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

[Kazu Hirata via llvm-commits]

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

None

>From 4d068967dfea14be2a5a568011256cb5ad78c48e Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Wed, 5 Feb 2025 09:54:09 -0800
Subject: [PATCH] [X86] Avoid repeated hash lookups (NFC)

---
 llvm/lib/Target/X86/X86AvoidStoreForwardingBlocks.cpp | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/llvm/lib/Target/X86/X86AvoidStoreForwardingBlocks.cpp b/llvm/lib/Target/X86/X86AvoidStoreForwardingBlocks.cpp
index 1919923f41bb201..fe9bacb6856a6a0 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.