diff options
| -rw-r--r-- | include/llvm/CodeGen/DAGISelHeader.h | 5 | ||||
| -rw-r--r-- | test/CodeGen/PowerPC/delete-node.ll | 22 |
2 files changed, 27 insertions, 0 deletions
diff --git a/include/llvm/CodeGen/DAGISelHeader.h b/include/llvm/CodeGen/DAGISelHeader.h index 3b4da6618e..28b227772a 100644 --- a/include/llvm/CodeGen/DAGISelHeader.h +++ b/include/llvm/CodeGen/DAGISelHeader.h @@ -108,6 +108,11 @@ void SelectRoot(SelectionDAG &DAG) { // node). while (ISelPosition != CurDAG->allnodes_begin()) { SDNode *Node = --ISelPosition; + // Skip dead nodes. DAGCombiner is expected to eliminate all dead nodes, + // but there are currently some corner cases that it misses. Also, this + // makes it theoretically possible to disable the DAGCombiner. + if (Node->use_empty()) + continue; #if 0 DAG.setSubgraphColor(Node, "red"); #endif diff --git a/test/CodeGen/PowerPC/delete-node.ll b/test/CodeGen/PowerPC/delete-node.ll new file mode 100644 index 0000000000..0b1d734f8a --- /dev/null +++ b/test/CodeGen/PowerPC/delete-node.ll @@ -0,0 +1,22 @@ +; RUN: llvm-as < %s | llc -march=ppc32 + +; The DAGCombiner leaves behind a dead node in this testcase. Currently +; ISel is ignoring dead nodes, though it would be preferable for +; DAGCombiner to be able to eliminate the dead node. + +define void @GrayATo32ARGBTabB(i8* %baseAddr, i16** %cmp, i32 %rowBytes) nounwind { +entry: + br label %bb1 + +bb1: ; preds = %bb1, %entry + %0 = load i16* null, align 2 ; <i16> [#uses=1] + %1 = ashr i16 %0, 4 ; <i16> [#uses=1] + %2 = sext i16 %1 to i32 ; <i32> [#uses=1] + %3 = getelementptr i8* null, i32 %2 ; <i8*> [#uses=1] + %4 = load i8* %3, align 1 ; <i8> [#uses=1] + %5 = zext i8 %4 to i32 ; <i32> [#uses=1] + %6 = shl i32 %5, 24 ; <i32> [#uses=1] + %7 = or i32 0, %6 ; <i32> [#uses=1] + store i32 %7, i32* null, align 4 + br label %bb1 +} |