Automerge: [RISCV] Support non-power-of-2 types when expanding memcmp

We can convert non-power-of-2 types into extended value types
and then they will be widen.

Reviewers: lukel97

Reviewed By: lukel97

Pull Request: llvm/llvm-project#114971

Author: wangpc-pp

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -16190,10 +16190,6 @@ combineVectorSizedSetCCEquality(EVT VT, SDValue X, SDValue Y, ISD::CondCode CC,
     return SDValue();
 
   unsigned OpSize = OpVT.getSizeInBits();
-  // TODO: Support non-power-of-2 types.
-  if (!isPowerOf2_32(OpSize))
-    return SDValue();
-
   // The size should be larger than XLen and smaller than the maximum vector
   // size.
   if (OpSize <= Subtarget.getXLen() ||
@@ -16214,14 +16210,25 @@ combineVectorSizedSetCCEquality(EVT VT, SDValue X, SDValue Y, ISD::CondCode CC,
           Attribute::NoImplicitFloat))
     return SDValue();
 
+  // Bail out for non-byte-sized types.
+  if (!OpVT.isByteSized())
+    return SDValue();
+
   unsigned VecSize = OpSize / 8;
-  EVT VecVT = MVT::getVectorVT(MVT::i8, VecSize);
-  EVT CmpVT = MVT::getVectorVT(MVT::i1, VecSize);
+  EVT VecVT = EVT::getVectorVT(*DAG.getContext(), MVT::i8, VecSize);
+  EVT CmpVT = EVT::getVectorVT(*DAG.getContext(), MVT::i1, VecSize);
 
   SDValue VecX = DAG.getBitcast(VecVT, X);
   SDValue VecY = DAG.getBitcast(VecVT, Y);
-  SDValue Cmp = DAG.getSetCC(DL, CmpVT, VecX, VecY, ISD::SETNE);
-  return DAG.getSetCC(DL, VT, DAG.getNode(ISD::VECREDUCE_OR, DL, XLenVT, Cmp),
+  SDValue Mask = DAG.getAllOnesConstant(DL, CmpVT);
+  SDValue VL = DAG.getConstant(VecSize, DL, XLenVT);
+
+  SDValue Cmp = DAG.getNode(ISD::VP_SETCC, DL, CmpVT, VecX, VecY,
+                            DAG.getCondCode(ISD::SETNE), Mask, VL);
+  return DAG.getSetCC(DL, VT,
+                      DAG.getNode(ISD::VP_REDUCE_OR, DL, XLenVT,
+                                  DAG.getConstant(0, DL, XLenVT), Cmp, Mask,
+                                  VL),
                       DAG.getConstant(0, DL, XLenVT), CC);
 }
 

llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp

@@ -2985,20 +2985,13 @@ RISCVTTIImpl::enableMemCmpExpansion(bool OptSize, bool IsZeroCmp) const {
   }
 
   if (IsZeroCmp && ST->hasVInstructions()) {
-    unsigned RealMinVLen = ST->getRealMinVLen();
-    // Support Fractional LMULs if the lengths are larger than XLen.
-    // TODO: Support non-power-of-2 types.
-    for (unsigned FLMUL = 8; FLMUL >= 2; FLMUL /= 2) {
-      unsigned Len = RealMinVLen / FLMUL;
-      if (Len > ST->getXLen())
-        Options.LoadSizes.insert(Options.LoadSizes.begin(), Len / 8);
-    }
-    for (unsigned LMUL = 1; LMUL <= ST->getMaxLMULForFixedLengthVectors();
-         LMUL *= 2) {
-      unsigned Len = RealMinVLen * LMUL;
-      if (Len > ST->getXLen())
-        Options.LoadSizes.insert(Options.LoadSizes.begin(), Len / 8);
-    }
+    unsigned VLenB = ST->getRealMinVLen() / 8;
+    // The minimum size should be `XLen / 8 + 1`, and the maxinum size should be
+    // `VLenB * MaxLMUL` so that it fits in a single register group.
+    unsigned MinSize = ST->getXLen() / 8 + 1;
+    unsigned MaxSize = VLenB * ST->getMaxLMULForFixedLengthVectors();
+    for (unsigned Size = MinSize; Size <= MaxSize; Size++)
+      Options.LoadSizes.insert(Options.LoadSizes.begin(), Size);
   }
   return Options;
 }

llvm/test/CodeGen/RISCV/icmp-non-byte-sized.ll

@@ -0,0 +1,41 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -mtriple=riscv32 -mattr=+v -O2 < %s | FileCheck %s --check-prefix=CHECK-RV32
+; RUN: llc -mtriple=riscv64 -mattr=+v -O2 < %s | FileCheck %s --check-prefix=CHECK-RV64
+
+define i1 @icmp_non_byte_type(ptr %p1, ptr %p2) nounwind {
+; CHECK-RV32-LABEL: icmp_non_byte_type:
+; CHECK-RV32:       # %bb.0:
+; CHECK-RV32-NEXT:    lw a2, 0(a0)
+; CHECK-RV32-NEXT:    lw a3, 4(a0)
+; CHECK-RV32-NEXT:    lw a4, 8(a0)
+; CHECK-RV32-NEXT:    lw a0, 12(a0)
+; CHECK-RV32-NEXT:    lw a5, 12(a1)
+; CHECK-RV32-NEXT:    lw a6, 4(a1)
+; CHECK-RV32-NEXT:    lw a7, 8(a1)
+; CHECK-RV32-NEXT:    lw a1, 0(a1)
+; CHECK-RV32-NEXT:    xor a0, a0, a5
+; CHECK-RV32-NEXT:    xor a3, a3, a6
+; CHECK-RV32-NEXT:    xor a4, a4, a7
+; CHECK-RV32-NEXT:    xor a1, a2, a1
+; CHECK-RV32-NEXT:    or a0, a3, a0
+; CHECK-RV32-NEXT:    or a1, a1, a4
+; CHECK-RV32-NEXT:    or a0, a1, a0
+; CHECK-RV32-NEXT:    seqz a0, a0
+; CHECK-RV32-NEXT:    ret
+;
+; CHECK-RV64-LABEL: icmp_non_byte_type:
+; CHECK-RV64:       # %bb.0:
+; CHECK-RV64-NEXT:    ld a2, 0(a0)
+; CHECK-RV64-NEXT:    ld a0, 8(a0)
+; CHECK-RV64-NEXT:    ld a3, 8(a1)
+; CHECK-RV64-NEXT:    ld a1, 0(a1)
+; CHECK-RV64-NEXT:    xor a0, a0, a3
+; CHECK-RV64-NEXT:    xor a1, a2, a1
+; CHECK-RV64-NEXT:    or a0, a1, a0
+; CHECK-RV64-NEXT:    seqz a0, a0
+; CHECK-RV64-NEXT:    ret
+  %v1 = load i127, ptr %p1
+  %v2 = load i127, ptr %p2
+  %ret = icmp eq i127 %v1, %v2
+  ret i1 %ret
+}