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Change FindEarliestCallSeqEnd (used by libcall insertion) to use a set to

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avoid revisiting nodes more than once.  This eliminates a source of
potentially exponential behavior.  For a small function in 191.fma3d
(hexah_stress_divergence_), this speeds up isel from taking > 20mins to
taking 0.07s.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22680 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-08-05 18:10:27 +00:00
parent c534395cb2
commit 82299e7097
1 changed files with 9 additions and 5 deletions
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14
lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
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@ -21,6 +21,7 @@
#include "llvm/CallingConv.h"
#include "llvm/Constants.h"
#include <iostream>
#include <set>
using namespace llvm;
//===----------------------------------------------------------------------===//
@ -2285,8 +2286,10 @@ static void FindLatestCallSeqStart(SDNode *Node, SDNode *&Found) {
/// FindEarliestCallSeqEnd - Scan down the dag to find the earliest (lowest
/// NodeDepth) node that is an CallSeqEnd operation and occurs more recent
/// than Found.
static void FindEarliestCallSeqEnd(SDNode *Node, SDNode *&Found) {
if (Found && Node->getNodeDepth() >= Found->getNodeDepth()) return;
static void FindEarliestCallSeqEnd(SDNode *Node, SDNode *&Found,
std::set<SDNode*> &Visited) {
if ((Found && Node->getNodeDepth() >= Found->getNodeDepth()) ||
!Visited.insert(Node).second) return;
// If we found an CALLSEQ_END, we already know this node occurs earlier
// than the Found node. Just remember this node and return.
@ -2299,10 +2302,10 @@ static void FindEarliestCallSeqEnd(SDNode *Node, SDNode *&Found) {
SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
if (UI == E) return;
for (--E; UI != E; ++UI)
FindEarliestCallSeqEnd(*UI, Found);
FindEarliestCallSeqEnd(*UI, Found, Visited);
// Tail recurse for the last iteration.
FindEarliestCallSeqEnd(*UI, Found);
FindEarliestCallSeqEnd(*UI, Found, Visited);
}
/// FindCallSeqEnd - Given a chained node that is part of a call sequence,
@ -2372,7 +2375,8 @@ static SDOperand FindInputOutputChains(SDNode *OpNode, SDNode *&OutChain,
// Finally, find the first call that this must come before, first we find the
// CallSeqEnd that ends the call.
OutChain = 0;
FindEarliestCallSeqEnd(OpNode, OutChain);
std::set<SDNode*> Visited;
FindEarliestCallSeqEnd(OpNode, OutChain, Visited);
// If we found one, translate from the adj up to the callseq_start.
if (OutChain)