[RISCV] Fix incorrect MemOperand copy converting splat+load to vlse.

[craig.topper]

Summary

Due to an incorrect copy/paste from load intrinsic handling we
checked if the splat node was a MemSDNode which of course it isn't.

Instead get the MemOperand from the LoadSDNode for the source of
the splat.

This enables LICM to see the load is loop invariant and hoist it
out of the loop.

[frasercrmck]

LGTM, good catch!

llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp

case RISCVISD::VFMV_V_F_VL: {
 
     RISCVII::VLMUL LMUL = RISCVTargetLowering::getLMUL(VT);
     const RISCV::VLEPseudo *P = RISCV::getVLEPseudo(
         /*IsMasked*/ false, /*IsTU*/ false, /*IsStrided*/ true, /*FF*/ false,
         Log2SEW, static_cast<unsigned>(LMUL));
     MachineSDNode *Load =
         CurDAG->getMachineNode(P->Pseudo, DL, Node->getVTList(), Operands);
 
-    if (auto *MemOp = dyn_cast<MemSDNode>(Node))
-      CurDAG->setNodeMemRefs(Load, {MemOp->getMemOperand()});
+    CurDAG->setNodeMemRefs(Load, {Ld->getMemOperand()});
 
     ReplaceNode(Node, Load);
     return;
   }
   }
 
   // Select the default instruction.
   SelectCode(Node);

llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fp-buildvec.ll

 ; LMULMAX2-NEXT:    vrgather.vx v10, v8, a0
 ; LMULMAX2-NEXT:    vmv.v.v v8, v10
 ; LMULMAX2-NEXT:    ret
   %x = extractelement <8 x float> %v, i64 %idx
   %ins = insertelement <8 x float> poison, float %x, i32 0
   %splat = shufflevector <8 x float> %ins, <8 x float> poison, <8 x i32> zeroinitializer
   ret <8 x float> %splat
 }
+
+; Test that we pull the vlse of the constant pool out of the loop.
+define dso_local void @splat_load_licm(float* %0) {
+; RV32-LABEL: splat_load_licm:
+; RV32:       # %bb.0:
+; RV32-NEXT:    lui a1, %hi(.LCPI12_0)
+; RV32-NEXT:    addi a1, a1, %lo(.LCPI12_0)
+; RV32-NEXT:    vsetivli zero, 4, e32, m1, ta, mu
+; RV32-NEXT:    vlse32.v v8, (a1), zero
+; RV32-NEXT:    li a1, 1024
+; RV32-NEXT:  .LBB12_1: # =>This Inner Loop Header: Depth=1
+; RV32-NEXT:    vse32.v v8, (a0)
+; RV32-NEXT:    addi a1, a1, -4
+; RV32-NEXT:    addi a0, a0, 16
+; RV32-NEXT:    bnez a1, .LBB12_1
+; RV32-NEXT:  # %bb.2:
+; RV32-NEXT:    ret
+;
+; RV64-LABEL: splat_load_licm:
+; RV64:       # %bb.0:
+; RV64-NEXT:    lui a1, %hi(.LCPI12_0)
+; RV64-NEXT:    addi a1, a1, %lo(.LCPI12_0)
+; RV64-NEXT:    vsetivli zero, 4, e32, m1, ta, mu
+; RV64-NEXT:    vlse32.v v8, (a1), zero
+; RV64-NEXT:    li a1, 0
+; RV64-NEXT:    li a2, 1024
+; RV64-NEXT:  .LBB12_1: # =>This Inner Loop Header: Depth=1
+; RV64-NEXT:    slli a3, a1, 2
+; RV64-NEXT:    add a3, a0, a3
+; RV64-NEXT:    addiw a1, a1, 4
+; RV64-NEXT:    vse32.v v8, (a3)
+; RV64-NEXT:    bne a1, a2, .LBB12_1
+; RV64-NEXT:  # %bb.2:
+; RV64-NEXT:    ret
+  br label %2
+
+2:                                                ; preds = %2, %1
+  %3 = phi i32 [ 0, %1 ], [ %6, %2 ]
+  %4 = getelementptr inbounds float, float* %0, i32 %3
+  %5 = bitcast float* %4 to <4 x float>*
+  store <4 x float> <float 3.000000e+00, float 3.000000e+00, float 3.000000e+00, float 3.000000e+00>, <4 x float>* %5, align 4
+  %6 = add nuw i32 %3, 4
+  %7 = icmp eq i32 %6, 1024
+  br i1 %7, label %8, label %2
+
+8:                                                ; preds = %2
+  ret void
+}