Index: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp =================================================================== --- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -8402,6 +8402,9 @@ SDValue DAGCombiner::CombineZExtLogicopShiftLoad(SDNode *N) { assert(N->getOpcode() == ISD::ZERO_EXTEND); EVT VT = N->getValueType(0); + EVT OrigVT = N->getOperand(0).getValueType(); + if (TLI.isZExtFree(OrigVT, VT)) + return SDValue(); // and/or/xor SDValue N0 = N->getOperand(0); Index: llvm/trunk/test/CodeGen/X86/pr39098.ll =================================================================== --- llvm/trunk/test/CodeGen/X86/pr39098.ll +++ llvm/trunk/test/CodeGen/X86/pr39098.ll @@ -0,0 +1,20 @@ +; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s + +define dso_local void @test_cancel2(i40* %p1, i40* %p2) { +; CHECK: # %entry +; CHECK-NEXT: movl (%rdi), %eax +; CHECK-NEXT: shrl %eax +; CHECK-NEXT: andl $524287, %eax +; CHECK-NEXT: movl %eax, (%rsi) +; CHECK-NEXT: movb $0, 4(%rsi) +; CHECK-NEXT: retq +entry: + %0 = load i40, i40* %p1, align 8 + %shl414 = shl i40 %0, 19 + %unsclear415 = and i40 %shl414, 549755813887 + %shr416 = lshr i40 %unsclear415, 20 + %unsclear417 = and i40 %shr416, 549755813887 + store i40 %unsclear417, i40* %p2, align 8 + ret void +} +