[clang] Avoid unnecessary call to clang::NamespaceDecl::isRedundantInlineQualifierFor().

[ZequanWu]

We observed 2X slowdown in lldb's expression evaluation with #109147 in some cases. It turns out that calling isRedundantInlineQualifierFor is quite expensive. Using short-circuit evaluation in the if statement to avoid unnecessary calls to that function.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Zequan Wu (ZequanWu)

Changes

We observed 2X slowdown in lldb's expression evaluation with #109147. It turns out that calling isRedundantInlineQualifierFor is quite expensive. Using short-circuit evaluation in the if statement to avoid unnecessary calls to that function.

---

Full diff: https://github.com/llvm/llvm-project/pull/115196.diff

1 Files Affected:

• (modified) clang/lib/AST/Decl.cpp (+2-3)

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 8204e3509dd563..a65dc85e04a83d 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -1738,13 +1738,12 @@ void NamedDecl::printNestedNameSpecifier(raw_ostream &OS,
 
     // Suppress inline namespace if it doesn't make the result ambiguous.
     if (Ctx->isInlineNamespace() && NameInScope) {
-      bool isRedundant =
-          cast<NamespaceDecl>(Ctx)->isRedundantInlineQualifierFor(NameInScope);
       if (P.SuppressInlineNamespace ==
               PrintingPolicy::SuppressInlineNamespaceMode::All ||
           (P.SuppressInlineNamespace ==
                PrintingPolicy::SuppressInlineNamespaceMode::Redundant &&
-           isRedundant)) {
+           cast<NamespaceDecl>(Ctx)->isRedundantInlineQualifierFor(
+               NameInScope))) {
         continue;
       }
     }

[labath]

This makes sense to me, but I'll leave the review to someone from the clang team.