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g_typeadjust: Use CF_CHAR for char args

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If lhs and rhs are either both signed char or both unsigned char,
return flags for that type instead of (unsigned) int.  The flags
are used only for codegen.  Currently, this does nothing, since
codegen treats chars as ints unless CF_FORCECHAR is set, but it
allows more efficient char x char -> int codegen to be added in
the future.
This commit is contained in:
Jesse Rosenstock 2020-11-13 09:01:26 +01:00 • committed by greg-king5
parent b2c1a77bb3
commit dfd047ce6a
1 changed files with 13 additions and 10 deletions
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23
src/cc65/codegen.c
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@ -1433,17 +1433,20 @@ unsigned g_typeadjust (unsigned lhs, unsigned rhs)
/* Note that this logic is largely duplicated by ArithmeticConvert. */
/* Before we apply the integral promotions, we check if both types are unsigned char.
** If so, we return unsigned int, rather than int, which would be returned by the standard
** rules. This is only a performance optimization and does not affect correctness, as
** the flags are only used for code generation, and not to determine types of other
** expressions containing this one. All unsigned char bit-patterns are valid as both int
** and unsigned int and represent the same value, so either signed or unsigned int operations
** can be used. This special case part is not duplicated by ArithmeticConvert.
/* Before we apply the integral promotions, we check if both types are the same character type.
** If so, we return that type, rather than int, which would be returned by the standard
** rules. This is only a performance optimization allowing the use of unsigned and/or char
** operations; it does not affect correctness, as the flags are only used for code generation,
** and not to determine types of other expressions containing this one. For codgen, CF_CHAR
** means the operands are char and the result is int (unless CF_FORCECHAR is also set, in
** which case the result is char). This special case part is not duplicated by
** ArithmeticConvert.
*/
if ((lhs & CF_TYPEMASK) == CF_CHAR && (lhs & CF_UNSIGNED) &&
(rhs & CF_TYPEMASK) == CF_CHAR && (rhs & CF_UNSIGNED)) {
return const_flag | CF_UNSIGNED | CF_INT;
if ((lhs & CF_TYPEMASK) == CF_CHAR && (rhs & CF_TYPEMASK) == CF_CHAR &&
(lhs & CF_UNSIGNED) == (rhs & CF_UNSIGNED)) {
/* Signedness flags are the same, so just use one of them. */
const unsigned unsigned_flag = lhs & CF_UNSIGNED;
return const_flag | unsigned_flag | CF_CHAR;
}
/* Apply integral promotions for types char/short. */