Updated the IR converter for the target to eliminate

spurious guard variables on expression statics.

Updated the AST result synthesizer to eliminate the
unneeded result pointer.

Very rudimentary expressions now evaluate correctly
in the target using the new JIT-based mechanism.

llvm-svn: 109317

lldb/include/lldb/Expression/IRForTarget.h

@@ -42,6 +42,8 @@ private:
                              bool Store);
     bool runOnBasicBlock(llvm::Module &M,
                          llvm::BasicBlock &BB);
+    bool removeGuards(llvm::Module &M,
+                      llvm::BasicBlock &BB);
     bool replaceVariables(llvm::Module &M,
                           llvm::Function *F);
     

lldb/source/Expression/ClangExpressionDeclMap.cpp

@@ -300,6 +300,12 @@ ClangExpressionDeclMap::DoMaterialize (bool dematerialize,
         return LLDB_INVALID_ADDRESS;
     }
     
+    if (!exe_ctx->frame)
+    {
+        err.SetErrorString("Received null execution frame");
+        return LLDB_INVALID_ADDRESS;
+    }
+    
     const SymbolContext &sym_ctx(exe_ctx->frame->GetSymbolContext(lldb::eSymbolContextEverything));
     
     if (!dematerialize)

lldb/source/Expression/ClangResultSynthesizer.cpp

@@ -147,9 +147,7 @@ ClangResultSynthesizer::SynthesizeResult (ASTContext &Ctx,
     }
     
     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(), 
@@ -189,87 +187,11 @@ ClangResultSynthesizer::SynthesizeResult (ASTContext &Ctx,
                                                                                        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());
+    *last_stmt_ptr = reinterpret_cast<Stmt*>(result_initialization_stmt_result.take());
 
     if (log)
     {

lldb/source/Expression/IRForTarget.cpp

@@ -162,6 +162,85 @@ PrintValue(llvm::Value *V, bool truncate = false)
     return s;
 }
 
+static bool isGuardVariableRef(llvm::Value *V)
+{
+    ConstantExpr *C = dyn_cast<ConstantExpr>(V);
+    
+    if (!C || C->getOpcode() != Instruction::BitCast)
+        return false;
+    
+    GlobalVariable *GV = dyn_cast<GlobalVariable>(C->getOperand(0));
+    
+    if (!GV || !GV->hasName() || !GV->getName().startswith("_ZGV"))
+        return false;
+    
+    return true;
+}
+
+static void TurnGuardLoadIntoZero(Instruction* guard_load, Module &M)
+{
+    Constant* zero(ConstantInt::get(Type::getInt8Ty(M.getContext()), 0, true));
+
+    Value::use_iterator ui;
+    
+    for (ui = guard_load->use_begin();
+         ui != guard_load->use_end();
+         ++ui)
+        ui->replaceUsesOfWith(guard_load, zero);
+    
+    guard_load->eraseFromParent();
+}
+
+static void ExciseGuardStore(Instruction* guard_store)
+{
+    guard_store->eraseFromParent();
+}
+
+bool
+IRForTarget::removeGuards(Module &M, BasicBlock &BB)
+{        
+    ///////////////////////////////////////////////////////
+    // Eliminate any reference to guard variables found.
+    //
+    
+    llvm::BasicBlock::iterator ii;
+    
+    typedef llvm::SmallVector <Instruction*, 2> InstrList;
+    typedef InstrList::iterator InstrIterator;
+    
+    InstrList guard_loads;
+    InstrList guard_stores;
+    
+    for (ii = BB.begin();
+         ii != BB.end();
+         ++ii)
+    {
+        Instruction &inst = *ii;
+        
+        if (LoadInst *load = dyn_cast<LoadInst>(&inst))
+            if (isGuardVariableRef(load->getPointerOperand()))
+                guard_loads.push_back(&inst);                
+        
+        if (StoreInst *store = dyn_cast<StoreInst>(&inst))            
+            if (isGuardVariableRef(store->getPointerOperand()))
+                guard_stores.push_back(&inst);
+    }
+    
+    InstrIterator iter;
+    
+    for (iter = guard_loads.begin();
+         iter != guard_loads.end();
+         ++iter)
+        TurnGuardLoadIntoZero(*iter, M);
+    
+    for (iter = guard_stores.begin();
+         iter != guard_stores.end();
+         ++iter)
+        ExciseGuardStore(*iter);
+    
+    return true;
+}
+
 // UnfoldConstant operates on a constant [C] which has just been replaced with a value
 // [new_value].  We assume that new_value has been properly placed early in the function,
 // most likely somewhere in front of the first instruction in the entry basic block 
@@ -363,6 +442,9 @@ IRForTarget::runOnModule(Module &M)
     {
         if (!runOnBasicBlock(M, *bbi))
             return false;
+        
+        if (!removeGuards(M, *bbi))
+            return false;
     }
     
     if (!replaceVariables(M, function))