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CLEANUP: improvements to the alignment macros

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- It is now possible to use the THREAD_ALIGN and THREAD_ALIGNED macros
  without a parameter. In this case, we automatically align on the cache
  line size.
- The cache line size is set to 64 by default to match the current code,
  but it can be overridden on the command line.
- This required moving the DEFVAL/DEFNULL/DEFZERO macros to compiler.h
  instead of tools-t.h, to avoid namespace pollution if we included
  tools-t.h from compiler.h.
This commit is contained in:
Maxime Henrion
2025-12-09 10:51:33 -05:00
committed by Olivier Houchard
parent 420b42df1c
commit 74719dc457
2 changed files with 30 additions and 24 deletions
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37
include/haproxy/compiler.h
View File

@@ -31,6 +31,23 @@
#include <stdlib.h>
#endif
/* DEFVAL() returns either the second argument as-is, or <def> if absent. This
* is for use in macros arguments.
*/
#define DEFVAL(_def,...) _FIRST_ARG(NULL, ##__VA_ARGS__, (_def))
/* DEFNULL() returns either the argument as-is, or NULL if absent. This is for
* use in macros arguments.
*/
#define DEFNULL(...) DEFVAL(NULL, ##__VA_ARGS__)
/* DEFZERO() returns either the argument as-is, or 0 if absent. This is for
* use in macros arguments.
*/
#define DEFZERO(...) DEFVAL(0, ##__VA_ARGS__)
#define _FIRST_ARG(a, b, ...) b
/*
* Gcc before 3.0 needs [0] to declare a variable-size array
*/
@@ -415,6 +432,13 @@
* for multi_threading, see THREAD_PAD() below. *
\*****************************************************************************/
/* Cache line size for alignment purposes. This value is incorrect for some
* Apple CPUs which have 128 bytes cache lines.
*/
#ifndef CACHELINE_SIZE
#define CACHELINE_SIZE 64
#endif
/* sets alignment for current field or variable */
#ifndef ALIGNED
#define ALIGNED(x) __attribute__((aligned(x)))
@@ -438,12 +462,12 @@
#endif
#endif
/* sets alignment for current field or variable only when threads are enabled.
* Typically used to respect cache line alignment to avoid false sharing.
/* Sets alignment for current field or variable only when threads are enabled.
* When no parameters are provided, we align to the cache line size.
*/
#ifndef THREAD_ALIGNED
#ifdef USE_THREAD
#define THREAD_ALIGNED(x) __attribute__((aligned(x)))
#define THREAD_ALIGNED(...) ALIGNED(DEFVAL(CACHELINE_SIZE, ##__VA_ARGS__))
#else
#define THREAD_ALIGNED(x)
#endif
@@ -476,13 +500,12 @@
#endif
#endif
/* add an optional alignment for next fields in a structure, only when threads
* are enabled. Typically used to respect cache line alignment to avoid false
* sharing.
/* Add an optional alignment for next fields in a structure, only when threads
* are enabled. When no parameters are provided, we align to the cache line size.
*/
#ifndef THREAD_ALIGN
#ifdef USE_THREAD
#define THREAD_ALIGN(x) union { } ALIGNED(x)
#define THREAD_ALIGN(...) union { } ALIGNED(DEFVAL(CACHELINE_SIZE, ##__VA_ARGS__))
#else
#define THREAD_ALIGN(x)
#endif

17
include/haproxy/tools-t.h
View File

@@ -47,23 +47,6 @@
/* return the largest possible integer of type <ret>, with all bits set */
#define MAX_RANGE(ret) (~(typeof(ret))0)
/* DEFVAL() returns either the second argument as-is, or <def> if absent. This
* is for use in macros arguments.
*/
#define DEFVAL(_def,...) _FIRST_ARG(NULL, ##__VA_ARGS__, (_def))
/* DEFNULL() returns either the argument as-is, or NULL if absent. This is for
* use in macros arguments.
*/
#define DEFNULL(...) DEFVAL(NULL, ##__VA_ARGS__)
/* DEFZERO() returns either the argument as-is, or 0 if absent. This is for
* use in macros arguments.
*/
#define DEFZERO(...) DEFVAL(0, ##__VA_ARGS__)
#define _FIRST_ARG(a, b, ...) b
/* options flags for parse_line() */
#define PARSE_OPT_SHARP 0x00000001 // '#' ends the line
#define PARSE_OPT_BKSLASH 0x00000002 // '\' escapes chars