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code generation error with wide chars and bitmaps (omitted 'goto' statement) #127

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skvadrik opened this issue Dec 9, 2015 · 1 comment

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@skvadrik
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commented Dec 9, 2015

Source code (err.re):

/*!re2c
    [^a]+ {}
    [a]   {}
*/

Skeleton helped me catch an error in code generation:

$ re2c -W -ubi err.re -S -o err.c && gcc err.c -o err && ./err
error: lex_line4: at position 294 (iteration 98):
        expected: match length 2, rule 0
        actual:   match length 1, rule 1

The generated code:

$ re2c -ubi err.re
/* Generated by re2c 0.15.3 on Wed Dec  9 11:07:24 2015 */

{
        YYCTYPE yych;
        static const unsigned char yybm[] = {
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128,   0, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
                128, 128, 128, 128, 128, 128, 128, 128,.
        };
        if (YYLIMIT <= YYCURSOR) YYFILL(1);
        yych = *YYCURSOR;
        if (yych & ~0xFF) {
        } else if (yybm[0+yych] & 128) {
                goto yy2;
        }
        goto yy5;
yy2:
        ++YYCURSOR;
        if (YYLIMIT <= YYCURSOR) YYFILL(1);
        yych = *YYCURSOR;
        if (yych & ~0xFF) {
                goto yy2;
        } else if (yybm[0+yych] & 128) {
                goto yy2;
        }
        {}
yy5:
        ++YYCURSOR;
        {}
}

The false part is:

        if (yych & ~0xFF) {
        } else if (yybm[0+yych] & 128) {
                goto yy2;
        }
        goto yy5;
yy2:

It should be:

        if (yych & ~0xFF) {
                goto yy2;
        } else if (yybm[0+yych] & 128) {
                goto yy2;
        }
        goto yy5;
yy2:

This is a false optimization: re2c thinks that since the next state is yy2, it can omit goto yy2;. But in this particular case there is a fallthrough to goto yy5;.

Previous versions also have this bug (re2c-0.13.6 generates even worse code: it has this error and another similar error).

@skvadrik skvadrik self-assigned this Dec 9, 2015

@skvadrik skvadrik added this to the 0.16 milestone Dec 9, 2015

skvadrik added a commit that referenced this issue Dec 9, 2015

Fixed bug #127: "code generation error with wide chars and bitmaps (o…
…mitted 'goto' statement)".

Minimal test case:
    /*!re2c
        [^a]+ {}
        [a]   {}
    */

Catched with skeleton:
    $ re2c -W -ubi err.re -S -o err.c && gcc err.c -o err && ./err
    error: lex_line4: at position 294 (iteration 98):
            expected: match length 2, rule 0
            actual:   match length 1, rule 1
@skvadrik

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commented Dec 9, 2015

Fixed in this coommit: 4fa27cf

@skvadrik skvadrik closed this Dec 9, 2015

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