[PowerPC] catch v2i64 shift left by 1 is add case (llvm#138772)

Catch missing case in PPC BE for v2i64 x << 1 and generate x + x.

Author: RolandF77

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

@@ -18456,10 +18456,46 @@ static SDValue stripModuloOnShift(const TargetLowering &TLI, SDNode *N,
   return SDValue();
 }
 
+SDValue PPCTargetLowering::combineVectorSHL(SDNode *N,
+                                            DAGCombinerInfo &DCI) const {
+  EVT VT = N->getValueType(0);
+  assert(VT.isVector() && "Vector type expected.");
+
+  SDValue N1 = N->getOperand(1);
+  if (!Subtarget.hasP8Altivec() || N1.getOpcode() != ISD::BUILD_VECTOR ||
+      !isOperationLegal(ISD::ADD, VT))
+    return SDValue();
+
+  // For 64-bit there is no splat immediate so we want to catch shift by 1 here
+  // before the BUILD_VECTOR is replaced by a load.
+  EVT EltTy = VT.getScalarType();
+  if (EltTy != MVT::i64)
+    return SDValue();
+
+  BuildVectorSDNode *BVN = cast<BuildVectorSDNode>(N1);
+  APInt APSplatBits, APSplatUndef;
+  unsigned SplatBitSize;
+  bool HasAnyUndefs;
+  bool BVNIsConstantSplat =
+      BVN->isConstantSplat(APSplatBits, APSplatUndef, SplatBitSize,
+                           HasAnyUndefs, 0, !Subtarget.isLittleEndian());
+  if (!BVNIsConstantSplat || SplatBitSize != EltTy.getSizeInBits())
+    return SDValue();
+  uint64_t SplatBits = APSplatBits.getZExtValue();
+  if (SplatBits != 1)
+    return SDValue();
+
+  SDValue N0 = N->getOperand(0);
+  return DCI.DAG.getNode(ISD::ADD, SDLoc(N), VT, N0, N0);
+}
+
 SDValue PPCTargetLowering::combineSHL(SDNode *N, DAGCombinerInfo &DCI) const {
   if (auto Value = stripModuloOnShift(*this, N, DCI.DAG))
     return Value;
 
+  if (N->getValueType(0).isVector())
+    return combineVectorSHL(N, DCI);
+
   SDValue N0 = N->getOperand(0);
   ConstantSDNode *CN1 = dyn_cast<ConstantSDNode>(N->getOperand(1));
   if (!Subtarget.isISA3_0() || !Subtarget.isPPC64() ||

llvm/lib/Target/PowerPC/PPCISelLowering.h

@@ -1441,6 +1441,7 @@ namespace llvm {
     SDValue combineStoreFPToInt(SDNode *N, DAGCombinerInfo &DCI) const;
     SDValue combineFPToIntToFP(SDNode *N, DAGCombinerInfo &DCI) const;
     SDValue combineSHL(SDNode *N, DAGCombinerInfo &DCI) const;
+    SDValue combineVectorSHL(SDNode *N, DAGCombinerInfo &DCI) const;
     SDValue combineSRA(SDNode *N, DAGCombinerInfo &DCI) const;
     SDValue combineSRL(SDNode *N, DAGCombinerInfo &DCI) const;
     SDValue combineMUL(SDNode *N, DAGCombinerInfo &DCI) const;

llvm/test/CodeGen/PowerPC/optimize-vector.ll

@@ -36,10 +36,7 @@ entry:
 define dso_local <2 x i64> @x2d(<2 x i64> noundef %x) {
 ; CHECK-LABEL: x2d:
 ; CHECK:       # %bb.0: # %entry
-; CHECK-NEXT:    addis r3, r2, .LCPI3_0@toc@ha
-; CHECK-NEXT:    addi r3, r3, .LCPI3_0@toc@l
-; CHECK-NEXT:    lxvd2x v3, 0, r3
-; CHECK-NEXT:    vsld v2, v2, v3
+; CHECK-NEXT:    vaddudm v2, v2, v2
 ; CHECK-NEXT:    blr
 entry:
   %add = shl <2 x i64> %x, <i64 1, i64 1>

llvm/test/CodeGen/PowerPC/pr47891.ll

@@ -7,26 +7,17 @@
 define dso_local void @poly2_lshift1(ptr nocapture %p) local_unnamed_addr #0 {
 ; CHECK-LABEL: poly2_lshift1:
 ; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    addis r6, r2, .LCPI0_0@toc@ha
 ; CHECK-NEXT:    li r4, 72
-; CHECK-NEXT:    addis r6, r2, .LCPI0_1@toc@ha
 ; CHECK-NEXT:    ld r5, 64(r3)
-; CHECK-NEXT:    lxvd2x vs0, r3, r4
-; CHECK-NEXT:    addi r6, r6, .LCPI0_1@toc@l
-; CHECK-NEXT:    lxvd2x v4, 0, r6
-; CHECK-NEXT:    addis r6, r2, .LCPI0_0@toc@ha
 ; CHECK-NEXT:    addi r6, r6, .LCPI0_0@toc@l
-; CHECK-NEXT:    xxswapd v2, vs0
-; CHECK-NEXT:    mtfprd f0, r5
-; CHECK-NEXT:    xxpermdi v3, v2, vs0, 2
-; CHECK-NEXT:    vsld v2, v2, v4
+; CHECK-NEXT:    lxvd2x vs0, r3, r4
 ; CHECK-NEXT:    lxvd2x v4, 0, r6
 ; CHECK-NEXT:    ld r6, 0(r3)
 ; CHECK-NEXT:    sldi r7, r6, 1
 ; CHECK-NEXT:    rotldi r6, r6, 1
 ; CHECK-NEXT:    std r7, 0(r3)
 ; CHECK-NEXT:    ld r7, 8(r3)
-; CHECK-NEXT:    vsrd v3, v3, v4
-; CHECK-NEXT:    xxlor vs0, v2, v3
 ; CHECK-NEXT:    rldimi r6, r7, 1, 0
 ; CHECK-NEXT:    rotldi r7, r7, 1
 ; CHECK-NEXT:    std r6, 8(r3)
@@ -44,6 +35,8 @@ define dso_local void @poly2_lshift1(ptr nocapture %p) local_unnamed_addr #0 {
 ; CHECK-NEXT:    std r7, 32(r3)
 ; CHECK-NEXT:    ld r7, 40(r3)
 ; CHECK-NEXT:    rldimi r6, r7, 1, 0
+; CHECK-NEXT:    xxswapd v2, vs0
+; CHECK-NEXT:    mtfprd f0, r5
 ; CHECK-NEXT:    rotldi r7, r7, 1
 ; CHECK-NEXT:    std r6, 40(r3)
 ; CHECK-NEXT:    ld r6, 48(r3)
@@ -54,10 +47,14 @@ define dso_local void @poly2_lshift1(ptr nocapture %p) local_unnamed_addr #0 {
 ; CHECK-NEXT:    rldimi r6, r7, 1, 0
 ; CHECK-NEXT:    std r6, 56(r3)
 ; CHECK-NEXT:    rotldi r6, r7, 1
-; CHECK-NEXT:    xxswapd vs0, vs0
-; CHECK-NEXT:    stxvd2x vs0, r3, r4
 ; CHECK-NEXT:    rldimi r6, r5, 1, 0
 ; CHECK-NEXT:    std r6, 64(r3)
+; CHECK-NEXT:    xxpermdi v3, v2, vs0, 2
+; CHECK-NEXT:    vsrd v3, v3, v4
+; CHECK-NEXT:    vaddudm v2, v2, v2
+; CHECK-NEXT:    xxlor vs0, v2, v3
+; CHECK-NEXT:    xxswapd vs0, vs0
+; CHECK-NEXT:    stxvd2x vs0, r3, r4
 ; CHECK-NEXT:    blr
 entry:
   %0 = load i64, ptr %p, align 8