RE: [PATCH 08/10] drm/i915/reg: replace __is_const_expr() by is_const_true() or is_const()

[David Laight <David.Laight@ACULAB.COM>]

From: Vincent Mailhol
> Sent: 02 December 2024 17:34
> 
> Most of the use of __is_const_expr() in i915_reg_defs.h are just to
> test whether an expression is known to be true. Because those checks
> are all done in a BUILD_BUG_ON_ZERO(), replace those with
> is_const_true().

Another place that could use statically_true() and BUILD_BUG_ON_MSG().

	David

> 
> Replace the few other occurrences of __is_const_expr() with is_const().
> 
> Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
> ---
>  drivers/gpu/drm/i915/i915_reg_defs.h | 47 +++++++++++++++++-------------------
>  1 file changed, 22 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg_defs.h b/drivers/gpu/drm/i915/i915_reg_defs.h
> index e251bcc0c89f5710125bc70f07851b2cb978c89c..6ed2fb9cf506a3bd6467ba30f9d0e863d62762f3 100644
> --- a/drivers/gpu/drm/i915/i915_reg_defs.h
> +++ b/drivers/gpu/drm/i915/i915_reg_defs.h
> @@ -19,8 +19,7 @@
>   */
>  #define REG_BIT(__n)							\
>  	((u32)(BIT(__n) +						\
> -	       BUILD_BUG_ON_ZERO(__is_constexpr(__n) &&		\
> -				 ((__n) < 0 || (__n) > 31))))
> +	       BUILD_BUG_ON_ZERO(is_const_true((__n) < 0 || (__n) > 31))))
> 
>  /**
>   * REG_BIT8() - Prepare a u8 bit value
> @@ -32,8 +31,7 @@
>   */
>  #define REG_BIT8(__n)                                                   \
>  	((u8)(BIT(__n) +                                                \
> -	       BUILD_BUG_ON_ZERO(__is_constexpr(__n) &&         \
> -				 ((__n) < 0 || (__n) > 7))))
> +	      BUILD_BUG_ON_ZERO(is_const_true((__n) < 0 || (__n) > 7))))
> 
>  /**
>   * REG_GENMASK() - Prepare a continuous u32 bitmask
> @@ -46,9 +44,9 @@
>   */
>  #define REG_GENMASK(__high, __low)					\
>  	((u32)(GENMASK(__high, __low) +					\
> -	       BUILD_BUG_ON_ZERO(__is_constexpr(__high) &&	\
> -				 __is_constexpr(__low) &&		\
> -				 ((__low) < 0 || (__high) > 31 || (__low) > (__high)))))
> +	       BUILD_BUG_ON_ZERO(is_const_true((__low) < 0 ||		\
> +					       (__high) > 31 ||		\
> +					       (__low) > (__high)))))
> 
>  /**
>   * REG_GENMASK64() - Prepare a continuous u64 bitmask
> @@ -61,9 +59,9 @@
>   */
>  #define REG_GENMASK64(__high, __low)					\
>  	((u64)(GENMASK_ULL(__high, __low) +				\
> -	       BUILD_BUG_ON_ZERO(__is_constexpr(__high) &&		\
> -				 __is_constexpr(__low) &&		\
> -				 ((__low) < 0 || (__high) > 63 || (__low) > (__high)))))
> +	       BUILD_BUG_ON_ZERO(is_const_true((__low) < 0 ||		\
> +					       (__high) > 63 ||		\
> +					       (__low) > (__high)))))
> 
>  /**
>   * REG_GENMASK8() - Prepare a continuous u8 bitmask
> @@ -76,9 +74,9 @@
>   */
>  #define REG_GENMASK8(__high, __low)                                     \
>  	((u8)(GENMASK(__high, __low) +                                  \
> -	       BUILD_BUG_ON_ZERO(__is_constexpr(__high) &&      \
> -				 __is_constexpr(__low) &&               \
> -				 ((__low) < 0 || (__high) > 7 || (__low) > (__high)))))
> +	      BUILD_BUG_ON_ZERO(is_const_true((__low) < 0 ||            \
> +					      (__high) > 7 ||           \
> +					      (__low) > (__high)))))
> 
>  /*
>   * Local integer constant expression version of is_power_of_2().
> @@ -97,10 +95,10 @@
>   */
>  #define REG_FIELD_PREP(__mask, __val)						\
>  	((u32)((((typeof(__mask))(__val) << __bf_shf(__mask)) & (__mask)) +	\
> -	       BUILD_BUG_ON_ZERO(!__is_constexpr(__mask)) +		\
> +	       BUILD_BUG_ON_ZERO(!is_const(__mask)) +				\
>  	       BUILD_BUG_ON_ZERO((__mask) == 0 || (__mask) > U32_MAX) +		\
>  	       BUILD_BUG_ON_ZERO(!IS_POWER_OF_2((__mask) + (1ULL << __bf_shf(__mask)))) + \
> -	       BUILD_BUG_ON_ZERO(__builtin_choose_expr(__is_constexpr(__val), (~((__mask) >>
> __bf_shf(__mask)) & (__val)), 0))))
> +	       BUILD_BUG_ON_ZERO(is_const_true(~((__mask) >> __bf_shf(__mask)) & (__val)))))
> 
>  /**
>   * REG_FIELD_PREP8() - Prepare a u8 bitfield value
> @@ -114,10 +112,10 @@
>   */
>  #define REG_FIELD_PREP8(__mask, __val)                                          \
>  	((u8)((((typeof(__mask))(__val) << __bf_shf(__mask)) & (__mask)) +      \
> -	       BUILD_BUG_ON_ZERO(!__is_constexpr(__mask)) +             \
> +	       BUILD_BUG_ON_ZERO(!is_const(__mask)) +                           \
>  	       BUILD_BUG_ON_ZERO((__mask) == 0 || (__mask) > U8_MAX) +          \
>  	       BUILD_BUG_ON_ZERO(!IS_POWER_OF_2((__mask) + (1ULL << __bf_shf(__mask)))) + \
> -	       BUILD_BUG_ON_ZERO(__builtin_choose_expr(__is_constexpr(__val), (~((__mask) >>
> __bf_shf(__mask)) & (__val)), 0))))
> +	       BUILD_BUG_ON_ZERO(is_const_true(~((__mask) >> __bf_shf(__mask)) & (__val)))))
> 
>  /**
>   * REG_FIELD_GET() - Extract a u32 bitfield value
> @@ -154,8 +152,7 @@
>   */
>  #define REG_BIT16(__n)                                                   \
>  	((u16)(BIT(__n) +                                                \
> -	       BUILD_BUG_ON_ZERO(__is_constexpr(__n) &&         \
> -				 ((__n) < 0 || (__n) > 15))))
> +	       BUILD_BUG_ON_ZERO(is_const_true((__n) < 0 || (__n) > 15))))
> 
>  /**
>   * REG_GENMASK16() - Prepare a continuous u8 bitmask
> @@ -169,9 +166,9 @@
>   */
>  #define REG_GENMASK16(__high, __low)                                     \
>  	((u16)(GENMASK(__high, __low) +                                  \
> -	       BUILD_BUG_ON_ZERO(__is_constexpr(__high) &&      \
> -				 __is_constexpr(__low) &&               \
> -				 ((__low) < 0 || (__high) > 15 || (__low) > (__high)))))
> +	       BUILD_BUG_ON_ZERO(is_const_true((__low) < 0 ||            \
> +					       (__high) > 15 ||          \
> +					       (__low) > (__high)))))
> 
>  /**
>   * REG_FIELD_PREP16() - Prepare a u16 bitfield value
> @@ -186,10 +183,10 @@
>   */
>  #define REG_FIELD_PREP16(__mask, __val)                                          \
>  	((u16)((((typeof(__mask))(__val) << __bf_shf(__mask)) & (__mask)) +      \
> -	       BUILD_BUG_ON_ZERO(!__is_constexpr(__mask)) +             \
> +	       BUILD_BUG_ON_ZERO(!is_const(__mask)) +                            \
>  	       BUILD_BUG_ON_ZERO((__mask) == 0 || (__mask) > U16_MAX) +          \
>  	       BUILD_BUG_ON_ZERO(!IS_POWER_OF_2((__mask) + (1ULL << __bf_shf(__mask)))) + \
> -	       BUILD_BUG_ON_ZERO(__builtin_choose_expr(__is_constexpr(__val), (~((__mask) >>
> __bf_shf(__mask)) & (__val)), 0))))
> +	       BUILD_BUG_ON_ZERO(is_const_true(~((__mask) >> __bf_shf(__mask)) & (__val)))))
> 
>  #define __MASKED_FIELD(mask, value) ((mask) << 16 | (value))
>  #define _MASKED_FIELD(mask, value) ({					   \
> @@ -237,7 +234,7 @@
>   *	...
>   */
>  #define _PICK_EVEN_2RANGES(__index, __c_index, __a, __b, __c, __d)		\
> -	(BUILD_BUG_ON_ZERO(!__is_constexpr(__c_index)) +			\
> +	(BUILD_BUG_ON_ZERO(!is_const(__c_index)) +				\
>  	 ((__index) < (__c_index) ? _PICK_EVEN(__index, __a, __b) :		\
>  				   _PICK_EVEN((__index) - (__c_index), __c, __d)))
> 
> 
> --
> 2.45.2
> 
> 

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