dbg_curr_process->handle, &ihsf, NULL))
+        SymEnumSymbols(dbg_curr_process->handle, 0, NULL, info_locals_cb, &ihsf);
-            SymEnumSymbols(dbg_curr_process->handle, 0, NULL, info_locals_cb, &ihsf);
     }
     return TRUE;
 }

programs/winedbg/winedbg.c

@@ -606,7 +606,6 @@ static unsigned dbg_exception_prolog(BOOL is_debug, const EXCEPTION_RECORD* rec)
     {
         ADDRESS tmp = addr;
         /* Show where we crashed */
-        stack_set_frame(0);
         memory_disasm_one_insn(&tmp);
     }
     source_list_from_addr(&addr, 0);