From: "Martin Liška" <mliska@suse.cz>
To: Jakub Jelinek <jakub@redhat.com>
Cc: "H.J. Lu" <hjl.tools@gmail.com>,
Richard Biener <richard.guenther@gmail.com>,
GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] Check endianess detection.
Date: Tue, 24 Mar 2020 11:32:32 +0100 [thread overview]
Message-ID: <b5a25c37-d29c-b636-04ef-eba959ad495b@suse.cz> (raw)
In-Reply-To: <20200324091805.GQ2156@tucnak>
[-- Attachment #1: Type: text/plain, Size: 2454 bytes --]
On 3/24/20 10:18 AM, Jakub Jelinek wrote:
> Hi!
>
> So, assuming I'm on glibc with GCC 4.5 on powerpc64-linux.
>
> On Tue, Mar 24, 2020 at 09:49:42AM +0100, Martin Liška wrote:
>> +/* Detect endianess based on __BYTE_ORDER__ macro. */
>> +#if defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && \
>> + defined(__ORDER_LITTLE_ENDIAN__) && defined(__ORDER_PDP_ENDIAN__)
>> +#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
>> +#define PLUGIN_LITTLE_ENDIAN 1
>> +#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
>> +#define PLUGIN_BIG_ENDIAN 1
>> +#elif __BYTE_ORDER__ == __ORDER_PDP_ENDIAN__
>> +#define PLUGIN_PDP_ENDIAN 1
>> +#endif
>> +#else
>> +/* Older GCC releases (<4.6.0) can make detection from glibc macros. */
>> +#if defined(__GLIBC__) || defined(__GNU_LIBRARY__) || defined(__ANDROID__)
>> +#include <endian.h>
>> +#if __BYTE_ORDER == __LITTLE_ENDIAN
>> +#define PLUGIN_LITTLE_ENDIAN 1
>> +#elif __BYTE_ORDER == __BIG_ENDIAN
>> +#define PLUGIN_BIG_ENDIAN 1
>> +#endif
>
> This will definePLUGIN_BIG_ENDIAN.
>
>> +#endif
>> +/* Include all necessary header files based on target. */
>> +#if defined(__SVR4) && defined(__sun)
>> +#include <sys/byteorder.h>
>> +#endif
>> +#if defined(__FreeBSD__) || defined(__NetBSD__) || \
>> + defined(__DragonFly__) || defined(__minix)
>> +#include <sys/endian.h>
>> +#endif
>> +#if defined(__OpenBSD__)
>> +#include <machine/endian.h>
>> +#endif
>
> The above headers will not be included.
>
>> +/* Detect endianess based on _BYTE_ORDER. */
>> +#if _BYTE_ORDER == _LITTLE_ENDIAN
>
> So most likely _BYTE_ORDER and _LITTLE_ENDIAN macros will not be defined.
> Which means this will be handled as #if 0 == 0 and override the
>> +#define PLUGIN_LITTLE_ENDIAN 1
>
> will define also PLUGIN_LITTLE_ENDIAN.
Ok, for being sure, I've wrapped all equality comparison with corresponding
check of the LHS is defined.
>
>> +#elif _BYTE_ORDER == _BIG_ENDIAN
>> +#define PLUGIN_BIG_ENDIAN 1
>> +#endif
>> +/* Detect based on _WIN32. */
>> +#if defined(_WIN32)
>> +#define PLUGIN_LITTLE_ENDIAN 1
>> +#endif
>> +/* Fallback to __BIG_ENDIAN__ and __LITTLE_ENDIAN__ */
>> +#ifdef __LITTLE_ENDIAN__
>> +#define PLUGIN_LITTLE_ENDIAN 1
>> +#endif
>> +#ifdef __BIG_ENDIAN__
>> +#define PLUGIN_BIG_ENDIAN 1
>> +#endif
>> +#endif
>
> and the above isn't really a fallback, because it isn't guarded with
> PLUGIN_*_ENDIAN not being defined yet.
This comment has been also updated.
Martin
>
> Jakub
>
[-- Attachment #2: 0001-Improve-endianess-detection.patch --]
[-- Type: text/x-patch, Size: 2934 bytes --]
From 82b8731f304c734353c34ddaf1b1265341a90882 Mon Sep 17 00:00:00 2001
From: Martin Liska <mliska@suse.cz>
Date: Tue, 24 Mar 2020 09:12:50 +0100
Subject: [PATCH] Improve endianess detection.
include/ChangeLog:
2020-03-24 Martin Liska <mliska@suse.cz>
PR lto/94249
* plugin-api.h: Add more robust endianess detection.
---
include/plugin-api.h | 65 ++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 63 insertions(+), 2 deletions(-)
diff --git a/include/plugin-api.h b/include/plugin-api.h
index 673f136ce68..864d2bf91ac 100644
--- a/include/plugin-api.h
+++ b/include/plugin-api.h
@@ -37,6 +37,60 @@
#error cannot find uint64_t type
#endif
+/* Detect endianess based on __BYTE_ORDER__ macro. */
+#if defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && \
+ defined(__ORDER_LITTLE_ENDIAN__) && defined(__ORDER_PDP_ENDIAN__)
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#define PLUGIN_LITTLE_ENDIAN 1
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#define PLUGIN_BIG_ENDIAN 1
+#elif __BYTE_ORDER__ == __ORDER_PDP_ENDIAN__
+#define PLUGIN_PDP_ENDIAN 1
+#endif
+#else
+/* Older GCC releases (<4.6.0) can make detection from glibc macros. */
+#if defined(__GLIBC__) || defined(__GNU_LIBRARY__) || defined(__ANDROID__)
+#include <endian.h>
+#ifdef _BYTE_ORDER
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+#define PLUGIN_LITTLE_ENDIAN 1
+#elif __BYTE_ORDER == __BIG_ENDIAN
+#define PLUGIN_BIG_ENDIAN 1
+#endif
+#endif
+#endif
+/* Include all necessary header files based on target. */
+#if defined(__SVR4) && defined(__sun)
+#include <sys/byteorder.h>
+#endif
+#if defined(__FreeBSD__) || defined(__NetBSD__) || \
+ defined(__DragonFly__) || defined(__minix)
+#include <sys/endian.h>
+#endif
+#if defined(__OpenBSD__)
+#include <machine/endian.h>
+#endif
+/* Detect endianess based on _BYTE_ORDER. */
+#ifdef _BYTE_ORDER
+#if _BYTE_ORDER == _LITTLE_ENDIAN
+#define PLUGIN_LITTLE_ENDIAN 1
+#elif _BYTE_ORDER == _BIG_ENDIAN
+#define PLUGIN_BIG_ENDIAN 1
+#endif
+#endif
+/* Detect based on _WIN32. */
+#if defined(_WIN32)
+#define PLUGIN_LITTLE_ENDIAN 1
+#endif
+/* Detect based on __BIG_ENDIAN__ and __LITTLE_ENDIAN__ */
+#ifdef __LITTLE_ENDIAN__
+#define PLUGIN_LITTLE_ENDIAN 1
+#endif
+#ifdef __BIG_ENDIAN__
+#define PLUGIN_BIG_ENDIAN 1
+#endif
+#endif
+
#ifdef __cplusplus
extern "C"
{
@@ -89,16 +143,23 @@ struct ld_plugin_symbol
char *version;
/* This is for compatibility with older ABIs. The older ABI defined
only 'def' field. */
-#ifdef __BIG_ENDIAN__
+#if PLUGIN_BIG_ENDIAN == 1
char unused;
char section_kind;
char symbol_type;
char def;
-#else
+#elif PLUGIN_LITTLE_ENDIAN == 1
char def;
char symbol_type;
char section_kind;
char unused;
+#elif PLUGIN_PDP_ENDIAN == 1
+ char symbol_type;
+ char def;
+ char unused;
+ char section_kind;
+#else
+#error "Could not detect architecture endianess"
#endif
int visibility;
uint64_t size;
--
2.25.1
next prev parent reply other threads:[~2020-03-24 10:32 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-23 9:25 Martin Liška
2020-03-23 9:43 ` Jakub Jelinek
2020-03-23 10:00 ` Martin Liška
2020-03-23 10:10 ` Jakub Jelinek
2020-03-23 10:28 ` Martin Liška
2020-03-23 10:35 ` Jakub Jelinek
2020-03-23 12:43 ` Martin Liška
2020-03-23 15:06 ` Martin Liška
2020-03-23 15:39 ` Richard Biener
2020-03-23 16:06 ` H.J. Lu
2020-03-23 17:17 ` Martin Liška
2020-03-23 17:40 ` H.J. Lu
2020-03-24 8:19 ` Martin Liška
2020-03-24 8:31 ` Jakub Jelinek
2020-03-24 8:49 ` Martin Liška
2020-03-24 9:18 ` Jakub Jelinek
2020-03-24 10:32 ` Martin Liška [this message]
2020-03-24 10:39 ` Jakub Jelinek
2020-03-31 13:27 ` [PATCH] PR lto/94249: Correct endianness detection with the __BYTE_ORDER macro Maciej W. Rozycki
2020-04-01 5:01 ` Hans-Peter Nilsson
2020-04-01 7:43 ` Martin Liška
2020-04-01 23:57 ` Hans-Peter Nilsson
2020-04-01 7:17 ` Richard Biener
2020-04-01 7:41 ` Martin Liška
2020-04-01 9:55 ` Maciej W. Rozycki
2020-04-01 10:01 ` Martin Liška
2020-04-01 15:59 ` Maciej W. Rozycki
2020-04-01 16:54 ` Martin Liška
2020-04-01 17:28 ` Maciej W. Rozycki
2020-04-01 10:04 ` Maciej W. Rozycki
2020-04-01 10:09 ` Martin Liška
2020-03-23 15:16 ` [PATCH] Check endianess detection Richard Biener
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