Merge #1611

1611: Initial state capture for closures r=philberty a=philberty

This patch set adds the initial support closure captures, move semantics are not
handled here. We track what variables are being captured by a closure during
name resolution so that when a VAR_DECL is resolved, we check if we are inside
a closure context node_id which is the same id as its associated rib id. So when
we resolve a name that resides in an outermost rib we can add this to set of 
node-id's that are captured by this closure.

There is a gap here for the case where we need to check if it is inside a nested
function and that function contains closures which could wrongly capture variables
in the enclosing function. This will also be a problem for nested functions in general.

Fixes #195

Co-authored-by: Philip Herron <[email protected]>

Author: bors[bot]

gcc/rust/backend/rust-compile-context.cc

@@ -142,5 +142,52 @@ Context::type_hasher (tree type)
   return hstate.end ();
 }
 
+void
+Context::push_closure_context (HirId id)
+{
+  auto it = closure_bindings.find (id);
+  rust_assert (it == closure_bindings.end ());
+
+  closure_bindings.insert ({id, {}});
+  closure_scope_bindings.push_back (id);
+}
+
+void
+Context::pop_closure_context ()
+{
+  rust_assert (!closure_scope_bindings.empty ());
+
+  HirId ref = closure_scope_bindings.back ();
+  closure_scope_bindings.pop_back ();
+  closure_bindings.erase (ref);
+}
+
+void
+Context::insert_closure_binding (HirId id, tree expr)
+{
+  rust_assert (!closure_scope_bindings.empty ());
+
+  HirId ref = closure_scope_bindings.back ();
+  closure_bindings[ref].insert ({id, expr});
+}
+
+bool
+Context::lookup_closure_binding (HirId id, tree *expr)
+{
+  if (closure_scope_bindings.empty ())
+    return false;
+
+  HirId ref = closure_scope_bindings.back ();
+  auto it = closure_bindings.find (ref);
+  rust_assert (it != closure_bindings.end ());
+
+  auto iy = it->second.find (id);
+  if (iy == it->second.end ())
+    return false;
+
+  *expr = iy->second;
+  return true;
+}
+
 } // namespace Compile
 } // namespace Rust

gcc/rust/backend/rust-compile-context.h

@@ -345,6 +345,11 @@ class Context
     return mangler.mangle_item (ty, path);
   }
 
+  void push_closure_context (HirId id);
+  void pop_closure_context ();
+  void insert_closure_binding (HirId id, tree expr);
+  bool lookup_closure_binding (HirId id, tree *expr);
+
   std::vector<tree> &get_type_decls () { return type_decls; }
   std::vector<::Bvariable *> &get_var_decls () { return var_decls; }
   std::vector<tree> &get_const_decls () { return const_decls; }
@@ -377,6 +382,10 @@ class Context
   std::map<HirId, tree> implicit_pattern_bindings;
   std::map<hashval_t, tree> main_variants;
 
+  // closure bindings
+  std::vector<HirId> closure_scope_bindings;
+  std::map<HirId, std::map<HirId, tree>> closure_bindings;
+
   // To GCC middle-end
   std::vector<tree> type_decls;
   std::vector<::Bvariable *> var_decls;

gcc/rust/backend/rust-compile-expr.cc

@@ -2824,10 +2824,25 @@ CompileExpr::visit (HIR::ClosureExpr &expr)
 
   // lets ignore state capture for now we need to instantiate the struct anyway
   // then generate the function
-
   std::vector<tree> vals;
-  // TODO
-  // setup argument captures based on the mode?
+  for (const auto &capture : closure_tyty->get_captures ())
+    {
+      // lookup the HirId
+      HirId ref = UNKNOWN_HIRID;
+      bool ok = ctx->get_mappings ()->lookup_node_to_hir (capture, &ref);
+      rust_assert (ok);
+
+      // lookup the var decl
+      Bvariable *var = nullptr;
+      bool found = ctx->lookup_var_decl (ref, &var);
+      rust_assert (found);
+
+      // FIXME
+      // this should bes based on the closure move-ability
+      tree var_expr = var->get_tree (expr.get_locus ());
+      tree val = address_expression (var_expr, expr.get_locus ());
+      vals.push_back (val);
+    }
 
   translated
     = ctx->get_backend ()->constructor_expression (compiled_closure_tyty, false,
@@ -2874,8 +2889,29 @@ CompileExpr::generate_closure_function (HIR::ClosureExpr &expr,
   DECL_ARTIFICIAL (self_param->get_decl ()) = 1;
   param_vars.push_back (self_param);
 
+  // push a new context
+  ctx->push_closure_context (expr.get_mappings ().get_hirid ());
+
   // setup the implicit argument captures
-  // TODO
+  size_t idx = 0;
+  for (const auto &capture : closure_tyty.get_captures ())
+    {
+      // lookup the HirId
+      HirId ref = UNKNOWN_HIRID;
+      bool ok = ctx->get_mappings ()->lookup_node_to_hir (capture, &ref);
+      rust_assert (ok);
+
+      // get the assessor
+      tree binding = ctx->get_backend ()->struct_field_expression (
+	self_param->get_tree (expr.get_locus ()), idx, expr.get_locus ());
+      tree indirection = indirect_expression (binding, expr.get_locus ());
+
+      // insert bindings
+      ctx->insert_closure_binding (ref, indirection);
+
+      // continue
+      idx++;
+    }
 
   // args tuple
   tree args_type
@@ -2905,7 +2941,10 @@ CompileExpr::generate_closure_function (HIR::ClosureExpr &expr,
     }
 
   if (!ctx->get_backend ()->function_set_parameters (fndecl, param_vars))
-    return error_mark_node;
+    {
+      ctx->pop_closure_context ();
+      return error_mark_node;
+    }
 
   // lookup locals
   HIR::Expr *function_body = expr.get_expr ().get ();
@@ -2972,6 +3011,7 @@ CompileExpr::generate_closure_function (HIR::ClosureExpr &expr,
   gcc_assert (TREE_CODE (bind_tree) == BIND_EXPR);
   DECL_SAVED_TREE (fndecl) = bind_tree;
 
+  ctx->pop_closure_context ();
   ctx->pop_fn ();
   ctx->push_function (fndecl);
 

gcc/rust/backend/rust-compile-resolve-path.cc

@@ -121,6 +121,14 @@ ResolvePathRef::resolve (const HIR::PathIdentSegment &final_segment,
       return constant_expr;
     }
 
+  // maybe closure binding
+  tree closure_binding = error_mark_node;
+  if (ctx->lookup_closure_binding (ref, &closure_binding))
+    {
+      TREE_USED (closure_binding) = 1;
+      return closure_binding;
+    }
+
   // this might be a variable reference or a function reference
   Bvariable *var = nullptr;
   if (ctx->lookup_var_decl (ref, &var))

gcc/rust/backend/rust-compile-type.cc

@@ -19,6 +19,7 @@
 #include "rust-compile-type.h"
 #include "rust-compile-expr.h"
 #include "rust-constexpr.h"
+#include "rust-gcc.h"
 
 #include "tree.h"
 
@@ -99,11 +100,39 @@ TyTyResolveCompile::visit (const TyTy::InferType &)
 void
 TyTyResolveCompile::visit (const TyTy::ClosureType &type)
 {
+  auto mappings = ctx->get_mappings ();
+
   std::vector<Backend::typed_identifier> fields;
+
+  size_t i = 0;
+  for (const auto &capture : type.get_captures ())
+    {
+      // lookup the HirId
+      HirId ref = UNKNOWN_HIRID;
+      bool ok = mappings->lookup_node_to_hir (capture, &ref);
+      rust_assert (ok);
+
+      // lookup the var decl type
+      TyTy::BaseType *lookup = nullptr;
+      bool found = ctx->get_tyctx ()->lookup_type (ref, &lookup);
+      rust_assert (found);
+
+      // FIXME get the var pattern name
+      std::string mappings_name = "capture_" + std::to_string (i);
+
+      // FIXME
+      // this should be based on the closure move-ability
+      tree decl_type = TyTyResolveCompile::compile (ctx, lookup);
+      tree capture_type = build_reference_type (decl_type);
+      fields.push_back (Backend::typed_identifier (mappings_name, capture_type,
+						   type.get_ident ().locus));
+    }
+
   tree type_record = ctx->get_backend ()->struct_type (fields);
   RS_CLOSURE_FLAG (type_record) = 1;
 
-  std::string named_struct_str = type.get_ident ().path.get () + "{{closure}}";
+  std::string named_struct_str
+    = type.get_ident ().path.get () + "::{{closure}}";
   translated = ctx->get_backend ()->named_type (named_struct_str, type_record,
 						type.get_ident ().locus);
 }

gcc/rust/resolve/rust-ast-resolve-expr.cc

@@ -209,7 +209,7 @@ ResolveExpr::visit (AST::IfLetExpr &expr)
 
   for (auto &pattern : expr.get_patterns ())
     {
-      PatternDeclaration::go (pattern.get ());
+      PatternDeclaration::go (pattern.get (), Rib::ItemType::Var);
     }
 
   ResolveExpr::go (expr.get_if_block ().get (), prefix, canonical_prefix);
@@ -343,7 +343,7 @@ ResolveExpr::visit (AST::LoopExpr &expr)
       auto label_lifetime_node_id = label.get_lifetime ().get_node_id ();
       resolver->get_label_scope ().insert (
 	CanonicalPath::new_seg (expr.get_node_id (), label_name),
-	label_lifetime_node_id, label.get_locus (), false,
+	label_lifetime_node_id, label.get_locus (), false, Rib::ItemType::Label,
 	[&] (const CanonicalPath &, NodeId, Location locus) -> void {
 	  rust_error_at (label.get_locus (), "label redefined multiple times");
 	  rust_error_at (locus, "was defined here");
@@ -400,7 +400,7 @@ ResolveExpr::visit (AST::WhileLoopExpr &expr)
       auto label_lifetime_node_id = label.get_lifetime ().get_node_id ();
       resolver->get_label_scope ().insert (
 	CanonicalPath::new_seg (label.get_node_id (), label_name),
-	label_lifetime_node_id, label.get_locus (), false,
+	label_lifetime_node_id, label.get_locus (), false, Rib::ItemType::Label,
 	[&] (const CanonicalPath &, NodeId, Location locus) -> void {
 	  rust_error_at (label.get_locus (), "label redefined multiple times");
 	  rust_error_at (locus, "was defined here");
@@ -429,7 +429,7 @@ ResolveExpr::visit (AST::ForLoopExpr &expr)
       auto label_lifetime_node_id = label.get_lifetime ().get_node_id ();
       resolver->get_label_scope ().insert (
 	CanonicalPath::new_seg (label.get_node_id (), label_name),
-	label_lifetime_node_id, label.get_locus (), false,
+	label_lifetime_node_id, label.get_locus (), false, Rib::ItemType::Label,
 	[&] (const CanonicalPath &, NodeId, Location locus) -> void {
 	  rust_error_at (label.get_locus (), "label redefined multiple times");
 	  rust_error_at (locus, "was defined here");
@@ -446,7 +446,7 @@ ResolveExpr::visit (AST::ForLoopExpr &expr)
   resolver->push_new_label_rib (resolver->get_type_scope ().peek ());
 
   // resolve the expression
-  PatternDeclaration::go (expr.get_pattern ().get ());
+  PatternDeclaration::go (expr.get_pattern ().get (), Rib::ItemType::Var);
   ResolveExpr::go (expr.get_iterator_expr ().get (), prefix, canonical_prefix);
   ResolveExpr::go (expr.get_loop_block ().get (), prefix, canonical_prefix);
 
@@ -520,7 +520,7 @@ ResolveExpr::visit (AST::MatchExpr &expr)
       // insert any possible new patterns
       for (auto &pattern : arm.get_patterns ())
 	{
-	  PatternDeclaration::go (pattern.get ());
+	  PatternDeclaration::go (pattern.get (), Rib::ItemType::Var);
 	}
 
       // resolve the body
@@ -581,9 +581,13 @@ ResolveExpr::visit (AST::ClosureExprInner &expr)
       resolve_closure_param (p);
     }
 
+  resolver->push_closure_context (expr.get_node_id ());
+
   ResolveExpr::go (expr.get_definition_expr ().get (), prefix,
 		   canonical_prefix);
 
+  resolver->pop_closure_context ();
+
   resolver->get_name_scope ().pop ();
   resolver->get_type_scope ().pop ();
   resolver->get_label_scope ().pop ();
@@ -606,9 +610,14 @@ ResolveExpr::visit (AST::ClosureExprInnerTyped &expr)
     }
 
   ResolveType::go (expr.get_return_type ().get ());
+
+  resolver->push_closure_context (expr.get_node_id ());
+
   ResolveExpr::go (expr.get_definition_block ().get (), prefix,
 		   canonical_prefix);
 
+  resolver->pop_closure_context ();
+
   resolver->get_name_scope ().pop ();
   resolver->get_type_scope ().pop ();
   resolver->get_label_scope ().pop ();
@@ -617,7 +626,7 @@ ResolveExpr::visit (AST::ClosureExprInnerTyped &expr)
 void
 ResolveExpr::resolve_closure_param (AST::ClosureParam &param)
 {
-  PatternDeclaration::go (param.get_pattern ().get ());
+  PatternDeclaration::go (param.get_pattern ().get (), Rib::ItemType::Param);
 
   if (param.has_type_given ())
     ResolveType::go (param.get_type ().get ());

gcc/rust/resolve/rust-ast-resolve-implitem.h

@@ -56,7 +56,7 @@ class ResolveToplevelImplItem : public ResolverBase
     auto path = prefix.append (decl);
 
     resolver->get_type_scope ().insert (
-      path, type.get_node_id (), type.get_locus (), false,
+      path, type.get_node_id (), type.get_locus (), false, Rib::ItemType::Type,
       [&] (const CanonicalPath &, NodeId, Location locus) -> void {
 	RichLocation r (type.get_locus ());
 	r.add_range (locus);
@@ -72,6 +72,7 @@ class ResolveToplevelImplItem : public ResolverBase
 
     resolver->get_name_scope ().insert (
       path, constant.get_node_id (), constant.get_locus (), false,
+      Rib::ItemType::Const,
       [&] (const CanonicalPath &, NodeId, Location locus) -> void {
 	RichLocation r (constant.get_locus ());
 	r.add_range (locus);
@@ -87,6 +88,7 @@ class ResolveToplevelImplItem : public ResolverBase
 
     resolver->get_name_scope ().insert (
       path, function.get_node_id (), function.get_locus (), false,
+      Rib::ItemType::Function,
       [&] (const CanonicalPath &, NodeId, Location locus) -> void {
 	RichLocation r (function.get_locus ());
 	r.add_range (locus);
@@ -102,6 +104,7 @@ class ResolveToplevelImplItem : public ResolverBase
 
     resolver->get_name_scope ().insert (
       path, method.get_node_id (), method.get_locus (), false,
+      Rib::ItemType::Function,
       [&] (const CanonicalPath &, NodeId, Location locus) -> void {
 	RichLocation r (method.get_locus ());
 	r.add_range (locus);
@@ -141,6 +144,7 @@ class ResolveTopLevelTraitItems : public ResolverBase
 
     resolver->get_name_scope ().insert (
       path, function.get_node_id (), function.get_locus (), false,
+      Rib::ItemType::Function,
       [&] (const CanonicalPath &, NodeId, Location locus) -> void {
 	RichLocation r (function.get_locus ());
 	r.add_range (locus);
@@ -159,6 +163,7 @@ class ResolveTopLevelTraitItems : public ResolverBase
 
     resolver->get_name_scope ().insert (
       path, method.get_node_id (), method.get_locus (), false,
+      Rib::ItemType::Function,
       [&] (const CanonicalPath &, NodeId, Location locus) -> void {
 	RichLocation r (method.get_locus ());
 	r.add_range (locus);
@@ -177,6 +182,7 @@ class ResolveTopLevelTraitItems : public ResolverBase
 
     resolver->get_name_scope ().insert (
       path, constant.get_node_id (), constant.get_locus (), false,
+      Rib::ItemType::Const,
       [&] (const CanonicalPath &, NodeId, Location locus) -> void {
 	RichLocation r (constant.get_locus ());
 	r.add_range (locus);
@@ -194,7 +200,7 @@ class ResolveTopLevelTraitItems : public ResolverBase
     auto cpath = canonical_prefix.append (decl);
 
     resolver->get_type_scope ().insert (
-      path, type.get_node_id (), type.get_locus (), false,
+      path, type.get_node_id (), type.get_locus (), false, Rib::ItemType::Type,
       [&] (const CanonicalPath &, NodeId, Location locus) -> void {
 	RichLocation r (type.get_locus ());
 	r.add_range (locus);
@@ -233,6 +239,7 @@ class ResolveToplevelExternItem : public ResolverBase
 
     resolver->get_name_scope ().insert (
       path, function.get_node_id (), function.get_locus (), false,
+      Rib::ItemType::Function,
       [&] (const CanonicalPath &, NodeId, Location locus) -> void {
 	RichLocation r (function.get_locus ());
 	r.add_range (locus);
@@ -251,6 +258,7 @@ class ResolveToplevelExternItem : public ResolverBase
 
     resolver->get_name_scope ().insert (
       path, item.get_node_id (), item.get_locus (), false,
+      Rib::ItemType::Static,
       [&] (const CanonicalPath &, NodeId, Location locus) -> void {
 	RichLocation r (item.get_locus ());
 	r.add_range (locus);