[llvm-commits] [llvm] r96956 - /llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

[Chris Lattner]

On Feb 23, 2010, at 9:37 AM, David Greene wrote:

> Author: greened
> Date: Tue Feb 23 11:37:50 2010
> New Revision: 96956
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=96956&view=rev
> Log:
> 
> Speed up cycle checking significantly by caching results.

Please use a SmallPtrSet instead of std::set, it is much faster for pointers.

-Chris

> 
> Modified:
>    llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
> 
> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp?rev=96956&r1=96955&r2=96956&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (original)
> +++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp Tue Feb 23 11:37:50 2010
> @@ -6315,7 +6315,11 @@
> }
> 
> static void checkForCyclesHelper(const SDNode *N,
> -                                 std::set<const SDNode *> &visited) {
> +                                 std::set<const SDNode *> &visited,
> +                                 std::set<const SDNode *> &checked) {
> +  if (checked.find(N) != checked.end())
> +    return;
> +
>   if (visited.find(N) != visited.end()) {
>     dbgs() << "Offending node:\n";
>     N->dumprFull();
> @@ -6329,16 +6333,18 @@
>   assert(inserted && "Missed cycle");
> 
>   for(unsigned i = 0; i < N->getNumOperands(); ++i) {
> -    checkForCyclesHelper(N->getOperand(i).getNode(), visited);
> +    checkForCyclesHelper(N->getOperand(i).getNode(), visited, checked);
>   }
>   visited.erase(i);
> +  checked.insert(N);
> }
> 
> void llvm::checkForCycles(const llvm::SDNode *N) {
> #ifdef XDEBUG
>   assert(N && "Checking nonexistant SDNode");
>   std::set<const SDNode *> visited;
> -  checkForCyclesHelper(N, visited);
> +  std::set<const SDNode *> checked;
> +  checkForCyclesHelper(N, visited, checked);
> #endif
> }
> 
> 
> 
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