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Bug#42733: Type-punning warnings when compiling MySQL --

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strict aliasing violations.

Essentially, the problem is that large parts of the server were
developed in simpler times (last decades, pre C99 standard) when
strict aliasing and compilers supporting such optimizations were
rare to non-existent. Thus, when compiling the server with a modern
compiler that uses strict aliasing rules to perform optimizations,
there are several places in the code that might trigger undefined
behavior.

As evinced by some recent bugs, GCC does a somewhat good of job
misoptimizing such code, but on the other hand also gives warnings
about suspicious code. One problem is that the warnings aren't
always accurate, yet we can't afford to just shut them off as we
might miss real cases. False-positive cases are aggravated mostly
by casts that are likely to trigger undefined behavior.

The solution is to start a cleanup process focused on fixing and
reducing the amount of strict-aliasing related warnings produced
by GCC and others compilers. A good deal of noise reduction can
be achieved by just removing useless casts that are product of
historical cruft and are likely to trigger undefined behavior if
dereferenced.
This commit is contained in:
Davi Arnaut
2010-06-10 17:16:43 -03:00
parent e3b4d33187
commit bb036c93b4
35 changed files with 1248 additions and 1111 deletions
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65
client/mysqltest.cc
View File

@@ -5836,18 +5836,18 @@ static struct my_option my_long_options[] =
{
{"help", '?', "Display this help and exit.", 0, 0, 0, GET_NO_ARG, NO_ARG,
0, 0, 0, 0, 0, 0},
{"basedir", 'b', "Basedir for tests.", (uchar**) &opt_basedir,
(uchar**) &opt_basedir, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"basedir", 'b', "Basedir for tests.", &opt_basedir,
&opt_basedir, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"character-sets-dir", OPT_CHARSETS_DIR,
"Directory for character set files.", (uchar**) &opt_charsets_dir,
(uchar**) &opt_charsets_dir, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
"Directory for character set files.", &opt_charsets_dir,
&opt_charsets_dir, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"compress", 'C', "Use the compressed server/client protocol.",
(uchar**) &opt_compress, (uchar**) &opt_compress, 0, GET_BOOL, NO_ARG, 0, 0, 0,
&opt_compress, &opt_compress, 0, GET_BOOL, NO_ARG, 0, 0, 0,
0, 0, 0},
{"cursor-protocol", OPT_CURSOR_PROTOCOL, "Use cursors for prepared statements.",
(uchar**) &cursor_protocol, (uchar**) &cursor_protocol, 0,
&cursor_protocol, &cursor_protocol, 0,
GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
{"database", 'D', "Database to use.", (uchar**) &opt_db, (uchar**) &opt_db, 0,
{"database", 'D', "Database to use.", &opt_db, &opt_db, 0,
GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
#ifdef DBUG_OFF
{"debug", '#', "This is a non-debug version. Catch this and exit",
@@ -5857,28 +5857,28 @@ static struct my_option my_long_options[] =
0, 0, 0, GET_STR, OPT_ARG, 0, 0, 0, 0, 0, 0},
#endif
{"debug-check", OPT_DEBUG_CHECK, "Check memory and open file usage at exit.",
(uchar**) &debug_check_flag, (uchar**) &debug_check_flag, 0,
&debug_check_flag, &debug_check_flag, 0,
GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
{"debug-info", OPT_DEBUG_INFO, "Print some debug info at exit.",
(uchar**) &debug_info_flag, (uchar**) &debug_info_flag,
&debug_info_flag, &debug_info_flag,
0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
{"host", 'h', "Connect to host.", (uchar**) &opt_host, (uchar**) &opt_host, 0,
{"host", 'h', "Connect to host.", &opt_host, &opt_host, 0,
GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"include", 'i', "Include SQL before each test case.", (uchar**) &opt_include,
(uchar**) &opt_include, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"logdir", OPT_LOG_DIR, "Directory for log files", (uchar**) &opt_logdir,
(uchar**) &opt_logdir, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"include", 'i', "Include SQL before each test case.", &opt_include,
&opt_include, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"logdir", OPT_LOG_DIR, "Directory for log files", &opt_logdir,
&opt_logdir, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"mark-progress", OPT_MARK_PROGRESS,
"Write line number and elapsed time to <testname>.progress.",
(uchar**) &opt_mark_progress, (uchar**) &opt_mark_progress, 0,
&opt_mark_progress, &opt_mark_progress, 0,
GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
{"max-connect-retries", OPT_MAX_CONNECT_RETRIES,
"Maximum number of attempts to connect to server.",
(uchar**) &opt_max_connect_retries, (uchar**) &opt_max_connect_retries, 0,
&opt_max_connect_retries, &opt_max_connect_retries, 0,
GET_INT, REQUIRED_ARG, 500, 1, 10000, 0, 0, 0},
{"max-connections", OPT_MAX_CONNECTIONS,
"Max number of open connections to server",
(uchar**) &opt_max_connections, (uchar**) &opt_max_connections, 0,
&opt_max_connections, &opt_max_connections, 0,
GET_INT, REQUIRED_ARG, 128, 8, 5120, 0, 0, 0},
{"password", 'p', "Password to use when connecting to server.",
0, 0, 0, GET_STR, OPT_ARG, 0, 0, 0, 0, 0, 0},
@@ -5888,18 +5888,17 @@ static struct my_option my_long_options[] =
"/etc/services, "
#endif
"built-in default (" STRINGIFY_ARG(MYSQL_PORT) ").",
(uchar**) &opt_port,
(uchar**) &opt_port, 0, GET_INT, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
&opt_port, &opt_port, 0, GET_INT, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"ps-protocol", OPT_PS_PROTOCOL,
"Use prepared-statement protocol for communication.",
(uchar**) &ps_protocol, (uchar**) &ps_protocol, 0,
&ps_protocol, &ps_protocol, 0,
GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
{"quiet", 's', "Suppress all normal output.", (uchar**) &silent,
(uchar**) &silent, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
{"quiet", 's', "Suppress all normal output.", &silent,
&silent, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
{"record", 'r', "Record output of test_file into result file.",
0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0},
{"result-file", 'R', "Read/store result from/in this file.",
(uchar**) &result_file_name, (uchar**) &result_file_name, 0,
&result_file_name, &result_file_name, 0,
GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"server-arg", 'A', "Send option value to embedded server as a parameter.",
0, 0, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
@@ -5907,28 +5906,28 @@ static struct my_option my_long_options[] =
0, 0, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
#ifdef HAVE_SMEM
{"shared-memory-base-name", OPT_SHARED_MEMORY_BASE_NAME,
"Base name of shared memory.", (uchar**) &shared_memory_base_name,
(uchar**) &shared_memory_base_name, 0, GET_STR, REQUIRED_ARG, 0, 0, 0,
"Base name of shared memory.", &shared_memory_base_name,
&shared_memory_base_name, 0, GET_STR, REQUIRED_ARG, 0, 0, 0,
0, 0, 0},
#endif
{"silent", 's', "Suppress all normal output. Synonym for --quiet.",
(uchar**) &silent, (uchar**) &silent, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
&silent, &silent, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
{"skip-safemalloc", OPT_SKIP_SAFEMALLOC,
"Don't use the memory allocation checking.", 0, 0, 0, GET_NO_ARG, NO_ARG,
0, 0, 0, 0, 0, 0},
{"sleep", 'T', "Always sleep this many seconds on sleep commands.",
(uchar**) &opt_sleep, (uchar**) &opt_sleep, 0, GET_INT, REQUIRED_ARG, -1, -1, 0,
&opt_sleep, &opt_sleep, 0, GET_INT, REQUIRED_ARG, -1, -1, 0,
0, 0, 0},
{"socket", 'S', "The socket file to use for connection.",
(uchar**) &unix_sock, (uchar**) &unix_sock, 0, GET_STR, REQUIRED_ARG, 0, 0, 0,
&unix_sock, &unix_sock, 0, GET_STR, REQUIRED_ARG, 0, 0, 0,
0, 0, 0},
{"sp-protocol", OPT_SP_PROTOCOL, "Use stored procedures for select.",
(uchar**) &sp_protocol, (uchar**) &sp_protocol, 0,
&sp_protocol, &sp_protocol, 0,
GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
#include "sslopt-longopts.h"
{"tail-lines", OPT_TAIL_LINES,
"Number of lines of the result to include in a failure report.",
(uchar**) &opt_tail_lines, (uchar**) &opt_tail_lines, 0,
&opt_tail_lines, &opt_tail_lines, 0,
GET_INT, REQUIRED_ARG, 0, 0, 10000, 0, 0, 0},
{"test-file", 'x', "Read test from/in this file (default stdin).",
0, 0, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
@@ -5936,14 +5935,14 @@ static struct my_option my_long_options[] =
0, 0, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"tmpdir", 't', "Temporary directory where sockets are put.",
0, 0, 0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"user", 'u', "User for login.", (uchar**) &opt_user, (uchar**) &opt_user, 0,
{"user", 'u', "User for login.", &opt_user, &opt_user, 0,
GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
{"verbose", 'v', "Write more.", (uchar**) &verbose, (uchar**) &verbose, 0,
{"verbose", 'v', "Write more.", &verbose, &verbose, 0,
GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
{"version", 'V', "Output version information and exit.",
0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0},
{"view-protocol", OPT_VIEW_PROTOCOL, "Use views for select.",
(uchar**) &view_protocol, (uchar**) &view_protocol, 0,
&view_protocol, &view_protocol, 0,
GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
{ 0, 0, 0, 0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0}
};