Added a SemaConsumer that transforms the ASTs for
an expression, adding code to put the value of the
last expression (if there is one) into a variable
and write the address of that variable to a global
pointer.


git-svn-id: https://llvm.org/svn/llvm-project/llvdb/trunk@107419 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/source/Expression/ClangResultSynthesizer.cpp b/source/Expression/ClangResultSynthesizer.cpp
new file mode 100644
index 0000000..3a5769b
--- /dev/null
+++ b/source/Expression/ClangResultSynthesizer.cpp
@@ -0,0 +1,341 @@
+//===-- ClangResultSynthesizer.cpp ------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "stdlib.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/DeclGroup.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/Stmt.h"
+#include "clang/Parse/Action.h"
+#include "clang/Parse/Parser.h"
+#include "clang/Parse/Scope.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/raw_ostream.h"
+#include "lldb/Core/Log.h"
+#include "lldb/Expression/ClangResultSynthesizer.h"
+
+using namespace llvm;
+using namespace clang;
+using namespace lldb_private;
+
+ClangResultSynthesizer::ClangResultSynthesizer(ASTConsumer *passthrough) :
+    m_passthrough(passthrough),
+    m_passthrough_sema(NULL),
+    m_sema(NULL),
+    m_ast_context(NULL)
+{
+    if (!m_passthrough)
+        return;
+    
+    m_passthrough_sema = dyn_cast<SemaConsumer>(passthrough);
+}
+
+ClangResultSynthesizer::~ClangResultSynthesizer()
+{
+}
+
+void
+ClangResultSynthesizer::Initialize(ASTContext &Context) 
+{
+    m_ast_context = &Context;
+    
+    if (m_passthrough)
+        m_passthrough->Initialize(Context);
+}
+
+void
+ClangResultSynthesizer::TransformTopLevelDecl(Decl* D)
+{
+    LinkageSpecDecl *linkage_spec_decl = dyn_cast<LinkageSpecDecl>(D);
+    
+    if (linkage_spec_decl)
+    {
+        RecordDecl::decl_iterator decl_iterator;
+        
+        for (decl_iterator = linkage_spec_decl->decls_begin();
+             decl_iterator != linkage_spec_decl->decls_end();
+             ++decl_iterator)
+        {
+            TransformTopLevelDecl(*decl_iterator);
+        }
+    }
+    
+    FunctionDecl *function_decl = dyn_cast<FunctionDecl>(D);
+    
+    if (m_ast_context &&
+        function_decl &&
+        !strcmp(function_decl->getNameAsCString(),
+                "___clang_expr"))
+    {
+        SynthesizeResult(*m_ast_context, function_decl);
+    }
+}
+
+void 
+ClangResultSynthesizer::HandleTopLevelDecl(DeclGroupRef D)
+{
+    DeclGroupRef::iterator decl_iterator;
+    
+    for (decl_iterator = D.begin();
+         decl_iterator != D.end();
+         ++decl_iterator)
+    {
+        Decl *decl = *decl_iterator;
+        
+        TransformTopLevelDecl(decl);
+    }
+    
+    if (m_passthrough)
+        m_passthrough->HandleTopLevelDecl(D);
+}
+
+bool 
+ClangResultSynthesizer::SynthesizeResult (ASTContext &Ctx,
+                                          FunctionDecl *FunDecl)
+{
+    Log *log = lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS);
+    
+    if (!m_sema)
+        return false;
+
+    FunctionDecl *function_decl = FunDecl;
+    
+    if (!function_decl)
+        return false;
+    
+    Stmt *function_body = function_decl->getBody();
+    CompoundStmt *compound_stmt = dyn_cast<CompoundStmt>(function_body);
+    
+    if (!compound_stmt)
+        return false;
+    
+    if (compound_stmt->body_empty())
+        return false;
+    
+    Stmt **last_stmt_ptr = compound_stmt->body_end() - 1;
+    Stmt *last_stmt = *last_stmt_ptr;
+    
+    Expr *last_expr = dyn_cast<Expr>(last_stmt);
+    
+    if (!last_expr)
+        // No auxiliary variable necessary; expression returns void
+        return true;
+    
+    QualType expr_qual_type = last_expr->getType();
+    clang::Type *expr_type = expr_qual_type.getTypePtr();
+    
+    if (!expr_type)
+        return false;
+    
+    if (expr_type->isVoidType())
+        return true;
+    
+    if (log)
+    {
+        std::string s = expr_qual_type.getAsString();
+        
+        log->Printf("Last statement's type: %s", s.c_str());
+    }
+    
+    IdentifierInfo &result_id = Ctx.Idents.get("___clang_expr_result");
+    
+    DeclContext *decl_context = function_decl->getDeclContext();
+    
+    clang::VarDecl *result_decl = VarDecl::Create(Ctx, 
+                                                  function_decl, 
+                                                  SourceLocation(), 
+                                                  &result_id, 
+                                                  expr_qual_type, 
+                                                  NULL, 
+                                                  VarDecl::Static, 
+                                                  VarDecl::Static);
+    
+    if (!result_decl)
+        return false;
+    
+    function_decl->addDecl(result_decl);
+    
+    ///////////////////////////////
+    // call AddInitializerToDecl
+    //
+    
+    Parser::DeclPtrTy result_decl_ptr;
+    result_decl_ptr.set(result_decl);
+    
+    m_action->AddInitializerToDecl(result_decl_ptr, Parser::ExprArg(*m_action, last_expr));
+    
+    /////////////////////////////////
+    // call ConvertDeclToDeclGroup
+    //
+    
+    Parser::DeclGroupPtrTy result_decl_group_ptr;
+    
+    result_decl_group_ptr = m_action->ConvertDeclToDeclGroup(result_decl_ptr);
+    
+    ////////////////////////
+    // call ActOnDeclStmt
+    //
+    
+    Parser::OwningStmtResult result_initialization_stmt_result(m_action->ActOnDeclStmt(result_decl_group_ptr,
+                                                                                       SourceLocation(),
+                                                                                       SourceLocation()));
+    
+    
+    ///////////////////////////////////////////////
+    // Synthesize external void pointer variable
+    //
+    
+    IdentifierInfo &result_ptr_id = Ctx.Idents.get("___clang_expr_result_ptr");
+    
+    clang::VarDecl *result_ptr_decl = VarDecl::Create(Ctx,
+                                                      decl_context,
+                                                      SourceLocation(),
+                                                      &result_ptr_id,
+                                                      Ctx.VoidPtrTy,
+                                                      NULL,
+                                                      VarDecl::Extern,
+                                                      VarDecl::Extern);
+    
+    /////////////////////////////////////////////
+    // Build a DeclRef for the result variable
+    //
+    
+    DeclRefExpr *result_decl_ref_expr = DeclRefExpr::Create(Ctx,
+                                                            NULL,
+                                                            SourceRange(),
+                                                            result_decl,
+                                                            SourceLocation(),
+                                                            expr_qual_type);
+    
+    ///////////////////////
+    // call ActOnUnaryOp
+    //
+    
+    Scope my_scope(NULL, (Scope::BlockScope | Scope::FnScope | Scope::DeclScope));
+    
+    Parser::DeclPtrTy result_ptr_decl_ptr;
+    result_ptr_decl_ptr.set(result_ptr_decl);
+        
+    Parser::OwningExprResult addressof_expr_result(m_action->ActOnUnaryOp(&my_scope,
+                                                                          SourceLocation(),
+                                                                          tok::amp,
+                                                                          Parser::ExprArg(*m_action, result_decl_ref_expr)));
+    
+    ////////////////////////////////////////////
+    // Build a DeclRef for the result pointer
+    //
+    
+    DeclRefExpr *result_ptr_decl_ref_expr = DeclRefExpr::Create(Ctx,
+                                                                NULL,
+                                                                SourceRange(),
+                                                                result_ptr_decl,
+                                                                SourceLocation(),
+                                                                Ctx.VoidPtrTy);
+    
+    ////////////////////////
+    // call ActOnBinaryOp
+    //
+    
+    Parser::OwningExprResult assignment_expr_result(m_action->ActOnBinOp(&my_scope,
+                                                                         SourceLocation(),
+                                                                         tok::equal,
+                                                                         Parser::ExprArg(*m_action, result_ptr_decl_ref_expr),
+                                                                         Parser::ExprArg(*m_action, addressof_expr_result.take())));
+    
+    ////////////////////////////
+    // call ActOnCompoundStmt
+    //
+    
+    void *stmts[2];
+    
+    stmts[0] = result_initialization_stmt_result.take();
+    stmts[1] = assignment_expr_result.take();
+    
+    Parser::OwningStmtResult compound_stmt_result(m_action->ActOnCompoundStmt(SourceLocation(), 
+                                                                              SourceLocation(), 
+                                                                              Parser::MultiStmtArg(*m_action, stmts, 2), 
+                                                                              false));
+    
+    ////////////////////////////////////////////////
+    // replace the old statement with the new one
+    //
+    
+    *last_stmt_ptr = reinterpret_cast<Stmt*>(compound_stmt_result.take());
+
+    if (log)
+    {
+        std::string s;
+        raw_string_ostream os(s);
+        
+        function_decl->print(os);
+        
+        os.flush();
+        
+        log->Printf("Transformed function AST:\n%s", s.c_str());
+    }
+    
+    return true;
+}
+
+void
+ClangResultSynthesizer::HandleTranslationUnit(ASTContext &Ctx)
+{    
+    if (m_passthrough)
+        m_passthrough->HandleTranslationUnit(Ctx);
+}
+
+void 
+ClangResultSynthesizer::HandleTagDeclDefinition(TagDecl *D)
+{
+    if (m_passthrough)
+        m_passthrough->HandleTagDeclDefinition(D);
+}
+
+void
+ClangResultSynthesizer::CompleteTentativeDefinition(VarDecl *D)
+{
+    if (m_passthrough)
+        m_passthrough->CompleteTentativeDefinition(D);
+}
+
+void 
+ClangResultSynthesizer::HandleVTable(CXXRecordDecl *RD, bool DefinitionRequired) 
+{
+    if (m_passthrough)
+        m_passthrough->HandleVTable(RD, DefinitionRequired);
+}
+
+void
+ClangResultSynthesizer::PrintStats() 
+{
+    if (m_passthrough)
+        m_passthrough->PrintStats();
+}
+
+void
+ClangResultSynthesizer::InitializeSema(Sema &S)
+{
+    m_sema = &S;
+    m_action = reinterpret_cast<Action*>(m_sema);
+    
+    if (m_passthrough_sema)
+        m_passthrough_sema->InitializeSema(S);
+}
+
+void 
+ClangResultSynthesizer::ForgetSema() 
+{
+    m_sema = NULL;
+    m_action = NULL;
+    
+    if (m_passthrough_sema)
+        m_passthrough_sema->ForgetSema();
+}