Add check for explicit lifetime when initialising static variables.

If a static variable declared in a task, function, or block has an
initialisation expression, SystemVerilog requires the declaration to
have an explicit static lifetime. This is supposed to be a compile
error, but for now just output a warning.

Implementing this required adding support in the parser for explicit
lifetimes in variable declarations. For now, just output an error if
the user asks for a lifetime that isn't the default for that scope.

(cherry picked from commit 9538c81d34)

PScope.cc

@@ -19,6 +19,11 @@
 
 # include  "PScope.h"
 
+bool LexicalScope::var_init_needs_explicit_lifetime() const
+{
+      return false;
+}
+
 PScope::PScope(perm_string n, LexicalScope*parent)
 : LexicalScope(parent), name_(n)
 {
@@ -58,4 +63,3 @@ PScopeExtra::PScopeExtra(perm_string n)
 PScopeExtra::~PScopeExtra()
 {
 }
-

PScope.h

@@ -53,11 +53,12 @@ class NetScope;
 class LexicalScope {
 
     public:
-      explicit LexicalScope(LexicalScope*parent) : parent_(parent) { }
+      enum lifetime_t { INHERITED, STATIC, AUTOMATIC };
+
+      explicit LexicalScope(LexicalScope*parent) : default_lifetime(INHERITED), parent_(parent) { }
 	// A virtual destructor is so that dynamic_cast can work.
       virtual ~LexicalScope() { }
 
-      enum lifetime_t { INHERITED, STATIC, AUTOMATIC };
       lifetime_t default_lifetime;
 
       struct range_t {
@@ -124,6 +125,8 @@ class LexicalScope {
 
       LexicalScope* parent_scope() const { return parent_; }
 
+      virtual bool var_init_needs_explicit_lifetime() const;
+
     protected:
       void dump_typedefs_(ostream&out, unsigned indent) const;
 

PTask.cc

@@ -30,6 +30,11 @@ PTaskFunc::~PTaskFunc()
 {
 }
 
+bool PTaskFunc::var_init_needs_explicit_lifetime() const
+{
+      return default_lifetime == STATIC;
+}
+
 void PTaskFunc::set_ports(vector<pform_tf_port_t>*p)
 {
       assert(ports_ == 0);

PTask.h

@@ -41,6 +41,8 @@ class PTaskFunc : public PScope, public LineInfo {
       PTaskFunc(perm_string name, LexicalScope*parent);
       ~PTaskFunc();
 
+      bool var_init_needs_explicit_lifetime() const;
+
       void set_ports(std::vector<pform_tf_port_t>*p);
 
       void set_this(class_type_t*use_type, PWire*this_wire);

Statement.cc

@@ -115,6 +115,11 @@ PBlock::~PBlock()
 	    delete list_[idx];
 }
 
+bool PBlock::var_init_needs_explicit_lifetime() const
+{
+      return default_lifetime == STATIC;
+}
+
 PChainConstructor* PBlock::extract_chain_constructor()
 {
       if (list_.empty())

Statement.h

@@ -183,6 +183,8 @@ class PBlock  : public PScope, public Statement {
 
       BL_TYPE bl_type() const { return bl_type_; }
 
+      bool var_init_needs_explicit_lifetime() const;
+
 	// This is only used if this block is the statement list for a
 	// constructor. We look for a PChainConstructor as the first
 	// statement, and if it is there, extract it.

parse.y

@@ -65,6 +65,10 @@ static PTask* current_task = 0;
 static PFunction* current_function = 0;
 static stack<PBlock*> current_block_stack;
 
+/* The variable declaration rules need to know if a lifetime has been
+   specified. */
+static LexicalScope::lifetime_t var_lifetime;
+
 static pform_name_t* pform_create_this(void)
 {
       name_component_t name (perm_string::literal("@"));
@@ -667,7 +671,7 @@ static void current_function_set_statement(const YYLTYPE&loc, vector<Statement*>
 %type <int_val> atom2_type
 %type <int_val> module_start module_end
 
-%type <lifetime> lifetime_opt
+%type <lifetime> lifetime lifetime_opt
 
 %token K_TAND
 %right K_PLUS_EQ K_MINUS_EQ K_MUL_EQ K_DIV_EQ K_MOD_EQ K_AND_EQ K_OR_EQ
@@ -1369,10 +1373,14 @@ jump_statement /* IEEE1800-2005: A.6.5 */
       }
   ;
 
-lifetime_opt /* IEEE1800-2005: A.2.1.3 */
+lifetime /* IEEE1800-2005: A.2.1.3 */
   : K_automatic { $$ = LexicalScope::AUTOMATIC; }
   | K_static    { $$ = LexicalScope::STATIC; }
-  |             { $$ = LexicalScope::INHERITED; }
+  ;
+
+lifetime_opt /* IEEE1800-2005: A.2.1.3 */
+  : lifetime { $$ = $1; }
+  |          { $$ = LexicalScope::INHERITED; }
   ;
 
   /* Loop statements are kinds of statements. */
@@ -2254,6 +2262,19 @@ variable_dimension /* IEEE1800-2005: A.2.5 */
       }
   ;
 
+variable_lifetime
+  : lifetime
+      { if (!gn_system_verilog()) {
+	      yyerror(@1, "error: overriding the default variable lifetime "
+			  "requires SystemVerilog.");
+	} else if ($1 != pform_peek_scope()->default_lifetime) {
+	      yyerror(@1, "sorry: overriding the default variable lifetime "
+			  "is not yet supported.");
+	}
+	var_lifetime = $1;
+      }
+  ;
+
   /* Verilog-2001 supports attribute lists, which can be attached to a
      variety of different objects. The syntax inside the (* *) is a
      comma separated list of names or names with assigned values. */
@@ -2328,10 +2349,20 @@ block_item_decl
       { if ($1) pform_set_data_type(@1, $1, $2, NetNet::REG, attributes_in_context);
       }
 
+  | variable_lifetime data_type register_variable_list ';'
+      { if ($2) pform_set_data_type(@2, $2, $3, NetNet::REG, attributes_in_context);
+	var_lifetime = LexicalScope::INHERITED;
+      }
+
   | K_reg data_type register_variable_list ';'
       { if ($2) pform_set_data_type(@2, $2, $3, NetNet::REG, attributes_in_context);
       }
 
+  | variable_lifetime K_reg data_type register_variable_list ';'
+      { if ($3) pform_set_data_type(@3, $3, $4, NetNet::REG, attributes_in_context);
+	var_lifetime = LexicalScope::INHERITED;
+      }
+
   | K_event event_variable_list ';'
       { if ($2) pform_make_events($2, @1.text, @1.first_line);
       }
@@ -5492,7 +5523,13 @@ register_variable
 	$$ = $1;
       }
   | IDENTIFIER dimensions_opt '=' expression
-      { perm_string name = lex_strings.make($1);
+      { if (pform_peek_scope()->var_init_needs_explicit_lifetime()
+	    && (var_lifetime == LexicalScope::INHERITED)) {
+	      cerr << @3 << ": warning: Static variable initialization requires "
+			    "explicit lifetime in this context." << endl;
+	      warn_count += 1;
+	}
+	perm_string name = lex_strings.make($1);
 	pform_makewire(@1, name, NetNet::REG,
 		       NetNet::NOT_A_PORT, IVL_VT_NO_TYPE, 0);
 	pform_set_reg_idx(name, $2);

pform.cc

@@ -513,6 +513,7 @@ PBlock* pform_push_block_scope(char*name, PBlock::BL_TYPE bt)
       }
 
       PBlock*block = new PBlock(block_name, lexical_scope, bt);
+      block->default_lifetime = find_lifetime(LexicalScope::INHERITED);
       lexical_scope = block;
 
       return block;