1 files changed, 62 insertions, 0 deletions
diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
index b2b3876..5dc27e1 100644
--- a/gcc/gimple-fold.c
+++ b/gcc/gimple-fold.c
@@ -51,6 +51,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "gimple-pretty-print.h"
 #include "tree-ssa-address.h"
 #include "langhooks.h"
+#include "gimplify-me.h"
 
 /* Return true when DECL can be referenced from current unit.
    FROM_DECL (if non-null) specify constructor of variable DECL was taken from.
@@ -3548,3 +3549,64 @@ gimple_fold_indirect_ref (tree t)
 
   return NULL_TREE;
 }
+
+/* Return true if CODE is an operation that when operating on signed
+   integer types involves undefined behavior on overflow and the
+   operation can be expressed with unsigned arithmetic.  */
+
+bool
+arith_code_with_undefined_signed_overflow (tree_code code)
+{
+  switch (code)
+    {
+    case PLUS_EXPR:
+    case MINUS_EXPR:
+    case MULT_EXPR:
+    case NEGATE_EXPR:
+    case POINTER_PLUS_EXPR:
+      return true;
+    default:
+      return false;
+    }
+}
+
+/* Rewrite STMT, an assignment with a signed integer or pointer arithmetic
+   operation that can be transformed to unsigned arithmetic by converting
+   its operand, carrying out the operation in the corresponding unsigned
+   type and converting the result back to the original type.
+
+   Returns a sequence of statements that replace STMT and also contain
+   a modified form of STMT itself.  */
+
+gimple_seq
+rewrite_to_defined_overflow (gimple stmt)
+{
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    {
+      fprintf (dump_file, "rewriting stmt with undefined signed "
+	       "overflow ");
+      print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
+    }
+
+  tree lhs = gimple_assign_lhs (stmt);
+  tree type = unsigned_type_for (TREE_TYPE (lhs));
+  gimple_seq stmts = NULL;
+  for (unsigned i = 1; i < gimple_num_ops (stmt); ++i)
+    {
+      gimple_seq stmts2 = NULL;
+      gimple_set_op (stmt, i,
+		     force_gimple_operand (fold_convert (type,
+							 gimple_op (stmt, i)),
+					   &stmts2, true, NULL_TREE));
+      gimple_seq_add_seq (&stmts, stmts2);
+    }
+  gimple_assign_set_lhs (stmt, make_ssa_name (type, stmt));
+  if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR)
+    gimple_assign_set_rhs_code (stmt, PLUS_EXPR);
+  gimple_seq_add_stmt (&stmts, stmt);
+  gimple cvt = gimple_build_assign_with_ops
+      (NOP_EXPR, lhs, gimple_assign_lhs (stmt), NULL_TREE);
+  gimple_seq_add_stmt (&stmts, cvt);
+
+  return stmts;
+}