Another bugfix in mem2reg code

frontends/ast/ast.h

@@ -220,7 +220,7 @@ namespace AST
 		void replace_ids(const std::string &prefix, const std::map<std::string, std::string> &rules);
 		void mem2reg_as_needed_pass1(dict<AstNode*, pool<std::string>> &mem2reg_places,
 				dict<AstNode*, uint32_t> &mem2reg_flags, dict<AstNode*, uint32_t> &proc_flags, uint32_t &status_flags);
-		bool mem2reg_as_needed_pass2(pool<AstNode*> &mem2reg_set, AstNode *mod, AstNode *block);
+		bool mem2reg_as_needed_pass2(pool<AstNode*> &mem2reg_set, AstNode *mod, AstNode *block, AstNode *&async_block);
 		bool mem2reg_check(pool<AstNode*> &mem2reg_set);
 		void mem2reg_remove(pool<AstNode*> &mem2reg_set, vector<AstNode*> &delnodes);
 		void meminfo(int &mem_width, int &mem_size, int &addr_bits);

frontends/ast/genrtlil.cc

@@ -540,6 +540,7 @@ struct AST_INTERNAL::ProcessGenerator
 			log_error("Found parameter declaration in block without label at at %s:%d!\n", ast->filename.c_str(), ast->linenum);
 			break;
 
+		case AST_NONE:
 		case AST_TCALL:
 		case AST_FOR:
 			break;
@@ -810,6 +811,7 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
 	// simply ignore this nodes.
 	// they are either leftovers from simplify() or are referenced by other nodes
 	// and are only accessed here thru this references
+	case AST_NONE:
 	case AST_TASK:
 	case AST_FUNCTION:
 	case AST_DPI_FUNCTION:

frontends/ast/simplify.cc

@@ -148,7 +148,8 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
 				}
 			}
 
-			while (mem2reg_as_needed_pass2(mem2reg_set, this, NULL)) { }
+			AstNode *async_block = NULL;
+			while (mem2reg_as_needed_pass2(mem2reg_set, this, NULL, async_block)) { }
 
 			vector<AstNode*> delnodes;
 			mem2reg_remove(mem2reg_set, delnodes);
@@ -2707,15 +2708,36 @@ void AstNode::mem2reg_remove(pool<AstNode*> &mem2reg_set, vector<AstNode*> &deln
 }
 
 // actually replace memories with registers
-bool AstNode::mem2reg_as_needed_pass2(pool<AstNode*> &mem2reg_set, AstNode *mod, AstNode *block)
+bool AstNode::mem2reg_as_needed_pass2(pool<AstNode*> &mem2reg_set, AstNode *mod, AstNode *block, AstNode *&async_block)
 {
 	bool did_something = false;
 
 	if (type == AST_BLOCK)
 		block = this;
 
-	if ((type == AST_ASSIGN_LE || type == AST_ASSIGN_EQ) && block != NULL &&
+	if (type == AST_FUNCTION || type == AST_TASK)
-			children[0]->mem2reg_check(mem2reg_set) && children[0]->children[0]->children[0]->type != AST_CONSTANT)
+		return false;
+
+	if (type == AST_ASSIGN && block == NULL && children[0]->mem2reg_check(mem2reg_set))
+	{
+		if (async_block == NULL) {
+			async_block = new AstNode(AST_ALWAYS, new AstNode(AST_BLOCK));
+			mod->children.push_back(async_block);
+		}
+
+		AstNode *newNode = clone();
+		newNode->type = AST_ASSIGN_EQ;
+		async_block->children[0]->children.push_back(newNode);
+
+		newNode = new AstNode(AST_NONE);
+		newNode->cloneInto(this);
+		delete newNode;
+
+		did_something = true;
+	}
+
+	if ((type == AST_ASSIGN_LE || type == AST_ASSIGN_EQ) && children[0]->mem2reg_check(mem2reg_set) &&
+			children[0]->children[0]->children[0]->type != AST_CONSTANT)
 	{
 		std::stringstream sstr;
 		sstr << "$mem2reg_wr$" << children[0]->str << "$" << filename << ":" << linenum << "$" << (autoidx++);
@@ -2791,7 +2813,7 @@ bool AstNode::mem2reg_as_needed_pass2(pool<AstNode*> &mem2reg_set, AstNode *mod,
 		else
 		{
 			std::stringstream sstr;
-			sstr << "$mem2reg_rd$" << children[0]->str << "$" << filename << ":" << linenum << "$" << (autoidx++);
+			sstr << "$mem2reg_rd$" << str << "$" << filename << ":" << linenum << "$" << (autoidx++);
 			std::string id_addr = sstr.str() + "_ADDR", id_data = sstr.str() + "_DATA";
 
 			int mem_width, mem_size, addr_bits;
@@ -2871,7 +2893,7 @@ bool AstNode::mem2reg_as_needed_pass2(pool<AstNode*> &mem2reg_set, AstNode *mod,
 
 	auto children_list = children;
 	for (size_t i = 0; i < children_list.size(); i++)
-		if (children_list[i]->mem2reg_as_needed_pass2(mem2reg_set, mod, block))
+		if (children_list[i]->mem2reg_as_needed_pass2(mem2reg_set, mod, block, async_block))
 			did_something = true;
 
 	return did_something;

tests/simple/mem2reg.v

@@ -59,3 +59,25 @@ always @(posedge clk)
 assign dout_b = dint_c[3];
 endmodule
 
+// ------------------------------------------------------
+
+module mem2reg_test4(result1, result2, result3);
+	output signed [9:0] result1;
+	output signed [9:0] result2;
+	output signed [9:0] result3;
+
+	wire signed [9:0] intermediate [0:3];
+
+	function integer depth2Index;
+		input integer depth;
+		depth2Index = depth;
+	endfunction
+
+	assign intermediate[depth2Index(1)] = 1;
+	assign intermediate[depth2Index(2)] = 2;
+	assign intermediate[3] = 3;
+	assign result1 = intermediate[1];
+	assign result2 = intermediate[depth2Index(2)];
+	assign result3 = intermediate[depth2Index(3)];
+endmodule
+