diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp index adfeea073bff6..a6a482ad42565 100644 --- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp @@ -21,6 +21,7 @@ #include "llvm/Analysis/ConstantFolding.h" #include "llvm/Analysis/TargetLibraryInfo.h" #include "llvm/CodeGen/ISDOpcodes.h" +#include "llvm/CodeGen/MachineFrameInfo.h" #include "llvm/CodeGen/MachineFunction.h" #include "llvm/CodeGen/MachineJumpTableInfo.h" #include "llvm/CodeGen/MachineMemOperand.h" @@ -1377,6 +1378,21 @@ void SelectionDAGLegalize::LegalizeOp(SDNode *Node) { } } +// Helper function that generates an MMO that considers the alignment of the +// stack, and the size of the stack object +static MachineMemOperand *getStackAlignedMMO(SDValue StackPtr, + MachineFunction &MF, + bool isObjectScalable) { + auto &MFI = MF.getFrameInfo(); + int FI = cast(StackPtr)->getIndex(); + MachinePointerInfo PtrInfo = MachinePointerInfo::getFixedStack(MF, FI); + uint64_t ObjectSize = isObjectScalable ? ~UINT64_C(0) : MFI.getObjectSize(FI); + MachineMemOperand *MMO = MF.getMachineMemOperand( + PtrInfo, MachineMemOperand::MOStore, ObjectSize, MFI.getObjectAlign(FI)); + + return MMO; +} + SDValue SelectionDAGLegalize::ExpandExtractFromVectorThroughStack(SDValue Op) { SDValue Vec = Op.getOperand(0); SDValue Idx = Op.getOperand(1); @@ -1426,8 +1442,9 @@ SDValue SelectionDAGLegalize::ExpandExtractFromVectorThroughStack(SDValue Op) { if (!Ch.getNode()) { // Store the value to a temporary stack slot, then LOAD the returned part. StackPtr = DAG.CreateStackTemporary(VecVT); - Ch = DAG.getStore(DAG.getEntryNode(), dl, Vec, StackPtr, - MachinePointerInfo()); + MachineMemOperand *StoreMMO = getStackAlignedMMO( + StackPtr, DAG.getMachineFunction(), VecVT.isScalableVector()); + Ch = DAG.getStore(DAG.getEntryNode(), dl, Vec, StackPtr, StoreMMO); } SDValue NewLoad; diff --git a/llvm/test/CodeGen/X86/unaligned_extract_from_vector_through_stack.ll b/llvm/test/CodeGen/X86/unaligned_extract_from_vector_through_stack.ll new file mode 100644 index 0000000000000..52d0c2b509128 --- /dev/null +++ b/llvm/test/CodeGen/X86/unaligned_extract_from_vector_through_stack.ll @@ -0,0 +1,20 @@ +; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py +; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s + +define i32 @foo(i32 %arg1) #0 { +; CHECK-LABEL: foo: +; CHECK: # %bb.0: # %entry +; CHECK-NEXT: # kill: def $edi killed $edi def $rdi +; CHECK-NEXT: vxorps %xmm0, %xmm0, %xmm0 +; CHECK-NEXT: vmovups %ymm0, -{{[0-9]+}}(%rsp) +; CHECK-NEXT: andl $31, %edi +; CHECK-NEXT: movzbl -40(%rsp,%rdi), %eax +; CHECK-NEXT: vzeroupper +; CHECK-NEXT: retq +entry: + %a = extractelement <32 x i8> zeroinitializer, i32 %arg1 + %b = zext i8 %a to i32 + ret i32 %b +} + +attributes #0 = { "no-realign-stack" "target-cpu"="skylake-avx512" }