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111
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1 /* Infrastructure to test the quality of debug information.
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2 Copyright (C) 2008, 2009, 2010 Free Software Foundation, Inc.
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3 Contributed by Alexandre Oliva <aoliva@redhat.com>.
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4
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5 This file is part of GCC.
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6
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7 GCC is free software; you can redistribute it and/or modify
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8 it under the terms of the GNU General Public License as published by
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9 the Free Software Foundation; either version 3, or (at your option)
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10 any later version.
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11
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12 GCC is distributed in the hope that it will be useful,
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13 but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 GNU General Public License for more details.
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16
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17 You should have received a copy of the GNU General Public License
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18 along with GCC; see the file COPYING3. If not see
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19 <http://www.gnu.org/licenses/>. */
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20
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21 #include <stdio.h>
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22 #include <stdlib.h>
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23 #include <string.h>
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24 #include <stdint.h>
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25 #include <unistd.h>
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26
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27 /* This is a first cut at checking that debug information matches
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28 run-time. The idea is to annotate programs with GUALCHK* macros
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29 that guide the tests.
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30
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31 In the current implementation, all of the macros expand to function
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32 calls. On the one hand, this interferes with optimizations; on the
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33 other hand, it establishes an optimization barrier and a clear
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34 inspection point, where previous operations (as in the abstract
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35 machine) should have been completed and have their effects visible,
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36 and future operations shouldn't have started yet.
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37
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38 In the current implementation of guality_check(), we fork a child
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39 process that runs gdb, attaches to the parent process (the one that
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40 called guality_check), moves up one stack frame (to the caller of
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41 guality_check) and then examines the given expression.
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42
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43 If it matches the expected value, we have a PASS. If it differs,
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44 we have a FAILure. If it is missing, we'll have a FAIL or an
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45 UNRESOLVED depending on whether the variable or expression might be
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46 unavailable at that point, as indicated by the third argument.
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47
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48 We envision a future alternate implementation with two compilation
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49 and execution cycles, say one that runs the program and uses the
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50 macros to log expressions and expected values, another in which the
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51 macros expand to nothing and the logs are used to guide a debug
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52 session that tests the values. How to identify the inspection
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53 points in the second case is yet to be determined. It is
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54 recommended that GUALCHK* macros be by themselves in source lines,
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55 so that __FILE__ and __LINE__ will be usable to identify them.
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56 */
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57
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58 #define GUALITY_TEST "guality/guality.h"
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59
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60 /* This is the type we use to pass values to guality_check. */
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61
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62 typedef intmax_t gualchk_t;
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63
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64 /* Convert a pointer or integral type to the widest integral type,
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65 as expected by guality_check. */
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66
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67 #ifndef __cplusplus
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68 #define GUALCVT(val) \
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69 ((gualchk_t)__builtin_choose_expr \
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70 (__builtin_types_compatible_p (__typeof (val), gualchk_t), \
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71 (val), \
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72 __builtin_choose_expr \
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73 (__builtin_classify_type (val) \
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74 == __builtin_classify_type (&guality_skip), \
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75 (uintptr_t)(val),(intptr_t)(val))))
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76 #else
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77 template <typename T>
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78 inline __attribute__((always_inline)) gualchk_t
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79 gualcvt (T *val)
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80 {
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81 return (uintptr_t) val;
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82 }
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83
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84 template <typename T>
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85 inline __attribute__((always_inline)) gualchk_t
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86 gualcvt (T val)
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87 {
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88 return (intptr_t) val;
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89 }
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90
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91 template <>
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92 inline __attribute__((always_inline)) gualchk_t
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93 gualcvt<gualchk_t> (gualchk_t val)
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94 {
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95 return val;
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96 }
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97
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98 #define GUALCVT(val) gualcvt (val)
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99 #endif
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100
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101 /* Attach a debugger to the current process and verify that the string
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102 EXPR, evaluated by the debugger, yields the gualchk_t number VAL.
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103 If the debugger cannot compute the expression, say because the
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104 variable is unavailable, this will count as an error, unless unkok
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105 is nonzero. */
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106
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107 #define GUALCHKXPRVAL(expr, val, unkok) \
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108 guality_check ((expr), (val), (unkok))
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109
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110 /* Check that a debugger knows that EXPR evaluates to the run-time
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111 value of EXPR. Unknown values are marked as acceptable,
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112 considering that EXPR may die right after this call. This will
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113 affect the generated code in that EXPR will be evaluated and forced
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114 to remain live at least until right before the call to
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115 guality_check, although not necessarily after the call. */
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116
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117 #define GUALCHKXPR(expr) \
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118 GUALCHKXPRVAL (#expr, GUALCVT (expr), 1)
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119
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120 /* Same as GUALCHKXPR, but issue an error if the variable is optimized
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121 away. */
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122
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123 #define GUALCHKVAL(expr) \
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124 GUALCHKXPRVAL (#expr, GUALCVT (expr), 0)
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125
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126 /* Check that a debugger knows that EXPR evaluates to the run-time
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127 value of EXPR. Unknown values are marked as errors, because the
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128 value of EXPR is forced to be available right after the call, for a
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129 range of at least one instruction. This will affect the generated
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130 code, in that EXPR *will* be evaluated before and preserved until
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131 after the call to guality_check. */
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132
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133 #define GUALCHKFLA(expr) do { \
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134 __typeof(expr) volatile __preserve_after; \
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135 __typeof(expr) __preserve_before = (expr); \
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136 GUALCHKXPRVAL (#expr, GUALCVT (__preserve_before), 0); \
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137 __preserve_after = __preserve_before; \
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138 asm ("" : : "m" (__preserve_after)); \
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139 } while (0)
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140
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141 /* GUALCHK is the simplest way to assert that debug information for an
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142 expression matches its run-time value. Whether to force the
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143 expression live after the call, so as to flag incompleteness
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144 errors, can be disabled by defining GUALITY_DONT_FORCE_LIVE_AFTER.
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145 Setting it to -1, an error is issued for optimized out variables,
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146 even though they are not forced live. */
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147
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148 #if ! GUALITY_DONT_FORCE_LIVE_AFTER
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149 #define GUALCHK(var) GUALCHKFLA(var)
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150 #elif GUALITY_DONT_FORCE_LIVE_AFTER < 0
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151 #define GUALCHK(var) GUALCHKVAL(var)
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152 #else
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153 #define GUALCHK(var) GUALCHKXPR(var)
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154 #endif
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155
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156 /* The name of the GDB program, with arguments to make it quiet. This
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157 is GUALITY_GDB_DEFAULT GUALITY_GDB_ARGS by default, but it can be
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158 overridden by setting the GUALITY_GDB environment variable, whereas
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159 GUALITY_GDB_DEFAULT can be overridden by setting the
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160 GUALITY_GDB_NAME environment variable. */
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161
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162 static const char *guality_gdb_command;
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163 #define GUALITY_GDB_DEFAULT "gdb"
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164 #if defined(__unix)
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165 # define GUALITY_GDB_REDIRECT " > /dev/null 2>&1"
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166 #elif defined (_WIN32) || defined (MSDOS)
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167 # define GUALITY_GDB_REDIRECT " > nul"
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168 #else
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169 # define GUALITY_GDB_REDIRECT ""
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170 #endif
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171 #define GUALITY_GDB_ARGS " -nx -nw --quiet" GUALITY_GDB_REDIRECT
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172
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173 /* Kinds of results communicated as exit status from child process
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174 that runs gdb to the parent process that's being monitored. */
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175
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176 enum guality_counter { PASS, INCORRECT, INCOMPLETE };
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177
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178 /* Count of passes and errors. */
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179
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180 static int guality_count[INCOMPLETE+1];
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181
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182 /* If --guality-skip is given in the command line, all the monitoring,
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183 forking and debugger-attaching action will be disabled. This is
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184 useful to run the monitor program within a debugger. */
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185
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186 static int guality_skip;
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187
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188 /* This is a file descriptor to which we'll issue gdb commands to
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189 probe and test. */
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190 FILE *guality_gdb_input;
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191
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192 /* This holds the line number where we're supposed to set a
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193 breakpoint. */
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194 int guality_breakpoint_line;
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195
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196 /* GDB should set this to true once it's connected. */
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197 int volatile guality_attached;
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198
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199 /* This function is the main guality program. It may actually be
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200 defined as main, because we #define main to it afterwards. Because
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201 of this wrapping, guality_main may not have an empty argument
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202 list. */
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203
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204 extern int guality_main (int argc, char *argv[]);
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205
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206 static void __attribute__((noinline))
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207 guality_check (const char *name, gualchk_t value, int unknown_ok);
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208
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209 /* Set things up, run guality_main, then print a summary and quit. */
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210
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211 int
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212 main (int argc, char *argv[])
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213 {
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214 int i;
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215 char *argv0 = argv[0];
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216
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217 guality_gdb_command = getenv ("GUALITY_GDB");
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218 if (!guality_gdb_command)
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219 {
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220 guality_gdb_command = getenv ("GUALITY_GDB_NAME");
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221 if (!guality_gdb_command)
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222 guality_gdb_command = GUALITY_GDB_DEFAULT GUALITY_GDB_ARGS;
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223 else
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224 {
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225 int len = strlen (guality_gdb_command) + sizeof (GUALITY_GDB_ARGS);
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226 char *buf = (char *) __builtin_alloca (len);
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227 strcpy (buf, guality_gdb_command);
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228 strcat (buf, GUALITY_GDB_ARGS);
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229 guality_gdb_command = buf;
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230 }
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231 }
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232
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233 if (argv[0])
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234 {
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235 int len = strlen (guality_gdb_command) + 1 + strlen (argv[0]);
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236 char *buf = (char *) __builtin_alloca (len);
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237 strcpy (buf, guality_gdb_command);
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238 strcat (buf, " ");
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239 strcat (buf, argv[0]);
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240 guality_gdb_command = buf;
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241 }
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242
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243 for (i = 1; i < argc; i++)
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244 if (strcmp (argv[i], "--guality-skip") == 0)
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245 guality_skip = 1;
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246 else
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247 break;
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248
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249 if (!guality_skip)
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250 {
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251 guality_gdb_input = popen (guality_gdb_command, "w");
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252 /* This call sets guality_breakpoint_line. */
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253 guality_check (NULL, 0, 0);
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254 if (!guality_gdb_input
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255 || fprintf (guality_gdb_input, "\
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256 set height 0\n\
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257 handle SIGINT pass nostop\n\
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258 handle SIGTERM pass nostop\n\
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259 handle SIGSEGV pass nostop\n\
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260 handle SIGBUS pass nostop\n\
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261 attach %i\n\
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262 set guality_attached = 1\n\
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263 b %i\n\
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264 continue\n\
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265 ", (int)getpid (), guality_breakpoint_line) <= 0
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266 || fflush (guality_gdb_input))
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267 {
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268 perror ("gdb");
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269 abort ();
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270 }
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271 }
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272
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273 argv[--i] = argv0;
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274
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275 guality_main (argc - i, argv + i);
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276
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277 i = guality_count[INCORRECT];
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278
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279 fprintf (stderr, "%s: " GUALITY_TEST ": %i PASS, %i FAIL, %i UNRESOLVED\n",
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280 i ? "FAIL" : "PASS",
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281 guality_count[PASS], guality_count[INCORRECT],
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282 guality_count[INCOMPLETE]);
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283
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284 return i;
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285 }
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286
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287 #define main guality_main
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288
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289 /* Tell the GDB child process to evaluate NAME in the caller. If it
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290 matches VALUE, we have a PASS; if it's unknown and UNKNOWN_OK, we
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291 have an UNRESOLVED. Otherwise, it's a FAIL. */
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292
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293 static void __attribute__((noinline))
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294 guality_check (const char *name, gualchk_t value, int unknown_ok)
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295 {
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296 int result;
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297
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298 if (guality_skip)
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299 return;
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300
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301 {
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302 volatile gualchk_t xvalue = -1;
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303 volatile int unavailable = 0;
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304 if (name)
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305 {
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306 /* The sequence below cannot distinguish an optimized away
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307 variable from one mapped to a non-lvalue zero. */
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308 if (fprintf (guality_gdb_input, "\
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309 up\n\
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310 set $value1 = 0\n\
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311 set $value1 = (%s)\n\
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312 set $value2 = -1\n\
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313 set $value2 = (%s)\n\
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314 set $value3 = $value1 - 1\n\
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315 set $value4 = $value1 + 1\n\
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316 set $value3 = (%s)++\n\
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317 set $value4 = --(%s)\n\
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318 down\n\
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319 set xvalue = $value1\n\
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320 set unavailable = $value1 != $value2 ? -1 : $value3 != $value4 ? 1 : 0\n\
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321 continue\n\
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322 ", name, name, name, name) <= 0
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323 || fflush (guality_gdb_input))
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324 {
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325 perror ("gdb");
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326 abort ();
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327 }
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328 else if (!guality_attached)
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329 {
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330 unsigned int timeout = 0;
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331
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332 /* Give GDB some more time to attach. Wrapping around a
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333 32-bit counter takes some seconds, it should be plenty
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334 of time for GDB to get a chance to start up and attach,
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335 but not long enough that, if GDB is unavailable or
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336 broken, we'll take far too long to give up. */
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337 while (--timeout && !guality_attached)
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338 ;
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339 if (!timeout && !guality_attached)
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340 {
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341 fprintf (stderr, "gdb: took too long to attach\n");
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342 abort ();
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343 }
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344 }
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345 }
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346 else
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347 {
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348 guality_breakpoint_line = __LINE__ + 5;
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349 return;
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350 }
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351 /* Do NOT add lines between the __LINE__ above and the line below,
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352 without also adjusting the added constant to match. */
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353 if (!unavailable || (unavailable > 0 && xvalue))
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354 {
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355 if (xvalue == value)
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356 result = PASS;
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357 else
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358 result = INCORRECT;
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359 }
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360 else
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361 result = INCOMPLETE;
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362 asm ("" : : "X" (name), "X" (value), "X" (unknown_ok), "m" (xvalue));
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363 switch (result)
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364 {
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365 case PASS:
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131
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366 fprintf (stderr, "PASS: " GUALITY_TEST ": %s is %lli\n", name,
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367 (long long int) value);
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111
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368 break;
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369 case INCORRECT:
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131
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370 fprintf (stderr, "FAIL: " GUALITY_TEST ": %s is %lli, not %lli\n", name,
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371 (long long int) xvalue, (long long int) value);
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111
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372 break;
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373 case INCOMPLETE:
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374 fprintf (stderr, "%s: " GUALITY_TEST ": %s is %s, expected %lli\n",
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375 unknown_ok ? "UNRESOLVED" : "FAIL", name,
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131
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376 unavailable < 0 ? "not computable" : "optimized away",
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377 (long long int) value);
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111
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378 result = unknown_ok ? INCOMPLETE : INCORRECT;
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379 break;
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380 default:
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381 abort ();
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382 }
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383 }
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384
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385 switch (result)
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386 {
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387 case PASS:
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388 case INCORRECT:
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389 case INCOMPLETE:
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390 ++guality_count[result];
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391 break;
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392
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393 default:
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394 abort ();
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395 }
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396 }
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