[LoongArch] Custom legalize vector_shuffle to xvinsve0.{w/d} when possible (llvm#161156)

Author: zhaoqi5

llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp

@@ -2319,6 +2319,53 @@ static SDValue lowerVECTOR_SHUFFLE_XVPICKOD(const SDLoc &DL, ArrayRef<int> Mask,
   return DAG.getNode(LoongArchISD::VPICKOD, DL, VT, V2, V1);
 }
 
+/// Lower VECTOR_SHUFFLE into XVINSVE0 (if possible).
+static SDValue
+lowerVECTOR_SHUFFLE_XVINSVE0(const SDLoc &DL, ArrayRef<int> Mask, MVT VT,
+                             SDValue V1, SDValue V2, SelectionDAG &DAG,
+                             const LoongArchSubtarget &Subtarget) {
+  // LoongArch LASX only supports xvinsve0.{w/d}.
+  if (VT != MVT::v8i32 && VT != MVT::v8f32 && VT != MVT::v4i64 &&
+      VT != MVT::v4f64)
+    return SDValue();
+
+  MVT GRLenVT = Subtarget.getGRLenVT();
+  int MaskSize = Mask.size();
+  assert(MaskSize == (int)VT.getVectorNumElements() && "Unexpected mask size");
+
+  // Check if exactly one element of the Mask is replaced by 'Replaced', while
+  // all other elements are either 'Base + i' or undef (-1). On success, return
+  // the index of the replaced element. Otherwise, just return -1.
+  auto checkReplaceOne = [&](int Base, int Replaced) -> int {
+    int Idx = -1;
+    for (int i = 0; i < MaskSize; ++i) {
+      if (Mask[i] == Base + i || Mask[i] == -1)
+        continue;
+      if (Mask[i] != Replaced)
+        return -1;
+      if (Idx == -1)
+        Idx = i;
+      else
+        return -1;
+    }
+    return Idx;
+  };
+
+  // Case 1: the lowest element of V2 replaces one element in V1.
+  int Idx = checkReplaceOne(0, MaskSize);
+  if (Idx != -1)
+    return DAG.getNode(LoongArchISD::XVINSVE0, DL, VT, V1, V2,
+                       DAG.getConstant(Idx, DL, GRLenVT));
+
+  // Case 2: the lowest element of V1 replaces one element in V2.
+  Idx = checkReplaceOne(MaskSize, 0);
+  if (Idx != -1)
+    return DAG.getNode(LoongArchISD::XVINSVE0, DL, VT, V2, V1,
+                       DAG.getConstant(Idx, DL, GRLenVT));
+
+  return SDValue();
+}
+
 /// Lower VECTOR_SHUFFLE into XVSHUF (if possible).
 static SDValue lowerVECTOR_SHUFFLE_XVSHUF(const SDLoc &DL, ArrayRef<int> Mask,
                                           MVT VT, SDValue V1, SDValue V2,
@@ -2595,6 +2642,9 @@ static SDValue lower256BitShuffle(const SDLoc &DL, ArrayRef<int> Mask, MVT VT,
   if ((Result = lowerVECTOR_SHUFFLEAsShift(DL, Mask, VT, V1, V2, DAG, Subtarget,
                                            Zeroable)))
     return Result;
+  if ((Result =
+           lowerVECTOR_SHUFFLE_XVINSVE0(DL, Mask, VT, V1, V2, DAG, Subtarget)))
+    return Result;
   if ((Result = lowerVECTOR_SHUFFLEAsByteRotate(DL, Mask, VT, V1, V2, DAG,
                                                 Subtarget)))
     return Result;
@@ -7453,6 +7503,7 @@ const char *LoongArchTargetLowering::getTargetNodeName(unsigned Opcode) const {
     NODE_NAME_CASE(XVPERM)
     NODE_NAME_CASE(XVREPLVE0)
     NODE_NAME_CASE(XVREPLVE0Q)
+    NODE_NAME_CASE(XVINSVE0)
     NODE_NAME_CASE(VPICK_SEXT_ELT)
     NODE_NAME_CASE(VPICK_ZEXT_ELT)
     NODE_NAME_CASE(VREPLVE)

llvm/lib/Target/LoongArch/LoongArchISelLowering.h

@@ -151,6 +151,7 @@ enum NodeType : unsigned {
   XVPERM,
   XVREPLVE0,
   XVREPLVE0Q,
+  XVINSVE0,
 
   // Extended vector element extraction
   VPICK_SEXT_ELT,

llvm/lib/Target/LoongArch/LoongArchLASXInstrInfo.td

@@ -20,6 +20,7 @@ def loongarch_xvpermi: SDNode<"LoongArchISD::XVPERMI", SDT_LoongArchV1RUimm>;
 def loongarch_xvperm: SDNode<"LoongArchISD::XVPERM", SDT_LoongArchXVPERM>;
 def loongarch_xvreplve0: SDNode<"LoongArchISD::XVREPLVE0", SDT_LoongArchXVREPLVE0>;
 def loongarch_xvreplve0q: SDNode<"LoongArchISD::XVREPLVE0Q", SDT_LoongArchXVREPLVE0>;
+def loongarch_xvinsve0 : SDNode<"LoongArchISD::XVINSVE0", SDT_LoongArchV2RUimm>;
 def loongarch_xvmskltz: SDNode<"LoongArchISD::XVMSKLTZ", SDT_LoongArchVMSKCOND>;
 def loongarch_xvmskgez: SDNode<"LoongArchISD::XVMSKGEZ", SDT_LoongArchVMSKCOND>;
 def loongarch_xvmskeqz: SDNode<"LoongArchISD::XVMSKEQZ", SDT_LoongArchVMSKCOND>;
@@ -1708,6 +1709,14 @@ def : Pat<(vector_insert v4f64:$xd, (f64(bitconvert i64:$rj)), uimm2:$imm),
           (XVINSGR2VR_D v4f64:$xd, GPR:$rj, uimm2:$imm)>;
 
 // XVINSVE0_{W/D}
+def : Pat<(loongarch_xvinsve0 v8i32:$xd, v8i32:$xj, uimm3:$imm),
+          (XVINSVE0_W v8i32:$xd, v8i32:$xj, uimm3:$imm)>;
+def : Pat<(loongarch_xvinsve0 v4i64:$xd, v4i64:$xj, uimm2:$imm),
+          (XVINSVE0_D v4i64:$xd, v4i64:$xj, uimm2:$imm)>;
+def : Pat<(loongarch_xvinsve0 v8f32:$xd, v8f32:$xj, uimm3:$imm),
+          (XVINSVE0_W v8f32:$xd, v8f32:$xj, uimm3:$imm)>;
+def : Pat<(loongarch_xvinsve0 v4f64:$xd, v4f64:$xj, uimm2:$imm),
+          (XVINSVE0_D v4f64:$xd, v4f64:$xj, uimm2:$imm)>;
 def : Pat<(vector_insert v8f32:$xd, FPR32:$fj, uimm3:$imm),
           (XVINSVE0_W v8f32:$xd, (SUBREG_TO_REG(i64 0), FPR32:$fj, sub_32),
               uimm3:$imm)>;