Force usage of temporary variables for "tainted" member accesses

This is required to handle the side effect of postfix- and unary-
increment/decrement expressions.

Regression of 32ffc862417be39d42a1b8eeb3d0748b3e138aff
and b9035aaf17a9a97a070812a8ee83251fd3893b1e

Fixes https://gitlab.gnome.org/GNOME/vala/issues/1061

diff --git a/codegen/valaccodebasemodule.vala b/codegen/valaccodebasemodule.vala
index 1021c6f69a6cb3b0ab1d6a493221a377e6568ad9..1720340cea82b869d61a6dcaf058d4085a8dfbb2 100644 (file)
--- a/codegen/valaccodebasemodule.vala
+++ b/codegen/valaccodebasemodule.vala
@@ -4413,7 +4413,7 @@ public abstract class Vala.CCodeBaseModule : CodeGenerator {
 
        public abstract TargetValue get_field_cvalue (Field field, TargetValue? instance);
 
-       public abstract TargetValue load_variable (Variable variable, TargetValue value);
+       public abstract TargetValue load_variable (Variable variable, TargetValue value, Expression? expr = null);
 
        public abstract TargetValue load_this_parameter (TypeSymbol sym);
 

diff --git a/codegen/valaccodememberaccessmodule.vala b/codegen/valaccodememberaccessmodule.vala
index 1cec90ac6a9a4037ae2ffb946346ef6be0b0012f..f46ea9dfde83493d9b51217fa2f143912a90b75d 100644 (file)
--- a/codegen/valaccodememberaccessmodule.vala
+++ b/codegen/valaccodememberaccessmodule.vala
@@ -134,7 +134,7 @@ public abstract class Vala.CCodeMemberAccessModule : CCodeControlFlowModule {
                        if (expr.lvalue) {
                                expr.target_value = get_field_cvalue (field, expr.inner != null ? expr.inner.target_value : null);
                        } else {
-                               expr.target_value = load_field (field, expr.inner != null ? expr.inner.target_value : null);
+                               expr.target_value = load_field (field, expr.inner != null ? expr.inner.target_value : null, expr);
                        }
                } else if (expr.symbol_reference is EnumValue) {
                        var ev = (EnumValue) expr.symbol_reference;
@@ -389,7 +389,7 @@ public abstract class Vala.CCodeMemberAccessModule : CCodeControlFlowModule {
                                if (expr.lvalue) {
                                        expr.target_value = get_local_cvalue (local);
                                } else {
-                                       expr.target_value = load_local (local);
+                                       expr.target_value = load_local (local, expr);
                                }
                        }
                } else if (expr.symbol_reference is Parameter) {
@@ -397,7 +397,7 @@ public abstract class Vala.CCodeMemberAccessModule : CCodeControlFlowModule {
                        if (expr.lvalue) {
                                expr.target_value = get_parameter_cvalue (param);
                        } else {
-                               expr.target_value = load_parameter (param);
+                               expr.target_value = load_parameter (param, expr);
                        }
                }
        }
@@ -732,7 +732,7 @@ public abstract class Vala.CCodeMemberAccessModule : CCodeControlFlowModule {
                return result;
        }
 
-       public override TargetValue load_variable (Variable variable, TargetValue value) {
+       public override TargetValue load_variable (Variable variable, TargetValue value, Expression? expr = null) {
                var result = (GLibValue) value;
                var array_type = result.value_type as ArrayType;
                var delegate_type = result.value_type as DelegateType;
@@ -804,6 +804,11 @@ public abstract class Vala.CCodeMemberAccessModule : CCodeControlFlowModule {
                        // no need to an extra copy of variables that are stack allocated simple types
                        use_temp = false;
                }
+               // our implementation of postfix-expressions require temporary variables
+               if (expr is MemberAccess && ((MemberAccess) expr).tainted_access) {
+                       use_temp = true;
+               }
+
                var local = variable as LocalVariable;
                if (local != null && local.name[0] == '.') {
                        // already a temporary variable generated internally
@@ -819,13 +824,13 @@ public abstract class Vala.CCodeMemberAccessModule : CCodeControlFlowModule {
        }
 
        /* Returns unowned access to the given local variable */
-       public override TargetValue load_local (LocalVariable local) {
-               return load_variable (local, get_local_cvalue (local));
+       public override TargetValue load_local (LocalVariable local, Expression? expr = null) {
+               return load_variable (local, get_local_cvalue (local), expr);
        }
 
        /* Returns unowned access to the given parameter */
-       public override TargetValue load_parameter (Parameter param) {
-               return load_variable (param, get_parameter_cvalue (param));
+       public override TargetValue load_parameter (Parameter param, Expression? expr = null) {
+               return load_variable (param, get_parameter_cvalue (param), expr);
        }
 
        /* Convenience method returning access to "this" */
@@ -835,7 +840,7 @@ public abstract class Vala.CCodeMemberAccessModule : CCodeControlFlowModule {
        }
 
        /* Returns unowned access to the given field */
-       public override TargetValue load_field (Field field, TargetValue? instance) {
-               return load_variable (field, get_field_cvalue (field, instance));
+       public override TargetValue load_field (Field field, TargetValue? instance, Expression? expr = null) {
+               return load_variable (field, get_field_cvalue (field, instance), expr);
        }
 }

diff --git a/vala/valacodegenerator.vala b/vala/valacodegenerator.vala
index cea0db8f68bb4e90e7e72e5406d12e9520bfc58e..9452b49a30fb4e590bb0bc145311d14d7a058c87 100644 (file)
--- a/vala/valacodegenerator.vala
+++ b/vala/valacodegenerator.vala
@@ -32,15 +32,15 @@ public abstract class Vala.CodeGenerator : CodeVisitor {
        public virtual void emit (CodeContext context) {
        }
 
-       public abstract TargetValue load_local (LocalVariable local);
+       public abstract TargetValue load_local (LocalVariable local, Expression? expr = null);
 
        public abstract void store_local (LocalVariable local, TargetValue value, bool initializer, SourceReference? source_reference = null);
 
-       public abstract TargetValue load_parameter (Parameter param);
+       public abstract TargetValue load_parameter (Parameter param, Expression? expr = null);
 
        public abstract void store_parameter (Parameter param, TargetValue value, bool capturing_parameter = false, SourceReference? source_reference = null);
 
-       public abstract TargetValue load_field (Field field, TargetValue? instance);
+       public abstract TargetValue load_field (Field field, TargetValue? instance, Expression? expr = null);
 
        public abstract void store_field (Field field, TargetValue? instance, TargetValue value, SourceReference? source_reference = null);
 }

diff --git a/vala/valamemberaccess.vala b/vala/valamemberaccess.vala
index d61e2f3fe2a09965006e6b3a1736cb5cbab49617..ae8c65bdb7f8faf139dfa36eabb3b4b69074d470 100644 (file)
--- a/vala/valamemberaccess.vala
+++ b/vala/valamemberaccess.vala
@@ -57,6 +57,11 @@ public class Vala.MemberAccess : Expression {
         */
        public bool prototype_access { get; set; }
 
+       /**
+        * Requires indirect access due to possible side-effects of parent expression.
+        */
+       public bool tainted_access { get; set; }
+
        /**
         * Specifies whether the member is used for object creation.
         */
@@ -992,6 +997,11 @@ public class Vala.MemberAccess : Expression {
                        value_type.check (context);
                }
 
+               // Provide some extra information for the code generator
+               if (!tainted_access) {
+                       tainted_access = is_tainted ();
+               }
+
                return !error;
        }
 
@@ -1075,4 +1085,36 @@ public class Vala.MemberAccess : Expression {
                        collection.add (param);
                }
        }
+
+       bool is_tainted () {
+               unowned CodeNode node = this;
+               if (node.parent_node is MemberAccess) {
+                       return false;
+               }
+
+               while (node.parent_node is Expression) {
+                       node = node.parent_node;
+                       if (node is Assignment || node is MethodCall) {
+                               break;
+                       }
+               }
+
+               bool found = false;
+               var traverse = new TraverseVisitor ((n) => {
+                       if (n is PostfixExpression) {
+                               found = true;
+                               return TraverseStatus.STOP;
+                       } else if (n is UnaryExpression) {
+                               unowned UnaryExpression e = (UnaryExpression) n;
+                               if (e.operator == UnaryOperator.INCREMENT || e.operator == UnaryOperator.DECREMENT) {
+                                       found = true;
+                                       return TraverseStatus.STOP;
+                               }
+                       }
+                       return TraverseStatus.CONTINUE;
+               });
+               node.accept (traverse);
+
+               return found;
+       }
 }