Support Simple LoopExpr

This is the building block for the rest of loops where we have a basic
infinite loop. Break/Continue reliest on the resolution of labels and
breaks can also make a loop into a BlockExpr

Fixes #106

7 files changed, 65 insertions, 0 deletions

diff --git a/gcc/rust/backend/rust-compile-expr.h b/gcc/rust/backend/rust-compile-expr.h
index 2dabe01..77b8888 100644
--- a/gcc/rust/backend/rust-compile-expr.h
+++ b/gcc/rust/backend/rust-compile-expr.h
@@ -580,6 +580,25 @@ public:
     translated = ResolvePathRef::Compile (&expr, ctx);
   }
 
+  void visit (HIR::LoopExpr &expr)
+  {
+    // loop_start:
+    //      <loop_body>
+    //   goto loop_start;
+    fncontext fnctx = ctx->peek_fn ();
+    Blabel *loop_start
+      = ctx->get_backend ()->label (fnctx.fndecl, "", expr.get_locus ());
+    Bstatement *label_decl_stmt
+      = ctx->get_backend ()->label_definition_statement (loop_start);
+    ctx->add_statement (label_decl_stmt);
+
+    translated = CompileExpr::Compile (expr.get_loop_block ().get (), ctx);
+
+    Bstatement *goto_loop_start_stmt
+      = ctx->get_backend ()->goto_statement (loop_start, Location ());
+    ctx->add_statement (goto_loop_start_stmt);
+  }
+
 private:
   CompileExpr (Context *ctx) : HIRCompileBase (ctx), translated (nullptr) {}
 
diff --git a/gcc/rust/hir/rust-ast-lower-block.h b/gcc/rust/hir/rust-ast-lower-block.h
index f81a242..d3c61df 100644
--- a/gcc/rust/hir/rust-ast-lower-block.h
+++ b/gcc/rust/hir/rust-ast-lower-block.h
@@ -134,6 +134,25 @@ public:
     translated = ASTLoweringBlock::translate (&expr, &terminated);
   }
 
+  void visit (AST::LoopExpr &expr)
+  {
+    std::vector<HIR::Attribute> outer_attribs;
+    HIR::BlockExpr *loop_block
+      = ASTLoweringBlock::translate (expr.get_loop_block ().get (),
+				     &terminated);
+
+    auto crate_num = mappings->get_current_crate ();
+    Analysis::NodeMapping mapping (crate_num, expr.get_node_id (),
+				   mappings->get_next_hir_id (crate_num),
+				   UNKNOWN_LOCAL_DEFID);
+
+    translated
+      = new HIR::LoopExpr (mapping,
+			   std::unique_ptr<HIR::BlockExpr> (loop_block),
+			   expr.get_locus (), HIR::LoopLabel::error (),
+			   std::move (outer_attribs));
+  }
+
 private:
   ASTLoweringExprWithBlock ()
     : ASTLoweringBase (), translated (nullptr), terminated (false)
diff --git a/gcc/rust/hir/rust-ast-lower-expr.h b/gcc/rust/hir/rust-ast-lower-expr.h
index cd1863f..49ac7f1 100644
--- a/gcc/rust/hir/rust-ast-lower-expr.h
+++ b/gcc/rust/hir/rust-ast-lower-expr.h
@@ -697,6 +697,11 @@ public:
 				  std::move (outer_attribs), expr.get_locus ());
   }
 
+  void visit (AST::LoopExpr &expr)
+  {
+    translated = ASTLoweringExprWithBlock::translate (&expr, &terminated);
+  }
+
 private:
   ASTLoweringExpr ()
     : translated (nullptr), translated_array_elems (nullptr), terminated (false)
diff --git a/gcc/rust/hir/tree/rust-hir-expr.h b/gcc/rust/hir/tree/rust-hir-expr.h
index d4af3c2..14b223a 100644
--- a/gcc/rust/hir/tree/rust-hir-expr.h
+++ b/gcc/rust/hir/tree/rust-hir-expr.h
@@ -3334,6 +3334,8 @@ public:
 
   Location get_locus () const { return locus; }
   Location get_locus_slow () const override { return get_locus (); }
+
+  std::unique_ptr<HIR::BlockExpr> &get_loop_block () { return loop_block; };
 };
 
 // 'Loop' expression (i.e. the infinite loop) HIR node
diff --git a/gcc/rust/resolve/rust-ast-resolve-expr.h b/gcc/rust/resolve/rust-ast-resolve-expr.h
index d563f93..e8ee8b3 100644
--- a/gcc/rust/resolve/rust-ast-resolve-expr.h
+++ b/gcc/rust/resolve/rust-ast-resolve-expr.h
@@ -241,6 +241,11 @@ public:
     ResolveExpr::go (expr.get_receiver_expr ().get (), expr.get_node_id ());
   }
 
+  void visit (AST::LoopExpr &expr)
+  {
+    ResolveExpr::go (expr.get_loop_block ().get (), expr.get_node_id ());
+  }
+
 private:
   ResolveExpr (NodeId parent) : ResolverBase (parent) {}
 };
diff --git a/gcc/rust/typecheck/rust-hir-type-check-expr.h b/gcc/rust/typecheck/rust-hir-type-check-expr.h
index cb92332..17e79d4 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-expr.h
+++ b/gcc/rust/typecheck/rust-hir-type-check-expr.h
@@ -741,6 +741,11 @@ public:
       }
   }
 
+  void visit (HIR::LoopExpr &expr)
+  {
+    infered = TypeCheckExpr::Resolve (expr.get_loop_block ().get ());
+  }
+
 private:
   TypeCheckExpr ()
     : TypeCheckBase (), infered (nullptr), infered_array_elems (nullptr)
diff --git a/gcc/testsuite/rust.test/compilable/loop1.rs b/gcc/testsuite/rust.test/compilable/loop1.rs
new file mode 100644
index 0000000..a8ee2f5
--- /dev/null
+++ b/gcc/testsuite/rust.test/compilable/loop1.rs
@@ -0,0 +1,10 @@
+fn main() {
+    let mut a = 1;
+    let mut b = 1;
+
+    loop {
+        let c = a + b;
+        a = b;
+        b = c;
+    }
+}