[clang] [Driver] Avoid repeated hash lookups (NFC) (PR #111468)

[Kazu Hirata via cfe-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/111468

None

>From 9bc29851603347edbc4324ccbdb4fef47a1c2626 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Mon, 7 Oct 2024 07:06:51 -0700
Subject: [PATCH] [Driver] Avoid repeated hash lookups (NFC)

---
 clang/lib/Driver/MultilibBuilder.cpp | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/clang/lib/Driver/MultilibBuilder.cpp b/clang/lib/Driver/MultilibBuilder.cpp
index 15adf501778093..4b365a164c4586 100644
--- a/clang/lib/Driver/MultilibBuilder.cpp
+++ b/clang/lib/Driver/MultilibBuilder.cpp
@@ -74,13 +74,11 @@ bool MultilibBuilder::isValid() const {
   llvm::StringMap<int> FlagSet;
   for (unsigned I = 0, N = Flags.size(); I != N; ++I) {
     StringRef Flag(Flags[I]);
-    llvm::StringMap<int>::iterator SI = FlagSet.find(Flag.substr(1));
+    auto [SI, Inserted] = FlagSet.try_emplace(Flag.substr(1), I);
 
     assert(StringRef(Flag).front() == '-' || StringRef(Flag).front() == '!');
 
-    if (SI == FlagSet.end())
-      FlagSet[Flag.substr(1)] = I;
-    else if (Flags[I] != Flags[SI->getValue()])
+    if (!Inserted && Flags[I] != Flags[SI->getValue()])
       return false;
   }
   return true;