github/verilator
1
0
Fork 1
mirror of https://github.com/verilator/verilator.git synced 2025-01-22 14:24:18 +00:00
Code Issues Packages Projects Releases Wiki Activity

Make AstNode::addHereThisAsNext always O(1)

Browse Source 
Using unlinkFrBackWithNext is O(n) in the size of the list if unlinking
from the middle, so addHereThisAsNext also had this complexity. This
patch implements addHereThisAsNext directly, which is always O(1).
This commit is contained in:
Geza Lore 2022-07-12 13:34:41 +01:00
parent 108c900387
commit 178e1789b5
1 changed files with 50 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

55
src/V3Ast.cpp
View File

@ -631,11 +631,56 @@ void AstNode::relinkOneLink(AstNode*& pointpr, // Ref to pointer that gets set
}
void AstNode::addHereThisAsNext(AstNode* newp) {
// {old}->this->{next} becomes {old}->new->this->{next}
VNRelinker handle;
this->unlinkFrBackWithNext(&handle);
newp->addNext(this);
handle.relink(newp);
// {back}->this->{next} becomes {back}->new->this->{next}
UASSERT_OBJ(!newp->backp(), newp, "New node already linked?");
UASSERT_OBJ(this->m_backp, this, "'this' node has no back, already unlinked?");
UASSERT_OBJ(newp->m_headtailp, newp, "m_headtailp not set on new node");
//
AstNode* const backp = this->m_backp;
AstNode* const newLastp = newp->m_headtailp;
//
this->editCountInc();
// Common linkage
newLastp->m_nextp = this;
this->m_backp = newLastp;
newp->m_backp = backp;
// newLastp will not be the last node in the list as 'this' will follow it.
// If newLastp == newp, then below handles newp becoming head
newLastp->m_headtailp = nullptr;
// Linkage dependent on position
if (backp && backp->m_nextp == this) {
// If 'this' is not at the head of a list, then the new node will also not be at the head
// of a list, so we can just link in the new node in the middle.
backp->m_nextp = newp;
newp->m_headtailp = nullptr;
} else {
// If 'this' is at the head of a list, then the new node becomes the head of that list.
if (backp) {
if (backp->m_op1p == this) {
backp->m_op1p = newp;
} else if (backp->m_op2p == this) {
backp->m_op2p = newp;
} else if (backp->m_op3p == this) {
backp->m_op3p = newp;
} else {
UASSERT_OBJ(backp->m_op4p == this, this, "Don't know where newp should go");
backp->m_op4p = newp;
}
}
// We also need to update m_headtailp.
AstNode* const tailp = this->m_headtailp;
this->m_headtailp = nullptr;
newp->m_headtailp = tailp;
tailp->m_headtailp = newp;
}
// Iterator fixup
if (newLastp->m_iterpp) {
*(newLastp->m_iterpp) = this;
} else if (this->m_iterpp) {
*(this->m_iterpp) = newp;
}
//
debugTreeChange(this, "-addHereThisAsNext: ", __LINE__, true);
}
void AstNode::swapWith(AstNode* bp) {