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

// Copyright (C) 2020-2023 Free Software Foundation, Inc.

// This file is part of GCC.

// GCC is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 3, or (at your option) any later
// version.

// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
// for more details.

// You should have received a copy of the GNU General Public License
// along with GCC; see the file COPYING3.  If not see
// <http://www.gnu.org/licenses/>.

#include "rust-compile-block.h"
#include "rust-compile-stmt.h"
#include "rust-compile-expr.h"

namespace Rust {
namespace Compile {

CompileBlock::CompileBlock (Context *ctx, Bvariable *result)
  : HIRCompileBase (ctx), translated (nullptr), result (result)
{}

tree
CompileBlock::compile (HIR::BlockExpr *expr, Context *ctx, Bvariable *result)
{
  CompileBlock compiler (ctx, result);
  compiler.visit (*expr);
  return compiler.translated;
}

void
CompileBlock::visit (HIR::BlockExpr &expr)
{
  fncontext fnctx = ctx->peek_fn ();
  tree fndecl = fnctx.fndecl;
  Location start_location = expr.get_locus ();
  Location end_location = expr.get_end_locus ();
  auto body_mappings = expr.get_mappings ();

  Resolver::Rib *rib = nullptr;
  if (!ctx->get_resolver ()->find_name_rib (body_mappings.get_nodeid (), &rib))
    {
      rust_fatal_error (expr.get_locus (), "failed to setup locals per block");
      return;
    }

  std::vector<Bvariable *> locals
    = compile_locals_for_block (ctx, *rib, fndecl);

  tree enclosing_scope = ctx->peek_enclosing_scope ();
  tree new_block = ctx->get_backend ()->block (fndecl, enclosing_scope, locals,
					       start_location, end_location);
  ctx->push_block (new_block);

  for (auto &s : expr.get_statements ())
    {
      auto compiled_expr = CompileStmt::Compile (s.get (), ctx);
      if (compiled_expr != nullptr)
	{
	  tree s = convert_to_void (compiled_expr, ICV_STATEMENT);
	  ctx->add_statement (s);
	}
    }

  if (expr.has_expr ())
    {
      // the previous passes will ensure this is a valid return or
      // a valid trailing expression
      tree compiled_expr = CompileExpr::Compile (expr.expr.get (), ctx);
      if (compiled_expr != nullptr)
	{
	  if (result == nullptr)
	    {
	      ctx->add_statement (compiled_expr);
	    }
	  else
	    {
	      tree result_reference = ctx->get_backend ()->var_expression (
		result, expr.get_final_expr ()->get_locus ());

	      tree assignment
		= ctx->get_backend ()->assignment_statement (result_reference,
							     compiled_expr,
							     expr.get_locus ());
	      ctx->add_statement (assignment);
	    }
	}
    }

  ctx->pop_block ();
  translated = new_block;
}

void
CompileConditionalBlocks::visit (HIR::IfExpr &expr)
{
  fncontext fnctx = ctx->peek_fn ();
  tree fndecl = fnctx.fndecl;
  tree condition_expr = CompileExpr::Compile (expr.get_if_condition (), ctx);
  tree then_block = CompileBlock::compile (expr.get_if_block (), ctx, result);

  translated
    = ctx->get_backend ()->if_statement (fndecl, condition_expr, then_block,
					 NULL, expr.get_locus ());
}

void
CompileConditionalBlocks::visit (HIR::IfExprConseqElse &expr)
{
  fncontext fnctx = ctx->peek_fn ();
  tree fndecl = fnctx.fndecl;
  tree condition_expr = CompileExpr::Compile (expr.get_if_condition (), ctx);
  tree then_block = CompileBlock::compile (expr.get_if_block (), ctx, result);
  tree else_block = CompileBlock::compile (expr.get_else_block (), ctx, result);

  translated
    = ctx->get_backend ()->if_statement (fndecl, condition_expr, then_block,
					 else_block, expr.get_locus ());
}

void
CompileConditionalBlocks::visit (HIR::IfExprConseqIf &expr)
{
  fncontext fnctx = ctx->peek_fn ();
  tree fndecl = fnctx.fndecl;
  tree condition_expr = CompileExpr::Compile (expr.get_if_condition (), ctx);
  tree then_block = CompileBlock::compile (expr.get_if_block (), ctx, result);

  // else block
  std::vector<Bvariable *> locals;
  Location start_location = expr.get_conseq_if_expr ()->get_locus ();
  Location end_location = expr.get_conseq_if_expr ()->get_locus (); // FIXME
  tree enclosing_scope = ctx->peek_enclosing_scope ();
  tree else_block = ctx->get_backend ()->block (fndecl, enclosing_scope, locals,
						start_location, end_location);
  ctx->push_block (else_block);

  tree else_stmt_decl
    = CompileConditionalBlocks::compile (expr.get_conseq_if_expr (), ctx,
					 result);
  ctx->add_statement (else_stmt_decl);

  ctx->pop_block ();

  translated
    = ctx->get_backend ()->if_statement (fndecl, condition_expr, then_block,
					 else_block, expr.get_locus ());
}

} // namespace Compile
} // namespace Rust