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0
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1 module dmd.ReturnStatement;
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2
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3 import dmd.Loc;
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4 import dmd.Statement;
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5 import dmd.GotoStatement;
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6 import dmd.STC;
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7 import dmd.CompoundStatement;
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8 import dmd.Id;
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9 import dmd.AssignExp;
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10 import dmd.ExpStatement;
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11 import dmd.FuncDeclaration;
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12 import dmd.IntegerExp;
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13 import dmd.ThisExp;
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14 import dmd.StructDeclaration;
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15 import dmd.TypeFunction;
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16 import dmd.CSX;
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17 import dmd.RET;
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18 import dmd.TOK;
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19 import dmd.Type;
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20 import dmd.Expression;
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21 import dmd.StructLiteralExp;
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22 import dmd.TypeStruct;
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23 import dmd.Scope;
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24 import dmd.OutBuffer;
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25 import dmd.HdrGenState;
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26 import dmd.InterState;
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27 import dmd.InlineCostState;
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28 import dmd.InlineDoState;
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29 import dmd.InlineScanState;
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30 import dmd.IRState;
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31 import dmd.TY;
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32 import dmd.WANT;
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33 import dmd.VarExp;
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34 import dmd.VarDeclaration;
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63
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35 import dmd.GlobalExpressions;
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0
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36 import dmd.BE;
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37 import dmd.codegen.Util;
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38
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39 import dmd.backend.Blockx;
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40 import dmd.backend.elem;
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41 import dmd.backend.TYM;
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42 import dmd.backend.Util;
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43 import dmd.backend.OPER;
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44 import dmd.backend.mTY;
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45 import dmd.backend.BC;
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46
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47 class ReturnStatement : Statement
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48 {
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49 Expression exp;
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50
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51 this(Loc loc, Expression exp)
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52 {
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53 super(loc);
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54 this.exp = exp;
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55 }
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56
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57 Statement syntaxCopy()
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58 {
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59 Expression e = exp ? exp.syntaxCopy() : null;
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60 return new ReturnStatement(loc, e);
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61 }
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62
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63 void toCBuffer(OutBuffer buf, HdrGenState* hgs)
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64 {
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65 assert(false);
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66 }
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67
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68 Statement semantic(Scope sc)
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69 {
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70 //printf("ReturnStatement.semantic() %s\n", toChars());
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71
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72 FuncDeclaration fd = sc.parent.isFuncDeclaration();
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73 Scope scx = sc;
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74 int implicit0 = 0;
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75
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76 if (sc.fes)
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77 {
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78 // Find scope of function foreach is in
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79 for (; 1; scx = scx.enclosing)
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80 {
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81 assert(scx);
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82 if (scx.func !is fd)
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83 {
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84 fd = scx.func; // fd is now function enclosing foreach
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85 break;
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86 }
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87 }
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88 }
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89
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90 Type tret = fd.type.nextOf();
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91 if (fd.tintro) {
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92 /* We'll be implicitly casting the return expression to tintro
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93 */
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94 tret = fd.tintro.nextOf();
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95 }
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96
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97 Type tbret = null;
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98
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99 if (tret) {
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100 tbret = tret.toBasetype();
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101 }
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102
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103 // main() returns 0, even if it returns void
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104 if (!exp && (!tbret || tbret.ty == TY.Tvoid) && fd.isMain())
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105 {
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106 implicit0 = 1;
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107 exp = new IntegerExp(0);
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108 }
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109
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110 if (sc.incontract || scx.incontract)
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111 error("return statements cannot be in contracts");
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112
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113 if (sc.tf || scx.tf)
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114 error("return statements cannot be in finally, scope(exit) or scope(success) bodies");
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115
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116 if (fd.isCtorDeclaration())
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117 {
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118 // Constructors implicitly do:
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119 // return this;
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120 if (exp && exp.op != TOK.TOKthis) {
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121 error("cannot return expression from constructor");
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122 }
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123
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124 exp = new ThisExp(Loc(0));
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125 }
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126
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127 if (!exp) {
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128 fd.nrvo_can = 0;
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129 }
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130
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131 if (exp)
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132 {
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133 fd.hasReturnExp |= 1;
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134
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135 exp = exp.semantic(sc);
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136 exp = resolveProperties(sc, exp);
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137 exp = exp.optimize(WANT.WANTvalue);
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138
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139 if (fd.nrvo_can && exp.op == TOK.TOKvar) {
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140 VarExp ve = cast(VarExp)exp;
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141 VarDeclaration v = ve.var.isVarDeclaration();
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142
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143 if ((cast(TypeFunction)fd.type).isref) {
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144 // Function returns a reference
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145 fd.nrvo_can = 0;
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146 } else if (!v || v.isOut() || v.isRef()) {
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147 fd.nrvo_can = 0;
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148 } else if (tbret.ty == TY.Tstruct && (cast(TypeStruct)tbret).sym.dtor) {
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149 // Struct being returned has destructors
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150 fd.nrvo_can = 0;
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151 } else if (fd.nrvo_var is null) {
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152 if (!v.isDataseg() && !v.isParameter() && v.toParent2() == fd) {
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153 //printf("Setting nrvo to %s\n", v.toChars());
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154 fd.nrvo_var = v;
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155 } else {
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156 fd.nrvo_can = 0;
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157 }
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158 } else if (fd.nrvo_var != v) {
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159 fd.nrvo_can = 0;
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160 }
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161 } else {
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162 fd.nrvo_can = 0;
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163 }
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164
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165 if (fd.returnLabel && tbret.ty != TY.Tvoid) {
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166 ;
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167 } else if (fd.inferRetType) {
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168 if (fd.type.nextOf()) {
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169 if (!exp.type.equals(fd.type.nextOf()))
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170 error("mismatched function return type inference of %s and %s", exp.type.toChars(), fd.type.nextOf().toChars());
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171 }
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172 else
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173 {
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174 (cast(TypeFunction)fd.type).next = exp.type;
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175 fd.type = fd.type.semantic(loc, sc);
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176 if (!fd.tintro)
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177 {
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178 tret = fd.type.nextOf();
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179 tbret = tret.toBasetype();
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180 }
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181 }
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182 } else if (tbret.ty != TY.Tvoid)
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183 {
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184 exp = exp.implicitCastTo(sc, tret);
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185 exp = exp.optimize(WANT.WANTvalue);
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186 }
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187 } else if (fd.inferRetType) {
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188 if (fd.type.nextOf())
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189 {
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190 if (fd.type.nextOf().ty != TY.Tvoid) {
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191 error("mismatched function return type inference of void and %s", fd.type.nextOf().toChars());
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192 }
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193 }
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194 else
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195 {
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196 (cast(TypeFunction*)fd.type).next = Type.tvoid;
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197 fd.type = fd.type.semantic(loc, sc);
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198 if (!fd.tintro)
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199 {
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200 tret = Type.tvoid;
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201 tbret = tret;
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202 }
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203 }
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204 }
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205 else if (tbret.ty != TY.Tvoid) {// if non-void return
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206 error("return expression expected");
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207 }
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208
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209 if (sc.fes)
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210 {
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211 Statement s;
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212
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213 if (exp && !implicit0)
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214 {
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215 exp = exp.implicitCastTo(sc, tret);
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216 }
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217 if (!exp || exp.op == TOK.TOKint64 || exp.op == TOK.TOKfloat64 ||
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218 exp.op == TOK.TOKimaginary80 || exp.op == TOK.TOKcomplex80 ||
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219 exp.op == TOK.TOKthis || exp.op == TOK.TOKsuper || exp.op == TOK.TOKnull ||
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220 exp.op == TOK.TOKstring)
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221 {
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222 sc.fes.cases.push(cast(void*)this);
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223 // Construct: return cases.dim+1;
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224 s = new ReturnStatement(Loc(0), new IntegerExp(sc.fes.cases.dim + 1));
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225 }
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226 else if (fd.type.nextOf().toBasetype() == Type.tvoid)
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227 {
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228 s = new ReturnStatement(Loc(0), null);
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229 sc.fes.cases.push(cast(void*)s);
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230
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231 // Construct: { exp; return cases.dim + 1; }
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232 Statement s1 = new ExpStatement(loc, exp);
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233 Statement s2 = new ReturnStatement(Loc(0), new IntegerExp(sc.fes.cases.dim + 1));
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234 s = new CompoundStatement(loc, s1, s2);
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235 }
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236 else
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237 {
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238 // Construct: return vresult;
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239 if (!fd.vresult)
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240 {
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241 // Declare vresult
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242 VarDeclaration v = new VarDeclaration(loc, tret, Id.result, null);
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243 v.noauto = true;
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244 v.semantic(scx);
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245 if (!scx.insert(v)) {
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246 assert(0);
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247 }
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248 v.parent = fd;
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249 fd.vresult = v;
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250 }
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251
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252 s = new ReturnStatement(Loc(0), new VarExp(Loc(0), fd.vresult));
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253 sc.fes.cases.push(cast(void*)s);
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254
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255 // Construct: { vresult = exp; return cases.dim + 1; }
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256 exp = new AssignExp(loc, new VarExp(Loc(0), fd.vresult), exp);
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257 exp.op = TOK.TOKconstruct;
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258 exp = exp.semantic(sc);
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259 Statement s1 = new ExpStatement(loc, exp);
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260 Statement s2 = new ReturnStatement(Loc(0), new IntegerExp(sc.fes.cases.dim + 1));
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261 s = new CompoundStatement(loc, s1, s2);
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262 }
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263 return s;
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264 }
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265
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266 if (exp)
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267 {
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268 if (fd.returnLabel && tbret.ty != TY.Tvoid)
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269 {
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270 assert(fd.vresult);
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271 VarExp v = new VarExp(Loc(0), fd.vresult);
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272
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273 exp = new AssignExp(loc, v, exp);
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274 exp.op = TOK.TOKconstruct;
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275 exp = exp.semantic(sc);
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276 }
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277
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278 if ((cast(TypeFunction)fd.type).isref && !fd.isCtorDeclaration())
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279 { // Function returns a reference
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280 if (tbret.isMutable())
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281 exp = exp.modifiableLvalue(sc, exp);
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282 else
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283 exp = exp.toLvalue(sc, exp);
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284
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285 if (exp.op == TOK.TOKvar)
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286 {
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287 VarExp ve = cast(VarExp)exp;
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288 VarDeclaration v = ve.var.isVarDeclaration();
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289 if (v && !v.isDataseg() && !(v.storage_class & (STC.STCref | STC.STCout))) {
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290 error("escaping reference to local variable %s", v.toChars());
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291 }
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292 }
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293 }
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294
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295 //exp.dump(0);
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296 //exp.print();
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297 exp.checkEscape();
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298 }
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299
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300 /* BUG: need to issue an error on:
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301 * this
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302 * { if (x) return;
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303 * super();
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304 * }
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305 */
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306
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307 if (sc.callSuper & CSX.CSXany_ctor && !(sc.callSuper & (CSX.CSXthis_ctor | CSX.CSXsuper_ctor))) {
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308 error("return without calling constructor");
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309 }
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310
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311 sc.callSuper |= CSX.CSXreturn;
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312
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313 // See if all returns are instead to be replaced with a goto returnLabel;
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314 if (fd.returnLabel)
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315 {
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316 GotoStatement gs = new GotoStatement(loc, Id.returnLabel);
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317
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318 gs.label = fd.returnLabel;
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319 if (exp)
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320 {
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321 /* Replace: return exp;
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322 * with: exp; goto returnLabel;
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323 */
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324 Statement s = new ExpStatement(Loc(0), exp);
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325 return new CompoundStatement(loc, s, gs);
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326 }
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327 return gs;
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328 }
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329
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330 if (exp && tbret.ty == TY.Tvoid && !fd.isMain())
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331 {
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332 /* Replace:
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333 * return exp;
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334 * with:
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335 * exp; return;
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336 */
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337 Statement s = new ExpStatement(loc, exp);
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338 loc = Loc(0);
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339 exp = null;
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340 return new CompoundStatement(loc, s, this);
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341 }
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342
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343 return this;
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344 }
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345
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346 BE blockExit()
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347 {
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348 BE result = BE.BEreturn;
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349 if (exp && exp.canThrow())
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350 result |= BE.BEthrow;
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351
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352 return result;
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353 }
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354
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63
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355 Expression interpret(InterState istate)
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0
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356 {
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63
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357 version (LOG) {
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358 printf("ReturnStatement.interpret(%s)\n", exp ? exp.toChars() : "");
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359 }
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360 mixin(START!());
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361 if (!exp)
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362 return EXP_VOID_INTERPRET;
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363 version (LOG) {
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364 Expression e = exp.interpret(istate);
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365 printf("e = %p\n", e);
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366 return e;
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367 } else {
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368 return exp.interpret(istate);
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369 }
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0
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370 }
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371
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372 int inlineCost(InlineCostState* ics)
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373 {
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374 // Can't handle return statements nested in if's
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375 if (ics.nested)
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376 return COST_MAX;
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377 return exp ? exp.inlineCost(ics) : 0;
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378 }
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379
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380 Expression doInline(InlineDoState ids)
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381 {
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382 //printf("ReturnStatement.doInline() '%s'\n", exp ? exp.toChars() : "");
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383 return exp ? exp.doInline(ids) : null;
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384 }
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385
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386 Statement inlineScan(InlineScanState* iss)
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387 {
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388 //printf("ReturnStatement.inlineScan()\n");
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389 if (exp)
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390 {
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391 exp = exp.inlineScan(iss);
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392 }
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393 return this;
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394 }
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395
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396 void toIR(IRState* irs)
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397 {
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398 Blockx* blx = irs.blx;
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399
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400 incUsage(irs, loc);
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401 if (exp)
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402 {
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403 elem *e;
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404
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405 FuncDeclaration func = irs.getFunc();
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406 assert(func);
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407 assert(func.type.ty == TY.Tfunction);
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408 TypeFunction tf = cast(TypeFunction)(func.type);
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409
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410 RET retmethod = tf.retStyle();
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411 if (retmethod == RET.RETstack)
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412 {
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413 elem* es;
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414
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415 /* If returning struct literal, write result
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416 * directly into return value
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417 */
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418 if (exp.op == TOK.TOKstructliteral)
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419 {
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420 assert(false);
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421 /*
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422 StructLiteralExp se = cast(StructLiteralExp)exp;
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423 char save[(StructLiteralExp).sizeof];
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424 memcpy(save, se, sizeof(StructLiteralExp));
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425 se.sym = irs.shidden;
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426 se.soffset = 0;
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427 se.fillHoles = 1;
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428 e = exp.toElem(irs);
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429 memcpy(se, save, sizeof(StructLiteralExp));
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430 */
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431 }
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432 else
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|
433 e = exp.toElem(irs);
|
|
|
434
|
|
|
435 assert(e);
|
|
|
436
|
|
|
437 if (exp.op == TOK.TOKstructliteral || (func.nrvo_can && func.nrvo_var))
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|
|
438 {
|
|
|
439 // Return value via hidden pointer passed as parameter
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|
|
440 // Write exp; return shidden;
|
|
|
441 es = e;
|
|
|
442 }
|
|
|
443 else
|
|
|
444 {
|
|
|
445 // Return value via hidden pointer passed as parameter
|
|
|
446 // Write *shidden=exp; return shidden;
|
|
|
447 int op;
|
|
|
448 tym_t ety;
|
|
|
449
|
|
|
450 ety = e.Ety;
|
|
|
451 es = el_una(OPER.OPind,ety,el_var(irs.shidden));
|
|
|
452 op = (tybasic(ety) == TYM.TYstruct) ? OPER.OPstreq : OPER.OPeq;
|
|
|
453 es = el_bin(op, ety, es, e);
|
|
|
454 if (op == OPER.OPstreq)
|
|
|
455 es.Enumbytes = cast(uint)exp.type.size();
|
|
|
456 version (DMDV2) {
|
|
|
457 /* Call postBlit() on *shidden
|
|
|
458 */
|
|
|
459 Type tb = exp.type.toBasetype();
|
|
|
460 //if (tb.ty == TY.Tstruct) exp.dump(0);
|
|
|
461 if ((exp.op == TOK.TOKvar || exp.op == TOK.TOKdotvar || exp.op == TOK.TOKstar) &&
|
|
|
462 tb.ty == TY.Tstruct)
|
|
|
463 { StructDeclaration sd = (cast(TypeStruct)tb).sym;
|
|
|
464 if (sd.postblit)
|
|
|
465 {
|
|
|
466 FuncDeclaration fd = sd.postblit;
|
|
|
467 elem* ec = el_var(irs.shidden);
|
|
|
468 ec = callfunc(loc, irs, 1, Type.tvoid, ec, tb.pointerTo(), fd, fd.type, null, null);
|
|
|
469 es = el_bin(OPER.OPcomma, ec.Ety, es, ec);
|
|
|
470 }
|
|
|
471
|
|
|
472 static if (false) {
|
|
|
473 /* It has been moved, so disable destructor
|
|
|
474 */
|
|
|
475 if (exp.op == TOK.TOKvar)
|
|
|
476 {
|
|
|
477 VarExp ve = cast(VarExp)exp;
|
|
|
478 VarDeclaration v = ve.var.isVarDeclaration();
|
|
|
479 if (v && v.rundtor)
|
|
|
480 {
|
|
|
481 elem* er = el_var(v.rundtor.toSymbol());
|
|
|
482 er = el_bin(OPER.OPeq, TYM.TYint, er, el_long(TYM.TYint, 0));
|
|
|
483 es = el_bin(OPER.OPcomma, TYM.TYint, es, er);
|
|
|
484 }
|
|
|
485 }
|
|
|
486 }
|
|
|
487 }
|
|
|
488 }
|
|
|
489 }
|
|
|
490 e = el_var(irs.shidden);
|
|
|
491 e = el_bin(OPER.OPcomma, e.Ety, es, e);
|
|
|
492 }
|
|
|
493 ///version (DMDV2) {
|
|
|
494 else if (tf.isref)
|
|
|
495 { // Reference return, so convert to a pointer
|
|
|
496 Expression ae = exp.addressOf(null);
|
|
|
497 e = ae.toElem(irs);
|
|
|
498 }
|
|
|
499 ///}
|
|
|
500 else
|
|
|
501 {
|
|
|
502 e = exp.toElem(irs);
|
|
|
503 assert(e);
|
|
|
504 }
|
|
|
505
|
|
|
506 block_appendexp(blx.curblock, e);
|
|
|
507 block_next(blx, BC.BCretexp, null);
|
|
|
508 }
|
|
|
509 else
|
|
|
510 block_next(blx, BC.BCret, null);
|
|
|
511 }
|
|
|
512
|
|
|
513 ReturnStatement isReturnStatement() { return this; }
|
|
|
514 } |
