[PATCH] D150038: [Clang] Improve compile times when forming a DeclRef outside of a capturing scope.

[Corentin Jabot via Phabricator via cfe-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGa7579b25df78: [Clang] Improve compile times when forming a DeclRef outside of a capturing… (authored by cor3ntin).

Changed prior to commit:
  https://reviews.llvm.org/D150038?vs=520082&id=520420#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D150038/new/

https://reviews.llvm.org/D150038

Files:
  clang/include/clang/Sema/Sema.h
  clang/lib/Sema/Sema.cpp
  clang/lib/Sema/SemaExpr.cpp


Index: clang/lib/Sema/SemaExpr.cpp
===================================================================
--- clang/lib/Sema/SemaExpr.cpp
+++ clang/lib/Sema/SemaExpr.cpp
@@ -19221,6 +19221,15 @@
   // An init-capture is notionally from the context surrounding its
   // declaration, but its parent DC is the lambda class.
   DeclContext *VarDC = Var->getDeclContext();
+  DeclContext *DC = CurContext;
+
+  // tryCaptureVariable is called every time a DeclRef is formed,
+  // it can therefore have non-negigible impact on performances.
+  // For local variables and when there is no capturing scope,
+  // we can bailout early.
+  if (CapturingFunctionScopes == 0 && (!BuildAndDiagnose || VarDC == DC))
+    return true;
+
   const auto *VD = dyn_cast<VarDecl>(Var);
   if (VD) {
     if (VD->isInitCapture())
@@ -19230,7 +19239,6 @@
   }
   assert(VD && "Cannot capture a null variable");
 
-  DeclContext *DC = CurContext;
   const unsigned MaxFunctionScopesIndex = FunctionScopeIndexToStopAt
       ? *FunctionScopeIndexToStopAt : FunctionScopes.size() - 1;
   // We need to sync up the Declaration Context with the
Index: clang/lib/Sema/Sema.cpp
===================================================================
--- clang/lib/Sema/Sema.cpp
+++ clang/lib/Sema/Sema.cpp
@@ -2138,11 +2138,13 @@
 void Sema::PushBlockScope(Scope *BlockScope, BlockDecl *Block) {
   FunctionScopes.push_back(new BlockScopeInfo(getDiagnostics(),
                                               BlockScope, Block));
+  CapturingFunctionScopes++;
 }
 
 LambdaScopeInfo *Sema::PushLambdaScope() {
   LambdaScopeInfo *const LSI = new LambdaScopeInfo(getDiagnostics());
   FunctionScopes.push_back(LSI);
+  CapturingFunctionScopes++;
   return LSI;
 }
 
@@ -2264,6 +2266,8 @@
 
 void Sema::PoppedFunctionScopeDeleter::
 operator()(sema::FunctionScopeInfo *Scope) const {
+  if (!Scope->isPlainFunction())
+    Self->CapturingFunctionScopes--;
   // Stash the function scope for later reuse if it's for a normal function.
   if (Scope->isPlainFunction() && !Self->CachedFunctionScope)
     Self->CachedFunctionScope.reset(Scope);
@@ -2694,6 +2698,7 @@
       OpenMPCaptureLevel);
   CSI->ReturnType = Context.VoidTy;
   FunctionScopes.push_back(CSI);
+  CapturingFunctionScopes++;
 }
 
 CapturedRegionScopeInfo *Sema::getCurCapturedRegion() {
Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -806,6 +806,9 @@
   /// context.
   unsigned FunctionScopesStart = 0;
 
+  /// Track the number of currently active capturing scopes.
+  unsigned CapturingFunctionScopes = 0;
+
   ArrayRef<sema::FunctionScopeInfo*> getFunctionScopes() const {
     return llvm::ArrayRef(FunctionScopes.begin() + FunctionScopesStart,
                           FunctionScopes.end());


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