[llvm] [CodeGen][NFC] Remove one meaningless `equal_to` specialization (PR #166115)

[A. Jiang via llvm-commits]

https://github.com/frederick-vs-ja created https://github.com/llvm/llvm-project/pull/166115

The `std::equal_to<llvm::rdf::RegisterAggr>` specialization (introduced in 9521704553e8a330cfdf5a0611885680073178b2) does the same things as the primary `std::equal_to` template. This is valid but meaningless. As a result, it's perhaps better to remove this full specialization.

>From 0959e18da5cf57b3247db9090780e467c02ef2c8 Mon Sep 17 00:00:00 2001
From: "A. Jiang" <de34 at live.cn>
Date: Mon, 3 Nov 2025 11:09:52 +0800
Subject: [PATCH] [CodeGen][NFC] Remove one meaningless `equal_to`
 specialization

The `std::equal_to<llvm::rdf::RegisterAggr>` specialization (introduced
in 9521704553e8a330cfdf5a0611885680073178b2) does the same things as the
primary `std::equal_to` template. This is valid but meaningless. As a
result, it's perhaps better to remove this full specialization.
---
 llvm/include/llvm/CodeGen/RDFRegisters.h | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/RDFRegisters.h b/llvm/include/llvm/CodeGen/RDFRegisters.h
index 3b7454e1e552f..4c15bf534d55f 100644
--- a/llvm/include/llvm/CodeGen/RDFRegisters.h
+++ b/llvm/include/llvm/CodeGen/RDFRegisters.h
@@ -361,13 +361,6 @@ template <> struct hash<llvm::rdf::RegisterAggr> {
   }
 };
 
-template <> struct equal_to<llvm::rdf::RegisterAggr> {
-  bool operator()(const llvm::rdf::RegisterAggr &A,
-                  const llvm::rdf::RegisterAggr &B) const {
-    return A == B;
-  }
-};
-
 } // namespace std
 
 namespace llvm::rdf {