Fix broken builtin functions in the expression command

[teemperor]

Summary

Calling any non-libc builtin function in the expression command currently just causes Clang
to state that the function is not known. The reason for this is that we actually never
initialize the list of builtin functions in the Builtin::Context.

This patch just calls the initializer for the builtins in the preprocessor. Also adds some tests
for the new builtins.

It also gets rid of the extra list of builtins in the ClangExpressionParser, as we can just reuse
the existing list in the Preprocessor for the ASTContext. Having just one list of builtins around
is also closer to the standard Clang behavior.

[teemperor]

I didn't disable Windows on the test as it shouldn't call any function in the target process. Just because I don't want to x-fail every test on Windows.

[teemperor]

(Adding the team as a reviewer, because the code this patch touches doesn't seem to have a dedicated code owner).

[vsk]

Thanks, LGTM!

[clayborg]

Changed look fine. Wondering if we want to be adding pexpect style tests though. Those tests tend to be flaky. This could easily be done with SB API calls instead of using pexpect.

[teemperor]

@clayborg Thanks, getting rid of pexpect sounds good.

TODO:

• Get rid of pexpect.
• Fix some of the comments in the test that are still referring to the test I copied this from.
• Reuse builtin_context instead of calling PP.getBuiltinInfo() twice in ClangExpressionParser.cpp.

[teemperor]

• Removed unrelated comments in the test.
• No longer using self.expect.
• Small refactoring in the parsing code.

packages/Python/lldbsuite/test/expression_command/call-function/TestCallBuiltinFunction.py

+"""
+Tests calling builtin functions using expression evaluation.
+"""
+
+from __future__ import print_function
+
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class ExprCommandCallBuiltinFunction(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    # Builtins are expanded by Clang, so debug info shouldn't matter.
+    NO_DEBUG_INFO_TESTCASE = True
+
+    def setUp(self):
+        TestBase.setUp(self)
+        # Find the line number to break for main.c.
+        self.line = line_number(
+            'main.cpp',
+            '// Please test these expressions while stopped at this line:')
+
+    def test(self):
+        self.build()
+
+        # Set breakpoint in main and run exe
+        self.runCmd("file " + self.getBuildArtifact("a.out"), CURRENT_EXECUTABLE_SET)
+        lldbutil.run_break_set_by_file_and_line(
+            self, "main.cpp", self.line, num_expected_locations=-1, loc_exact=True)
+
+        self.runCmd("run", RUN_SUCCEEDED)
+
+        interp = self.dbg.GetCommandInterpreter()
+        result = lldb.SBCommandReturnObject()
+
+        # Test different builtin functions.
+
+        interp.HandleCommand("expr __builtin_isinf(0.0f)", result)
+        self.assertEqual(result.GetOutput(), "(int) $0 = 0\n")
+
+        interp.HandleCommand("expr __builtin_isnormal(0.0f)", result)
+        self.assertEqual(result.GetOutput(), "(int) $1 = 0\n")
+
+        interp.HandleCommand("expr __builtin_constant_p(1)", result)
+        self.assertEqual(result.GetOutput(), "(int) $2 = 1\n")
+
+        interp.HandleCommand("expr __builtin_abs(-14)", result)
+        self.assertEqual(result.GetOutput(), "(int) $3 = 14\n")

source/Plugins/ExpressionParser/Clang/ClangExpressionParser.h

 
 private:
   std::unique_ptr<llvm::LLVMContext>
       m_llvm_context; ///< The LLVM context to generate IR into
   std::unique_ptr<clang::FileManager>
       m_file_manager; ///< The Clang file manager object used by the compiler
   std::unique_ptr<clang::CompilerInstance>
       m_compiler; ///< The Clang compiler used to parse expressions into IR
-  std::unique_ptr<clang::Builtin::Context>
-      m_builtin_context; ///< Context for Clang built-ins
   std::unique_ptr<clang::SelectorTable>
       m_selector_table; ///< Selector table for Objective-C methods
   std::unique_ptr<clang::CodeGenerator>
       m_code_generator; ///< The Clang object that generates IR
 
   class LLDBPreprocessorCallbacks;
   LLDBPreprocessorCallbacks *m_pp_callbacks; ///< Called when the preprocessor
                                              ///encounters module imports
   std::unique_ptr<ClangASTContext> m_ast_context;
 };
 }
 
 #endif // liblldb_ClangExpressionParser_h_

source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp

if (ClangModulesDeclVendor *decl_vendor =
     m_pp_callbacks =
         static_cast<LLDBPreprocessorCallbacks *>(pp_callbacks.get());
     m_compiler->getPreprocessor().addPPCallbacks(std::move(pp_callbacks));
   }
 
   // 8. Most of this we get from the CompilerInstance, but we also want to give
   // the context an ExternalASTSource.
   m_selector_table.reset(new SelectorTable());
-  m_builtin_context.reset(new Builtin::Context());
+
+  // We enable all builtin functions beside the builtins from libc/libm (e.g.
+  // 'fopen'). Those libc functions are already correctly handled by LLDB, and
+  // additionally enabling them as expandable builtins is breaking Clang.
+  m_compiler->getLangOpts().NoBuiltin = true;
+
+  auto &PP = m_compiler->getPreprocessor();
+  auto &builtin_context = PP.getBuiltinInfo();
+  builtin_context.initializeBuiltins(PP.getIdentifierTable(),
+                                     m_compiler->getLangOpts());
 
   std::unique_ptr<clang::ASTContext> ast_context(
       new ASTContext(m_compiler->getLangOpts(), m_compiler->getSourceManager(),
                      m_compiler->getPreprocessor().getIdentifierTable(),
-                     *m_selector_table.get(), *m_builtin_context.get()));
+                     *m_selector_table.get(), builtin_context));
 
   ast_context->InitBuiltinTypes(m_compiler->getTarget());
 
   ClangExpressionHelper *type_system_helper =
       dyn_cast<ClangExpressionHelper>(m_expr.GetTypeSystemHelper());
   ClangExpressionDeclMap *decl_map = type_system_helper->DeclMap();
 
   if (decl_map) {