Add in ContinueExpr support

We made an implicit loop begin label that can be referenced in a goto to
restart the loop.

Fixes #188

3 files changed, 83 insertions, 6 deletions

diff --git a/gcc/rust/backend/rust-compile-context.h b/gcc/rust/backend/rust-compile-context.h
index 288b917..76255b0 100644
--- a/gcc/rust/backend/rust-compile-context.h
+++ b/gcc/rust/backend/rust-compile-context.h
@@ -219,6 +219,20 @@ public:
     return back;
   }
 
+  void push_loop_begin_label (Blabel *label)
+  {
+    loop_begin_labels.push_back (label);
+  }
+
+  Blabel *peek_loop_begin_label () { return loop_begin_labels.back (); }
+
+  Blabel *pop_loop_begin_label ()
+  {
+    Blabel *pop = loop_begin_labels.back ();
+    loop_begin_labels.pop_back ();
+    return pop;
+  }
+
 private:
   ::Backend *backend;
   Resolver::Resolver *resolver;
@@ -235,6 +249,7 @@ private:
   std::vector< ::std::vector<Bstatement *> > statements;
   std::vector< ::Bblock *> scope_stack;
   std::vector< ::Bvariable *> loop_value_stack;
+  std::vector< ::Blabel *> loop_begin_labels;
 
   // To GCC middle-end
   std::vector< ::Btype *> type_decls;
diff --git a/gcc/rust/backend/rust-compile-expr.h b/gcc/rust/backend/rust-compile-expr.h
index 1ca7631..1e4aef6 100644
--- a/gcc/rust/backend/rust-compile-expr.h
+++ b/gcc/rust/backend/rust-compile-expr.h
@@ -625,6 +625,13 @@ public:
 	  loop_label.get_lifetime ().get_mappings ().get_hirid (), label);
       }
 
+    Blabel *loop_begin_label
+      = ctx->get_backend ()->label (fnctx.fndecl, "", expr.get_locus ());
+    Bstatement *loop_begin_label_decl
+      = ctx->get_backend ()->label_definition_statement (loop_begin_label);
+    ctx->add_statement (loop_begin_label_decl);
+    ctx->push_loop_begin_label (loop_begin_label);
+
     Bblock *code_block
       = CompileBlock::compile (expr.get_loop_block ().get (), ctx, nullptr);
     Bexpression *loop_expr
@@ -639,6 +646,7 @@ public:
 	translated
 	  = ctx->get_backend ()->var_expression (tmp, expr.get_locus ());
       }
+    ctx->pop_loop_begin_label ();
   }
 
   void visit (HIR::WhileLoopExpr &expr)
@@ -668,6 +676,13 @@ public:
 				    start_location, end_location);
     ctx->push_block (loop_block);
 
+    Blabel *loop_begin_label
+      = ctx->get_backend ()->label (fnctx.fndecl, "", expr.get_locus ());
+    Bstatement *loop_begin_label_decl
+      = ctx->get_backend ()->label_definition_statement (loop_begin_label);
+    ctx->add_statement (loop_begin_label_decl);
+    ctx->push_loop_begin_label (loop_begin_label);
+
     Bexpression *condition
       = CompileExpr::Compile (expr.get_predicate_expr ().get (), ctx);
     Bexpression *exit_expr
@@ -682,6 +697,7 @@ public:
       = ctx->get_backend ()->block_statement (code_block);
     ctx->add_statement (code_block_stmt);
 
+    ctx->pop_loop_begin_label ();
     ctx->pop_block ();
 
     Bexpression *loop_expr
@@ -754,6 +770,45 @@ public:
       }
   }
 
+  void visit (HIR::ContinueExpr &expr)
+  {
+    Blabel *label = ctx->peek_loop_begin_label ();
+    if (expr.has_label ())
+      {
+	NodeId resolved_node_id = UNKNOWN_NODEID;
+	if (!ctx->get_resolver ()->lookup_resolved_label (
+	      expr.get_label ().get_mappings ().get_nodeid (),
+	      &resolved_node_id))
+	  {
+	    rust_error_at (
+	      expr.get_label ().get_locus (),
+	      "failed to resolve compiled label for label %s",
+	      expr.get_label ().get_mappings ().as_string ().c_str ());
+	    return;
+	  }
+
+	HirId ref = UNKNOWN_HIRID;
+	if (!ctx->get_mappings ()->lookup_node_to_hir (
+	      expr.get_mappings ().get_crate_num (), resolved_node_id, &ref))
+	  {
+	    rust_fatal_error (expr.get_locus (),
+			      "reverse lookup label failure");
+	    return;
+	  }
+
+	if (!ctx->lookup_label_decl (ref, &label))
+	  {
+	    rust_error_at (expr.get_label ().get_locus (),
+			   "failed to lookup compiled label");
+	    return;
+	  }
+      }
+
+    Bstatement *goto_label
+      = ctx->get_backend ()->goto_statement (label, expr.get_locus ());
+    ctx->add_statement (goto_label);
+  }
+
 private:
   CompileExpr (Context *ctx) : HIRCompileBase (ctx), translated (nullptr) {}
 
diff --git a/gcc/rust/backend/rust-compile-stmt.h b/gcc/rust/backend/rust-compile-stmt.h
index d021240e4..add969a 100644
--- a/gcc/rust/backend/rust-compile-stmt.h
+++ b/gcc/rust/backend/rust-compile-stmt.h
@@ -66,10 +66,6 @@ public:
 	return;
       }
 
-    // there is an ICE in GCC for void_node
-    if (ty->get_kind () == TyTy::TypeKind::UNIT)
-      return;
-
     Bvariable *var = nullptr;
     if (!ctx->lookup_var_decl (stmt.get_mappings ().get_hirid (), &var))
       {
@@ -79,10 +75,21 @@ public:
       }
 
     Bexpression *init = CompileExpr::Compile (stmt.get_init_expr (), ctx);
+    if (init == nullptr)
+      return;
 
     auto fnctx = ctx->peek_fn ();
-    auto s = ctx->get_backend ()->init_statement (fnctx.fndecl, var, init);
-    ctx->add_statement (s);
+    if (ty->get_kind () == TyTy::TypeKind::UNIT)
+      {
+	Bstatement *expr_stmt
+	  = ctx->get_backend ()->expression_statement (fnctx.fndecl, init);
+	ctx->add_statement (expr_stmt);
+      }
+    else
+      {
+	auto s = ctx->get_backend ()->init_statement (fnctx.fndecl, var, init);
+	ctx->add_statement (s);
+      }
   }
 
 private: