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Fixed algorithmic complexity of AST simplification of long expressions

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This commit is contained in:
Clifford Wolf 2014-01-20 20:25:20 +01:00
parent 32a91458a7
commit 88fbdd4916
3 changed files with 13 additions and 6 deletions
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1
frontends/ast/ast.cc
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@ -181,6 +181,7 @@ AstNode::AstNode(AstNodeType type, AstNode *child1, AstNode *child2)
range_right = 0;
integer = 0;
id2ast = NULL;
basic_prep = false;
if (child1)
children.push_back(child1);

3
frontends/ast/ast.h
View file

@ -153,6 +153,9 @@ namespace AST
// this is set by simplify and used during RTLIL generation
AstNode *id2ast;
// this is used by simplify to detect if basic analysis has been performed already on the node
bool basic_prep;
// this is the original sourcecode location that resulted in this AST node
// it is automatically set by the constructor using AST::current_filename and
// the AST::get_line_num() callback function.

15
frontends/ast/simplify.cc
View file

@ -237,8 +237,8 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
case AST_ASSIGN_EQ:
case AST_ASSIGN_LE:
case AST_ASSIGN:
while (children[0]->simplify(false, false, true, stage, -1, false) == true) { }
while (children[1]->simplify(false, false, false, stage, -1, false) == true) { }
while (!children[0]->basic_prep && children[0]->simplify(false, false, true, stage, -1, false) == true) { }
while (!children[1]->basic_prep && children[1]->simplify(false, false, false, stage, -1, false) == true) { }
children[0]->detectSignWidth(backup_width_hint, backup_sign_hint);
children[1]->detectSignWidth(width_hint, sign_hint);
width_hint = std::max(width_hint, backup_width_hint);
@ -247,11 +247,11 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
case AST_PARAMETER:
case AST_LOCALPARAM:
while (children[0]->simplify(false, false, false, stage, -1, false) == true) { }
while (!children[0]->basic_prep && children[0]->simplify(false, false, false, stage, -1, false) == true) { }
children[0]->detectSignWidth(width_hint, sign_hint);
if (children.size() > 1) {
assert(children[1]->type == AST_RANGE);
while (children[1]->simplify(false, false, false, stage, -1, false) == true) { }
while (!children[1]->basic_prep && children[1]->simplify(false, false, false, stage, -1, false) == true) { }
if (!children[1]->range_valid)
log_error("Non-constant width range on parameter decl at %s:%d.\n", filename.c_str(), linenum);
width_hint = std::max(width_hint, children[1]->range_left - children[1]->range_right + 1);
@ -306,7 +306,7 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
width_hint = -1;
sign_hint = true;
for (auto child : children) {
while (child->simplify(false, false, in_lvalue, stage, -1, false) == true) { }
while (!child->basic_prep && child->simplify(false, false, in_lvalue, stage, -1, false) == true) { }
child->detectSignWidthWorker(width_hint, sign_hint);
}
reset_width_after_children = true;
@ -336,7 +336,7 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
if (detect_width_simple && width_hint < 0) {
for (auto child : children)
while (child->simplify(false, false, in_lvalue, stage, -1, false) == true) { }
while (!child->basic_prep && child->simplify(false, false, in_lvalue, stage, -1, false) == true) { }
if (type == AST_REPLICATE)
while (children[0]->simplify(true, false, in_lvalue, stage, -1, false) == true) { }
detectSignWidth(width_hint, sign_hint);
@ -1425,6 +1425,9 @@ apply_newNode:
did_something = true;
}
if (!did_something)
basic_prep = true;
return did_something;
}