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Support local register variables

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Similar to GCC a local asm register variable enforces the use of a
specified register in asm operands (and doesn't otherwise
matter).  Works only if the variable is directly mentioned as
operand.  For that we now generally store a backpointer from
an SValue to a Sym when the SValue was the result of unary()
parsing a symbol identifier.
This commit is contained in:
Michael Matz
2016-10-06 04:05:30 +02:00
parent 3bc9c325c5
commit f081acbfba
4 changed files with 58 additions and 6 deletions
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20
tccgen.c
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@ -386,7 +386,7 @@ ST_FUNC Sym *sym_push2(Sym **ps, int v, int t, long c)
Sym *s;
s = sym_malloc();
s->asm_label = 0;
s->scope = 0;
s->v = v;
s->type.t = t;
s->type.ref = NULL;
@ -577,6 +577,7 @@ static void vsetc(CType *type, int r, CValue *vc)
vtop->r = r;
vtop->r2 = VT_CONST;
vtop->c = *vc;
vtop->sym = NULL;
}
/* push constant of type "type" with useless value */
@ -4599,11 +4600,17 @@ ST_FUNC void unary(void)
r = VT_SYM | VT_CONST;
} else {
r = s->r;
/* A symbol that has a register is a local register variable,
which starts out as VT_LOCAL value. */
if ((r & VT_VALMASK) < VT_CONST)
r = (r & ~VT_VALMASK) | VT_LOCAL;
}
vset(&s->type, r, s->c);
/* if forward reference, we must point to s */
/* Point to s as backpointer (even without r&VT_SYM).
Will be used by at least the x86 inline asm parser for
regvars. */
vtop->sym = s;
if (vtop->r & VT_SYM) {
vtop->sym = s;
vtop->c.i = 0;
}
break;
@ -6462,6 +6469,13 @@ static void decl_initializer_alloc(CType *type, AttributeDef *ad, int r,
#endif
if (v) {
/* local variable */
#ifdef CONFIG_TCC_ASM
if (ad->asm_label) {
int reg = asm_parse_regvar(ad->asm_label);
if (reg >= 0)
r = (r & ~VT_VALMASK) | reg;
}
#endif
sym_push(v, type, r, addr);
} else {
/* push local reference */