From: Nicolai Stange <nicstange@xxxxxxxxx> The official constraints on constant expressions [6.6] are insanely strict in that they do not allow some constructs commonly used in the wild. Relax them by treating - address constants cast to different pointer type as address constants again, - address constants cast to arithmetic type as arithmetic constant expressions - conditional expressions whose true and false branches both yield address constants as address constants, - and conditional expressions whose condition is an address constant as an constant expression to the extent their true and false branches allow. Signed-off-by: Nicolai Stange <nicstange@xxxxxxxxx> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx> --- evaluate.c | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-) diff --git a/evaluate.c b/evaluate.c index be72b22b9..022c7b5f3 100644 --- a/evaluate.c +++ b/evaluate.c @@ -1136,10 +1136,20 @@ static struct symbol *evaluate_conditional_expression(struct expression *expr) expr->flags = (expr->conditional->flags & (*true)->flags & expr->cond_false->flags & ~CEF_CONST_MASK); /* + * A conditional operator yields a particular constant + * expression type only if all of its three subexpressions are + * of that type [6.6(6), 6.6(8)]. + * As an extension, relax this restriction by allowing any + * constant expression type for the condition expression. + * * A conditional operator never yields an address constant * [6.6(9)]. + * However, as an extension, if the condition is any constant + * expression, and the true and false expressions are both + * address constants, mark the result as an address constant. */ - expr->flags &= ~CEF_ADDR; + if (expr->conditional->flags & (CEF_ACE | CEF_ADDR)) + expr->flags = (*true)->flags & expr->cond_false->flags & ~CEF_CONST_MASK; lclass = classify_type(ltype, <ype); rclass = classify_type(rtype, &rtype); @@ -2762,6 +2772,14 @@ static int cast_flags(struct expression *expr, struct expression *old) * constants [6.6(9)]. */ flags &= ~CEF_ADDR; + + /* + * As an extension, treat address constants cast to + * integer type as an arithmetic constant. + */ + if (old->flags & CEF_ADDR) + flags = CEF_ACE; + /* * Cast to float type -> not an integer constant * expression [6.6(6)]. @@ -2778,8 +2796,15 @@ static int cast_flags(struct expression *expr, struct expression *old) /* * Casts of integer literals to pointer type yield * address constants [6.6(9)]. + * + * As an extension, treat address constants cast to a + * different pointer type as address constants again. + * + * As another extension, treat integer constant + * expressions (in contrast to literals) cast to + * pointer type as address constants. */ - if (old->flags & CEF_INT) + if (old->flags & (CEF_ICE | CEF_ADDR)) flags = CEF_ADDR; } -- 2.12.0 -- To unsubscribe from this list: send the line "unsubscribe linux-sparse" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
