gccrs: backend: Add overflow checks to every arithmetic operation

gcc/rust/ChangeLog:

	* backend/rust-compile-expr.cc (CompileExpr::visit): Insert overflow
	checks logic.
	(CompileExpr::array_copied_expr): Insert overflow checks logic.
	* backend/rust-compile-item.cc (CompileItem::visit): Insert overflow
	checks logic.
	* backend/rust-compile-type.cc (TyTyResolveCompile::visit): Insert
	overflow checks logic.
	* rust-gcc.cc (Gcc_backend::arithmetic_or_logical_expression): Differentiate
	existing function from `arithmetic_or_logical_expression_checked`.
	This function does insert perform overflow checks.
	(Gcc_backend::arithmetic_or_logical_expression_checked): New
	function.
	(is_overflowing_expr): New function. Check if an expression is an
	overflowing one (ADD, SUB, MUL).
	(fetch_overflow_builtins): New function.
	* rust-backend.h: Declare `arithmetic_or_logical_expression_checked` in
	abstract `Backend` class.

gcc/testsuite/ChangeLog:

	* rust/debug/win64-abi.rs: Fix assertion to take into account
	overflow builtins
	* rust/compile/torture/macro-issue1426.rs: Moved to...
	* rust/execute/torture/macro-issue1426.rs: ...here.
	* rust/execute/torture/overflow1.rs: New test.

3 files changed, 55 insertions, 10 deletions

diff --git a/gcc/rust/backend/rust-compile-expr.cc b/gcc/rust/backend/rust-compile-expr.cc
index 9db14a2..ea14673 100644
--- a/gcc/rust/backend/rust-compile-expr.cc
+++ b/gcc/rust/backend/rust-compile-expr.cc
@@ -26,6 +26,7 @@
 #include "rust-compile-block.h"
 #include "rust-compile-implitem.h"
 #include "rust-constexpr.h"
+#include "rust-gcc.h"
 
 #include "fold-const.h"
 #include "realmpfr.h"
@@ -146,9 +147,26 @@ CompileExpr::visit (HIR::ArithmeticOrLogicalExpr &expr)
       return;
     }
 
-  translated
-    = ctx->get_backend ()->arithmetic_or_logical_expression (op, lhs, rhs,
-							     expr.get_locus ());
+  if (ctx->in_fn () && !ctx->const_context_p ())
+    {
+      auto receiver_tmp = NULL_TREE;
+      auto receiver
+	= ctx->get_backend ()->temporary_variable (ctx->peek_fn ().fndecl,
+						   NULL_TREE, TREE_TYPE (lhs),
+						   lhs, true, expr.get_locus (),
+						   &receiver_tmp);
+      auto check
+	= ctx->get_backend ()->arithmetic_or_logical_expression_checked (
+	  op, lhs, rhs, expr.get_locus (), receiver);
+
+      ctx->add_statement (check);
+      translated = receiver->get_tree (expr.get_locus ());
+    }
+  else
+    {
+      translated = ctx->get_backend ()->arithmetic_or_logical_expression (
+	op, lhs, rhs, expr.get_locus ());
+    }
 }
 
 void
@@ -176,13 +194,27 @@ CompileExpr::visit (HIR::CompoundAssignmentExpr &expr)
       return;
     }
 
-  auto operator_expr
-    = ctx->get_backend ()->arithmetic_or_logical_expression (op, lhs, rhs,
-							     expr.get_locus ());
-  tree assignment
-    = ctx->get_backend ()->assignment_statement (lhs, operator_expr,
-						 expr.get_locus ());
-  ctx->add_statement (assignment);
+  if (ctx->in_fn () && !ctx->const_context_p ())
+    {
+      auto tmp = NULL_TREE;
+      auto receiver
+	= ctx->get_backend ()->temporary_variable (ctx->peek_fn ().fndecl,
+						   NULL_TREE, TREE_TYPE (lhs),
+						   lhs, true, expr.get_locus (),
+						   &tmp);
+      auto check
+	= ctx->get_backend ()->arithmetic_or_logical_expression_checked (
+	  op, lhs, rhs, expr.get_locus (), receiver);
+      ctx->add_statement (check);
+
+      translated = ctx->get_backend ()->assignment_statement (
+	lhs, receiver->get_tree (expr.get_locus ()), expr.get_locus ());
+    }
+  else
+    {
+      translated = ctx->get_backend ()->arithmetic_or_logical_expression (
+	op, lhs, rhs, expr.get_locus ());
+    }
 }
 
 void
@@ -2383,7 +2415,10 @@ CompileExpr::array_copied_expr (Location expr_locus,
       return error_mark_node;
     }
 
+  ctx->push_const_context ();
   tree capacity_expr = CompileExpr::Compile (elems.get_num_copies_expr (), ctx);
+  ctx->pop_const_context ();
+
   if (!TREE_CONSTANT (capacity_expr))
     {
       rust_error_at (expr_locus, "non const num copies %qT", array_type);
diff --git a/gcc/rust/backend/rust-compile-item.cc b/gcc/rust/backend/rust-compile-item.cc
index 6977dde..634b983 100644
--- a/gcc/rust/backend/rust-compile-item.cc
+++ b/gcc/rust/backend/rust-compile-item.cc
@@ -160,6 +160,9 @@ CompileItem::visit (HIR::Function &function)
     function.get_mappings ().get_nodeid (), &canonical_path);
   rust_assert (ok);
 
+  if (function.get_qualifiers ().is_const ())
+    ctx->push_const_context ();
+
   tree fndecl
     = compile_function (ctx, function.get_function_name (),
 			function.get_self_param (),
@@ -169,6 +172,9 @@ CompileItem::visit (HIR::Function &function)
 			function.get_definition ().get (), canonical_path,
 			fntype, function.has_function_return_type ());
   reference = address_expression (fndecl, ref_locus);
+
+  if (function.get_qualifiers ().is_const ())
+    ctx->pop_const_context ();
 }
 
 void
diff --git a/gcc/rust/backend/rust-compile-type.cc b/gcc/rust/backend/rust-compile-type.cc
index a81aed7..fe1b7ce 100644
--- a/gcc/rust/backend/rust-compile-type.cc
+++ b/gcc/rust/backend/rust-compile-type.cc
@@ -370,7 +370,11 @@ TyTyResolveCompile::visit (const TyTy::ArrayType &type)
 {
   tree element_type
     = TyTyResolveCompile::compile (ctx, type.get_element_type ());
+
+  ctx->push_const_context ();
   tree capacity_expr = CompileExpr::Compile (&type.get_capacity_expr (), ctx);
+  ctx->pop_const_context ();
+
   tree folded_capacity_expr = fold_expr (capacity_expr);
 
   translated