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verilog: add support for SystemVerilog string literals.

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Differences are new escape sequences (including escaped newline
continuations and hex escapes) and triple-quoted literals.
This commit is contained in:
Gary Wong 2025-07-03 20:51:12 -06:00
parent 7b0c1fe491
commit 5feb1a1752
4 changed files with 386 additions and 47 deletions
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168
frontends/verilog/verilog_lexer.l
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@ -112,6 +112,129 @@ static bool isUserType(std::string &s)
return false;
}
static bool is_hex_dig(char c, int *val)
{
if ('0' <= c && c <= '9') {
*val = c - '0';
return true;
} else if ('a' <= c && c <= 'f') {
*val = c - 'a' + 0xA;
return true;
} else if ('A' <= c && c <= 'F') {
*val = c - 'A' + 0xA;
return true;
} else if (c == 'x' || c == 'X' || c == 'z' || c == 'Z' || c == '?') {
log_file_warning(AST::current_filename.c_str(), frontend_verilog_yyget_lineno(), "'%c' not a valid digit in hex escape sequence.\n", c);
*val = 0; // not semantically valid in hex escape...
return true; // ...but still processed as part of hex token
}
return false;
}
static bool is_oct_dig(char c, int *val)
{
if ('0' <= c && c <= '7') {
*val = c - '0';
return true;
} else if (c == 'x' || c == 'X' || c == 'z' || c == 'Z' || c == '?') {
log_file_warning(AST::current_filename.c_str(), frontend_verilog_yyget_lineno(), "'%c' not a valid digit in octal escape sequence.\n", c);
*val = 0; // not semantically valid in octal escape...
return true; // ...but still processed as part of octal token
}
return false;
}
static std::string *process_str(char *str, int len, bool triple)
{
char *in, *out; // Overwrite input buffer: flex manual states "Actions
// are free to modify 'yytext' except for lengthening it".
for (in = str, out = str; in < str + len; in++)
switch (*in) {
case '\n':
case '\r':
if (in + 1 < str + len && (in[1] ^ *in) == ('\n' ^ '\r'))
in++;
if (!triple)
log_file_warning(AST::current_filename.c_str(), frontend_verilog_yyget_lineno(), "Multi-line string literals should be triple-quoted or escaped.\n");
*out++ = '\n';
break;
case '\\':
in++;
log_assert(in < str + len);
switch (*in) {
case 'a':
*out++ = '\a';
break;
case 'f':
*out++ = '\f';
break;
case 'n':
*out++ = '\n';
break;
case 'r': /* not part of IEEE-1800 2023, but seems
like a good idea to support it anyway */
*out++ = '\r';
break;
case 't':
*out++ = '\t';
break;
case 'v':
*out++ = '\v';
break;
case 'x':
int val;
if (in + 1 < str + len && is_hex_dig(in[1], &val)) {
*out = val;
in++;
if (in + 1 < str + len && is_hex_dig(in[1], &val)) {
*out = *out * 0x10 + val;
in++;
}
out++;
} else
log_file_warning(AST::current_filename.c_str(), frontend_verilog_yyget_lineno(), "ignoring invalid hex escape.\n");
break;
case '\\':
*out++ = '\\';
break;
case '"':
*out++ = '"';
break;
case '\n':
case '\r':
if (in + 1 < str + len && (in[1] ^ *in) == ('\n' ^ '\r'))
in++;
break;
default:
if ('0' <= *in && *in <= '7') {
int val;
*out = *in - '0';
if (in + 1 < str + len && is_oct_dig(in[1], &val)) {
*out = *out * 010 + val;
in++;
if (in + 1 < str + len && is_oct_dig(in[1], &val)) {
if (*out >= 040)
log_file_warning(AST::current_filename.c_str(), frontend_verilog_yyget_lineno(), "octal escape exceeds \\377\n");
*out = *out * 010 + val;
in++;
}
}
out++;
} else
*out++ = *in;
}
break;
default:
*out++ = *in;
}
return new std::string(str, out - str);
}
%}
%option yylineno
@ -122,7 +245,6 @@ static bool isUserType(std::string &s)
%option prefix="frontend_verilog_yy"
%x COMMENT
%x STRING
%x SYNOPSYS_TRANSLATE_OFF
%x SYNOPSYS_FLAGS
%x IMPORT_DPI
@ -335,47 +457,9 @@ TIME_SCALE_SUFFIX [munpf]?s
return TOK_REALVAL;
}
\" { BEGIN(STRING); }
<STRING>([^\\"]|\\.)+ { yymore(); real_location = old_location; }
<STRING>\" {
BEGIN(0);
char *yystr = strdup(yytext);
yystr[strlen(yytext) - 1] = 0;
int i = 0, j = 0;
while (yystr[i]) {
if (yystr[i] == '\\' && yystr[i + 1]) {
i++;
if (yystr[i] == 'a')
yystr[i] = '\a';
else if (yystr[i] == 'f')
yystr[i] = '\f';
else if (yystr[i] == 'n')
yystr[i] = '\n';
else if (yystr[i] == 'r')
yystr[i] = '\r';
else if (yystr[i] == 't')
yystr[i] = '\t';
else if (yystr[i] == 'v')
yystr[i] = '\v';
else if ('0' <= yystr[i] && yystr[i] <= '7') {
yystr[i] = yystr[i] - '0';
if ('0' <= yystr[i + 1] && yystr[i + 1] <= '7') {
yystr[i + 1] = yystr[i] * 8 + yystr[i + 1] - '0';
i++;
}
if ('0' <= yystr[i + 1] && yystr[i + 1] <= '7') {
yystr[i + 1] = yystr[i] * 8 + yystr[i + 1] - '0';
i++;
}
}
}
yystr[j++] = yystr[i++];
}
yystr[j] = 0;
yylval->string = new std::string(yystr, j);
free(yystr);
return TOK_STRING;
}
\"([^\\"]|\\.|\\\n)*\" { yylval->string = process_str(yytext + 1, yyleng - 2, false); return TOK_STRING; }
\"{3}(\"{0,2}([^\\"]|\\.|\\\n))*\"{3} { yylval->string = process_str(yytext + 3, yyleng - 6, true); return TOK_STRING; }
and|nand|or|nor|xor|xnor|not|buf|bufif0|bufif1|notif0|notif1 {
yylval->string = new std::string(yytext);