[llvm] [AMDGPU] Avoid repeated hash lookups (NFC) (PR #127445)

[Kazu Hirata via llvm-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/127445

None

>From 4b41e35a3ff40c1b58071bffa230c82d922b4dcb Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Sun, 16 Feb 2025 08:28:52 -0800
Subject: [PATCH] [AMDGPU] Avoid repeated hash lookups (NFC)

---
 llvm/lib/Target/AMDGPU/R600OptimizeVectorRegisters.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Target/AMDGPU/R600OptimizeVectorRegisters.cpp b/llvm/lib/Target/AMDGPU/R600OptimizeVectorRegisters.cpp
index ac11526da0919..17f724c3173d9 100644
--- a/llvm/lib/Target/AMDGPU/R600OptimizeVectorRegisters.cpp
+++ b/llvm/lib/Target/AMDGPU/R600OptimizeVectorRegisters.cpp
@@ -270,9 +270,10 @@ bool R600VectorRegMerger::tryMergeUsingCommonSlot(RegSeqInfo &RSI,
       MOE = RSI.Instr->operands_end(); MOp != MOE; ++MOp) {
     if (!MOp->isReg())
       continue;
-    if (PreviousRegSeqByReg[MOp->getReg()].empty())
+    auto &Insts = PreviousRegSeqByReg[MOp->getReg()];
+    if (Insts.empty())
       continue;
-    for (MachineInstr *MI : PreviousRegSeqByReg[MOp->getReg()]) {
+    for (MachineInstr *MI : Insts) {
       CompatibleRSI = PreviousRegSeq[MI];
       if (RSI == CompatibleRSI)
         continue;