[Concepts] Constraint Satisfaction Caching

Add a simple cache for constraint satisfaction results. Whether or not this simple caching
would be permitted in final C++2a is currently being discussed but it is required for
acceptable performance so we use it in the meantime, with the possibility of adding some
cache invalidation mechanisms later.

Differential Revision: https://reviews.llvm.org/D72552

(cherry picked from commit b933d37cd3774e5431b35e82187eebb59b1ff59e)

1 files changed, 2 insertions, 0 deletions

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index e1e59565083..af5113f0aba 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2853,6 +2853,8 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
     Opts.NewAlignOverride = 0;
   }
   Opts.ConceptsTS = Args.hasArg(OPT_fconcepts_ts);
+  Opts.ConceptSatisfactionCaching =
+      !Args.hasArg(OPT_fno_concept_satisfaction_caching);
   Opts.HeinousExtensions = Args.hasArg(OPT_fheinous_gnu_extensions);
   Opts.AccessControl = !Args.hasArg(OPT_fno_access_control);
   Opts.ElideConstructors = !Args.hasArg(OPT_fno_elide_constructors);