[SelectionDAG] Modify legalizing intrinsic get.active.lane.mask

[SjoerdMeijer]

Summary

Adapt legalization of get.active.lane.mask to the new semantics as proposed in D86147.
Because the second argument is now tripcount, we legalize it to an icmp ULT instead of an ULE when it was the backedge-taken count.

[arsenm]

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

6891

Why is this expanded here in the first place?

[SjoerdMeijer]

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

6891

The intrinsic is used to communicate information from middle-end to back-end. The back-end transformation could reject it for different reasons. If the transformation is not triggering, the intrinsic has to be expanded to its original semantics somewhere. This place seems to be a good fit and is generic, so if there will be more use-cases than only the ARM back-end than that's covered.

[dmgreen]

Seems OK, to go along with the update to the semantics.

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

case Intrinsic::ptrmask: {
     SDValue Const = getValue(I.getOperand(1));
 
     EVT PtrVT = Ptr.getValueType();
     setValue(&I, DAG.getNode(ISD::AND, getCurSDLoc(), PtrVT, Ptr,
                              DAG.getZExtOrTrunc(Const, getCurSDLoc(), PtrVT)));
     return;
   }
   case Intrinsic::get_active_lane_mask: {
     auto DL = getCurSDLoc();
     SDValue Index = getValue(I.getOperand(0));
-    SDValue BTC = getValue(I.getOperand(1));
+    SDValue TripCount = getValue(I.getOperand(1));
     Type *ElementTy = I.getOperand(0)->getType();
     EVT VT = TLI.getValueType(DAG.getDataLayout(), I.getType());
     unsigned VecWidth = VT.getVectorNumElements();
 
-    SmallVector<SDValue, 16> OpsBTC;
+    SmallVector<SDValue, 16> OpsTripCount;
     SmallVector<SDValue, 16> OpsIndex;
     SmallVector<SDValue, 16> OpsStepConstants;
     for (unsigned i = 0; i < VecWidth; i++) {
-      OpsBTC.push_back(BTC);
+      OpsTripCount.push_back(TripCount);
       OpsIndex.push_back(Index);
       OpsStepConstants.push_back(DAG.getConstant(i, DL, MVT::getVT(ElementTy)));
     }
 
     EVT CCVT = MVT::i1;
     CCVT = EVT::getVectorVT(I.getContext(), CCVT, VecWidth);
 
     auto VecTy = MVT::getVT(FixedVectorType::get(ElementTy, VecWidth));
     SDValue VectorIndex = DAG.getBuildVector(VecTy, DL, OpsIndex);
     SDValue VectorStep = DAG.getBuildVector(VecTy, DL, OpsStepConstants);
     SDValue VectorInduction = DAG.getNode(
        ISD::UADDO, DL, DAG.getVTList(VecTy, CCVT), VectorIndex, VectorStep);
-    SDValue VectorBTC = DAG.getBuildVector(VecTy, DL, OpsBTC);
+    SDValue VectorTripCount = DAG.getBuildVector(VecTy, DL, OpsTripCount);
     SDValue SetCC = DAG.getSetCC(DL, CCVT, VectorInduction.getValue(0),
-                                 VectorBTC, ISD::CondCode::SETULE);
+                                 VectorTripCount, ISD::CondCode::SETULT);
     setValue(&I, DAG.getNode(ISD::AND, DL, CCVT,
                              DAG.getNOT(DL, VectorInduction.getValue(1), CCVT),
                              SetCC));
     return;
   }
   }
 }
 

llvm/test/CodeGen/Thumb2/LowOverheadLoops/tail-pred-intrinsic-round.ll

 ; CHECK-NEXT:  .LBB5_1: @ %vector.body
 ; CHECK-NEXT:    @ =>This Inner Loop Header: Depth=1
 ; CHECK-NEXT:    vadd.i32 q2, q0, r12
 ; CHECK-NEXT:    vdup.32 q3, r12
 ; CHECK-NEXT:    vcmp.u32 hi, q3, q2
 ; CHECK-NEXT:    add.w r12, r12, #4
 ; CHECK-NEXT:    vpnot
 ; CHECK-NEXT:    vpstt
-; CHECK-NEXT:    vcmpt.u32 cs, q1, q2
+; CHECK-NEXT:    vcmpt.u32 hi, q1, q2
 ; CHECK-NEXT:    vldrwt.u32 q2, [r0], #16
 ; CHECK-NEXT:    vrintr.f32 s15, s11
 ; CHECK-NEXT:    vrintr.f32 s14, s10
 ; CHECK-NEXT:    vrintr.f32 s13, s9
 ; CHECK-NEXT:    vrintr.f32 s12, s8
 ; CHECK-NEXT:    vpst
 ; CHECK-NEXT:    vstrwt.32 q3, [r1], #16
 ; CHECK-NEXT:    le lr, .LBB5_1

llvm/test/CodeGen/Thumb2/active_lane_mask.ll

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -mtriple=thumbv8.1m.main -mattr=+mve %s -o - | FileCheck %s
 
 define <4 x i32> @v4i32(i32 %index, i32 %BTC, <4 x i32> %V1, <4 x i32> %V2) {
 ; CHECK-LABEL: v4i32:
 ; CHECK:       @ %bb.0:
 ; CHECK-NEXT:    adr.w r12, .LCPI0_0
 ; CHECK-NEXT:    vdup.32 q1, r0
 ; CHECK-NEXT:    vldrw.u32 q0, [r12]
 ; CHECK-NEXT:    vadd.i32 q0, q0, r0
 ; CHECK-NEXT:    add r0, sp, #8
 ; CHECK-NEXT:    vcmp.u32 hi, q1, q0
 ; CHECK-NEXT:    vdup.32 q1, r1
 ; CHECK-NEXT:    vpnot
 ; CHECK-NEXT:    vpst
-; CHECK-NEXT:    vcmpt.u32 cs, q1, q0
+; CHECK-NEXT:    vcmpt.u32 hi, q1, q0
 ; CHECK-NEXT:    vmov d0, r2, r3
 ; CHECK-NEXT:    vldr d1, [sp]
 ; CHECK-NEXT:    vldrw.u32 q1, [r0]
 ; CHECK-NEXT:    vpsel q0, q0, q1
 ; CHECK-NEXT:    vmov r0, r1, d0
 ; CHECK-NEXT:    vmov r2, r3, d1
 ; CHECK-NEXT:    bx lr
 ; CHECK-NEXT:    .p2align 4

 ; CHECK:       @ %bb.0:
 ; CHECK-NEXT:    vpush {d8, d9, d10, d11, d12, d13}
 ; CHECK-NEXT:    adr.w r12, .LCPI1_0
 ; CHECK-NEXT:    vdup.32 q5, r1
 ; CHECK-NEXT:    vldrw.u32 q0, [r12]
 ; CHECK-NEXT:    vmov.i8 q1, #0x0
 ; CHECK-NEXT:    vmov.i8 q2, #0xff
 ; CHECK-NEXT:    vadd.i32 q3, q0, r0
-; CHECK-NEXT:    vcmp.u32 cs, q5, q3
+; CHECK-NEXT:    vcmp.u32 hi, q5, q3
 ; CHECK-NEXT:    vpsel q4, q2, q1
 ; CHECK-NEXT:    vmov r1, s16
 ; CHECK-NEXT:    vmov.16 q0[0], r1
 ; CHECK-NEXT:    vmov r1, s17
 ; CHECK-NEXT:    vmov.16 q0[1], r1
 ; CHECK-NEXT:    vmov r1, s18
 ; CHECK-NEXT:    vmov.16 q0[2], r1
 ; CHECK-NEXT:    vmov r1, s19
 ; CHECK-NEXT:    vmov.16 q0[3], r1
 ; CHECK-NEXT:    adr r1, .LCPI1_1
 ; CHECK-NEXT:    vldrw.u32 q4, [r1]
 ; CHECK-NEXT:    vadd.i32 q4, q4, r0
-; CHECK-NEXT:    vcmp.u32 cs, q5, q4
+; CHECK-NEXT:    vcmp.u32 hi, q5, q4
 ; CHECK-NEXT:    vpsel q5, q2, q1
 ; CHECK-NEXT:    vmov r1, s20
 ; CHECK-NEXT:    vmov.16 q0[4], r1
 ; CHECK-NEXT:    vmov r1, s21
 ; CHECK-NEXT:    vmov.16 q0[5], r1
 ; CHECK-NEXT:    vmov r1, s22
 ; CHECK-NEXT:    vmov.16 q0[6], r1
 ; CHECK-NEXT:    vmov r1, s23

 ; CHECK-NEXT:    vpush {d8, d9, d10, d11, d12, d13, d14, d15}
 ; CHECK-NEXT:    sub sp, #16
 ; CHECK-NEXT:    adr.w r12, .LCPI2_0
 ; CHECK-NEXT:    vdup.32 q7, r1
 ; CHECK-NEXT:    vldrw.u32 q0, [r12]
 ; CHECK-NEXT:    vmov.i8 q5, #0x0
 ; CHECK-NEXT:    vmov.i8 q4, #0xff
 ; CHECK-NEXT:    vadd.i32 q1, q0, r0
-; CHECK-NEXT:    vcmp.u32 cs, q7, q1
+; CHECK-NEXT:    vcmp.u32 hi, q7, q1
 ; CHECK-NEXT:    vpsel q0, q4, q5
 ; CHECK-NEXT:    vmov r1, s0
 ; CHECK-NEXT:    vmov.16 q2[0], r1
 ; CHECK-NEXT:    vmov r1, s1
 ; CHECK-NEXT:    vmov.16 q2[1], r1
 ; CHECK-NEXT:    vmov r1, s2
 ; CHECK-NEXT:    vmov.16 q2[2], r1
 ; CHECK-NEXT:    vmov r1, s3
 ; CHECK-NEXT:    vmov.16 q2[3], r1
 ; CHECK-NEXT:    adr r1, .LCPI2_1
 ; CHECK-NEXT:    vldrw.u32 q0, [r1]
 ; CHECK-NEXT:    vadd.i32 q3, q0, r0
-; CHECK-NEXT:    vcmp.u32 cs, q7, q3
+; CHECK-NEXT:    vcmp.u32 hi, q7, q3
 ; CHECK-NEXT:    vpsel q0, q4, q5
 ; CHECK-NEXT:    vmov r1, s0
 ; CHECK-NEXT:    vmov.16 q2[4], r1
 ; CHECK-NEXT:    vmov r1, s1
 ; CHECK-NEXT:    vmov.16 q2[5], r1
 ; CHECK-NEXT:    vmov r1, s2
 ; CHECK-NEXT:    vmov.16 q2[6], r1
 ; CHECK-NEXT:    vmov r1, s3

 ; CHECK-NEXT:    vmov.8 q2[5], r1
 ; CHECK-NEXT:    vmov.u16 r1, q0[6]
 ; CHECK-NEXT:    vmov.8 q2[6], r1
 ; CHECK-NEXT:    vmov.u16 r1, q0[7]
 ; CHECK-NEXT:    vmov.8 q2[7], r1
 ; CHECK-NEXT:    adr r1, .LCPI2_2
 ; CHECK-NEXT:    vldrw.u32 q0, [r1]
 ; CHECK-NEXT:    vadd.i32 q0, q0, r0
-; CHECK-NEXT:    vcmp.u32 cs, q7, q0
+; CHECK-NEXT:    vcmp.u32 hi, q7, q0
 ; CHECK-NEXT:    vstrw.32 q0, [sp] @ 16-byte Spill
 ; CHECK-NEXT:    vpsel q6, q4, q5
 ; CHECK-NEXT:    vmov r1, s24
 ; CHECK-NEXT:    vmov.16 q0[0], r1
 ; CHECK-NEXT:    vmov r1, s25
 ; CHECK-NEXT:    vmov.16 q0[1], r1
 ; CHECK-NEXT:    vmov r1, s26
 ; CHECK-NEXT:    vmov.16 q0[2], r1
 ; CHECK-NEXT:    vmov r1, s27
 ; CHECK-NEXT:    vmov.16 q0[3], r1
 ; CHECK-NEXT:    adr r1, .LCPI2_3
 ; CHECK-NEXT:    vldrw.u32 q6, [r1]
 ; CHECK-NEXT:    vadd.i32 q6, q6, r0
-; CHECK-NEXT:    vcmp.u32 cs, q7, q6
+; CHECK-NEXT:    vcmp.u32 hi, q7, q6
 ; CHECK-NEXT:    vpsel q7, q4, q5
 ; CHECK-NEXT:    vmov r1, s28
 ; CHECK-NEXT:    vmov.16 q0[4], r1
 ; CHECK-NEXT:    vmov r1, s29
 ; CHECK-NEXT:    vmov.16 q0[5], r1
 ; CHECK-NEXT:    vmov r1, s30
 ; CHECK-NEXT:    vmov.16 q0[6], r1
 ; CHECK-NEXT:    vmov r1, s31