diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp index 6571ddd7cb12b..fce26dd6c21f5 100644 --- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp +++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp @@ -14442,15 +14442,23 @@ AArch64TargetLowering::isDesirableToCommuteWithShift(const SDNode *N, SDValue ShiftLHS = N->getOperand(0); EVT VT = N->getValueType(0); - // If ShiftLHS is unsigned bit extraction: ((x >> C) & mask), then do not combine - // it with shift 'N' to let it be lowered to UBFX. + // If ShiftLHS is unsigned bit extraction: ((x >> C) & mask), then do not + // combine it with shift 'N' to let it be lowered to UBFX except: + // ((x >> C) & mask) << C. if (ShiftLHS.getOpcode() == ISD::AND && (VT == MVT::i32 || VT == MVT::i64) && isa(ShiftLHS.getOperand(1))) { uint64_t TruncMask = ShiftLHS.getConstantOperandVal(1); - if (isMask_64(TruncMask) && - ShiftLHS.getOperand(0).getOpcode() == ISD::SRL && - isa(ShiftLHS.getOperand(0).getOperand(1))) - return false; + if (isMask_64(TruncMask)) { + SDValue AndLHS = ShiftLHS.getOperand(0); + if (AndLHS.getOpcode() == ISD::SRL) { + if (auto *SRLC = dyn_cast(AndLHS.getOperand(1))) { + if (N->getOpcode() == ISD::SHL) + if (auto *SHLC = dyn_cast(N->getOperand(1))) + return SRLC->getZExtValue() == SHLC->getZExtValue(); + return false; + } + } + } } return true; } diff --git a/llvm/test/CodeGen/AArch64/shift-logic.ll b/llvm/test/CodeGen/AArch64/shift-logic.ll index af684bbb8aff7..be1ddccf901b8 100644 --- a/llvm/test/CodeGen/AArch64/shift-logic.ll +++ b/llvm/test/CodeGen/AArch64/shift-logic.ll @@ -151,3 +151,46 @@ define i32 @lshr_or_extra_use(i32 %x, i32 %y, i32* %p) nounwind { %sh1 = lshr i32 %r, 7 ret i32 %sh1 } + +define i64 @desirable_to_commute1(i64 %x) { +; CHECK-LABEL: desirable_to_commute1: +; CHECK: // %bb.0: +; CHECK-NEXT: and x0, x0, #0x7fff8 +; CHECK-NEXT: ret + %s1 = lshr i64 %x, 3 + %a = and i64 %s1, 65535 + %s2 = shl i64 %a, 3 + ret i64 %s2 +} + +define i64 @desirable_to_commute2(i64* %p, i64 %i) { +; CHECK-LABEL: desirable_to_commute2: +; CHECK: // %bb.0: +; CHECK-NEXT: and x8, x1, #0x1ff8 +; CHECK-NEXT: ldr x0, [x0, x8] +; CHECK-NEXT: ret + %lshr = lshr i64 %i, 3 + %and = and i64 %lshr, 1023 + %pidx = getelementptr i64, i64* %p, i64 %and + %r = load i64, i64* %pidx + ret i64 %r +} + +; Shrink demanded op will shrink the shl to i32, +; Lshr and shl will have different shift amount type. +; Compare apint will cause crash when type is different. +define void @apint_type_mismatch(i16 %a, i32* %p) { +; CHECK-LABEL: apint_type_mismatch: +; CHECK: // %bb.0: // %entry +; CHECK-NEXT: and w8, w0, #0x7f8 +; CHECK-NEXT: str w8, [x1] +; CHECK-NEXT: ret +entry: + %lshr = lshr i16 %a, 3 + %and = and i16 %lshr, 255 + %zext = zext i16 %and to i64 + %shl = shl i64 %zext, 3 + %trunc = trunc i64 %shl to i32 + store i32 %trunc, i32* %p + ret void +}