[llvm] [InlineCost] Use a const reference (NFC) (PR #95687)

[Kazu Hirata via llvm-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/95687

The use of a const reference here saves 0.18% of heap allocations
during the compilation of a large preprocessed file, namely
X86ISelLowering.cpp, for the X86 target.

Note that GetTLI returns a const reference, so we don't have to worry
about a dangling reference.

>From c2d7b0b57eac367c24d8f09189c35aed43f9f2f5 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Sun, 21 Jan 2024 20:08:44 -0800
Subject: [PATCH] [InlineCost] Use a const reference (NFC)

The use of a const reference here saves 0.18% of heap allocations
during the compilation of a large preprocessed file, namely
X86ISelLowering.cpp, for the X86 target.

Note that GetTLI returns a const reference, so we don't have to worry
about a dangling reference.
---
 llvm/lib/Analysis/InlineCost.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/llvm/lib/Analysis/InlineCost.cpp b/llvm/lib/Analysis/InlineCost.cpp
index f5b17dca49735..c3aeac7492804 100644
--- a/llvm/lib/Analysis/InlineCost.cpp
+++ b/llvm/lib/Analysis/InlineCost.cpp
@@ -2887,7 +2887,7 @@ static bool functionsHaveCompatibleAttributes(
   // caches the most recently created TLI in the TargetLibraryInfoWrapperPass
   // object, and always returns the same object (which is overwritten on each
   // GetTLI call). Therefore we copy the first result.
-  auto CalleeTLI = GetTLI(*Callee);
+  const auto &CalleeTLI = GetTLI(*Callee);
   return (IgnoreTTIInlineCompatible ||
           TTI.areInlineCompatible(Caller, Callee)) &&
          GetTLI(*Caller).areInlineCompatible(CalleeTLI,