[Mesa-dev] [PATCH] nv50/ir: make sure cfg iterator always hits all blocks

[Samuel Pitoiset]

Reviewed-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>

On 08/19/2016 06:45 AM, Ilia Mirkin wrote:
> In some very specially-crafted cases, we could attempt to visit a node
> that has already been visited, and then run out of bb's to visit, while
> there were still cross blocks on the list. Make sure that those get
> moved over in that case.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96274
> Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
> Cc: mesa-stable at lists.freedesktop.org
> ---
>  src/gallium/drivers/nouveau/codegen/nv50_ir_graph.cpp | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_graph.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_graph.cpp
> index 23414d5..b1076cf 100644
> --- a/src/gallium/drivers/nouveau/codegen/nv50_ir_graph.cpp
> +++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_graph.cpp
> @@ -280,21 +280,24 @@ public:
>     virtual void next() { if (pos < count) ++pos; }
>     virtual void reset() { pos = 0; }
>
>  private:
>     void search(Graph::Node *node, const int sequence)
>     {
>        Stack bb, cross;
>
>        bb.push(node);
>
> -      while (bb.getSize()) {
> +      while (bb.getSize() || cross.getSize()) {
> +         if (bb.getSize() == 0)
> +            cross.moveTo(bb);
> +
>           node = reinterpret_cast<Graph::Node *>(bb.pop().u.p);
>           assert(node);
>           if (!node->visit(sequence))
>              continue;
>           node->tag = 0;
>
>           for (Graph::EdgeIterator ei = node->outgoing(); !ei.end(); ei.next()) {
>              switch (ei.getType()) {
>              case Graph::Edge::TREE:
>              case Graph::Edge::FORWARD:
> @@ -307,23 +310,20 @@ private:
>              case Graph::Edge::CROSS:
>                 if (++(ei.getNode()->tag) == 1)
>                    cross.push(ei.getNode());
>                 break;
>              default:
>                 assert(!"unknown edge kind in CFG");
>                 break;
>              }
>           }
>           nodes[count++] = node;
> -
> -         if (bb.getSize() == 0)
> -            cross.moveTo(bb);
>        }
>     }
>
>  private:
>     Graph::Node **nodes;
>     int count;
>     int pos;
>  };
>
>  IteratorRef Graph::iteratorCFG()
>