Support #pragma weak for PCH.

llvm-svn: 110323

clang/include/clang/Frontend/PCHBitCodes.h

@@ -250,7 +250,10 @@ namespace clang {
       REDECLS_UPDATE_LATEST = 29,
 
       /// \brief Record code for declarations that Sema keeps references of.
-      SEMA_DECL_REFS = 30
+      SEMA_DECL_REFS = 30,
+
+      /// \brief Record code for weak undeclared identifiers.
+      WEAK_UNDECLARED_IDENTIFIERS = 31
     };
 
     /// \brief Record types used within a source manager block.

clang/include/clang/Frontend/PCHReader.h

@@ -379,6 +379,9 @@ private:
   /// \brief The set of unused static functions stored in the the PCH
   /// file.
   llvm::SmallVector<uint64_t, 16> UnusedStaticFuncs;
+  
+  /// \brief The set of weak undeclared identifiers stored in the the PCH file.
+  llvm::SmallVector<uint64_t, 64> WeakUndeclaredIdentifiers;
 
   /// \brief The set of locally-scoped external declarations stored in
   /// the the PCH file.

clang/lib/Frontend/PCHReader.cpp

@@ -1642,6 +1642,15 @@ PCHReader::ReadPCHBlock(PerFileData &F) {
                                  Record.begin(), Record.end());
       break;
 
+    case pch::WEAK_UNDECLARED_IDENTIFIERS:
+      // Optimization for the first block.
+      if (WeakUndeclaredIdentifiers.empty())
+        WeakUndeclaredIdentifiers.swap(Record);
+      else
+        WeakUndeclaredIdentifiers.insert(WeakUndeclaredIdentifiers.end(),
+                                         Record.begin(), Record.end());
+      break;
+
     case pch::LOCALLY_SCOPED_EXTERNAL_DECLS:
       // Optimization for the first block.
       if (LocallyScopedExternalDecls.empty())
@@ -3131,6 +3140,21 @@ void PCHReader::InitializeSema(Sema &S) {
     SemaObj->UnusedStaticFuncs.push_back(FD);
   }
 
+  // If there were any weak undeclared identifiers, deserialize them and add to
+  // Sema's list of weak undeclared identifiers.
+  if (!WeakUndeclaredIdentifiers.empty()) {
+    unsigned Idx = 0;
+    for (unsigned I = 0, N = WeakUndeclaredIdentifiers[Idx++]; I != N; ++I) {
+      IdentifierInfo *WeakId = GetIdentifierInfo(WeakUndeclaredIdentifiers,Idx);
+      IdentifierInfo *AliasId=GetIdentifierInfo(WeakUndeclaredIdentifiers,Idx);
+      SourceLocation Loc = ReadSourceLocation(WeakUndeclaredIdentifiers, Idx);
+      bool Used = WeakUndeclaredIdentifiers[Idx++];
+      Sema::WeakInfo WI(AliasId, Loc);
+      WI.setUsed(Used);
+      SemaObj->WeakUndeclaredIdentifiers.insert(std::make_pair(WeakId, WI));
+    }
+  }
+
   // If there were any locally-scoped external declarations,
   // deserialize them and add them to Sema's table of locally-scoped
   // external declarations.

clang/lib/Frontend/PCHWriter.cpp

@@ -2207,6 +2207,20 @@ void PCHWriter::WritePCHCore(Sema &SemaRef, MemorizeStatCalls *StatCalls,
   RecordData UnusedStaticFuncs;
   for (unsigned i=0, e = SemaRef.UnusedStaticFuncs.size(); i !=e; ++i)
     AddDeclRef(SemaRef.UnusedStaticFuncs[i], UnusedStaticFuncs);
+  
+  RecordData WeakUndeclaredIdentifiers;
+  if (!SemaRef.WeakUndeclaredIdentifiers.empty()) {
+    WeakUndeclaredIdentifiers.push_back(
+                                      SemaRef.WeakUndeclaredIdentifiers.size());
+    for (llvm::DenseMap<IdentifierInfo*,Sema::WeakInfo>::iterator
+         I = SemaRef.WeakUndeclaredIdentifiers.begin(),
+         E = SemaRef.WeakUndeclaredIdentifiers.end(); I != E; ++I) {
+      AddIdentifierRef(I->first, WeakUndeclaredIdentifiers);
+      AddIdentifierRef(I->second.getAlias(), WeakUndeclaredIdentifiers);
+      AddSourceLocation(I->second.getLocation(), WeakUndeclaredIdentifiers);
+      WeakUndeclaredIdentifiers.push_back(I->second.getUsed());
+    }
+  }
 
   // Build a record containing all of the locally-scoped external
   // declarations in this header file. Generally, this record will be
@@ -2311,6 +2325,11 @@ void PCHWriter::WritePCHCore(Sema &SemaRef, MemorizeStatCalls *StatCalls,
   if (!UnusedStaticFuncs.empty())
     Stream.EmitRecord(pch::UNUSED_STATIC_FUNCS, UnusedStaticFuncs);
 
+  // Write the record containing weak undeclared identifiers.
+  if (!WeakUndeclaredIdentifiers.empty())
+    Stream.EmitRecord(pch::WEAK_UNDECLARED_IDENTIFIERS,
+                      WeakUndeclaredIdentifiers);
+
   // Write the record containing locally-scoped external definitions.
   if (!LocallyScopedExternalDecls.empty())
     Stream.EmitRecord(pch::LOCALLY_SCOPED_EXTERNAL_DECLS,

clang/lib/Sema/Sema.cpp

@@ -243,6 +243,9 @@ void Sema::ActOnEndOfTranslationUnit() {
                                           true)), 
                           UnusedStaticFuncs.end());
 
+  if (!CompleteTranslationUnit)
+    return;
+
   // Check for #pragma weak identifiers that were never declared
   // FIXME: This will cause diagnostics to be emitted in a non-determinstic
   // order!  Iterating over a densemap like this is bad.
@@ -255,9 +258,6 @@ void Sema::ActOnEndOfTranslationUnit() {
       << I->first;
   }
 
-  if (!CompleteTranslationUnit)
-    return;
-
   // C99 6.9.2p2:
   //   A declaration of an identifier for an object that has file
   //   scope without an initializer, and without a storage-class

clang/test/PCH/pragma-weak.c

@@ -0,0 +1,10 @@
+// Test this without pch.
+// RUN: %clang_cc1 -include %S/pragma-weak.h %s -verify -emit-llvm -o - | FileCheck %s
+
+// Test with pch.
+// RUN: %clang_cc1 -x c-header -emit-pch -o %t %S/pragma-weak.h
+// RUN: %clang_cc1 -include-pch %t %s -verify -emit-llvm -o - | FileCheck %s
+
+// CHECK: @weakvar = weak global i32 0
+int weakvar;
+// expected-warning {{weak identifier 'undeclaredvar' never declared}}

clang/test/PCH/pragma-weak.h

@@ -0,0 +1,10 @@
+// Header for PCH test pragma-weak.c
+
+#pragma weak weakvar
+
+
+
+
+
+
+#pragma weak undeclaredvar