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1 module dmd.IfStatement;
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2
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3 import dmd.Statement;
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4 import dmd.Argument;
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5 import dmd.Loc;
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6 import dmd.Expression;
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7 import dmd.VarDeclaration;
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8 import dmd.Scope;
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9 import dmd.InterState;
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10 import dmd.OutBuffer;
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11 import dmd.HdrGenState;
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12 import dmd.InlineCostState;
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13 import dmd.InlineDoState;
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14 import dmd.InlineScanState;
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15 import dmd.IRState;
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16 import dmd.BE;
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17 import dmd.WANT;
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18 import dmd.ScopeDsymbol;
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19 import dmd.Type;
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20 import dmd.CondExp;
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21 import dmd.AndAndExp;
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22 import dmd.OrOrExp;
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23 import dmd.AssignExp;
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24 import dmd.VarExp;
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25
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26 import dmd.backend.elem;
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27 import dmd.backend.Util;
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28 import dmd.backend.block;
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29 import dmd.backend.Blockx;
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30 import dmd.backend.BC;
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31
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32 class IfStatement : Statement
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33 {
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34 Argument arg;
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35 Expression condition;
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36 Statement ifbody;
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37 Statement elsebody;
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38
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39 VarDeclaration match; // for MatchExpression results
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40
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41 this(Loc loc, Argument arg, Expression condition, Statement ifbody, Statement elsebody)
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42 {
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43 super(loc);
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44 this.arg = arg;
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45 this.condition = condition;
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46 this.ifbody = ifbody;
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47 this.elsebody = elsebody;
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48 }
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49
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50 Statement syntaxCopy()
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51 {
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52 assert(false);
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53 }
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54
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55 Statement semantic(Scope sc)
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56 {
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57 condition = condition.semantic(sc);
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58 condition = resolveProperties(sc, condition);
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59 condition = condition.checkToBoolean();
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60
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61 // If we can short-circuit evaluate the if statement, don't do the
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62 // semantic analysis of the skipped code.
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63 // This feature allows a limited form of conditional compilation.
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64 condition = condition.optimize(WANT.WANTflags);
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65
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66 // Evaluate at runtime
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67 uint cs0 = sc.callSuper;
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68 uint cs1;
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69
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70 Scope scd;
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71 if (arg)
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72 {
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73 /* Declare arg, which we will set to be the
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74 * result of condition.
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75 */
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76 ScopeDsymbol sym = new ScopeDsymbol();
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77 sym.parent = sc.scopesym;
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78 scd = sc.push(sym);
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79
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80 Type t = arg.type ? arg.type : condition.type;
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81 match = new VarDeclaration(loc, t, arg.ident, null);
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82 match.noauto = true;
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83 match.semantic(scd);
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84 if (!scd.insert(match))
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85 assert(0);
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86
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87 match.parent = sc.func;
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88
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89 /* Generate:
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90 * (arg = condition)
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91 */
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92 VarExp v = new VarExp(Loc(0), match);
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93 condition = new AssignExp(loc, v, condition);
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94 condition = condition.semantic(scd);
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95 }
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96 else
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97 scd = sc.push();
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98
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99 ifbody = ifbody.semantic(scd);
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100 scd.pop();
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101
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102 cs1 = sc.callSuper;
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103 sc.callSuper = cs0;
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104 if (elsebody)
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105 elsebody = elsebody.semanticScope(sc, null, null);
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106
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107 sc.mergeCallSuper(loc, cs1);
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108
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109 return this;
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110 }
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111
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112 Expression interpret(InterState* istate)
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113 {
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114 assert(false);
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115 }
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116
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117 void toCBuffer(OutBuffer buf, HdrGenState* hgs)
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118 {
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119 assert(false);
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120 }
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121
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122 bool usesEH()
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123 {
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124 assert(false);
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125 }
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126
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127 BE blockExit()
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128 {
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129 //printf("IfStatement::blockExit(%p)\n", this);
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130
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131 BE result = BE.BEnone;
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132 if (condition.canThrow())
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133 result |= BE.BEthrow;
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134 if (condition.isBool(true))
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135 {
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136 if (ifbody)
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137 result |= ifbody.blockExit();
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138 else
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139 result |= BE.BEfallthru;
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140 }
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141 else if (condition.isBool(false))
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142 {
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143 if (elsebody)
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144 result |= elsebody.blockExit();
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145 else
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146 result |= BE.BEfallthru;
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147 }
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148 else
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149 {
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150 if (ifbody)
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151 result |= ifbody.blockExit();
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152 else
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153 result |= BE.BEfallthru;
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154
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155 if (elsebody)
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156 result |= elsebody.blockExit();
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157 else
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158 result |= BE.BEfallthru;
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159 }
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160
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161 //printf("IfStatement::blockExit(%p) = x%x\n", this, result);
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162 return result;
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163 }
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164
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165 IfStatement isIfStatement() { return this; }
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166
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167 int inlineCost(InlineCostState* ics)
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168 {
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169 int cost;
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170
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171 /* Can't declare variables inside ?: expressions, so
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172 * we cannot inline if a variable is declared.
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173 */
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174 if (arg)
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175 return COST_MAX;
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176
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177 cost = condition.inlineCost(ics);
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178
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179 /* Specifically allow:
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180 * if (condition)
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181 * return exp1;
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182 * else
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183 * return exp2;
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184 * Otherwise, we can't handle return statements nested in if's.
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185 */
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186
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187 if (elsebody && ifbody &&
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188 ifbody.isReturnStatement() &&
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189 elsebody.isReturnStatement())
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190 {
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191 cost += ifbody.inlineCost(ics);
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192 cost += elsebody.inlineCost(ics);
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193 //printf("cost = %d\n", cost);
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194 }
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195 else
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196 {
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197 ics.nested += 1;
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198 if (ifbody)
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199 cost += ifbody.inlineCost(ics);
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200 if (elsebody)
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201 cost += elsebody.inlineCost(ics);
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202 ics.nested -= 1;
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203 }
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204 return cost;
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205 }
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206
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207 Expression doInline(InlineDoState ids)
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208 {
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209 Expression econd;
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210 Expression e1;
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211 Expression e2;
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212 Expression e;
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213
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214 assert(!arg);
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215 econd = condition.doInline(ids);
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216 assert(econd);
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217 if (ifbody)
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218 e1 = ifbody.doInline(ids);
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219 else
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220 e1 = null;
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221 if (elsebody)
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222 e2 = elsebody.doInline(ids);
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223 else
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224 e2 = null;
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225 if (e1 && e2)
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226 {
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227 e = new CondExp(econd.loc, econd, e1, e2);
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228 e.type = e1.type;
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229 }
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230 else if (e1)
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231 {
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232 e = new AndAndExp(econd.loc, econd, e1);
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233 e.type = Type.tvoid;
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234 }
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235 else if (e2)
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236 {
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237 e = new OrOrExp(econd.loc, econd, e2);
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238 e.type = Type.tvoid;
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239 }
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240 else
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241 {
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242 e = econd;
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243 }
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244 return e;
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245 }
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246
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247 Statement inlineScan(InlineScanState* iss)
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248 {
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249 condition = condition.inlineScan(iss);
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250 if (ifbody)
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251 ifbody = ifbody.inlineScan(iss);
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252 if (elsebody)
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253 elsebody = elsebody.inlineScan(iss);
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254 return this;
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255 }
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256
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257 void toIR(IRState* irs)
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258 {
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259 elem* e;
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260 Blockx* blx = irs.blx;
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261
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262 //printf("IfStatement::toIR('%s')\n", condition.toChars());
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263
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264 IRState mystate = IRState(irs, this);
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265
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266 // bexit is the block that gets control after this IfStatement is done
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267 block* bexit = mystate.breakBlock ? mystate.breakBlock : block_calloc();
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268
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269 incUsage(irs, loc);
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270 static if (false) {
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271 if (match)
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272 {
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273 /* Generate:
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274 * if (match = RTLSYM_IFMATCH(string, pattern)) ...
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275 */
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276 assert(condition.op == TOK.TOKmatch);
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277 e = matchexp_toelem(cast(MatchExp)condition, &mystate, RTLSYM.RTLSYM_IFMATCH);
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278 Symbol *s = match.toSymbol();
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279 symbol_add(s);
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280 e = el_bin(OPeq, TYnptr, el_var(s), e);
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281 }
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282 else
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283 {
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284 e = condition.toElem(&mystate);
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285 }
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286 } else {
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287 e = condition.toElem(&mystate);
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288 }
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289 block_appendexp(blx.curblock, e);
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290 block* bcond = blx.curblock;
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291 block_next(blx, BC.BCiftrue, null);
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292
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293 list_append(&bcond.Bsucc, blx.curblock);
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294 if (ifbody)
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295 ifbody.toIR(&mystate);
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296
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297 list_append(&blx.curblock.Bsucc, bexit);
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298
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299 if (elsebody)
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300 {
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301 block_next(blx, BC.BCgoto, null);
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302 list_append(&bcond.Bsucc, blx.curblock);
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303 elsebody.toIR(&mystate);
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304 list_append(&blx.curblock.Bsucc, bexit);
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305 }
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306 else
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307 list_append(&bcond.Bsucc, bexit);
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308
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309 block_next(blx, BC.BCgoto, bexit);
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310 }
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311 } |
