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Fix floating point unary minus and plus

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negate(x) is subtract(-0,x), not subtract(+0,x), which makes
a difference with signed zeros.  Also +x was expressed as x+0,
in order for the integer promotions to happen, but also mangles signed
zeros, so just don't do that with floating types.
This commit is contained in:
Michael Matz
2014-01-12 04:44:27 +01:00
parent 9c6ddbfe90
commit 05c9b76131
2 changed files with 45 additions and 17 deletions
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38
tccgen.c
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@ -3702,12 +3702,16 @@ ST_FUNC void unary(void)
break;
case '+':
next();
/* in order to force cast, we add zero */
unary();
if ((vtop->type.t & VT_BTYPE) == VT_PTR)
tcc_error("pointer not accepted for unary plus");
vpushi(0);
gen_op('+');
/* In order to force cast, we add zero, except for floating point
where we really need an noop (otherwise -0.0 will be transformed
into +0.0). */
if (!is_float(vtop->type.t)) {
vpushi(0);
gen_op('+');
}
break;
case TOK_SIZEOF:
case TOK_ALIGNOF1:
@ -3822,20 +3826,20 @@ ST_FUNC void unary(void)
next();
unary();
t = vtop->type.t & VT_BTYPE;
/* handle (-)0.0 */
if ((vtop->r & (VT_VALMASK | VT_LVAL | VT_SYM)) == VT_CONST &&
is_float(t)) {
if (t == VT_FLOAT)
vtop->c.f = -vtop->c.f;
else if (t == VT_DOUBLE)
vtop->c.d = -vtop->c.d;
else
vtop->c.ld = -vtop->c.ld;
} else {
vpushi(0);
vswap();
gen_op('-');
}
if (is_float(t)) {
/* In IEEE negate(x) isn't subtract(0,x), but rather
subtract(-0, x). */
vpush(&vtop->type);
if (t == VT_FLOAT)
vtop->c.f = -0.0f;
else if (t == VT_DOUBLE)
vtop->c.d = -0.0;
else
vtop->c.ld = -0.0;
} else
vpushi(0);
vswap();
gen_op('-');
break;
case TOK_LAND:
if (!gnu_ext)