xfnw/plan9fox
1
0
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity

cc: promote integer constants according to c99 spec.

Browse source 
C99 integer constants with no type suffix promote differently
depending on the way that they're written: hex and oct consts
promote as int => uint => long => ulong => vlong => uvlong.
Decimal constants are always signed.

We used to promote all values to uint on overflow, and never
went wider. This change fixes that, and adds a warning when
a decimal constant that would have been promoted to uint in
the past gets promoted to int.
This commit is contained in:
Ori Bernstein 2020-08-08 11:39:25 -07:00
parent ac4e21f52d
commit 3ba1d83d20
2 changed files with 12 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
sys/src/cmd/8c/txt.c
View file

@ -865,7 +865,7 @@ gmove(Node *f, Node *t)
gmove(f, &fregnode0);
gins(AFADDD, nodfconst(-2147483648.), &fregnode0);
gins(AFMOVLP, f, &nod);
gins(ASUBL, nodconst(-2147483648), &nod);
gins(ASUBL, nodconst(-0x80000000), &nod);
gmove(&nod, t);
return;

13
sys/src/cmd/cc/lex.c
View file

@ -444,7 +444,7 @@ long
yylex(void)
{
vlong vv;
long c, c1, t;
long c, c1, t, w;
char *cp;
Rune rune;
Sym *s;
@ -844,7 +844,16 @@ ncu:
yyerror("overflow in constant");
vv = yylval.vval;
if(c1 & Numvlong) {
/*
* c99 is silly: decimal constants stay signed,
* hex and octal go unsigned before widening.
*/
w = 32;
if((c1 & (Numdec|Numuns)) == Numdec)
w = 31;
if(c1 & Numvlong || (c1 & Numlong) == 0 && (uvlong)vv >= 1ULL<<w){
if((c1&(Numdec|Numvlong)) == Numdec && vv < 1ULL<<32)
warn(Z, "int constant widened to vlong: %s", symb);
if((c1 & Numuns) || convvtox(vv, TVLONG) < 0) {
c = LUVLCONST;
t = TUVLONG;