[llvm] [RISCV] Remove last use of @llvm.experimental.vp.splat in RISCVCodeGenPrepare. NFCI (PR #170543)

[Luke Lau via llvm-commits]

https://github.com/lukel97 updated https://github.com/llvm/llvm-project/pull/170543

>From cc39d386a1a12a9f4721d0b9faaf0212b11d2cbd Mon Sep 17 00:00:00 2001
From: Luke Lau <luke at igalia.com>
Date: Thu, 4 Dec 2025 03:40:46 +0800
Subject: [PATCH] [RISCV] Remove last use of experimental.vp.splat in
 RISCVCodeGenPrepare. NFCI

Stacked on #170539

RISCVCodeGenPrepare is the last user of the vp.splat intrinsic, where it uses it to expand a zero strided load into a scalar load and splat. This replaces it with a regular splat followed by a vp_merge to set the lanes past EVL as poison. We need to set the EVL here because RISCVISelDAGToDAG will try and recombine it back into a zero strided load, and we want to preserve the original VL.

We need to set
---
 llvm/lib/Target/RISCV/RISCVCodeGenPrepare.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Target/RISCV/RISCVCodeGenPrepare.cpp b/llvm/lib/Target/RISCV/RISCVCodeGenPrepare.cpp
index ab450f9c4a61d..1ee4c66a5bde5 100644
--- a/llvm/lib/Target/RISCV/RISCVCodeGenPrepare.cpp
+++ b/llvm/lib/Target/RISCV/RISCVCodeGenPrepare.cpp
@@ -271,8 +271,10 @@ bool RISCVCodeGenPrepare::expandVPStrideLoad(IntrinsicInst &II) {
   IRBuilder<> Builder(&II);
   Type *STy = VTy->getElementType();
   Value *Val = Builder.CreateLoad(STy, BasePtr);
-  Value *Res = Builder.CreateIntrinsic(Intrinsic::experimental_vp_splat, {VTy},
-                                       {Val, II.getOperand(2), VL});
+  Value *Res = Builder.CreateIntrinsic(
+      Intrinsic::vp_merge, VTy,
+      {II.getOperand(2), Builder.CreateVectorSplat(VTy->getElementCount(), Val),
+       PoisonValue::get(VTy), VL});
 
   II.replaceAllUsesWith(Res);
   II.eraseFromParent();