ast: cap dynamic range select to size of signal, suppresses warnings

diff --git a/frontends/ast/simplify.cc b/frontends/ast/simplify.cc
index 073b9cbbe4907d7774a88cbf97c575518b2a0391..26c1cc7a97f6522237c0023006502e198aaaf6c1 100644 (file)
--- a/frontends/ast/simplify.cc
+++ b/frontends/ast/simplify.cc
@@ -1732,8 +1732,9 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
                        AstNode *cond = new AstNode(AST_COND, mkconst_int(start_bit, true));
                        AstNode *lvalue = children[0]->clone();
                        lvalue->delete_children();
+                       int end_bit = std::min(start_bit+result_width,source_width) - 1;
                        lvalue->children.push_back(new AstNode(AST_RANGE,
-                                       mkconst_int(start_bit+result_width-1, true), mkconst_int(start_bit, true)));
+                                       mkconst_int(end_bit, true), mkconst_int(start_bit, true)));
                        cond->children.push_back(new AstNode(AST_BLOCK, new AstNode(type, lvalue, children[1]->clone())));
                        newNode->children.push_back(cond);
                }