AST simplifier: optimize constant AST_CASE nodes before recursively descending

diff --git a/frontends/ast/simplify.cc b/frontends/ast/simplify.cc
index 75a2a2364235a4b90544ca40c651bbe7ca547545..d8fdb4c5efc22e2555bd2b150466a41791e53ac6 100644 (file)
--- a/frontends/ast/simplify.cc
+++ b/frontends/ast/simplify.cc
@@ -384,6 +384,41 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
                }
        }
 
+       if (const_fold && type == AST_CASE)
+       {
+               while (children[0]->simplify(const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param)) { }
+               if (children[0]->type == AST_CONSTANT && children[0]->bits_only_01()) {
+                       std::vector<AstNode*> new_children;
+                       new_children.push_back(children[0]);
+                       for (int i = 1; i < GetSize(children); i++) {
+                               AstNode *child = children[i];
+                               log_assert(child->type == AST_COND);
+                               for (auto v : child->children) {
+                                       if (v->type == AST_DEFAULT)
+                                               goto keep_const_cond;
+                                       if (v->type == AST_BLOCK)
+                                               continue;
+                                       while (v->simplify(const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param)) { }
+                                       if (v->type == AST_CONSTANT && v->bits_only_01()) {
+                                               if (v->bits == children[0]->bits) {
+                                                       while (i+1 < GetSize(children))
+                                                               delete children[++i];
+                                                       goto keep_const_cond;
+                                               }
+                                               continue;
+                                       }
+                                       goto keep_const_cond;
+                               }
+                               if (0)
+                       keep_const_cond:
+                                       new_children.push_back(child);
+                               else
+                                       delete child;
+                       }
+                       new_children.swap(children);
+               }
+       }
+
        // simplify all children first
        // (iterate by index as e.g. auto wires can add new children in the process)
        for (size_t i = 0; i < children.size(); i++) {
@@ -1883,37 +1918,6 @@ skip_dynamic_range_lvalue_expansion:;
                                        newNode->realvalue = -children[0]->asReal(sign_hint);
                        }
                        break;
-               case AST_CASE:
-                       if (children[0]->type == AST_CONSTANT && children[0]->bits_only_01()) {
-                               std::vector<AstNode*> new_children;
-                               new_children.push_back(children[0]);
-                               for (int i = 1; i < GetSize(children); i++) {
-                                       AstNode *child = children[i];
-                                       log_assert(child->type == AST_COND);
-                                       for (auto v : child->children) {
-                                               if (v->type == AST_DEFAULT)
-                                                       goto keep_const_cond;
-                                               if (v->type == AST_BLOCK)
-                                                       continue;
-                                               if (v->type == AST_CONSTANT && v->bits_only_01()) {
-                                                       if (v->bits == children[0]->bits) {
-                                                               while (i+1 < GetSize(children))
-                                                                       delete children[++i];
-                                                               goto keep_const_cond;
-                                                       }
-                                                       continue;
-                                               }
-                                               goto keep_const_cond;
-                                       }
-                                       if (0)
-                               keep_const_cond:
-                                               new_children.push_back(child);
-                                       else
-                                               delete child;
-                               }
-                               new_children.swap(children);
-                       }
-                       break;
                case AST_TERNARY:
                        if (children[0]->isConst())
                        {