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Accept more asm expressions

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In particular subtracting a defined symbol from current section
makes the value PC relative, and .org accepts symbolic expressions
as well, if the symbol is from the current section.
This commit is contained in:
Michael Matz
2016-06-29 15:57:32 +02:00
parent c82e52d55b
commit 8e4da42384
4 changed files with 60 additions and 23 deletions
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55
tccasm.c
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@ -67,11 +67,13 @@ static void asm_expr_unary(TCCState *s1, ExprValue *pe)
sym->type.t = VT_STATIC | VT_VOID;
}
}
pe->v = 0;
pe->sym = sym;
pe->v = 0;
pe->sym = sym;
pe->pcrel = 0;
} else if (*p == '\0') {
pe->v = n;
pe->sym = NULL;
pe->pcrel = 0;
} else {
tcc_error("invalid number syntax");
}
@ -97,6 +99,7 @@ static void asm_expr_unary(TCCState *s1, ExprValue *pe)
case TOK_LCHAR:
pe->v = tokc.i;
pe->sym = NULL;
pe->pcrel = 0;
next();
break;
case '(':
@ -107,6 +110,7 @@ static void asm_expr_unary(TCCState *s1, ExprValue *pe)
case '.':
pe->v = 0;
pe->sym = &sym_dot;
pe->pcrel = 0;
sym_dot.type.t = VT_VOID | VT_STATIC;
sym_dot.r = cur_text_section->sh_num;
sym_dot.jnext = ind;
@ -125,9 +129,11 @@ static void asm_expr_unary(TCCState *s1, ExprValue *pe)
/* if absolute symbol, no need to put a symbol value */
pe->v = sym->jnext;
pe->sym = NULL;
pe->pcrel = 0;
} else {
pe->v = 0;
pe->sym = sym;
pe->pcrel = 0;
}
next();
} else {
@ -230,20 +236,21 @@ static inline void asm_expr_sum(TCCState *s1, ExprValue *pe)
pe->v -= e2.v;
/* NOTE: we are less powerful than gas in that case
because we store only one symbol in the expression */
if (!pe->sym && !e2.sym) {
/* OK */
} else if (pe->sym && !e2.sym) {
/* OK */
} else if (pe->sym && e2.sym) {
if (pe->sym == e2.sym) {
/* OK */
} else if (pe->sym->r == e2.sym->r && pe->sym->r != 0) {
/* we also accept defined symbols in the same section */
pe->v += pe->sym->jnext - e2.sym->jnext;
} else {
goto cannot_relocate;
}
pe->sym = NULL; /* same symbols can be subtracted to NULL */
if (!e2.sym) {
/* OK */
} else if (pe->sym == e2.sym) {
/* OK */
pe->sym = NULL; /* same symbols can be subtracted to NULL */
} else if (pe->sym && pe->sym->r == e2.sym->r && pe->sym->r != 0) {
/* we also accept defined symbols in the same section */
pe->v += pe->sym->jnext - e2.sym->jnext;
pe->sym = NULL;
} else if (e2.sym->r == cur_text_section->sh_num) {
/* When subtracting a defined symbol in current section
this actually makes the value PC-relative. */
pe->v -= e2.sym->jnext - ind - 4;
pe->pcrel = 1;
e2.sym = NULL;
} else {
cannot_relocate:
tcc_error("invalid operation with label");
@ -531,9 +538,15 @@ static void asm_parse_directive(TCCState *s1)
case TOK_ASMDIR_org:
{
unsigned long n;
ExprValue e;
next();
/* XXX: handle section symbols too */
n = asm_int_expr(s1);
asm_expr(s1, &e);
n = e.v;
if (e.sym) {
if (e.sym->r != cur_text_section->sh_num)
expect("constant or same-section symbol");
n += e.sym->jnext;
}
if (n < ind)
tcc_error("attempt to .org backwards");
v = 0;
@ -703,6 +716,7 @@ static void asm_parse_directive(TCCState *s1)
case TOK_ASMDIR_section:
{
char sname[256];
int old_nb_section = s1->nb_sections;
tok1 = tok;
/* XXX: support more options */
@ -733,6 +747,11 @@ static void asm_parse_directive(TCCState *s1)
use_section(s1, sname);
else
push_section(s1, sname);
/* If we just allocated a new section reset its alignment to
1. new_section normally acts for GCC compatibility and
sets alignment to PTR_SIZE. The assembler behaves different. */
if (old_nb_section != s1->nb_sections)
cur_text_section->sh_addralign = 1;
}
break;
case TOK_ASMDIR_previous: