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From: adr <adr@SDF.ORG>
To: 9fans <9fans@9fans.net>
Subject: Re: [9fans] Conversion of constants in C compiler
Date: Tue, 10 May 2022 13:06:01 +0000 (UTC)	[thread overview]
Message-ID: <942ed10-fc38-1b94-4f4c-9f2f632f86d4@SDF.ORG> (raw)
In-Reply-To: <c950fbd9-2053-1c2-b71d-d0e233c64d4@SDF.ORG>

I think I got it right at last:

[...]
        vv = yylval.vval;
        if(c1 & Numvlong ||
          (uvlong)convvtox(vv, TUVLONG) > convvtox(vv, TULONG)){
                /* unsigned suffix or hex occupying the sing bit */
                if((c1 & Numuns) || convvtox(vv, TVLONG) < 0 && (c1 & Numdec) == 0) {
                        c = LUVLCONST;
                        t = TUVLONG;
                        goto nret;
                }
                c = LVLCONST;
                t = TVLONG;
                goto nret;
        }
        if(c1 & Numlong ||
          (uvlong)convvtox(vv, TULONG) > convvtox(vv, TUINT)){
                if((c1 & Numuns) || convvtox(vv, TLONG) < 0 && (c1 & Numdec) == 0) {
                        c = LULCONST;
                        t = TULONG;
                        goto nret;
                }
                /* decimal occupying the sing bit */
                if(convvtox(vv, TLONG) < 0 && (c1 & Numdec) == 0) {
                        c = LVLCONST;
                        t = TVLONG;
                        goto nret;
                }
                c = LLCONST;
                t = TLONG;
                goto nret;
        }
        if((c1 & Numuns) || convvtox(vv, TINT) < 0 && (c1 & Numdec) == 0) {
                c = LUCONST;
                t = TUINT;
                goto nret;
        }
        if(convvtox(vv, TINT) < 0 && (c1 & Numdec) == 0) {
                c = LLCONST;
                t = TLONG;
                goto nret;
        }
        c = LCONST;
        t = TINT;
        goto nret;
[...]

I used the cast also in (uvlong)convvtox(vv, TULONG) because the
standard only specifies that long long can't be smaller than long.

After playing with this I'm thinking about using the original code
and substituting the warning for an error when a constant is
truncated. Makes sense to me and Plan9's C isn't C99 anyway.

adr.

------------------------------------------
9fans: 9fans
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  reply	other threads:[~2022-05-10 13:06 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-20 10:19 adr
2022-04-20 11:38 ` Charles Forsyth
2022-04-20 14:37   ` adr
2022-04-20 14:37 ` ori
2022-04-21  7:54   ` adr
2022-04-21 15:29     ` ori
2022-04-28  1:10     ` ori
2022-05-01 12:03       ` adr
2022-04-28  2:43     ` ori
2022-04-28  3:12       ` ori
2022-05-01 12:35       ` adr
2022-05-09 19:31         ` adr
2022-05-10 13:06           ` adr [this message]
2022-05-10 14:48             ` adr
2022-06-06  0:35 adr

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