SCEVTraversal: Add a visited set.

Expression trees may be DAGs. Make sure traversal has linear complexity.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160426 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2012-07-18 05:14:03 +00:00
parent 76bd9386f1
commit 18a1b616ea

View File

@ -15,6 +15,7 @@
#define LLVM_ANALYSIS_SCALAREVOLUTION_EXPRESSIONS_H
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Support/ErrorHandling.h"
namespace llvm {
@ -505,9 +506,10 @@ namespace llvm {
class SCEVTraversal {
SV &Visitor;
SmallVector<const SCEV *, 8> Worklist;
SmallPtrSet<const SCEV *, 8> Visited;
void push(const SCEV *S) {
if (Visitor.follow(S))
if (Visited.insert(S) && Visitor.follow(S))
Worklist.push_back(S);
}
public: