compiler: Use backend interface for stack allocation.

Stack allocation was being done by making a temporary variable and
taking its address.  This does not work when allocating in a loop
because every allocated variable will refer to the same address.
The backend now provides a way to safely allocate in a loop.

	* go-gcc.cc (Gcc_backend::stack_allocation_expression): New
	method.

From-SVN: r222657

1 files changed, 14 insertions, 0 deletions

diff --git a/gcc/go/go-gcc.cc b/gcc/go/go-gcc.cc
index 08f014f..82ce3ee6 100644
--- a/gcc/go/go-gcc.cc
+++ b/gcc/go/go-gcc.cc
@@ -324,6 +324,9 @@ class Gcc_backend : public Backend
   call_expression(Bexpression* fn, const std::vector<Bexpression*>& args,
                   Bexpression* static_chain, Location);
 
+  Bexpression*
+  stack_allocation_expression(int64_t size, Location);
+
   // Statements.
 
   Bstatement*
@@ -1884,6 +1887,17 @@ Gcc_backend::call_expression(Bexpression* fn_expr,
   return this->make_expression(ret);
 }
 
+// Return an expression that allocates SIZE bytes on the stack.
+
+Bexpression*
+Gcc_backend::stack_allocation_expression(int64_t size, Location location)
+{
+  tree alloca = builtin_decl_explicit(BUILT_IN_ALLOCA);
+  tree size_tree = build_int_cst(integer_type_node, size);
+  tree ret = build_call_expr_loc(location.gcc_location(), alloca, 1, size_tree);
+  return this->make_expression(ret);
+}
+
 // An expression as a statement.
 
 Bstatement*