Rework __ctz and __clz macros

Rework __ctz and __clz macros

[Norbert Lange]

Those are commonly used in Frameworks (eg libc++),
This series renamed __ctz and replaces the __clz
with something simpler that could be evaluated in constant
contexts aswell (and doesnt use GCC statement expressions).

Ideally though these would be moved out of the public header
into something private for the xenomai build.

[PATCH 1/2] Rename __ctz to xenomai_count_trailing_zeros

[Norbert Lange]

Because of conflicts with libc++ (v1/bit include file).
Simplify the macro as there shouldnt be any bad cornercases

Signed-off-by: Norbert Lange <norbert.lange@andritz.com>
---
 include/boilerplate/compiler.h    | 23 +++++------------------
 lib/boilerplate/heapmem.c         |  2 +-
 lib/copperplate/heapobj-pshared.c |  2 +-
 3 files changed, 7 insertions(+), 20 deletions(-)

diff --git a/include/boilerplate/compiler.h b/include/boilerplate/compiler.h
index 0fcc17be1..e25ab5d2c 100644
--- a/include/boilerplate/compiler.h
+++ b/include/boilerplate/compiler.h
@@ -74,24 +74,11 @@ extern "C" {
 	
 void __invalid_operand_size(void);
 
-#define __ctz(__v)							\
-	({								\
-		int __ret;						\
-		if (!__v)						\
-			__ret = sizeof(__v) * 8;			\
-		else							\
-			switch (sizeof(__v)) {				\
-			case sizeof(int):				\
-				__ret = __builtin_ctz((unsigned int)__v); \
-				break;					\
-			case sizeof(long long):				\
-				__ret = __builtin_ctzll(__v);		\
-				break;					\
-			default:					\
-				__invalid_operand_size();		\
-			}						\
-		__ret;							\
-	})
+#define xenomai_count_trailing_zeros(x)					\
+	( (x) == 0 ? (int)(sizeof(x) * __CHAR_BIT__)			\
+	: sizeof(x) <= sizeof(unsigned) ? __builtin_ctz(x)		\
+	: sizeof(x) <= sizeof(unsigned long) ? __builtin_ctzl(x)	\
+	: __builtin_ctzll(x))
 
 #define xenomai_count_leading_zeros(__v)				\
 	({								\
diff --git a/lib/boilerplate/heapmem.c b/lib/boilerplate/heapmem.c
index 8728e0d15..e6369c715 100644
--- a/lib/boilerplate/heapmem.c
+++ b/lib/boilerplate/heapmem.c
@@ -476,7 +476,7 @@ void *heapmem_alloc(struct heap_memory *heap, size_t size)
 			bmask = ext->pagemap[pg].map;
 			if (bmask == -1U)
 				break;
-			b = __ctz(~bmask);
+			b = xenomai_count_trailing_zeros(~bmask);
 
 			/*
 			 * Got one block from the heading per-bucket
diff --git a/lib/copperplate/heapobj-pshared.c b/lib/copperplate/heapobj-pshared.c
index 5310d9092..d6cc51ae9 100644
--- a/lib/copperplate/heapobj-pshared.c
+++ b/lib/copperplate/heapobj-pshared.c
@@ -529,7 +529,7 @@ static void *sheapmem_alloc(struct shared_heap_memory *heap, size_t size)
 			bmask = ext->pagemap[pg].map;
 			if (bmask == -1U)
 				break;
-			b = __ctz(~bmask);
+			b = xenomai_count_trailing_zeros(~bmask);
 
 			/*
 			 * Got one block from the heading per-bucket
-- 
2.20.1

[PATCH 2/2] Simplify xenomai_count_leading_zeros

[Norbert Lange]

Covers now all standard integer types,
no need for corner cases.

Signed-off-by: Norbert Lange <norbert.lange@andritz.com>
---
 include/boilerplate/compiler.h | 27 +++++++--------------------
 1 file changed, 7 insertions(+), 20 deletions(-)

diff --git a/include/boilerplate/compiler.h b/include/boilerplate/compiler.h
index e25ab5d2c..828755cc1 100644
--- a/include/boilerplate/compiler.h
+++ b/include/boilerplate/compiler.h
@@ -72,32 +72,19 @@
 extern "C" {
 #endif
 
-void __invalid_operand_size(void);
-
 #define xenomai_count_trailing_zeros(x)					\
 	( (x) == 0 ? (int)(sizeof(x) * __CHAR_BIT__)			\
 	: sizeof(x) <= sizeof(unsigned) ? __builtin_ctz(x)		\
 	: sizeof(x) <= sizeof(unsigned long) ? __builtin_ctzl(x)	\
 	: __builtin_ctzll(x))
 
-#define xenomai_count_leading_zeros(__v)				\
-	({								\
-		int __ret;						\
-		if (!__v)						\
-			__ret = sizeof(__v) * 8;			\
-		else							\
-			switch (sizeof(__v)) {				\
-			case sizeof(int):				\
-				__ret = __builtin_clz((unsigned int)__v); \
-				break;					\
-			case sizeof(long long):				\
-				__ret = __builtin_clzll(__v);		\
-				break;					\
-			default:					\
-				__invalid_operand_size();		\
-			}						\
-		__ret;							\
-	})
+#define xenomai_count_leading_zeros(x)					\
+	(int)( (x) == 0 ? sizeof(x) * __CHAR_BIT__			\
+	: ( sizeof(x) <= sizeof(unsigned) ?				\
+			__builtin_clz(x) + sizeof(unsigned) - sizeof(x)	\
+		: sizeof(x) <= sizeof(unsigned long) ?			\
+			__builtin_clzl(x) + sizeof(unsigned long) - sizeof(x) \
+		: __builtin_clzll(x) + sizeof(unsigned long long) - sizeof(x)))
 
 #ifdef __cplusplus
 }
-- 
2.20.1

Re: [PATCH 2/2] Simplify xenomai_count_leading_zeros

[Jan Kiszka]

On 13.03.19 18:16, Norbert Lange via Xenomai wrote:
> Covers now all standard integer types,
> no need for corner cases.
>
> Signed-off-by: Norbert Lange <norbert.lange@andritz.com>
> ---
>   include/boilerplate/compiler.h | 27 +++++++--------------------
>   1 file changed, 7 insertions(+), 20 deletions(-)
>
> diff --git a/include/boilerplate/compiler.h b/include/boilerplate/compiler.h
> index e25ab5d2c..828755cc1 100644
> --- a/include/boilerplate/compiler.h
> +++ b/include/boilerplate/compiler.h
> @@ -72,32 +72,19 @@
>   extern "C" {
>   #endif
>
> -void __invalid_operand_size(void);
> -
>   #define xenomai_count_trailing_zeros(x)					\
>   	( (x) == 0 ? (int)(sizeof(x) * __CHAR_BIT__)			\
>   	: sizeof(x) <= sizeof(unsigned) ? __builtin_ctz(x)		\
>   	: sizeof(x) <= sizeof(unsigned long) ? __builtin_ctzl(x)	\
>   	: __builtin_ctzll(x))
>
> -#define xenomai_count_leading_zeros(__v)				\
> -	({								\
> -		int __ret;						\
> -		if (!__v)						\
> -			__ret = sizeof(__v) * 8;			\
> -		else							\
> -			switch (sizeof(__v)) {				\
> -			case sizeof(int):				\
> -				__ret = __builtin_clz((unsigned int)__v); \
> -				break;					\
> -			case sizeof(long long):				\
> -				__ret = __builtin_clzll(__v);		\
> -				break;					\
> -			default:					\
> -				__invalid_operand_size();		\
> -			}						\
> -		__ret;							\
> -	})
> +#define xenomai_count_leading_zeros(x)					\
> +	(int)( (x) == 0 ? sizeof(x) * __CHAR_BIT__			\
> +	: ( sizeof(x) <= sizeof(unsigned) ?				\
> +			__builtin_clz(x) + sizeof(unsigned) - sizeof(x)	\
> +		: sizeof(x) <= sizeof(unsigned long) ?			\
> +			__builtin_clzl(x) + sizeof(unsigned long) - sizeof(x) \
> +		: __builtin_clzll(x) + sizeof(unsigned long long) - sizeof(x)))
>
>   #ifdef __cplusplus
>   }
>

Looks functionally ok, but why is it differently structured than patch 1? Can we
use that formatting for this one as well?

Jan