From 5144469bb4a801c289e47377b9399aa685e5ce99 Mon Sep 17 00:00:00 2001 From: Andrea Di Biagio Date: Tue, 28 Jan 2014 12:53:56 +0000 Subject: [PATCH] [DAGCombiner] Avoid introducing an illegal build_vector when folding a sign_extend. Make sure that we don't introduce illegal build_vector dag nodes when trying to fold a sign_extend of a build_vector. This fixes a regression introduced by r200234. Added test CodeGen/X86/fold-vector-sext-crash.ll to verify that llc no longer crashes with an assertion failure due to an illegal build_vector of type MVT::v4i64. Thanks to Ilia Filippov for spotting this regression and for providing a reproducible test case. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200313 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 24 ++++++++++++++-------- test/CodeGen/X86/fold-vector-sext-crash.ll | 12 +++++++++++ 2 files changed, 27 insertions(+), 9 deletions(-) create mode 100644 test/CodeGen/X86/fold-vector-sext-crash.ll diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 1b0b2ef8979..e96a7aaaf08 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -4583,7 +4583,8 @@ SDValue DAGCombiner::visitSETCC(SDNode *N) { // dag nodes (see for example method DAGCombiner::visitSIGN_EXTEND). // Vector extends are not folded if operations are legal; this is to // avoid introducing illegal build_vector dag nodes. -static SDNode *tryToFoldExtendOfConstant(SDNode *N, SelectionDAG &DAG, +static SDNode *tryToFoldExtendOfConstant(SDNode *N, const TargetLowering &TLI, + SelectionDAG &DAG, bool LegalTypes, bool LegalOperations) { unsigned Opcode = N->getOpcode(); SDValue N0 = N->getOperand(0); @@ -4601,12 +4602,14 @@ static SDNode *tryToFoldExtendOfConstant(SDNode *N, SelectionDAG &DAG, // fold (sext (build_vector AllConstants) -> (build_vector AllConstants) // fold (zext (build_vector AllConstants) -> (build_vector AllConstants) // fold (aext (build_vector AllConstants) -> (build_vector AllConstants) - if (!(VT.isVector() && !LegalOperations && + EVT SVT = VT.getScalarType(); + if (!(VT.isVector() && + (!LegalTypes || (!LegalOperations && TLI.isTypeLegal(SVT))) && ISD::isBuildVectorOfConstantSDNodes(N0.getNode()))) return 0; // We can fold this node into a build_vector. - unsigned VTBits = VT.getScalarType().getSizeInBits(); + unsigned VTBits = SVT.getSizeInBits(); unsigned EVTBits = N0->getValueType(0).getScalarType().getSizeInBits(); unsigned ShAmt = VTBits - EVTBits; SmallVector Elts; @@ -4616,7 +4619,7 @@ static SDNode *tryToFoldExtendOfConstant(SDNode *N, SelectionDAG &DAG, for (unsigned i=0; i != NumElts; ++i) { SDValue Op = N0->getOperand(i); if (Op->getOpcode() == ISD::UNDEF) { - Elts.push_back(DAG.getUNDEF(VT.getScalarType())); + Elts.push_back(DAG.getUNDEF(SVT)); continue; } @@ -4624,10 +4627,10 @@ static SDNode *tryToFoldExtendOfConstant(SDNode *N, SelectionDAG &DAG, const APInt &C = APInt(VTBits, CurrentND->getAPIntValue().getZExtValue()); if (Opcode == ISD::SIGN_EXTEND) Elts.push_back(DAG.getConstant(C.shl(ShAmt).ashr(ShAmt).getZExtValue(), - VT.getScalarType())); + SVT)); else Elts.push_back(DAG.getConstant(C.shl(ShAmt).lshr(ShAmt).getZExtValue(), - VT.getScalarType())); + SVT)); } return DAG.getNode(ISD::BUILD_VECTOR, DL, VT, &Elts[0], NumElts).getNode(); @@ -4723,7 +4726,8 @@ SDValue DAGCombiner::visitSIGN_EXTEND(SDNode *N) { SDValue N0 = N->getOperand(0); EVT VT = N->getValueType(0); - if (SDNode *Res = tryToFoldExtendOfConstant(N, DAG, LegalOperations)) + if (SDNode *Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes, + LegalOperations)) return SDValue(Res, 0); // fold (sext (sext x)) -> (sext x) @@ -4978,7 +4982,8 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) { SDValue N0 = N->getOperand(0); EVT VT = N->getValueType(0); - if (SDNode *Res = tryToFoldExtendOfConstant(N, DAG, LegalOperations)) + if (SDNode *Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes, + LegalOperations)) return SDValue(Res, 0); // fold (zext (zext x)) -> (zext x) @@ -5247,7 +5252,8 @@ SDValue DAGCombiner::visitANY_EXTEND(SDNode *N) { SDValue N0 = N->getOperand(0); EVT VT = N->getValueType(0); - if (SDNode *Res = tryToFoldExtendOfConstant(N, DAG, LegalOperations)) + if (SDNode *Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes, + LegalOperations)) return SDValue(Res, 0); // fold (aext (aext x)) -> (aext x) diff --git a/test/CodeGen/X86/fold-vector-sext-crash.ll b/test/CodeGen/X86/fold-vector-sext-crash.ll new file mode 100644 index 00000000000..52ea7a912b9 --- /dev/null +++ b/test/CodeGen/X86/fold-vector-sext-crash.ll @@ -0,0 +1,12 @@ +; RUN: llc < %s -mcpu=core-avx-i -mtriple=i386-unknown-linux-gnu -mattr=+avx,+popcnt,+cmov + +; Make sure that we don't introduce illegal build_vector dag nodes +; when trying to fold a sign_extend of a constant build_vector. +; After r200234 the test case below was crashing the compiler with an assertion failure +; due to an illegal build_vector of type MVT::v4i64. + +define <4 x i64> @foo(<4 x i64> %A) { + %1 = select <4 x i1> , <4 x i64> %A, <4 x i64> + ret <4 x i64> %1 +} +