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AST simplifier: optimize constant AST_CASE nodes before recursively descending

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This commit is contained in:
Clifford Wolf 2014-10-29 08:29:51 +01:00
parent f9c096eeda
commit 37aa2e02db
1 changed files with 35 additions and 31 deletions
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66
frontends/ast/simplify.cc
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@ -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())
{