[PATCH] support $$vars and $$parms

[Stan Cox <scox at redhat dot com>]

Given: 
probe kernel.statement("bio_map_kern@fs/bio.c:850") {print ($$vars) }
Results:
q=0xffffffffdea58ca8 data=0xffffffffdf5c6d88 gfp_mask=0x10
bio=0xd5362c00 

$$vars expands to sprintf("%#x %#x %#x %#x\n", parm1, parm2, var1, var2)
$$parms expands to sprintf("%#x %#x\n", parm1, parm2)
where parm are the function parameters and var are local variables live
at that location.

Testing and documentation are in progress.




/work/scox/systemtap/src /work/scox/systemtap/bld/i386-redhat-linux /work/scox/systemtap ~
diff --git a/ChangeLog b/ChangeLog
index d38a370..12680a6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2008-07-24  Stan Cox  <scox@redhat.com>
+
+	* tapsets.cxx (dwarf_var_expanding_copy_visitor::visit_target_symbol): 
+	Add support for $$vars and $$parms.
+	
 2008-07-23  Frank Ch. Eigler  <fche@elastic.org>
 
 	From James Bottomley <James.Bottomley@HansenPartnership.com>:
diff --git a/tapsets.cxx b/tapsets.cxx
index 5a3fbdc..185019b 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -2534,7 +2534,7 @@ struct dwarf_query : public base_query
 // It arises because we sometimes try to fix up slightly-off
 // .statement() probes (something we find out in fairly low-level).
 //
-// An alternative would be to put some more intellgence into query_cu(),
+// An alternative would be to put some more intelligence into query_cu(),
 // and have it print additional suggestions after finding that
 // q->dw.iterate_over_srcfile_lines resulted in no new finished_results.
 
@@ -4248,6 +4248,79 @@ dwarf_var_expanding_copy_visitor::visit_target_symbol (target_symbol *e)
       return;
     }
 
+  if (e->base_name == "$$vars" || e->base_name == "$$parms")
+    {
+      Dwarf_Die *scopes;
+      if (dwarf_getscopes_die (scope_die, &scopes) == 0)
+	return;
+	
+      target_symbol *tsym = new target_symbol;
+      print_format* pf = new print_format;
+
+      // Convert $$parms to sprintf of a list of parms and active local vars
+      // which we recursively evaluate
+      token* tmp_tok = new token;
+      tmp_tok->type = tok_identifier;
+      tmp_tok->content = "sprintf";
+      pf->tok = tmp_tok;
+      pf->print_to_stream = false;
+      pf->print_with_format = true;
+      pf->print_with_delim = false;
+      pf->print_with_newline = false;
+      pf->print_char = false;
+
+      Dwarf_Die result;
+      if (dwarf_child (&scopes[0], &result) == 0)
+	do
+	  {
+	    switch (dwarf_tag (&result))
+	      {
+	      case DW_TAG_variable:
+		if (e->base_name == "$$parms")
+		  continue;
+	      case DW_TAG_formal_parameter:
+		break;
+
+	      default:
+		continue;
+	      }
+
+	    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;
+	    Dwarf_Attribute attr_mem;
+
+	    // Ignore any variable that isn't accessible.
+	    // dwarf_attr_integrate is checked by literal_stmt_for_local
+	    // dwarf_getlocation_addr is checked by translate_location
+	    // but if those fail we cannot catch semantic_error.
+	    if (dwarf_attr_integrate (&result, DW_AT_location, &attr_mem) != NULL)
+	      {
+		Dwarf_Op *expr;
+		size_t len;
+		if (dwarf_getlocation_addr (&attr_mem, addr - q.dw.module_bias,
+					    &expr, &len, 1) == 0)
+		  continue;
+		this->visit_target_symbol(tsym);
+		pf->raw_components += diename;
+		pf->raw_components += "=%#x ";
+		pf->args.push_back(*(expression**)this->targets.top());
+	      }
+	  }
+	while (dwarf_siblingof (&result, &result) == 0);
+
+      pf->raw_components += "\\n";
+      pf->components = print_format::string_to_components(pf->raw_components);
+      provide <print_format*> (this, pf);
+
+      return;
+    }
+
   // Synthesize a function.
   functiondecl *fdecl = new functiondecl;
   fdecl->tok = e->tok;