From 8f520a73b2b7c721c494662949ca9dde1e013bad Mon Sep 17 00:00:00 2001 From: Justin Bogner Date: Mon, 30 Jan 2017 18:29:46 +0000 Subject: [PATCH] SDAG: Update ChainNodesMatched during UpdateChains if a node is replaced Previously, we would hit UB (or the ISD::DELETED_NODE assert) if we happened to replace a node during UpdateChains, because it would be left in the list we were iterating over. This nulls out the pointer when that happens so that we can avoid the issue. Fixes llvm.org/PR31710 llvm-svn: 293522 --- llvm/include/llvm/CodeGen/SelectionDAGISel.h | 2 +- .../CodeGen/SelectionDAG/SelectionDAGISel.cpp | 12 +++++- llvm/test/CodeGen/SystemZ/pr31710.ll | 39 +++++++++++++++++++ 3 files changed, 51 insertions(+), 2 deletions(-) create mode 100644 llvm/test/CodeGen/SystemZ/pr31710.ll diff --git a/llvm/include/llvm/CodeGen/SelectionDAGISel.h b/llvm/include/llvm/CodeGen/SelectionDAGISel.h index f7dc327f3023..c204ce2be069 100644 --- a/llvm/include/llvm/CodeGen/SelectionDAGISel.h +++ b/llvm/include/llvm/CodeGen/SelectionDAGISel.h @@ -307,7 +307,7 @@ private: std::vector OpcodeOffset; void UpdateChains(SDNode *NodeToMatch, SDValue InputChain, - const SmallVectorImpl &ChainNodesMatched, + SmallVectorImpl &ChainNodesMatched, bool isMorphNodeTo); }; diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp index 508ba73315c7..d9d8d0c1fd10 100644 --- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp @@ -2308,7 +2308,7 @@ GetVBR(uint64_t Val, const unsigned char *MatcherTable, unsigned &Idx) { /// to use the new results. void SelectionDAGISel::UpdateChains( SDNode *NodeToMatch, SDValue InputChain, - const SmallVectorImpl &ChainNodesMatched, bool isMorphNodeTo) { + SmallVectorImpl &ChainNodesMatched, bool isMorphNodeTo) { SmallVector NowDeadNodes; // Now that all the normal results are replaced, we replace the chain and @@ -2320,6 +2320,11 @@ void SelectionDAGISel::UpdateChains( // Replace all the chain results with the final chain we ended up with. for (unsigned i = 0, e = ChainNodesMatched.size(); i != e; ++i) { SDNode *ChainNode = ChainNodesMatched[i]; + // If ChainNode is null, it's because we replaced it on a previous + // iteration and we cleared it out of the map. Just skip it. + if (!ChainNode) + continue; + assert(ChainNode->getOpcode() != ISD::DELETED_NODE && "Deleted node left in chain"); @@ -2332,6 +2337,11 @@ void SelectionDAGISel::UpdateChains( if (ChainVal.getValueType() == MVT::Glue) ChainVal = ChainVal.getValue(ChainVal->getNumValues()-2); assert(ChainVal.getValueType() == MVT::Other && "Not a chain?"); + SelectionDAG::DAGNodeDeletedListener NDL( + *CurDAG, [&](SDNode *N, SDNode *E) { + std::replace(ChainNodesMatched.begin(), ChainNodesMatched.end(), N, + static_cast(nullptr)); + }); CurDAG->ReplaceAllUsesOfValueWith(ChainVal, InputChain); // If the node became dead and we haven't already seen it, delete it. diff --git a/llvm/test/CodeGen/SystemZ/pr31710.ll b/llvm/test/CodeGen/SystemZ/pr31710.ll new file mode 100644 index 000000000000..1123827fd939 --- /dev/null +++ b/llvm/test/CodeGen/SystemZ/pr31710.ll @@ -0,0 +1,39 @@ +; RUN: llc < %s -mtriple=s390x-redhat-linux | FileCheck %s +; +; Triggers a path in SelectionDAG's UpdateChains where a node is +; deleted but we try to read it later (pr31710), invoking UB in +; release mode or hitting an assert if they're enabled. + +; CHECK: btldata: +define void @btldata(i64* %u0, i32** %p0, i32** %p1, i32** %p3, i32** %p5, i32** %p7) { +entry: + %x0 = load i32*, i32** %p0, align 8, !tbaa !0 + store i64 0, i64* %u0, align 8, !tbaa !4 + %x1 = load i32*, i32** %p1, align 8, !tbaa !0 + %x2 = load i32, i32* %x1, align 4, !tbaa !6 + %x2ext = sext i32 %x2 to i64 + store i32 %x2, i32* %x1, align 4, !tbaa !6 + %x3 = load i32*, i32** %p3, align 8, !tbaa !0 + %ptr = getelementptr inbounds i32, i32* %x3, i64 %x2ext + %x4 = load i32, i32* %ptr, align 4, !tbaa !6 + %x4inc = add nsw i32 %x4, 1 + store i32 %x4inc, i32* %ptr, align 4, !tbaa !6 + store i64 undef, i64* %u0, align 8, !tbaa !4 + %x5 = load i32*, i32** %p5, align 8, !tbaa !0 + %x6 = load i32, i32* %x5, align 4, !tbaa !6 + store i32 %x6, i32* %x5, align 4, !tbaa !6 + %x7 = load i32*, i32** %p7, align 8, !tbaa !0 + %x8 = load i32, i32* %x7, align 4, !tbaa !6 + %x8inc = add nsw i32 %x8, 1 + store i32 %x8inc, i32* %x7, align 4, !tbaa !6 + ret void +} + +!0 = !{!1, !1, i64 0} +!1 = !{!"any pointer", !2, i64 0} +!2 = !{!"omnipotent char", !3, i64 0} +!3 = !{!"Simple C/C++ TBAA"} +!4 = !{!5, !5, i64 0} +!5 = !{!"long", !2, i64 0} +!6 = !{!7, !7, i64 0} +!7 = !{!"int", !2, i64 0}