[llvm-branch-commits] [llvm] [RISCV] Support non-power-of-2 types when expanding memcmp (PR #114971)

[Pengcheng Wang via llvm-branch-commits]

https://github.com/wangpc-pp updated https://github.com/llvm/llvm-project/pull/114971

>From 3fd27bd1405a8b2c068786a200d610b9cacb65ef Mon Sep 17 00:00:00 2001
From: Wang Pengcheng <wangpengcheng.pp at bytedance.com>
Date: Tue, 5 Nov 2024 20:38:44 +0800
Subject: [PATCH] Set max bytes

Created using spr 1.3.6-beta.1
---
 llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
index c65feb9755633c..a1c5f76bae0099 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
@@ -2508,7 +2508,10 @@ RISCVTTIImpl::enableMemCmpExpansion(bool OptSize, bool IsZeroCmp) const {
     Options.LoadSizes = {4, 2, 1};
   if (IsZeroCmp && ST->hasVInstructions()) {
     unsigned VLenB = ST->getRealMinVLen() / 8;
-    for (unsigned Size = ST->getXLen() / 8 + 1;
+    // The minimum size should be the maximum bytes between `VLen * LMUL_MF8`
+    // and `XLen + 8`.
+    unsigned MinSize = std::max(VLenB / 8, ST->getXLen() / 8 + 1);
+    for (unsigned Size = MinSize;
          Size <= VLenB * ST->getMaxLMULForFixedLengthVectors(); Size++)
       Options.LoadSizes.insert(Options.LoadSizes.begin(), Size);
   }