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

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-aarch64

Author: Philipp Tomsich (ptomsich)

<details>
<summary>Changes</summary>

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.

---
Full diff: https://github.com/llvm/llvm-project/pull/81295.diff


1 Files Affected:

- (modified) llvm/lib/Target/AArch64/AArch64.td (+1) 


``````````diff
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]>;

``````````

</details>


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