diff options
| author | Nicolai Stange <nicstange@gmail.com> | 2016-02-01 03:31:47 +0100 |
|---|---|---|
| committer | Luc Van Oostenryck <luc.vanoostenryck@gmail.com> | 2017-03-31 02:14:10 +0200 |
| commit | 1b62f0f61f38d8f6881c6ee14da2f9137bd68fc7 (patch) | |
| tree | 2f2596bbdfd95512d57ae0da2dc3c7acc51f9f73 | |
| parent | 2919ca4cd57c4633bccf26b01cb2b8c00271446d (diff) | |
| download | sparse-dev-1b62f0f61f38d8f6881c6ee14da2f9137bd68fc7.tar.gz | |
constexpr: examine constness of casts at evaluation only
Move the whole calculation of cast expressions' constness flags to the
evaluation phase such that expressions like
(int)__builtin_choose_expr(0, 0, 0)
can now be recognized as qualifying as integer constant expressions.
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
| -rw-r--r-- | evaluate.c | 37 | ||||
| -rw-r--r-- | expression.c | 19 | ||||
| -rw-r--r-- | expression.h | 7 | ||||
| -rw-r--r-- | validation/constexpr-cast.c | 25 |
4 files changed, 61 insertions, 27 deletions
@@ -271,6 +271,7 @@ warn_for_different_enum_types (struct position pos, } } +static int cast_flags(struct expression *expr, struct expression *target); static struct symbol *cast_to_bool(struct expression *expr); /* @@ -323,10 +324,10 @@ static struct expression * cast_to(struct expression *old, struct symbol *type) } expr = alloc_expression(old->pos, EXPR_IMPLIED_CAST); - expr->flags = old->flags; expr->ctype = type; expr->cast_type = type; expr->cast_expression = old; + expr->flags = cast_flags(expr, old); if (is_bool_type(type)) cast_to_bool(expr); @@ -2720,6 +2721,32 @@ static struct symbol *cast_to_bool(struct expression *expr) return expr->ctype; } +static int cast_flags(struct expression *expr, struct expression *old) +{ + struct symbol *t; + int class; + int flags = CEF_NONE; + + class = classify_type(expr->ctype, &t); + if (class & TYPE_NUM) { + flags = old->flags & ~CEF_CONST_MASK; + /* + * Cast to float type -> not an integer constant + * expression [6.6(6)]. + */ + if (class & TYPE_FLOAT) + flags &= ~CEF_CLR_ICE; + /* + * Casts of float literals to integer type results in + * a constant integer expression [6.6(6)]. + */ + else if (old->flags & CEF_FLOAT) + flags = CEF_SET_ICE; + } + + return flags; +} + static struct symbol *evaluate_cast(struct expression *expr) { struct expression *target = expr->cast_expression; @@ -2768,13 +2795,7 @@ static struct symbol *evaluate_cast(struct expression *expr) class1 = classify_type(ctype, &t1); - /* cast to non-integer type -> not an integer constant expression */ - if (!is_int(class1)) - expr->flags = CEF_NONE; - /* if argument turns out to be not an integer constant expression *and* - it was not a floating literal to start with -> too bad */ - else if (expr->flags & CEF_ICE && !(target->flags & CEF_ICE)) - expr->flags = CEF_NONE; + expr->flags = cast_flags(expr, target); /* * You can always throw a value away by casting to diff --git a/expression.c b/expression.c index 4189e5f3..3262cf22 100644 --- a/expression.c +++ b/expression.c @@ -722,25 +722,6 @@ static struct token *cast_expression(struct token *token, struct expression **tr if (!v) return token; cast->cast_expression = v; - - cast->flags = v->flags & ~CEF_CONST_MASK; - /* - * Up to now, we missed the (int).0 case here - * which should really get a - * CEF_ICE marker. Also, - * conversion to non-numeric types is not - * properly reflected up to this point. - * However, we do not know until evaluation. - * For the moment, in order to preserve - * semantics, speculatively set - * CEF_ICE if - * CEF_FLOAT is - * set. evaluate_cast() will unset - * inappropriate flags again after examining - * type information. - */ - if (v->flags & CEF_FLOAT) - cast->flags |= CEF_SET_ICE; return token; } } diff --git a/expression.h b/expression.h index ec94ff4a..c084783c 100644 --- a/expression.h +++ b/expression.h @@ -120,6 +120,13 @@ enum constexpr_flag { CEF_CONST_MASK = (CEF_INT | CEF_FLOAT | CEF_CHAR), }; +/* + * not an integer constant expression => neither of integer, + * enumeration and character constant + */ +#define CEF_CLR_ICE \ + (CEF_ICE | CEF_INT | CEF_ENUM | CEF_CHAR) + enum { Taint_comma = 1, }; /* for expr->taint */ diff --git a/validation/constexpr-cast.c b/validation/constexpr-cast.c new file mode 100644 index 00000000..27069614 --- /dev/null +++ b/validation/constexpr-cast.c @@ -0,0 +1,25 @@ +static int a[] = { + [(int)0] = 0, // OK + [(int)(int)0] = 0, // OK + [(int)0.] = 0, // OK + [(int)(int)0.] = 0, // OK + [(int)__builtin_choose_expr(0, 0, 0)] = 0, // OK + [(int)__builtin_choose_expr(0, 0, 0.)] = 0, // OK + + [(int)(float)0] = 0, // KO + [(int)(float)0.] = 0, // KO + + [(int)(void*)0] = 0, // KO + [(int)(void*)0.] = 0, // KO + +}; +/* + * check-name: Expression constness propagation in casts + * + * check-error-start +constexpr-cast.c:9:11: error: bad integer constant expression +constexpr-cast.c:10:11: error: bad integer constant expression +constexpr-cast.c:12:11: error: bad integer constant expression +constexpr-cast.c:13:11: error: bad integer constant expression + * check-error-end + */ |