[llvm] [AArch64] Consider MOVaddr* as cheap if fuse-adrp-add (PR #121904)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-aarch64

Author: Guy David (guy-david)

<details>
<summary>Changes</summary>

These pseudo-instructions usually translate into a pair of adrp+add and have a single cycle latency on some micro-architectures.

---
Full diff: https://github.com/llvm/llvm-project/pull/121904.diff


1 Files Affected:

- (modified) llvm/lib/Target/AArch64/AArch64InstrInfo.cpp (+8) 


``````````diff
diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
index fd24e49f948a20..6cb84d8623ea86 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -936,6 +936,14 @@ bool AArch64InstrInfo::isAsCheapAsAMove(const MachineInstr &MI) const {
     return isCheapImmediate(MI, 32);
   case AArch64::MOVi64imm:
     return isCheapImmediate(MI, 64);
+
+  case AArch64::MOVaddr:
+  case AArch64::MOVaddrJT:
+  case AArch64::MOVaddrCP:
+  case AArch64::MOVaddrTLS:
+  case AArch64::MOVaddrEXT:
+    return Subtarget.hasFuseAdrpAdd() &&
+           !(MI.getOperand(1).getTargetFlags() & AArch64II::MO_TAGGED);
   }
 }
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/121904