On 10/2/19 5:14 PM, Luc Van Oostenryck wrote:
> GCC expands at compile time builtins like __builtin_ffs()
> when their argument is constant.
>
> A driver in the kernel uses such a builtin in a case statement,
> causing sparse to report:
> error: Expected constant expression in case statement
>
> So, let sparse also expand such builtins, somehow like it was
> done for bswap16/32/64 but now for ffs/ffsl/ffsll, clz, ctz,
> clrsb, popcount & parity.
>
> Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
Tested-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Thanks.
> ---
> builtin.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 56 insertions(+)
>
> diff --git a/builtin.c b/builtin.c
> index 221c98991..3e2d77e75 100644
> --- a/builtin.c
> +++ b/builtin.c
> @@ -230,6 +230,44 @@ static struct symbol_op bswap_op = {
> };
>
>
> +#define EXPAND_FINDBIT(name) \
> +static int expand_##name(struct expression *expr, int cost) \
> +{ \
> + struct expression *arg; \
> + long long val; \
> + \
> + if (cost) \
> + return cost; \
> + \
> + arg = first_expression(expr->args); \
> + val = get_expression_value_silent(arg); \
> + switch (expr->ctype->bit_size) { \
> + case sizeof(int) * 8: \
> + val = __builtin_##name(val); break; \
> + case sizeof(long long) * 8: \
> + val = __builtin_##name##ll(val); break; \
> + default: /* impossible error */ \
> + return SIDE_EFFECTS; \
> + } \
> + \
> + expr->value = val; \
> + expr->type = EXPR_VALUE; \
> + expr->taint = 0; \
> + return 0; \
> +} \
> + \
> +static struct symbol_op name##_op = { \
> + .evaluate = evaluate_pure_unop, \
> + .expand = expand_##name, \
> +}
> +
> +EXPAND_FINDBIT(clz);
> +EXPAND_FINDBIT(ctz);
> +EXPAND_FINDBIT(clrsb);
> +EXPAND_FINDBIT(ffs);
> +EXPAND_FINDBIT(parity);
> +EXPAND_FINDBIT(popcount);
> +
> static int evaluate_fp_unop(struct expression *expr)
> {
> struct expression *arg;
> @@ -334,11 +372,29 @@ static struct sym_init {
> { "__builtin_bswap16", &builtin_fn_type, MOD_TOPLEVEL, &bswap_op },
> { "__builtin_bswap32", &builtin_fn_type, MOD_TOPLEVEL, &bswap_op },
> { "__builtin_bswap64", &builtin_fn_type, MOD_TOPLEVEL, &bswap_op },
> + { "__builtin_clrsb", &builtin_fn_type, MOD_TOPLEVEL, &clrsb_op },
> + { "__builtin_clrsbl", &builtin_fn_type, MOD_TOPLEVEL, &clrsb_op },
> + { "__builtin_clrsbll", &builtin_fn_type, MOD_TOPLEVEL, &clrsb_op },
> + { "__builtin_clz", &builtin_fn_type, MOD_TOPLEVEL, &clz_op },
> + { "__builtin_clzl", &builtin_fn_type, MOD_TOPLEVEL, &clz_op },
> + { "__builtin_clzll", &builtin_fn_type, MOD_TOPLEVEL, &clz_op },
> + { "__builtin_ctz", &builtin_fn_type, MOD_TOPLEVEL, &ctz_op },
> + { "__builtin_ctzl", &builtin_fn_type, MOD_TOPLEVEL, &ctz_op },
> + { "__builtin_ctzll", &builtin_fn_type, MOD_TOPLEVEL, &ctz_op },
> + { "__builtin_ffs", &builtin_fn_type, MOD_TOPLEVEL, &ffs_op },
> + { "__builtin_ffsl", &builtin_fn_type, MOD_TOPLEVEL, &ffs_op },
> + { "__builtin_ffsll", &builtin_fn_type, MOD_TOPLEVEL, &ffs_op },
> { "__builtin_isfinite", &builtin_fn_type, MOD_TOPLEVEL, &fp_unop_op },
> { "__builtin_isinf", &builtin_fn_type, MOD_TOPLEVEL, &fp_unop_op },
> { "__builtin_isinf_sign", &builtin_fn_type, MOD_TOPLEVEL, &fp_unop_op },
> { "__builtin_isnan", &builtin_fn_type, MOD_TOPLEVEL, &fp_unop_op },
> { "__builtin_isnormal", &builtin_fn_type, MOD_TOPLEVEL, &fp_unop_op },
> + { "__builtin_parity", &builtin_fn_type, MOD_TOPLEVEL, &parity_op },
> + { "__builtin_parityl", &builtin_fn_type, MOD_TOPLEVEL, &parity_op },
> + { "__builtin_parityll", &builtin_fn_type, MOD_TOPLEVEL, &parity_op },
> + { "__builtin_popcount", &builtin_fn_type, MOD_TOPLEVEL, &popcount_op },
> + { "__builtin_popcountl", &builtin_fn_type, MOD_TOPLEVEL, &popcount_op },
> + { "__builtin_popcountll", &builtin_fn_type, MOD_TOPLEVEL, &popcount_op },
> { "__builtin_signbit", &builtin_fn_type, MOD_TOPLEVEL, &fp_unop_op },
> { "__builtin_add_overflow", &builtin_fn_type, MOD_TOPLEVEL, &overflow_op },
> { "__builtin_sub_overflow", &builtin_fn_type, MOD_TOPLEVEL, &overflow_op },
>
--
~Randy
