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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT COMPILER COMPONENTS --
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4 -- --
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5 -- C H E C K S --
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6 -- --
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7 -- S p e c --
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8 -- --
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131
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9 -- Copyright (C) 1992-2018, Free Software Foundation, Inc. --
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111
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10 -- --
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11 -- GNAT is free software; you can redistribute it and/or modify it under --
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12 -- terms of the GNU General Public License as published by the Free Soft- --
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13 -- ware Foundation; either version 3, or (at your option) any later ver- --
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14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
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17 -- for more details. You should have received a copy of the GNU General --
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18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
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19 -- http://www.gnu.org/licenses for a complete copy of the license. --
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20 -- --
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21 -- GNAT was originally developed by the GNAT team at New York University. --
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22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
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23 -- --
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24 ------------------------------------------------------------------------------
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25
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26 -- Package containing routines used to deal with runtime checks. These
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27 -- routines are used both by the semantics and by the expander. In some
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28 -- cases, checks are enabled simply by setting flags for gigi, and in
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29 -- other cases the code for the check is expanded.
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30
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31 -- The approach used for range and length checks, in regards to suppressed
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32 -- checks, is to attempt to detect at compilation time that a constraint
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33 -- error will occur. If this is detected a warning or error is issued and the
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34 -- offending expression or statement replaced with a constraint error node.
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35 -- This always occurs whether checks are suppressed or not. Dynamic range
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36 -- checks are, of course, not inserted if checks are suppressed.
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37
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38 with Errout; use Errout;
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39 with Namet; use Namet;
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40 with Table;
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41 with Types; use Types;
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42 with Uintp; use Uintp;
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43 with Urealp; use Urealp;
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44
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45 package Checks is
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46
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47 procedure Initialize;
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48 -- Called for each new main source program, to initialize internal
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49 -- variables used in the package body of the Checks unit.
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50
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51 function Access_Checks_Suppressed (E : Entity_Id) return Boolean;
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52 function Accessibility_Checks_Suppressed (E : Entity_Id) return Boolean;
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53 function Alignment_Checks_Suppressed (E : Entity_Id) return Boolean;
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54 function Allocation_Checks_Suppressed (E : Entity_Id) return Boolean;
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55 function Atomic_Synchronization_Disabled (E : Entity_Id) return Boolean;
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56 function Discriminant_Checks_Suppressed (E : Entity_Id) return Boolean;
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57 function Division_Checks_Suppressed (E : Entity_Id) return Boolean;
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58 function Duplicated_Tag_Checks_Suppressed (E : Entity_Id) return Boolean;
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59 function Elaboration_Checks_Suppressed (E : Entity_Id) return Boolean;
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60 function Index_Checks_Suppressed (E : Entity_Id) return Boolean;
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61 function Length_Checks_Suppressed (E : Entity_Id) return Boolean;
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62 function Overflow_Checks_Suppressed (E : Entity_Id) return Boolean;
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63 function Predicate_Checks_Suppressed (E : Entity_Id) return Boolean;
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64 function Range_Checks_Suppressed (E : Entity_Id) return Boolean;
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65 function Storage_Checks_Suppressed (E : Entity_Id) return Boolean;
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66 function Tag_Checks_Suppressed (E : Entity_Id) return Boolean;
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67 function Validity_Checks_Suppressed (E : Entity_Id) return Boolean;
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68 -- These functions check to see if the named check is suppressed, either
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69 -- by an active scope suppress setting, or because the check has been
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70 -- specifically suppressed for the given entity. If no entity is relevant
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71 -- for the current check, then Empty is used as an argument. Note: the
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72 -- reason we insist on specifying Empty is to force the caller to think
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73 -- about whether there is any relevant entity that should be checked.
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74
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75 function Is_Check_Suppressed (E : Entity_Id; C : Check_Id) return Boolean;
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76 -- This function is called if Checks_May_Be_Suppressed (E) is True to
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77 -- determine whether check C is suppressed either on the entity E or
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78 -- as the result of a scope suppress pragma. If Checks_May_Be_Suppressed
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79 -- is False, then the status of the check can be determined simply by
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80 -- examining Scope_Suppress, so this routine is not called in that case.
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81
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82 function Overflow_Check_Mode return Overflow_Mode_Type;
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83 -- Returns current overflow checking mode, taking into account whether
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84 -- we are inside an assertion expression and the assertion policy.
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85
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86 -----------------------------------------
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87 -- Control of Alignment Check Warnings --
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88 -----------------------------------------
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89
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90 -- When we have address clauses, there is an issue of whether the address
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91 -- specified is appropriate to the alignment. In the general case where the
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92 -- address is dynamic, we generate a check and a possible warning (this
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93 -- warning occurs for example if we have a restricted run time with the
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94 -- restriction No_Exception_Propagation). We also issue this warning in
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95 -- the case where the address is static, but we don't know the alignment
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96 -- at the time we process the address clause. In such a case, we issue the
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97 -- warning, but we may be able to find out later (after the back end has
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98 -- annotated the actual alignment chosen) that the warning was not needed.
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99
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100 -- To deal with deleting these potentially annoying warnings, we save the
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101 -- warning information in a table, and then delete the waranings in the
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102 -- post compilation validation stage if we can tell that the check would
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103 -- never fail (in general the back end will also optimize away the check
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104 -- in such cases).
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105
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106 -- Table used to record information
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107
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108 type Alignment_Warnings_Record is record
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109 E : Entity_Id;
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110 -- Entity whose alignment possibly warrants a warning
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111
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112 A : Uint;
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113 -- Compile time known value of address clause for which the alignment
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114 -- is to be checked once we know the alignment.
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115
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116 W : Error_Msg_Id;
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117 -- Id of warning message we might delete
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118 end record;
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119
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120 package Alignment_Warnings is new Table.Table (
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121 Table_Component_Type => Alignment_Warnings_Record,
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122 Table_Index_Type => Int,
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123 Table_Low_Bound => 0,
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124 Table_Initial => 10,
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125 Table_Increment => 200,
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126 Table_Name => "Alignment_Warnings");
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127
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128 procedure Validate_Alignment_Check_Warnings;
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129 -- This routine is called after back annotation of type data to delete any
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130 -- alignment warnings that turn out to be false alarms, based on knowing
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131 -- the actual alignment, and a compile-time known alignment value.
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132
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133 -------------------------------------------
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134 -- Procedures to Activate Checking Flags --
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135 -------------------------------------------
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136
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137 procedure Activate_Division_Check (N : Node_Id);
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138 pragma Inline (Activate_Division_Check);
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139 -- Sets Do_Division_Check flag in node N, and handles possible local raise.
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140 -- Always call this routine rather than calling Set_Do_Division_Check to
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141 -- set an explicit value of True, to ensure handling the local raise case.
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142
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143 procedure Activate_Overflow_Check (N : Node_Id);
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144 pragma Inline (Activate_Overflow_Check);
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145 -- Sets Do_Overflow_Check flag in node N, and handles possible local raise.
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146 -- Always call this routine rather than calling Set_Do_Overflow_Check to
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147 -- set an explicit value of True, to ensure handling the local raise case.
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148 -- Note that for discrete types, this call has no effect for MOD, REM, and
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149 -- unary "+" for which overflow is never possible in any case.
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150 --
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151 -- Note: for the discrete-type case, it is legitimate to call this routine
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152 -- on an unanalyzed node where the Etype field is not set. However, for the
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153 -- floating-point case, Etype must be set (to a floating-point type).
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154 --
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155 -- For floating-point, we set the flag if we have automatic overflow checks
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156 -- on the target, or if Check_Float_Overflow mode is set. For the floating-
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157 -- point case, we ignore all the unary operators ("+", "-", and abs) since
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158 -- none of these can result in overflow. If there are no overflow checks on
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159 -- the target, and Check_Float_Overflow mode is not set, then the call has
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160 -- no effect, since in such cases we want to generate NaN's and infinities.
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161
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162 procedure Activate_Range_Check (N : Node_Id);
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163 pragma Inline (Activate_Range_Check);
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164 -- Sets Do_Range_Check flag in node N, and handles possible local raise
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165 -- Always call this routine rather than calling Set_Do_Range_Check to
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166 -- set an explicit value of True, to ensure handling the local raise case.
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167
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168 --------------------------------
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169 -- Procedures to Apply Checks --
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170 --------------------------------
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171
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172 -- General note on following checks. These checks are always active if
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173 -- Expander_Active and not Inside_A_Generic. They are inactive and have
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174 -- no effect Inside_A_Generic. In the case where not Expander_Active
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175 -- and not Inside_A_Generic, most of them are inactive, but some of them
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176 -- operate anyway since they may generate useful compile time warnings.
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177
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178 procedure Apply_Access_Check (N : Node_Id);
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179 -- Determines whether an expression node requires a runtime access
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180 -- check and if so inserts the appropriate run-time check.
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181
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182 procedure Apply_Accessibility_Check
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183 (N : Node_Id;
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184 Typ : Entity_Id;
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185 Insert_Node : Node_Id);
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186 -- Given a name N denoting an access parameter, emits a run-time
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187 -- accessibility check (if necessary), checking that the level of
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188 -- the object denoted by the access parameter is not deeper than the
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189 -- level of the type Typ. Program_Error is raised if the check fails.
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190 -- Insert_Node indicates the node where the check should be inserted.
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191
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192 procedure Apply_Address_Clause_Check (E : Entity_Id; N : Node_Id);
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193 -- E is the entity for an object which has an address clause. If checks
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194 -- are enabled, then this procedure generates a check that the specified
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195 -- address has an alignment consistent with the alignment of the object,
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196 -- raising PE if this is not the case. The resulting check (if one is
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197 -- generated) is prepended to the Actions list of N_Freeze_Entity node N.
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198 -- Note that the check references E'Alignment, so it cannot be emitted
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199 -- before N (its freeze node), otherwise this would cause an illegal
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200 -- access before elaboration error in GIGI. For the case of a clear overlay
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201 -- situation, we also check that the size of the overlaying object is not
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202 -- larger than the overlaid object.
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203
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204 procedure Apply_Arithmetic_Overflow_Check (N : Node_Id);
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205 -- Handle overflow checking for an arithmetic operator. Also handles the
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206 -- cases of ELIMINATED and MINIMIZED overflow checking mode. If the mode
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207 -- is one of the latter two, then this routine can also be called with
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208 -- an if or case expression node to make sure that we properly handle
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209 -- overflow checking for dependent expressions. This routine handles
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210 -- front end vs back end overflow checks (in the front end case it expands
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211 -- the necessary check). Note that divide is handled separately using
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212 -- Apply_Divide_Checks. Node N may or may not have Do_Overflow_Check.
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213 -- In STRICT mode, there is nothing to do if this flag is off, but in
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214 -- MINIMIZED/ELIMINATED mode we still have to deal with possible use
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215 -- of doing operations in Long_Long_Integer or Bignum mode.
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216
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217 procedure Apply_Constraint_Check
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218 (N : Node_Id;
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219 Typ : Entity_Id;
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220 No_Sliding : Boolean := False);
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221 -- Top-level procedure, calls all the others depending on the class of
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222 -- Typ. Checks that expression N satisfies the constraint of type Typ.
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223 -- No_Sliding is only relevant for constrained array types, if set to
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224 -- True, it checks that indexes are in range.
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225
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226 procedure Apply_Discriminant_Check
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227 (N : Node_Id;
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228 Typ : Entity_Id;
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229 Lhs : Node_Id := Empty);
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230 -- Given an expression N of a discriminated type, or of an access type
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231 -- whose designated type is a discriminanted type, generates a check to
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232 -- ensure that the expression can be converted to the subtype given as
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233 -- the second parameter. Lhs is empty except in the case of assignments,
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234 -- where the target object may be needed to determine the subtype to
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235 -- check against (such as the cases of unconstrained formal parameters
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236 -- and unconstrained aliased objects). For the case of unconstrained
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237 -- formals, the check is performed only if the corresponding actual is
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238 -- constrained, i.e., whether Lhs'Constrained is True.
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239
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240 procedure Apply_Divide_Checks (N : Node_Id);
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241 -- The node kind is N_Op_Divide, N_Op_Mod, or N_Op_Rem if either of the
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242 -- flags Do_Division_Check or Do_Overflow_Check is set, then this routine
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243 -- ensures that the appropriate checks are made. Note that overflow can
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244 -- occur in the signed case for the case of the largest negative number
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245 -- divided by minus one. This procedure only applies to Integer types.
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246
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247 procedure Apply_Parameter_Aliasing_Checks
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248 (Call : Node_Id;
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249 Subp : Entity_Id);
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250 -- Given a subprogram call Call, add a check to verify that none of the
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251 -- actuals overlap. Subp denotes the subprogram being called.
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252
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253 procedure Apply_Parameter_Validity_Checks (Subp : Entity_Id);
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254 -- Given a subprogram Subp, add both a pre and post condition pragmas that
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255 -- verify the proper initialization of scalars in parameters and function
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256 -- results.
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257
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258 procedure Apply_Predicate_Check
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259 (N : Node_Id;
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260 Typ : Entity_Id;
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261 Fun : Entity_Id := Empty);
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262 -- N is an expression to which a predicate check may need to be applied for
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263 -- Typ, if Typ has a predicate function. When N is an actual in a call, Fun
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264 -- is the function being called, which is used to generate a better warning
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265 -- if the call leads to an infinite recursion.
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266
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267 procedure Apply_Type_Conversion_Checks (N : Node_Id);
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268 -- N is an N_Type_Conversion node. A type conversion actually involves
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269 -- two sorts of checks. The first check is the checks that ensures that
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270 -- the operand in the type conversion fits onto the base type of the
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271 -- subtype it is being converted to (see RM 4.6 (28)-(50)). The second
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272 -- check is there to ensure that once the operand has been converted to
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273 -- a value of the target type, this converted value meets the
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274 -- constraints imposed by the target subtype (see RM 4.6 (51)).
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275
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276 procedure Apply_Universal_Integer_Attribute_Checks (N : Node_Id);
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277 -- The argument N is an attribute reference node intended for processing
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278 -- by gigi. The attribute is one that returns a universal integer, but
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279 -- the attribute reference node is currently typed with the expected
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280 -- result type. This routine deals with range and overflow checks needed
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281 -- to make sure that the universal result is in range.
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282
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283 function Build_Discriminant_Checks
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284 (N : Node_Id;
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285 T_Typ : Entity_Id)
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286 return Node_Id;
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287 -- Subsidiary routine for Apply_Discriminant_Check. Builds the expression
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288 -- that compares discriminants of the expression with discriminants of the
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289 -- type. Also used directly for membership tests (see Exp_Ch4.Expand_N_In).
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290
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291 function Convert_From_Bignum (N : Node_Id) return Node_Id;
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292 -- Returns result of converting node N from Bignum. The returned value is
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293 -- not analyzed, the caller takes responsibility for this. Node N must be
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294 -- a subexpression node of type Bignum. The result is Long_Long_Integer.
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295
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296 function Convert_To_Bignum (N : Node_Id) return Node_Id;
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297 -- Returns result of converting node N to Bignum. The returned value is not
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298 -- analyzed, the caller takes responsibility for this. Node N must be a
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299 -- subexpression node of a signed integer type or Bignum type (if it is
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300 -- already a Bignum, the returned value is Relocate_Node (N)).
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301
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302 procedure Determine_Range
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303 (N : Node_Id;
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304 OK : out Boolean;
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305 Lo : out Uint;
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306 Hi : out Uint;
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307 Assume_Valid : Boolean := False);
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308 -- N is a node for a subexpression. If N is of a discrete type with no
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309 -- error indications, and no other peculiarities (e.g. missing Etype),
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310 -- then OK is True on return, and Lo and Hi are set to a conservative
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311 -- estimate of the possible range of values of N. Thus if OK is True on
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312 -- return, the value of the subexpression N is known to lie in the range
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131
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313 -- Lo .. Hi (inclusive). For enumeration and character literals the values
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314 -- returned are the Pos value in the relevant enumeration type. If the
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315 -- expression is not of a discrete type, or some kind of error condition
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316 -- is detected, then OK is False on exit, and Lo/Hi are set to No_Uint.
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317 -- Thus the significance of OK being False on return is that no useful
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318 -- information is available on the range of the expression. Assume_Valid
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319 -- determines whether the processing is allowed to assume that values are
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320 -- in range of their subtypes. If it is set to True, then this assumption
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321 -- is valid, if False, then processing is done using base types to allow
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322 -- invalid values.
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111
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323
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324 procedure Determine_Range_R
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325 (N : Node_Id;
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326 OK : out Boolean;
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327 Lo : out Ureal;
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328 Hi : out Ureal;
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329 Assume_Valid : Boolean := False);
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330 -- Similar to Determine_Range, but for a node N of floating-point type. OK
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331 -- is True on return only for IEEE floating-point types and only if we do
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332 -- not have to worry about extended precision (i.e. on the x86, we must be
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333 -- using -msse2 -mfpmath=sse). At the current time, this is used only in
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334 -- GNATprove, though we could consider using it more generally in future.
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335 -- For that to happen, the possibility of arguments of infinite or NaN
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336 -- value should be taken into account, which is not the case currently.
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337
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338 procedure Install_Null_Excluding_Check (N : Node_Id);
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339 -- Determines whether an access node requires a runtime access check and
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340 -- if so inserts the appropriate run-time check.
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341
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342 procedure Install_Primitive_Elaboration_Check (Subp_Body : Node_Id);
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343 -- Insert a check which ensures that subprogram body Subp_Body has been
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344 -- properly elaborated. The check is installed only when Subp_Body is the
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345 -- body of a nonabstract library-level primitive of a tagged type. Further
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346 -- restrictions may apply, see the body for details.
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347
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348 function Make_Bignum_Block (Loc : Source_Ptr) return Node_Id;
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349 -- This function is used by top level overflow checking routines to do a
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350 -- mark/release operation on the secondary stack around bignum operations.
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351 -- The block created looks like:
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|
352 --
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353 -- declare
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354 -- M : Mark_Id := SS_Mark;
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355 -- begin
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|
356 -- SS_Release (M);
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357 -- end;
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358 --
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|
359 -- The idea is that the caller will insert any needed extra declarations
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360 -- after the declaration of M, and any needed statements (in particular
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|
361 -- the bignum operations) before the call to SS_Release, and then do an
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362 -- Insert_Action of the whole block (it is returned unanalyzed). The Loc
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363 -- parameter is used to supply Sloc values for the constructed tree.
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364
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365 procedure Minimize_Eliminate_Overflows
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366 (N : Node_Id;
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367 Lo : out Uint;
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368 Hi : out Uint;
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369 Top_Level : Boolean);
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370 -- This is the main routine for handling MINIMIZED and ELIMINATED overflow
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371 -- processing. On entry N is a node whose result is a signed integer
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372 -- subtype. The Do_Overflow_Check flag may or may not be set on N. If the
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373 -- node is an arithmetic operation, then a range analysis is carried out,
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374 -- and there are three possibilities:
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375 --
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376 -- The node is left unchanged (apart from expansion of an exponentiation
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377 -- operation). This happens if the routine can determine that the result
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378 -- is definitely in range. The Do_Overflow_Check flag is turned off in
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379 -- this case.
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380 --
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381 -- The node is transformed into an arithmetic operation with a result
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382 -- type of Long_Long_Integer.
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383 --
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384 -- The node is transformed into a function call that calls an appropriate
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385 -- function in the System.Bignums package to compute a Bignum result.
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386 --
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387 -- In the first two cases, Lo and Hi are set to the bounds of the possible
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388 -- range of results, computed as accurately as possible. In the third case
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389 -- Lo and Hi are set to No_Uint (there are some cases where we could get an
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390 -- advantage from keeping result ranges for Bignum values, but it could use
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391 -- a lot of space and is very unlikely to be valuable).
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392 --
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393 -- If the node is not an arithmetic operation, then it is unchanged but
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394 -- Lo and Hi are still set (to the bounds of the result subtype if nothing
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395 -- better can be determined).
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396 --
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397 -- Note: this function is recursive, if called with an arithmetic operator,
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398 -- recursive calls are made to process the operands using this procedure.
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|
399 -- So we end up doing things top down. Nothing happens to an arithmetic
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400 -- expression until this procedure is called on the top level node and
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401 -- then the recursive calls process all the children. We have to do it
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402 -- this way. If we try to do it bottom up in natural expansion order, then
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|
403 -- there are two problems. First, where do we stash the bounds, and more
|
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|
404 -- importantly, semantic processing will be messed up. Consider A+B+C where
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|
405 -- A,B,C are all of type integer, if we processed A+B before doing semantic
|
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|
406 -- analysis of the addition of this result to C, that addition could end up
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|
|
407 -- with a Long_Long_Integer left operand and an Integer right operand, and
|
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|
408 -- we would get a semantic error.
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|
409 --
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|
410 -- The routine is called in three situations if we are operating in either
|
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|
411 -- MINIMIZED or ELIMINATED modes.
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|
|
412 --
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|
413 -- Overflow processing applied to the top node of an expression tree when
|
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|
414 -- that node is an arithmetic operator. In this case the result is
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|
|
415 -- converted to the appropriate result type (there is special processing
|
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|
416 -- when the parent is a conversion, see body for details).
|
|
|
417 --
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|
418 -- Overflow processing applied to the operands of a comparison operation.
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|
|
419 -- In this case, the comparison is done on the result Long_Long_Integer
|
|
|
420 -- or Bignum values, without raising any exceptions.
|
|
|
421 --
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|
|
422 -- Overflow processing applied to the left operand of a membership test.
|
|
|
423 -- In this case no exception is raised if a Long_Long_Integer or Bignum
|
|
|
424 -- result is outside the range of the type of that left operand (it is
|
|
|
425 -- just that the result of IN is false in that case).
|
|
|
426 --
|
|
|
427 -- Note that if Bignum values appear, the caller must take care of doing
|
|
|
428 -- the appropriate mark/release operations on the secondary stack.
|
|
|
429 --
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|
|
430 -- Top_Level is used to avoid inefficient unnecessary transitions into the
|
|
|
431 -- Bignum domain. If Top_Level is True, it means that the caller will have
|
|
|
432 -- to convert any Bignum value back to Long_Long_Integer, possibly checking
|
|
|
433 -- that the value is in range. This is the normal case for a top level
|
|
|
434 -- operator in a subexpression. There is no point in going into Bignum mode
|
|
|
435 -- to avoid an overflow just so we can check for overflow the next moment.
|
|
|
436 -- For calls from comparisons and membership tests, and for all recursive
|
|
|
437 -- calls, we do want to transition into the Bignum domain if necessary.
|
|
|
438 -- Note that this setting is only relevant in ELIMINATED mode.
|
|
|
439
|
|
|
440 -------------------------------------------------------
|
|
|
441 -- Control and Optimization of Range/Overflow Checks --
|
|
|
442 -------------------------------------------------------
|
|
|
443
|
|
|
444 -- Range checks are controlled by the Do_Range_Check flag. The front end
|
|
|
445 -- is responsible for setting this flag in relevant nodes. Originally
|
|
|
446 -- the back end generated all corresponding range checks. But later on
|
|
|
447 -- we decided to generate many range checks in the front end. We are now
|
|
|
448 -- in the transitional phase where some of these checks are still done
|
|
|
449 -- by the back end, but many are done by the front end. It is possible
|
|
|
450 -- that in the future we might move all the checks to the front end. The
|
|
|
451 -- main remaining back end checks are for subscript checking.
|
|
|
452
|
|
|
453 -- Overflow checks are similarly controlled by the Do_Overflow_Check flag.
|
|
|
454 -- The difference here is that if back end overflow checks are inactive
|
|
|
455 -- (Backend_Overflow_Checks_On_Target set False), then the actual overflow
|
|
|
456 -- checks are generated by the front end, but if back end overflow checks
|
|
|
457 -- are active (Backend_Overflow_Checks_On_Target set True), then the back
|
|
|
458 -- end does generate the checks.
|
|
|
459
|
|
|
460 -- The following two routines are used to set these flags, they allow
|
|
|
461 -- for the possibility of eliminating checks. Checks can be eliminated
|
|
|
462 -- if an identical check has already been performed.
|
|
|
463
|
|
|
464 procedure Enable_Overflow_Check (N : Node_Id);
|
|
|
465 -- First this routine determines if an overflow check is needed by doing
|
|
|
466 -- an appropriate range check. If a check is not needed, then the call
|
|
|
467 -- has no effect. If a check is needed then this routine sets the flag
|
|
|
468 -- Do_Overflow_Check in node N to True, unless it can be determined that
|
|
|
469 -- the check is not needed. The only condition under which this is the
|
|
|
470 -- case is if there was an identical check earlier on.
|
|
|
471
|
|
|
472 procedure Enable_Range_Check (N : Node_Id);
|
|
|
473 -- Set Do_Range_Check flag in node N True, unless it can be determined
|
|
|
474 -- that the check is not needed. The only condition under which this is
|
|
|
475 -- the case is if there was an identical check earlier on. This routine
|
|
|
476 -- is not responsible for doing range analysis to determine whether or
|
|
|
477 -- not such a check is needed -- the caller is expected to do this. The
|
|
|
478 -- one other case in which the request to set the flag is ignored is
|
|
|
479 -- when Kill_Range_Check is set in an N_Unchecked_Conversion node.
|
|
|
480
|
|
|
481 -- The following routines are used to keep track of processing sequences
|
|
|
482 -- of statements (e.g. the THEN statements of an IF statement). A check
|
|
|
483 -- that appears within such a sequence can eliminate an identical check
|
|
|
484 -- within this sequence of statements. However, after the end of the
|
|
|
485 -- sequence of statements, such a check is no longer of interest, since
|
|
|
486 -- it may not have been executed.
|
|
|
487
|
|
|
488 procedure Conditional_Statements_Begin;
|
|
|
489 -- This call marks the start of processing of a sequence of statements.
|
|
|
490 -- Every call to this procedure must be followed by a matching call to
|
|
|
491 -- Conditional_Statements_End.
|
|
|
492
|
|
|
493 procedure Conditional_Statements_End;
|
|
|
494 -- This call removes from consideration all saved checks since the
|
|
|
495 -- corresponding call to Conditional_Statements_Begin. These two
|
|
|
496 -- procedures operate in a stack like manner.
|
|
|
497
|
|
|
498 -- The mechanism for optimizing checks works by remembering checks
|
|
|
499 -- that have already been made, but certain conditions, for example
|
|
|
500 -- an assignment to a variable involved in a check, may mean that the
|
|
|
501 -- remembered check is no longer valid, in the sense that if the same
|
|
|
502 -- expression appears again, another check is required because the
|
|
|
503 -- value may have changed.
|
|
|
504
|
|
|
505 -- The following routines are used to note conditions which may render
|
|
|
506 -- some or all of the stored and remembered checks to be invalidated.
|
|
|
507
|
|
|
508 procedure Kill_Checks (V : Entity_Id);
|
|
|
509 -- This procedure records an assignment or other condition that causes
|
|
|
510 -- the value of the variable to be changed, invalidating any stored
|
|
|
511 -- checks that reference the value. Note that all such checks must
|
|
|
512 -- be discarded, even if they are not in the current statement range.
|
|
|
513
|
|
|
514 procedure Kill_All_Checks;
|
|
|
515 -- This procedure kills all remembered checks
|
|
|
516
|
|
|
517 -----------------------------
|
|
|
518 -- Length and Range Checks --
|
|
|
519 -----------------------------
|
|
|
520
|
|
|
521 -- In the following procedures, there are three arguments which have
|
|
|
522 -- a common meaning as follows:
|
|
|
523
|
|
|
524 -- Expr The expression to be checked. If a check is required,
|
|
|
525 -- the appropriate flag will be placed on this node. Whether
|
|
|
526 -- this node is further examined depends on the setting of
|
|
|
527 -- the parameter Source_Typ, as described below.
|
|
|
528
|
|
|
529 -- ??? Apply_Length_Check and Apply_Range_Check do not have an Expr
|
|
|
530 -- formal
|
|
|
531
|
|
|
532 -- ??? Apply_Length_Check and Apply_Range_Check have a Ck_Node formal
|
|
|
533 -- which is undocumented, is it the same as Expr?
|
|
|
534
|
|
|
535 -- Target_Typ The target type on which the check is to be based. For
|
|
|
536 -- example, if we have a scalar range check, then the check
|
|
|
537 -- is that we are in range of this type.
|
|
|
538
|
|
|
539 -- Source_Typ Normally Empty, but can be set to a type, in which case
|
|
|
540 -- this type is used for the check, see below.
|
|
|
541
|
|
|
542 -- The checks operate in one of two modes:
|
|
|
543
|
|
|
544 -- If Source_Typ is Empty, then the node Expr is examined, at the very
|
|
|
545 -- least to get the source subtype. In addition for some of the checks,
|
|
|
546 -- the actual form of the node may be examined. For example, a node of
|
|
|
547 -- type Integer whose actual form is an Integer conversion from a type
|
|
|
548 -- with range 0 .. 3 can be determined to have a value in range 0 .. 3.
|
|
|
549
|
|
|
550 -- If Source_Typ is given, then nothing can be assumed about the Expr,
|
|
|
551 -- and indeed its contents are not examined. In this case the check is
|
|
|
552 -- based on the assumption that Expr can be an arbitrary value of the
|
|
|
553 -- given Source_Typ.
|
|
|
554
|
|
|
555 -- Currently, the only case in which a Source_Typ is explicitly supplied
|
|
|
556 -- is for the case of Out and In_Out parameters, where, for the conversion
|
|
|
557 -- on return (the Out direction), the types must be reversed. This is
|
|
|
558 -- handled by the caller.
|
|
|
559
|
|
|
560 procedure Apply_Length_Check
|
|
|
561 (Ck_Node : Node_Id;
|
|
|
562 Target_Typ : Entity_Id;
|
|
|
563 Source_Typ : Entity_Id := Empty);
|
|
|
564 -- This procedure builds a sequence of declarations to do a length check
|
|
|
565 -- that checks if the lengths of the two arrays Target_Typ and source type
|
|
|
566 -- are the same. The resulting actions are inserted at Node using a call
|
|
|
567 -- to Insert_Actions.
|
|
|
568 --
|
|
|
569 -- For access types, the Directly_Designated_Type is retrieved and
|
|
|
570 -- processing continues as enumerated above, with a guard against null
|
|
|
571 -- values.
|
|
|
572 --
|
|
|
573 -- Note: calls to Apply_Length_Check currently never supply an explicit
|
|
|
574 -- Source_Typ parameter, but Apply_Length_Check takes this parameter and
|
|
|
575 -- processes it as described above for consistency with the other routines
|
|
|
576 -- in this section.
|
|
|
577
|
|
|
578 procedure Apply_Range_Check
|
|
|
579 (Ck_Node : Node_Id;
|
|
|
580 Target_Typ : Entity_Id;
|
|
|
581 Source_Typ : Entity_Id := Empty);
|
|
|
582 -- For a Node of kind N_Range, constructs a range check action that tests
|
|
|
583 -- first that the range is not null and then that the range is contained in
|
|
|
584 -- the Target_Typ range.
|
|
|
585 --
|
|
|
586 -- For scalar types, constructs a range check action that first tests that
|
|
|
587 -- the expression is contained in the Target_Typ range. The difference
|
|
|
588 -- between this and Apply_Scalar_Range_Check is that the latter generates
|
|
|
589 -- the actual checking code against the Etype of the expression.
|
|
|
590 --
|
|
|
591 -- For constrained array types, construct series of range check actions
|
|
|
592 -- to check that each Expr range is properly contained in the range of
|
|
|
593 -- Target_Typ.
|
|
|
594 --
|
|
|
595 -- For a type conversion to an unconstrained array type, constructs a range
|
|
|
596 -- check action to check that the bounds of the source type are within the
|
|
|
597 -- constraints imposed by the Target_Typ.
|
|
|
598 --
|
|
|
599 -- For access types, the Directly_Designated_Type is retrieved and
|
|
|
600 -- processing continues as enumerated above, with a guard against null
|
|
|
601 -- values.
|
|
|
602 --
|
|
|
603 -- The source type is used by type conversions to unconstrained array
|
|
|
604 -- types to retrieve the corresponding bounds.
|
|
|
605
|
|
|
606 procedure Apply_Static_Length_Check
|
|
|
607 (Expr : Node_Id;
|
|
|
608 Target_Typ : Entity_Id;
|
|
|
609 Source_Typ : Entity_Id := Empty);
|
|
|
610 -- Tries to determine statically whether the two array types source type
|
|
|
611 -- and Target_Typ have the same length. If it can be determined at compile
|
|
|
612 -- time that they do not, then an N_Raise_Constraint_Error node replaces
|
|
|
613 -- Expr, and a warning message is issued.
|
|
|
614
|
|
|
615 procedure Apply_Scalar_Range_Check
|
|
|
616 (Expr : Node_Id;
|
|
|
617 Target_Typ : Entity_Id;
|
|
|
618 Source_Typ : Entity_Id := Empty;
|
|
|
619 Fixed_Int : Boolean := False);
|
|
|
620 -- For scalar types, determines whether an expression node should be
|
|
|
621 -- flagged as needing a runtime range check. If the node requires such a
|
|
|
622 -- check, the Do_Range_Check flag is turned on. The Fixed_Int flag if set
|
|
|
623 -- causes any fixed-point values to be treated as though they were discrete
|
|
|
624 -- values (i.e. the underlying integer value is used).
|
|
|
625
|
|
|
626 type Check_Result is private;
|
|
|
627 -- Type used to return result of Get_Range_Checks call, for later use in
|
|
|
628 -- call to Insert_Range_Checks procedure.
|
|
|
629
|
|
|
630 function Get_Range_Checks
|
|
|
631 (Ck_Node : Node_Id;
|
|
|
632 Target_Typ : Entity_Id;
|
|
|
633 Source_Typ : Entity_Id := Empty;
|
|
|
634 Warn_Node : Node_Id := Empty) return Check_Result;
|
|
|
635 -- Like Apply_Range_Check, except it does not modify anything. Instead
|
|
|
636 -- it returns an encapsulated result of the check operations for later
|
|
|
637 -- use in a call to Insert_Range_Checks. If Warn_Node is non-empty, its
|
|
|
638 -- Sloc is used, in the static case, for the generated warning or error.
|
|
|
639 -- Additionally, it is used rather than Expr (or Low/High_Bound of Expr)
|
|
|
640 -- in constructing the check.
|
|
|
641
|
|
|
642 procedure Append_Range_Checks
|
|
|
643 (Checks : Check_Result;
|
|
|
644 Stmts : List_Id;
|
|
|
645 Suppress_Typ : Entity_Id;
|
|
|
646 Static_Sloc : Source_Ptr;
|
|
|
647 Flag_Node : Node_Id);
|
|
|
648 -- Called to append range checks as returned by a call to Get_Range_Checks.
|
|
|
649 -- Stmts is a list to which either the dynamic check is appended or the
|
|
|
650 -- raise Constraint_Error statement is appended (for static checks).
|
|
|
651 -- Static_Sloc is the Sloc at which the raise CE node points, Flag_Node is
|
|
|
652 -- used as the node at which to set the Has_Dynamic_Check flag. Checks_On
|
|
|
653 -- is a boolean value that says if range and index checking is on or not.
|
|
|
654
|
|
|
655 procedure Insert_Range_Checks
|
|
|
656 (Checks : Check_Result;
|
|
|
657 Node : Node_Id;
|
|
|
658 Suppress_Typ : Entity_Id;
|
|
|
659 Static_Sloc : Source_Ptr := No_Location;
|
|
|
660 Flag_Node : Node_Id := Empty;
|
|
|
661 Do_Before : Boolean := False);
|
|
|
662 -- Called to insert range checks as returned by a call to Get_Range_Checks.
|
|
|
663 -- Node is the node after which either the dynamic check is inserted or
|
|
|
664 -- the raise Constraint_Error statement is inserted (for static checks).
|
|
|
665 -- Suppress_Typ is the type to check to determine if checks are suppressed.
|
|
|
666 -- Static_Sloc, if passed, is the Sloc at which the raise CE node points,
|
|
|
667 -- otherwise Sloc (Node) is used. The Has_Dynamic_Check flag is normally
|
|
|
668 -- set at Node. If Flag_Node is present, then this is used instead as the
|
|
|
669 -- node at which to set the Has_Dynamic_Check flag. Normally the check is
|
|
|
670 -- inserted after, if Do_Before is True, the check is inserted before
|
|
|
671 -- Node.
|
|
|
672
|
|
|
673 -----------------------
|
|
|
674 -- Expander Routines --
|
|
|
675 -----------------------
|
|
|
676
|
|
|
677 -- Some of the earlier processing for checks results in temporarily setting
|
|
|
678 -- the Do_Range_Check flag rather than actually generating checks. Now we
|
|
|
679 -- are moving the generation of such checks into the front end for reasons
|
|
|
680 -- of efficiency and simplicity (there were difficulties in handling this
|
|
|
681 -- in the back end when side effects were present in the expressions being
|
|
|
682 -- checked).
|
|
|
683
|
|
|
684 -- Probably we could eliminate the Do_Range_Check flag entirely and
|
|
|
685 -- generate the checks earlier, but this is a delicate area and it
|
|
|
686 -- seemed safer to implement the following routines, which are called
|
|
|
687 -- late on in the expansion process. They check the Do_Range_Check flag
|
|
|
688 -- and if it is set, generate the actual checks and reset the flag.
|
|
|
689
|
|
|
690 procedure Generate_Range_Check
|
|
|
691 (N : Node_Id;
|
|
|
692 Target_Type : Entity_Id;
|
|
|
693 Reason : RT_Exception_Code);
|
|
|
694 -- This procedure is called to actually generate and insert a range check.
|
|
|
695 -- A check is generated to ensure that the value of N lies within the range
|
|
|
696 -- of the target type. Note that the base type of N may be different from
|
|
|
697 -- the base type of the target type. This happens in the conversion case.
|
|
|
698 -- The Reason parameter is the exception code to be used for the exception
|
|
|
699 -- if raised.
|
|
|
700 --
|
|
|
701 -- Note: if the expander is not active, or if we are in GNATprove mode,
|
|
|
702 -- then we do not generate explicit range code. Instead we just turn the
|
|
|
703 -- Do_Range_Check flag on, since in these cases that's what we want to see
|
|
|
704 -- in the tree (GNATprove in particular depends on this flag being set). If
|
|
|
705 -- we generate the actual range check, then we make sure the flag is off,
|
|
|
706 -- since the code we generate takes complete care of the check.
|
|
|
707 --
|
|
|
708 -- Historical note: We used to just pass on the Do_Range_Check flag to the
|
|
|
709 -- back end to generate the check, but now in code-generation mode we never
|
|
|
710 -- have this flag set, since the front end takes care of the check. The
|
|
|
711 -- normal processing flow now is that the analyzer typically turns on the
|
|
|
712 -- Do_Range_Check flag, and if it is set, this routine is called, which
|
|
|
713 -- turns the flag off in code-generation mode.
|
|
|
714
|
|
|
715 procedure Generate_Index_Checks (N : Node_Id);
|
|
|
716 -- This procedure is called to generate index checks on the subscripts for
|
|
|
717 -- the indexed component node N. Each subscript expression is examined, and
|
|
|
718 -- if the Do_Range_Check flag is set, an appropriate index check is
|
|
|
719 -- generated and the flag is reset.
|
|
|
720
|
|
|
721 -- Similarly, we set the flag Do_Discriminant_Check in the semantic
|
|
|
722 -- analysis to indicate that a discriminant check is required for selected
|
|
|
723 -- component of a discriminated type. The following routine is called from
|
|
|
724 -- the expander to actually generate the call.
|
|
|
725
|
|
|
726 procedure Generate_Discriminant_Check (N : Node_Id);
|
|
|
727 -- N is a selected component for which a discriminant check is required to
|
|
|
728 -- make sure that the discriminants have appropriate values for the
|
|
|
729 -- selection. This is done by calling the appropriate discriminant checking
|
|
|
730 -- routine for the selector.
|
|
|
731
|
|
|
732 -----------------------
|
|
|
733 -- Validity Checking --
|
|
|
734 -----------------------
|
|
|
735
|
|
|
736 -- In (RM 13.9.1(9-11)) we have the following rules on invalid values
|
|
|
737
|
|
|
738 -- If the representation of a scalar object does not represent value of
|
|
|
739 -- the object's subtype (perhaps because the object was not initialized),
|
|
|
740 -- the object is said to have an invalid representation. It is a bounded
|
|
|
741 -- error to evaluate the value of such an object. If the error is
|
|
|
742 -- detected, either Constraint_Error or Program_Error is raised.
|
|
|
743 -- Otherwise, execution continues using the invalid representation. The
|
|
|
744 -- rules of the language outside this subclause assume that all objects
|
|
|
745 -- have valid representations. The semantics of operations on invalid
|
|
|
746 -- representations are as follows:
|
|
|
747 --
|
|
|
748 -- 10 If the representation of the object represents a value of the
|
|
|
749 -- object's type, the value of the type is used.
|
|
|
750 --
|
|
|
751 -- 11 If the representation of the object does not represent a value
|
|
|
752 -- of the object's type, the semantics of operations on such
|
|
|
753 -- representations is implementation-defined, but does not by
|
|
|
754 -- itself lead to erroneous or unpredictable execution, or to
|
|
|
755 -- other objects becoming abnormal.
|
|
|
756
|
|
|
757 -- We quote the rules in full here since they are quite delicate. Most
|
|
|
758 -- of the time, we can just compute away with wrong values, and get a
|
|
|
759 -- possibly wrong result, which is well within the range of allowed
|
|
|
760 -- implementation defined behavior. The two tricky cases are subscripted
|
|
|
761 -- array assignments, where we don't want to do wild stores, and case
|
|
|
762 -- statements where we don't want to do wild jumps.
|
|
|
763
|
|
|
764 -- In GNAT, we control validity checking with a switch -gnatV that can take
|
|
|
765 -- three parameters, n/d/f for None/Default/Full. These modes have the
|
|
|
766 -- following meanings:
|
|
|
767
|
|
|
768 -- None (no validity checking)
|
|
|
769
|
|
|
770 -- In this mode, there is no specific checking for invalid values
|
|
|
771 -- and the code generator assumes that all stored values are always
|
|
|
772 -- within the bounds of the object subtype. The consequences are as
|
|
|
773 -- follows:
|
|
|
774
|
|
|
775 -- For case statements, an out of range invalid value will cause
|
|
|
776 -- Constraint_Error to be raised, or an arbitrary one of the case
|
|
|
777 -- alternatives will be executed. Wild jumps cannot result even
|
|
|
778 -- in this mode, since we always do a range check
|
|
|
779
|
|
|
780 -- For subscripted array assignments, wild stores will result in
|
|
|
781 -- the expected manner when addresses are calculated using values
|
|
|
782 -- of subscripts that are out of range.
|
|
|
783
|
|
|
784 -- It could perhaps be argued that this mode is still conformant with
|
|
|
785 -- the letter of the RM, since implementation defined is a rather
|
|
|
786 -- broad category, but certainly it is not in the spirit of the
|
|
|
787 -- RM requirement, since wild stores certainly seem to be a case of
|
|
|
788 -- erroneous behavior.
|
|
|
789
|
|
|
790 -- Default (default standard RM-compatible validity checking)
|
|
|
791
|
|
|
792 -- In this mode, which is the default, minimal validity checking is
|
|
|
793 -- performed to ensure no erroneous behavior as follows:
|
|
|
794
|
|
|
795 -- For case statements, an out of range invalid value will cause
|
|
|
796 -- Constraint_Error to be raised.
|
|
|
797
|
|
|
798 -- For subscripted array assignments, invalid out of range
|
|
|
799 -- subscript values will cause Constraint_Error to be raised.
|
|
|
800
|
|
|
801 -- Full (Full validity checking)
|
|
|
802
|
|
|
803 -- In this mode, the protections guaranteed by the standard mode are
|
|
|
804 -- in place, and the following additional checks are made:
|
|
|
805
|
|
|
806 -- For every assignment, the right side is checked for validity
|
|
|
807
|
|
|
808 -- For every call, IN and IN OUT parameters are checked for validity
|
|
|
809
|
|
|
810 -- For every subscripted array reference, both for stores and loads,
|
|
|
811 -- all subscripts are checked for validity.
|
|
|
812
|
|
|
813 -- These checks are not required by the RM, but will in practice
|
|
|
814 -- improve the detection of uninitialized variables, particularly
|
|
|
815 -- if used in conjunction with pragma Normalize_Scalars.
|
|
|
816
|
|
|
817 -- In the above description, we talk about performing validity checks,
|
|
|
818 -- but we don't actually generate a check in a case where the compiler
|
|
|
819 -- can be sure that the value is valid. Note that this assurance must
|
|
|
820 -- be achieved without assuming that any uninitialized value lies within
|
|
|
821 -- the range of its type. The following are cases in which values are
|
|
|
822 -- known to be valid. The flag Is_Known_Valid is used to keep track of
|
|
|
823 -- some of these cases.
|
|
|
824
|
|
|
825 -- If all possible stored values are valid, then any uninitialized
|
|
|
826 -- value must be valid.
|
|
|
827
|
|
|
828 -- Literals, including enumeration literals, are clearly always valid
|
|
|
829
|
|
|
830 -- Constants are always assumed valid, with a validity check being
|
|
|
831 -- performed on the initializing value where necessary to ensure that
|
|
|
832 -- this is the case.
|
|
|
833
|
|
|
834 -- For variables, the status is set to known valid if there is an
|
|
|
835 -- initializing expression. Again a check is made on the initializing
|
|
|
836 -- value if necessary to ensure that this assumption is valid. The
|
|
|
837 -- status can change as a result of local assignments to a variable.
|
|
|
838 -- If a known valid value is unconditionally assigned, then we mark
|
|
|
839 -- the left side as known valid. If a value is assigned that is not
|
|
|
840 -- known to be valid, then we mark the left side as invalid. This
|
|
|
841 -- kind of processing does NOT apply to non-local variables since we
|
|
|
842 -- are not following the flow graph (more properly the flow of actual
|
|
|
843 -- processing only corresponds to the flow graph for local assignments).
|
|
|
844 -- For non-local variables, we preserve the current setting, i.e. a
|
|
|
845 -- validity check is performed when assigning to a knonwn valid global.
|
|
|
846
|
|
|
847 -- Note: no validity checking is required if range checks are suppressed
|
|
|
848 -- regardless of the setting of the validity checking mode.
|
|
|
849
|
|
|
850 -- The following procedures are used in handling validity checking
|
|
|
851
|
|
|
852 procedure Apply_Subscript_Validity_Checks (Expr : Node_Id);
|
|
|
853 -- Expr is the node for an indexed component. If validity checking and
|
|
|
854 -- range checking are enabled, all subscripts for this indexed component
|
|
|
855 -- are checked for validity.
|
|
|
856
|
|
|
857 procedure Check_Valid_Lvalue_Subscripts (Expr : Node_Id);
|
|
|
858 -- Expr is a lvalue, i.e. an expression representing the target of an
|
|
|
859 -- assignment. This procedure checks for this expression involving an
|
|
|
860 -- assignment to an array value. We have to be sure that all the subscripts
|
|
|
861 -- in such a case are valid, since according to the rules in (RM
|
|
|
862 -- 13.9.1(9-11)) such assignments are not permitted to result in erroneous
|
|
|
863 -- behavior in the case of invalid subscript values.
|
|
|
864
|
|
|
865 procedure Ensure_Valid
|
|
|
866 (Expr : Node_Id;
|
|
|
867 Holes_OK : Boolean := False;
|
|
|
868 Related_Id : Entity_Id := Empty;
|
|
|
869 Is_Low_Bound : Boolean := False;
|
|
|
870 Is_High_Bound : Boolean := False);
|
|
|
871 -- Ensure that Expr represents a valid value of its type. If this type
|
|
|
872 -- is not a scalar type, then the call has no effect, since validity
|
|
|
873 -- is only an issue for scalar types. The effect of this call is to
|
|
|
874 -- check if the value is known valid, if so, nothing needs to be done.
|
|
|
875 -- If this is not known, then either Expr is set to be range checked,
|
|
|
876 -- or specific checking code is inserted so that an exception is raised
|
|
|
877 -- if the value is not valid.
|
|
|
878 --
|
|
|
879 -- The optional argument Holes_OK indicates whether it is necessary to
|
|
|
880 -- worry about enumeration types with non-standard representations leading
|
|
|
881 -- to "holes" in the range of possible representations. If Holes_OK is
|
|
|
882 -- True, then such values are assumed valid (this is used when the caller
|
|
|
883 -- will make a separate check for this case anyway). If Holes_OK is False,
|
|
|
884 -- then this case is checked, and code is inserted to ensure that Expr is
|
|
|
885 -- valid, raising Constraint_Error if the value is not valid.
|
|
|
886 --
|
|
|
887 -- Related_Id denotes the entity of the context where Expr appears. Flags
|
|
|
888 -- Is_Low_Bound and Is_High_Bound specify whether the expression to check
|
|
|
889 -- is the low or the high bound of a range. These three optional arguments
|
|
|
890 -- signal Remove_Side_Effects to create an external symbol of the form
|
|
|
891 -- Chars (Related_Id)_FIRST/_LAST. For suggested use of these parameters
|
|
|
892 -- see the warning in the body of Sem_Ch3.Process_Range_Expr_In_Decl.
|
|
|
893
|
|
|
894 function Expr_Known_Valid (Expr : Node_Id) return Boolean;
|
|
|
895 -- This function tests it the value of Expr is known to be valid in the
|
|
|
896 -- sense of RM 13.9.1(9-11). In the case of GNAT, it is only discrete types
|
|
|
897 -- which are a concern, since for non-discrete types we simply continue
|
|
|
898 -- computation with invalid values, which does not lead to erroneous
|
|
|
899 -- behavior. Thus Expr_Known_Valid always returns True if the type of Expr
|
|
|
900 -- is non-discrete. For discrete types the value returned is True only if
|
|
|
901 -- it can be determined that the value is Valid. Otherwise False is
|
|
|
902 -- returned.
|
|
|
903
|
|
|
904 procedure Insert_Valid_Check
|
|
|
905 (Expr : Node_Id;
|
|
|
906 Related_Id : Entity_Id := Empty;
|
|
|
907 Is_Low_Bound : Boolean := False;
|
|
|
908 Is_High_Bound : Boolean := False);
|
|
|
909 -- Inserts code that will check for the value of Expr being valid, in the
|
|
|
910 -- sense of the 'Valid attribute returning True. Constraint_Error will be
|
|
|
911 -- raised if the value is not valid.
|
|
|
912 --
|
|
|
913 -- Related_Id denotes the entity of the context where Expr appears. Flags
|
|
|
914 -- Is_Low_Bound and Is_High_Bound specify whether the expression to check
|
|
|
915 -- is the low or the high bound of a range. These three optional arguments
|
|
|
916 -- signal Remove_Side_Effects to create an external symbol of the form
|
|
|
917 -- Chars (Related_Id)_FIRST/_LAST. For suggested use of these parameters
|
|
|
918 -- see the warning in the body of Sem_Ch3.Process_Range_Expr_In_Decl.
|
|
|
919
|
|
|
920 procedure Null_Exclusion_Static_Checks
|
|
|
921 (N : Node_Id;
|
|
|
922 Comp : Node_Id := Empty;
|
|
|
923 Array_Comp : Boolean := False);
|
|
|
924 -- Ada 2005 (AI-231): Test for and warn on null-excluding objects or
|
|
|
925 -- components that will raise an exception due to initialization by null.
|
|
|
926 --
|
|
|
927 -- When a value for Comp is supplied (as in the case of an uninitialized
|
|
|
928 -- null-excluding component within a composite object), a reported warning
|
|
|
929 -- will indicate the offending component instead of the object itself.
|
|
|
930 -- Array_Comp being True indicates an array object with null-excluding
|
|
|
931 -- components, and any reported warning will indicate that.
|
|
|
932
|
|
|
933 procedure Remove_Checks (Expr : Node_Id);
|
|
|
934 -- Remove all checks from Expr except those that are only executed
|
|
|
935 -- conditionally (on the right side of And Then/Or Else. This call
|
|
|
936 -- removes only embedded checks (Do_Range_Check, Do_Overflow_Check).
|
|
|
937
|
|
|
938 procedure Validity_Check_Range
|
|
|
939 (N : Node_Id;
|
|
|
940 Related_Id : Entity_Id := Empty);
|
|
|
941 -- If N is an N_Range node, then Ensure_Valid is called on its bounds, if
|
|
|
942 -- validity checking of operands is enabled. Related_Id denotes the entity
|
|
|
943 -- of the context where N appears.
|
|
|
944
|
|
|
945 -----------------------------
|
|
|
946 -- Handling of Check Names --
|
|
|
947 -----------------------------
|
|
|
948
|
|
|
949 -- The following table contains Name_Id's for recognized checks. The first
|
|
|
950 -- entries (corresponding to the values of the subtype Predefined_Check_Id)
|
|
|
951 -- contain the Name_Id values for the checks that are predefined, including
|
|
|
952 -- All_Checks (see Types). Remaining entries are those that are introduced
|
|
|
953 -- by pragma Check_Names.
|
|
|
954
|
|
|
955 package Check_Names is new Table.Table (
|
|
|
956 Table_Component_Type => Name_Id,
|
|
|
957 Table_Index_Type => Check_Id,
|
|
|
958 Table_Low_Bound => 1,
|
|
|
959 Table_Initial => 30,
|
|
|
960 Table_Increment => 200,
|
|
|
961 Table_Name => "Name_Check_Names");
|
|
|
962
|
|
|
963 function Get_Check_Id (N : Name_Id) return Check_Id;
|
|
|
964 -- Function to search above table for matching name. If found returns the
|
|
|
965 -- corresponding Check_Id value in the range 1 .. Check_Name.Last. If not
|
|
|
966 -- found returns No_Check_Id.
|
|
|
967
|
|
|
968 private
|
|
|
969
|
|
|
970 type Check_Result is array (Positive range 1 .. 2) of Node_Id;
|
|
|
971 -- There are two cases for the result returned by Range_Check:
|
|
|
972 --
|
|
|
973 -- For the static case the result is one or two nodes that should cause
|
|
|
974 -- a Constraint_Error. Typically these will include Expr itself or the
|
|
|
975 -- direct descendants of Expr, such as Low/High_Bound (Expr)). It is the
|
|
|
976 -- responsibility of the caller to rewrite and substitute the nodes with
|
|
|
977 -- N_Raise_Constraint_Error nodes.
|
|
|
978 --
|
|
|
979 -- For the non-static case a single N_Raise_Constraint_Error node with a
|
|
|
980 -- non-empty Condition field is returned.
|
|
|
981 --
|
|
|
982 -- Unused entries in Check_Result, if any, are simply set to Empty For
|
|
|
983 -- external clients, the required processing on this result is achieved
|
|
|
984 -- using the Insert_Range_Checks routine.
|
|
|
985
|
|
|
986 pragma Inline (Apply_Length_Check);
|
|
|
987 pragma Inline (Apply_Range_Check);
|
|
|
988 pragma Inline (Apply_Static_Length_Check);
|
|
|
989 end Checks;
|
