[Sema] Avoid repeated hash lookups (NFC) (#131263)

Author: kazutakahirata

clang/lib/Sema/SemaOpenMP.cpp

@@ -6836,22 +6836,21 @@ SemaOpenMP::DeclGroupPtrTy SemaOpenMP::ActOnOpenMPDeclareSimdDirective(
                     ->getCanonicalDecl() == CanonPVD) {
           // OpenMP  [2.15.3.7, linear Clause, Restrictions]
           // A list-item cannot appear in more than one linear clause.
-          if (LinearArgs.count(CanonPVD) > 0) {
+          if (auto It = LinearArgs.find(CanonPVD); It != LinearArgs.end()) {
             Diag(E->getExprLoc(), diag::err_omp_wrong_dsa)
                 << getOpenMPClauseName(OMPC_linear)
                 << getOpenMPClauseName(OMPC_linear) << E->getSourceRange();
-            Diag(LinearArgs[CanonPVD]->getExprLoc(),
-                 diag::note_omp_explicit_dsa)
+            Diag(It->second->getExprLoc(), diag::note_omp_explicit_dsa)
                 << getOpenMPClauseName(OMPC_linear);
             continue;
           }
           // Each argument can appear in at most one uniform or linear clause.
-          if (UniformedArgs.count(CanonPVD) > 0) {
+          if (auto It = UniformedArgs.find(CanonPVD);
+              It != UniformedArgs.end()) {
             Diag(E->getExprLoc(), diag::err_omp_wrong_dsa)
                 << getOpenMPClauseName(OMPC_linear)
                 << getOpenMPClauseName(OMPC_uniform) << E->getSourceRange();
-            Diag(UniformedArgs[CanonPVD]->getExprLoc(),
-                 diag::note_omp_explicit_dsa)
+            Diag(It->second->getExprLoc(), diag::note_omp_explicit_dsa)
                 << getOpenMPClauseName(OMPC_uniform);
             continue;
           }