diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 09e0c3e0008..80ba27f4646 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -4055,16 +4055,54 @@ SDOperand DAGCombiner::visitLOAD(SDNode *N) { if (!LD->isVolatile()) { if (N->getValueType(1) == MVT::Other) { // Unindexed loads. - if (N->hasNUsesOfValue(0, 0)) - return CombineTo(N, DAG.getNode(ISD::UNDEF, N->getValueType(0)), Chain); + if (N->hasNUsesOfValue(0, 0)) { + // It's not safe to use the two value CombineTo variant here. e.g. + // v1, chain2 = load chain1, loc + // v2, chain3 = load chain2, loc + // v3 = add v2, c + // Now we replace use of v1 with undef, use of chain2 with chain1. + // ReplaceAllUsesWith() will iterate through uses of the first load and + // update operands: + // v1, chain2 = load chain1, loc + // v2, chain3 = load chain1, loc + // v3 = add v2, c + // Now the second load is the same as the first load, SelectionDAG cse + // will ensure the use of second load is replaced with the first load. + // v1, chain2 = load chain1, loc + // v3 = add v1, c + // Then v1 is replaced with undef and bad things happen. + std::vector NowDead; + SDOperand Undef = DAG.getNode(ISD::UNDEF, N->getValueType(0)); + DOUT << "\nReplacing.6 "; DEBUG(N->dump(&DAG)); + DOUT << "\nWith: "; DEBUG(Undef.Val->dump(&DAG)); + DOUT << " and 1 other value\n"; + DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 0), Undef, &NowDead); + DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 1), Chain, &NowDead); + removeFromWorkList(N); + for (unsigned i = 0, e = NowDead.size(); i != e; ++i) + removeFromWorkList(NowDead[i]); + DAG.DeleteNode(N); + return SDOperand(N, 0); // Return N so it doesn't get rechecked! + } } else { // Indexed loads. assert(N->getValueType(2) == MVT::Other && "Malformed indexed loads?"); if (N->hasNUsesOfValue(0, 0) && N->hasNUsesOfValue(0, 1)) { - SDOperand Undef0 = DAG.getNode(ISD::UNDEF, N->getValueType(0)); - SDOperand Undef1 = DAG.getNode(ISD::UNDEF, N->getValueType(1)); - SDOperand To[] = { Undef0, Undef1, Chain }; - return CombineTo(N, To, 3); + std::vector NowDead; + SDOperand Undef = DAG.getNode(ISD::UNDEF, N->getValueType(0)); + DOUT << "\nReplacing.6 "; DEBUG(N->dump(&DAG)); + DOUT << "\nWith: "; DEBUG(Undef.Val->dump(&DAG)); + DOUT << " and 2 other values\n"; + DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 0), Undef, &NowDead); + DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 1), + DAG.getNode(ISD::UNDEF, N->getValueType(1)), + &NowDead); + DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 2), Chain, &NowDead); + removeFromWorkList(N); + for (unsigned i = 0, e = NowDead.size(); i != e; ++i) + removeFromWorkList(NowDead[i]); + DAG.DeleteNode(N); + return SDOperand(N, 0); // Return N so it doesn't get rechecked! } } } diff --git a/test/CodeGen/X86/2008-01-16-InvalidDAGCombineXform.ll b/test/CodeGen/X86/2008-01-16-InvalidDAGCombineXform.ll new file mode 100644 index 00000000000..4feb078671f --- /dev/null +++ b/test/CodeGen/X86/2008-01-16-InvalidDAGCombineXform.ll @@ -0,0 +1,30 @@ +; RUN: llvm-as < %s | llc -march=x86 | not grep IMPLICIT_DEF + + %struct.node_t = type { double*, %struct.node_t*, %struct.node_t**, double**, double*, i32, i32 } + +define void @localize_local_bb19_bb(%struct.node_t** %cur_node) { +newFuncRoot: + %tmp1 = load %struct.node_t** %cur_node, align 4 ; <%struct.node_t*> [#uses=1] + %tmp2 = getelementptr %struct.node_t* %tmp1, i32 0, i32 4 ; [#uses=1] + %tmp3 = load double** %tmp2, align 4 ; [#uses=1] + %tmp4 = load %struct.node_t** %cur_node, align 4 ; <%struct.node_t*> [#uses=1] + %tmp5 = getelementptr %struct.node_t* %tmp4, i32 0, i32 4 ; [#uses=1] + store double* %tmp3, double** %tmp5, align 4 + %tmp6 = load %struct.node_t** %cur_node, align 4 ; <%struct.node_t*> [#uses=1] + %tmp7 = getelementptr %struct.node_t* %tmp6, i32 0, i32 3 ; [#uses=1] + %tmp8 = load double*** %tmp7, align 4 ; [#uses=1] + %tmp9 = load %struct.node_t** %cur_node, align 4 ; <%struct.node_t*> [#uses=1] + %tmp10 = getelementptr %struct.node_t* %tmp9, i32 0, i32 3 ; [#uses=1] + store double** %tmp8, double*** %tmp10, align 4 + %tmp11 = load %struct.node_t** %cur_node, align 4 ; <%struct.node_t*> [#uses=1] + %tmp12 = getelementptr %struct.node_t* %tmp11, i32 0, i32 0 ; [#uses=1] + %tmp13 = load double** %tmp12, align 4 ; [#uses=1] + %tmp14 = load %struct.node_t** %cur_node, align 4 ; <%struct.node_t*> [#uses=1] + %tmp15 = getelementptr %struct.node_t* %tmp14, i32 0, i32 0 ; [#uses=1] + store double* %tmp13, double** %tmp15, align 4 + %tmp16 = load %struct.node_t** %cur_node, align 4 ; <%struct.node_t*> [#uses=1] + %tmp17 = getelementptr %struct.node_t* %tmp16, i32 0, i32 1 ; <%struct.node_t**> [#uses=1] + %tmp18 = load %struct.node_t** %tmp17, align 4 ; <%struct.node_t*> [#uses=1] + store %struct.node_t* %tmp18, %struct.node_t** %cur_node, align 4 + ret void +}