From: Craig Topper Date: Tue, 22 Aug 2017 05:40:17 +0000 (+0000) Subject: [X86] Prevent several calls to ISD::isConstantSplatVector from returning a narrower... X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=03d86003806680cb5e7b955728e7331206c15562;p=llvm [X86] Prevent several calls to ISD::isConstantSplatVector from returning a narrower APInt than the original scalar type ISD::isConstantSplatVector can shrink to the smallest splat width. But we don't check the size of the resulting APInt at all. This can cause us to misinterpret the results. This patch just adds a flag to prevent the APInt from changing width. Fixes PR34271. Differential Revision: https://reviews.llvm.org/D36996 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311429 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/include/llvm/CodeGen/SelectionDAGNodes.h b/include/llvm/CodeGen/SelectionDAGNodes.h index db42fb6c170..051c93601d3 100644 --- a/include/llvm/CodeGen/SelectionDAGNodes.h +++ b/include/llvm/CodeGen/SelectionDAGNodes.h @@ -85,7 +85,10 @@ namespace ISD { /// If N is a BUILD_VECTOR node whose elements are all the same constant or /// undefined, return true and return the constant value in \p SplatValue. - bool isConstantSplatVector(const SDNode *N, APInt &SplatValue); + /// This sets \p SplatValue to the smallest possible splat unless AllowShrink + /// is set to false. + bool isConstantSplatVector(const SDNode *N, APInt &SplatValue, + bool AllowShrink = true); /// Return true if the specified node is a BUILD_VECTOR where all of the /// elements are ~0 or undef. diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index 508316a1fad..6489ca57b33 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -116,7 +116,8 @@ bool ConstantFPSDNode::isValueValidForType(EVT VT, // ISD Namespace //===----------------------------------------------------------------------===// -bool ISD::isConstantSplatVector(const SDNode *N, APInt &SplatVal) { +bool ISD::isConstantSplatVector(const SDNode *N, APInt &SplatVal, + bool AllowShrink) { auto *BV = dyn_cast(N); if (!BV) return false; @@ -124,9 +125,11 @@ bool ISD::isConstantSplatVector(const SDNode *N, APInt &SplatVal) { APInt SplatUndef; unsigned SplatBitSize; bool HasUndefs; - EVT EltVT = N->getValueType(0).getVectorElementType(); - return BV->isConstantSplat(SplatVal, SplatUndef, SplatBitSize, HasUndefs) && - EltVT.getSizeInBits() >= SplatBitSize; + unsigned EltSize = N->getValueType(0).getVectorElementType().getSizeInBits(); + unsigned MinSplatBits = AllowShrink ? 0 : EltSize; + return BV->isConstantSplat(SplatVal, SplatUndef, SplatBitSize, HasUndefs, + MinSplatBits) && + EltSize >= SplatBitSize; } // FIXME: AllOnes and AllZeros duplicate a lot of code. Could these be diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp index ce00a4a9665..42c33953507 100644 --- a/lib/Target/X86/X86ISelLowering.cpp +++ b/lib/Target/X86/X86ISelLowering.cpp @@ -29567,8 +29567,9 @@ static bool detectZextAbsDiff(const SDValue &Select, SDValue &Op0, // In SetLT case, The second operand of the comparison can be either 1 or 0. APInt SplatVal; if ((CC == ISD::SETLT) && - !((ISD::isConstantSplatVector(SetCC.getOperand(1).getNode(), SplatVal) && - SplatVal == 1) || + !((ISD::isConstantSplatVector(SetCC.getOperand(1).getNode(), SplatVal, + /*AllowShrink*/false) && + SplatVal.isOneValue()) || (ISD::isBuildVectorAllZeros(SetCC.getOperand(1).getNode())))) return false; @@ -32083,7 +32084,8 @@ static SDValue combineAndMaskToShift(SDNode *N, SelectionDAG &DAG, return SDValue(); APInt SplatVal; - if (!ISD::isConstantSplatVector(Op1.getNode(), SplatVal) || + if (!ISD::isConstantSplatVector(Op1.getNode(), SplatVal, + /*AllowShrink*/false) || !SplatVal.isMask()) return SDValue(); @@ -32667,7 +32669,8 @@ static SDValue detectUSatPattern(SDValue In, EVT VT) { "Unexpected types for truncate operation"); APInt C; - if (ISD::isConstantSplatVector(In.getOperand(1).getNode(), C)) { + if (ISD::isConstantSplatVector(In.getOperand(1).getNode(), C, + /*AllowShrink*/false)) { // C should be equal to UINT32_MAX / UINT16_MAX / UINT8_MAX according // the element size of the destination type. return C.isMask(VT.getScalarSizeInBits()) ? In.getOperand(0) : @@ -35374,7 +35377,8 @@ static SDValue combineIncDecVector(SDNode *N, SelectionDAG &DAG) { SDNode *N1 = N->getOperand(1).getNode(); APInt SplatVal; - if (!ISD::isConstantSplatVector(N1, SplatVal) || !SplatVal.isOneValue()) + if (!ISD::isConstantSplatVector(N1, SplatVal, /*AllowShrink*/false) || + !SplatVal.isOneValue()) return SDValue(); SDValue AllOnesVec = getOnesVector(VT, DAG, SDLoc(N)); diff --git a/test/CodeGen/X86/pr34271-1.ll b/test/CodeGen/X86/pr34271-1.ll new file mode 100644 index 00000000000..2e2f0fd0aa9 --- /dev/null +++ b/test/CodeGen/X86/pr34271-1.ll @@ -0,0 +1,14 @@ +; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py +; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu -mattr=avx512vl,avx512bw | FileCheck %s + +define <16 x i16> @foo(<16 x i32> %i) { +; CHECK-LABEL: foo: +; CHECK: # BB#0: +; CHECK-NEXT: vpminud {{.*}}(%rip){1to16}, %zmm0, %zmm0 +; CHECK-NEXT: vpmovdw %zmm0, %ymm0 +; CHECK-NEXT: retq + %x3 = icmp ult <16 x i32> %i, + %x5 = select <16 x i1> %x3, <16 x i32> %i, <16 x i32> + %x6 = trunc <16 x i32> %x5 to <16 x i16> + ret <16 x i16> %x6 +} diff --git a/test/CodeGen/X86/pr34271.ll b/test/CodeGen/X86/pr34271.ll new file mode 100644 index 00000000000..40d01617c30 --- /dev/null +++ b/test/CodeGen/X86/pr34271.ll @@ -0,0 +1,14 @@ +; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py +; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s + +; CHECK: .LCPI0_0: +; CHECK-NEXT: .zero 16,1 + +define <4 x i32> @f(<4 x i32> %a) { +; CHECK-LABEL: f: +; CHECK: # BB#0: +; CHECK-NEXT: paddd .LCPI0_0(%rip), %xmm0 +; CHECK-NEXT: retq + %v = add nuw nsw <4 x i32> %a, + ret <4 x i32> %v +}