PR6836: $$vars extensions, $$return

1 files changed, 78 insertions, 43 deletions

diff --git a/tapsets.cxx b/tapsets.cxx
index 664dfb1f..1f7d2555 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -4002,7 +4002,11 @@ dwarf_var_expanding_copy_visitor::visit_target_symbol (target_symbol *e)
   if (lvalue && !q.sess.guru_mode)
     throw semantic_error("write to target variable not permitted", e->tok);
 
-  if (q.has_return && e->base_name != "$return")
+  // See if we need to generate a new probe to save/access function
+  // parameters from a return probe.  PR 1382.
+  if (q.has_return
+      && e->base_name != "$return" // not the special return-value variable handled below
+      && e->base_name != "$$return") // nor the other special variable handled below
     {
       if (lvalue)
 	throw semantic_error("write to target variable not permitted in .return probes", e->tok);
@@ -4287,7 +4291,8 @@ dwarf_var_expanding_copy_visitor::visit_target_symbol (target_symbol *e)
 
   if (e->base_name == "$$vars"
       || e->base_name == "$$parms"
-      || e->base_name == "$$locals")
+      || e->base_name == "$$locals"
+      || (q.has_return && (e->base_name == "$$return")))
     {
       Dwarf_Die *scopes;
       if (dwarf_getscopes_die (scope_die, &scopes) == 0)
@@ -4298,55 +4303,85 @@ dwarf_var_expanding_copy_visitor::visit_target_symbol (target_symbol *e)
 
       // Convert $$parms to sprintf of a list of parms and active local vars
       // which we recursively evaluate
-      token* tmp_tok = new token;
-      tmp_tok->type = tok_identifier;
-      tmp_tok->content = "sprintf";
-      pf->tok = tmp_tok;
+
+      // NB: we synthesize a new token here rather than reusing
+      // e->tok, because print_format::print likes to use
+      // its tok->content.
+      token* pf_tok = new token;
+      pf_tok->location = e->tok->location;
+      pf_tok->type = tok_identifier;
+      pf_tok->content = "sprint";
+
+      pf->tok = pf_tok;
       pf->print_to_stream = false;
       pf->print_with_format = true;
       pf->print_with_delim = false;
       pf->print_with_newline = false;
       pf->print_char = false;
 
-      Dwarf_Die result;
-      if (dwarf_child (&scopes[0], &result) == 0)
-	do
-	  {
-	    switch (dwarf_tag (&result))
-	      {
-	      case DW_TAG_variable:
-		if (e->base_name == "$$parms")
-		  continue;
-		break;
-	      case DW_TAG_formal_parameter:
-		if (e->base_name == "$$locals")
-		  continue;
-		break;
-
-	      default:
-		continue;
-	      }
+      if (q.has_return && (e->base_name == "$$return"))
+        {
+          tsym->tok = e->tok;
+          tsym->base_name = "$return";
+          
+          // Ignore any variable that isn't accessible.
+          tsym->saved_conversion_error = 0;
+          this->visit_target_symbol(tsym); // NB: throws nothing ...
+          if (tsym->saved_conversion_error) // ... but this is how we know it happened.
+            {
 
-	    const char *diename = dwarf_diename (&result);
-	    token* sym_tok = new token;
-	    sym_tok->location = e->get_tok()->location;
-	    sym_tok->type = tok_identifier;
-	    sym_tok->content = diename;
-	    tsym->tok = sym_tok;
-	    tsym->base_name = "$";
-	    tsym->base_name += diename;
-
-	    // Ignore any variable that isn't accessible.
-            tsym->saved_conversion_error = 0;
-            this->visit_target_symbol(tsym); // NB: throws nothing ...
-            if (! tsym->saved_conversion_error) // ... but this is how we know it happened.
+            }
+          else
+            {
+              pf->raw_components += "$return";
+              pf->raw_components += "=%#x ";
+              pf->args.push_back(*(expression**)this->targets.top());
+            }
+        }
+      else
+        {
+          // non-.return probe: support $$parms, $$vars, $$locals
+          Dwarf_Die result;
+          if (dwarf_child (&scopes[0], &result) == 0)
+            do
               {
-                pf->raw_components += diename;
-                pf->raw_components += "=%#x ";
-                pf->args.push_back(*(expression**)this->targets.top());
+                switch (dwarf_tag (&result))
+                  {
+                  case DW_TAG_variable:
+                    if (e->base_name == "$$parms")
+                      continue;
+                    break;
+                  case DW_TAG_formal_parameter:
+                    if (e->base_name == "$$locals")
+                      continue;
+                    break;
+                    
+                  default:
+                    continue;
+                  }
+                
+                const char *diename = dwarf_diename (&result);
+                tsym->tok = e->tok;
+                tsym->base_name = "$";
+                tsym->base_name += diename;
+                
+                // Ignore any variable that isn't accessible.
+                tsym->saved_conversion_error = 0;
+                this->visit_target_symbol(tsym); // NB: throws nothing ...
+                if (tsym->saved_conversion_error) // ... but this is how we know it happened.
+                  {
+                    pf->raw_components += diename;
+                    pf->raw_components += "=? ";
+                  }
+                else
+                  {
+                    pf->raw_components += diename;
+                    pf->raw_components += "=%#x ";
+                    pf->args.push_back(*(expression**)this->targets.top());
+                  }
               }
-	  }
-	while (dwarf_siblingof (&result, &result) == 0);
+            while (dwarf_siblingof (&result, &result) == 0);
+        }
 
       pf->components = print_format::string_to_components(pf->raw_components);
       provide <print_format*> (this, pf);
@@ -4366,7 +4401,7 @@ dwarf_var_expanding_copy_visitor::visit_target_symbol (target_symbol *e)
 
   try
     {
-      if (q.has_return && e->base_name == "$return")
+      if (q.has_return && (e->base_name == "$return"))
         {
 	  ec->code = q.dw.literal_stmt_for_return (scope_die,
 						   addr,