[llvm] [AArch64] Add FeatureFuseAddSub2RegAndConstOne for Ampere1A (PR #81295)

[Philipp Tomsich via llvm-commits]

https://github.com/ptomsich created https://github.com/llvm/llvm-project/pull/81295

Ampere1A introduced the Fusion for A+B+1/A-B-1.
However, the Feature flag to enable that fusion-case never was added to TuneAmpere1A.
This commit corrects that omission.

>From 2f8f1fbb23d3fbe4d69b8f16b2bb177389831ac1 Mon Sep 17 00:00:00 2001
From: Philipp Tomsich <philipp.tomsich at vrull.eu>
Date: Thu, 8 Feb 2024 18:43:06 +0100
Subject: [PATCH] [AArch64] Add FeatureFuseAddSub2RegAndConstOne for Ampere1A

---
 llvm/lib/Target/AArch64/AArch64.td | 1 +
 1 file changed, 1 insertion(+)

diff --git a/llvm/lib/Target/AArch64/AArch64.td b/llvm/lib/Target/AArch64/AArch64.td
index 02fb01caf7e801..ea0c498263411d 100644
--- a/llvm/lib/Target/AArch64/AArch64.td
+++ b/llvm/lib/Target/AArch64/AArch64.td
@@ -1372,6 +1372,7 @@ def TuneAmpere1A : SubtargetFeature<"ampere1a", "ARMProcFamily", "Ampere1A",
                                     FeatureFuseAddress,
                                     FeatureFuseLiterals,
                                     FeatureFuseLiterals,
+                                    FeatureFuseAddSub2RegAndConstOne,
                                     FeatureStorePairSuppress,
                                     FeatureLdpAlignedOnly,
                                     FeatureStpAlignedOnly]>;