[llvm] [X86] Avoid repeated hash lookups (NFC) (PR #126006)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-x86

Author: Kazu Hirata (kazutakahirata)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/126006.diff


1 Files Affected:

- (modified) llvm/lib/Target/X86/X86AvoidStoreForwardingBlocks.cpp (+4-7) 


``````````diff
diff --git a/llvm/lib/Target/X86/X86AvoidStoreForwardingBlocks.cpp b/llvm/lib/Target/X86/X86AvoidStoreForwardingBlocks.cpp
index 1919923f41bb20..fe9bacb6856a6a 100644
--- a/llvm/lib/Target/X86/X86AvoidStoreForwardingBlocks.cpp
+++ b/llvm/lib/Target/X86/X86AvoidStoreForwardingBlocks.cpp
@@ -625,13 +625,10 @@ static bool isBlockingStore(int64_t LoadDispImm, unsigned LoadSize,
 static void
 updateBlockingStoresDispSizeMap(DisplacementSizeMap &BlockingStoresDispSizeMap,
                                 int64_t DispImm, unsigned Size) {
-  if (BlockingStoresDispSizeMap.count(DispImm)) {
-    // Choose the smallest blocking store starting at this displacement.
-    if (BlockingStoresDispSizeMap[DispImm] > Size)
-      BlockingStoresDispSizeMap[DispImm] = Size;
-
-  } else
-    BlockingStoresDispSizeMap[DispImm] = Size;
+  auto [It, Inserted] = BlockingStoresDispSizeMap.try_emplace(DispImm, Size);
+  // Choose the smallest blocking store starting at this displacement.
+  if (!Inserted && It->second > Size)
+    It->second = Size;
 }
 
 // Remove blocking stores contained in each other.

``````````

</details>


https://github.com/llvm/llvm-project/pull/126006