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verilog: Support void functions

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The difference between void functions and tasks is that always_comb's
implicit sensitivity list behaves as if functions were inlined, but
ignores signals read only in tasks. This only matters for event based
simulation, and for synthesis we can treat a void function like a task.
This commit is contained in:
Jannis Harder 2023-03-20 12:50:14 +01:00
parent 61da330a38
commit fb1c2be76b
3 changed files with 56 additions and 1 deletions
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1
frontends/verilog/verilog_lexer.l
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@ -276,6 +276,7 @@ TIME_SCALE_SUFFIX [munpf]?s
"byte" { SV_KEYWORD(TOK_BYTE); }
"shortint" { SV_KEYWORD(TOK_SHORTINT); }
"longint" { SV_KEYWORD(TOK_LONGINT); }
"void" { SV_KEYWORD(TOK_VOID); }
"eventually" { if (formal_mode) return TOK_EVENTUALLY; SV_KEYWORD(TOK_EVENTUALLY); }
"s_eventually" { if (formal_mode) return TOK_EVENTUALLY; SV_KEYWORD(TOK_EVENTUALLY); }

19
frontends/verilog/verilog_parser.y
View file

@ -372,7 +372,7 @@ static void rewriteGenForDeclInit(AstNode *loop)
%token TOK_POS_INDEXED TOK_NEG_INDEXED TOK_PROPERTY TOK_ENUM TOK_TYPEDEF
%token TOK_RAND TOK_CONST TOK_CHECKER TOK_ENDCHECKER TOK_EVENTUALLY
%token TOK_INCREMENT TOK_DECREMENT TOK_UNIQUE TOK_UNIQUE0 TOK_PRIORITY
%token TOK_STRUCT TOK_PACKED TOK_UNSIGNED TOK_INT TOK_BYTE TOK_SHORTINT TOK_LONGINT TOK_UNION
%token TOK_STRUCT TOK_PACKED TOK_UNSIGNED TOK_INT TOK_BYTE TOK_SHORTINT TOK_LONGINT TOK_VOID TOK_UNION
%token TOK_BIT_OR_ASSIGN TOK_BIT_AND_ASSIGN TOK_BIT_XOR_ASSIGN TOK_ADD_ASSIGN
%token TOK_SUB_ASSIGN TOK_DIV_ASSIGN TOK_MOD_ASSIGN TOK_MUL_ASSIGN
%token TOK_SHL_ASSIGN TOK_SHR_ASSIGN TOK_SSHL_ASSIGN TOK_SSHR_ASSIGN
@ -1020,6 +1020,23 @@ task_func_decl:
current_function_or_task = NULL;
ast_stack.pop_back();
} |
attr TOK_FUNCTION opt_automatic TOK_VOID TOK_ID {
// The difference between void functions and tasks is that
// always_comb's implicit sensitivity list behaves as if functions were
// inlined, but ignores signals read only in tasks. This only matters
// for event based simulation, and for synthesis we can treat a void
// function like a task.
current_function_or_task = new AstNode(AST_TASK);
current_function_or_task->str = *$5;
append_attr(current_function_or_task, $1);
ast_stack.back()->children.push_back(current_function_or_task);
ast_stack.push_back(current_function_or_task);
current_function_or_task_port_id = 1;
delete $5;
} task_func_args_opt ';' task_func_body TOK_ENDFUNCTION {
current_function_or_task = NULL;
ast_stack.pop_back();
} |
attr TOK_FUNCTION opt_automatic func_return_type TOK_ID {
current_function_or_task = new AstNode(AST_FUNCTION);
current_function_or_task->str = *$5;