[llvm] [MCA] Avoid repeated hash lookups (NFC) (PR #129192)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-tools-llvm-mca

Author: Kazu Hirata (kazutakahirata)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/129192.diff


1 Files Affected:

- (modified) llvm/lib/MCA/InstrBuilder.cpp (+2-4) 


``````````diff
diff --git a/llvm/lib/MCA/InstrBuilder.cpp b/llvm/lib/MCA/InstrBuilder.cpp
index 2cb1908695308..2bac99b6309af 100644
--- a/llvm/lib/MCA/InstrBuilder.cpp
+++ b/llvm/lib/MCA/InstrBuilder.cpp
@@ -634,16 +634,14 @@ InstrBuilder::createInstrDescImpl(const MCInst &MCI,
   bool IsVariadic = MCDesc.isVariadic();
   if ((ID->IsRecyclable = !IsVariadic && !IsVariant)) {
     auto DKey = std::make_pair(MCI.getOpcode(), SchedClassID);
-    Descriptors[DKey] = std::move(ID);
-    return *Descriptors[DKey];
+    return *(Descriptors[DKey] = std::move(ID));
   }
 
   auto VDKey = std::make_pair(hashMCInst(MCI), SchedClassID);
   assert(
       !VariantDescriptors.contains(VDKey) &&
       "Expected VariantDescriptors to not already have a value for this key.");
-  VariantDescriptors[VDKey] = std::move(ID);
-  return *VariantDescriptors[VDKey];
+  return *(VariantDescriptors[VDKey] = std::move(ID));
 }
 
 Expected<const InstrDesc &>

``````````

</details>


https://github.com/llvm/llvm-project/pull/129192