[lldb][libc++] Adds valarray data formatters.

The code is heavily based on the vector data formatter.

lldb/source/Plugins/Language/CPlusPlus/CMakeLists.txt

@@ -17,6 +17,7 @@ add_lldb_library(lldbPluginCPlusPlusLanguage PLUGIN
   LibCxxTuple.cpp
   LibCxxUnorderedMap.cpp
   LibCxxVariant.cpp
+  LibCxxValarray.cpp
   LibCxxVector.cpp
   LibStdcpp.cpp
   LibStdcppTuple.cpp

lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp

@@ -750,6 +750,11 @@ static void LoadLibCxxFormatters(lldb::TypeCategoryImplSP cpp_category_sp) {
       lldb_private::formatters::LibcxxStdVectorSyntheticFrontEndCreator,
       "libc++ std::vector synthetic children",
       "^std::__[[:alnum:]]+::vector<.+>$", stl_deref_flags, true);
+  AddCXXSynthetic(
+      cpp_category_sp,
+      lldb_private::formatters::LibcxxStdValarraySyntheticFrontEndCreator,
+      "libc++ std::valarray synthetic children",
+      "^std::__[[:alnum:]]+::valarray<.+>(( )?&)?$", stl_deref_flags, true);
   AddCXXSynthetic(
       cpp_category_sp,
       lldb_private::formatters::LibcxxStdForwardListSyntheticFrontEndCreator,
@@ -871,6 +876,10 @@ static void LoadLibCxxFormatters(lldb::TypeCategoryImplSP cpp_category_sp) {
                 lldb_private::formatters::LibcxxContainerSummaryProvider,
                 "libc++ std::vector summary provider",
                 "^std::__[[:alnum:]]+::vector<.+>$", stl_summary_flags, true);
+  AddCXXSummary(
+      cpp_category_sp, lldb_private::formatters::LibcxxContainerSummaryProvider,
+      "libc++ std::valarray summary provider",
+      "^std::__[[:alnum:]]+::valarray<.+>(( )?&)?$", stl_summary_flags, true);
   AddCXXSummary(
       cpp_category_sp, lldb_private::formatters::LibcxxContainerSummaryProvider,
       "libc++ std::list summary provider",

lldb/source/Plugins/Language/CPlusPlus/LibCxx.h

@@ -219,6 +219,10 @@ SyntheticChildrenFrontEnd *
 LibcxxStdVectorSyntheticFrontEndCreator(CXXSyntheticChildren *,
                                         lldb::ValueObjectSP);
 
+SyntheticChildrenFrontEnd *
+LibcxxStdValarraySyntheticFrontEndCreator(CXXSyntheticChildren *,
+                                          lldb::ValueObjectSP);
+
 SyntheticChildrenFrontEnd *
 LibcxxStdListSyntheticFrontEndCreator(CXXSyntheticChildren *,
                                       lldb::ValueObjectSP);

lldb/source/Plugins/Language/CPlusPlus/LibCxxValarray.cpp

@@ -0,0 +1,140 @@
+//===-- LibCxxValarray.cpp ------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "LibCxx.h"
+
+#include "lldb/Core/ValueObject.h"
+#include "lldb/DataFormatters/FormattersHelpers.h"
+#include <optional>
+
+using namespace lldb;
+using namespace lldb_private;
+using namespace lldb_private::formatters;
+
+namespace lldb_private {
+namespace formatters {
+class LibcxxStdValarraySyntheticFrontEnd : public SyntheticChildrenFrontEnd {
+public:
+  LibcxxStdValarraySyntheticFrontEnd(lldb::ValueObjectSP valobj_sp);
+
+  ~LibcxxStdValarraySyntheticFrontEnd() override;
+
+  size_t CalculateNumChildren() override;
+
+  lldb::ValueObjectSP GetChildAtIndex(size_t idx) override;
+
+  bool Update() override;
+
+  bool MightHaveChildren() override;
+
+  size_t GetIndexOfChildWithName(ConstString name) override;
+
+private:
+  ValueObject *m_start = nullptr;
+  ValueObject *m_finish = nullptr;
+  CompilerType m_element_type;
+  uint32_t m_element_size = 0;
+};
+
+} // namespace formatters
+} // namespace lldb_private
+
+lldb_private::formatters::LibcxxStdValarraySyntheticFrontEnd::
+    LibcxxStdValarraySyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
+    : SyntheticChildrenFrontEnd(*valobj_sp), m_element_type() {
+  if (valobj_sp)
+    Update();
+}
+
+lldb_private::formatters::LibcxxStdValarraySyntheticFrontEnd::
+    ~LibcxxStdValarraySyntheticFrontEnd() {
+  // these need to stay around because they are child objects who will follow
+  // their parent's life cycle
+  // delete m_start;
+  // delete m_finish;
+}
+
+size_t lldb_private::formatters::LibcxxStdValarraySyntheticFrontEnd::
+    CalculateNumChildren() {
+  if (!m_start || !m_finish)
+    return 0;
+  uint64_t start_val = m_start->GetValueAsUnsigned(0);
+  uint64_t finish_val = m_finish->GetValueAsUnsigned(0);
+
+  if (start_val == 0 || finish_val == 0)
+    return 0;
+
+  if (start_val >= finish_val)
+    return 0;
+
+  size_t num_children = (finish_val - start_val);
+  if (num_children % m_element_size)
+    return 0;
+  return num_children / m_element_size;
+}
+
+lldb::ValueObjectSP
+lldb_private::formatters::LibcxxStdValarraySyntheticFrontEnd::GetChildAtIndex(
+    size_t idx) {
+  if (!m_start || !m_finish)
+    return lldb::ValueObjectSP();
+
+  uint64_t offset = idx * m_element_size;
+  offset = offset + m_start->GetValueAsUnsigned(0);
+  StreamString name;
+  name.Printf("[%" PRIu64 "]", (uint64_t)idx);
+  return CreateValueObjectFromAddress(name.GetString(), offset,
+                                      m_backend.GetExecutionContextRef(),
+                                      m_element_type);
+}
+
+bool lldb_private::formatters::LibcxxStdValarraySyntheticFrontEnd::Update() {
+  m_start = m_finish = nullptr;
+
+  CompilerType type = m_backend.GetCompilerType();
+  if (type.GetNumTemplateArguments() == 0)
+    return false;
+
+  m_element_type = type.GetTypeTemplateArgument(0);
+  if (std::optional<uint64_t> size = m_element_type.GetByteSize(nullptr))
+    m_element_size = *size;
+
+  if (m_element_size == 0)
+    return false;
+
+  ValueObjectSP start = m_backend.GetChildMemberWithName("__begin_");
+  ValueObjectSP finish = m_backend.GetChildMemberWithName("__end_");
+
+  if (!start || !finish)
+    return false;
+
+  m_start = start.get();
+  m_finish = finish.get();
+
+  return false;
+}
+
+bool lldb_private::formatters::LibcxxStdValarraySyntheticFrontEnd::
+    MightHaveChildren() {
+  return true;
+}
+
+size_t lldb_private::formatters::LibcxxStdValarraySyntheticFrontEnd::
+    GetIndexOfChildWithName(ConstString name) {
+  if (!m_start || !m_finish)
+    return UINT32_MAX;
+  return ExtractIndexFromString(name.GetCString());
+}
+
+lldb_private::SyntheticChildrenFrontEnd *
+lldb_private::formatters::LibcxxStdValarraySyntheticFrontEndCreator(
+    CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
+  if (!valobj_sp)
+    return nullptr;
+  return new LibcxxStdValarraySyntheticFrontEnd(valobj_sp);
+}

lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/valarray/Makefile

@@ -0,0 +1,5 @@
+CXX_SOURCES := main.cpp
+
+USE_LIBCPP := 1
+
+include Makefile.rules

lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/valarray/TestDataFormatterLibcxxValarray.py

@@ -0,0 +1,78 @@
+"""
+Test lldb data formatter subsystem.
+"""
+
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class LibcxxChronoDataFormatterTestCase(TestBase):
+    @add_test_categories(["libc++"])
+    def test_with_run_command(self):
+        """Test that that file and class static variables display correctly."""
+        self.build()
+        (self.target, process, thread, bkpt) = lldbutil.run_to_source_breakpoint(
+            self, "break here", lldb.SBFileSpec("main.cpp", False)
+        )
+
+        self.expect(
+            "frame variable va_int",
+            substrs=[
+                "va_int = size=4",
+                "[0] = 0",
+                "[1] = 0",
+                "[2] = 0",
+                "[3] = 0",
+                "}",
+            ],
+        )
+
+        lldbutil.continue_to_breakpoint(process, bkpt)
+        self.expect(
+            "frame variable va_int",
+            substrs=[
+                "va_int = size=4",
+                "[0] = 1",
+                "[1] = 12",
+                "[2] = 123",
+                "[3] = 1234",
+                "}",
+            ],
+        )
+
+        # check access-by-index
+        self.expect("frame variable va_int[0]", substrs=["1"])
+        self.expect("frame variable va_int[1]", substrs=["12"])
+        self.expect("frame variable va_int[2]", substrs=["123"])
+        self.expect("frame variable va_int[3]", substrs=["1234"])
+        self.expect(
+            "frame variable va_int[4]",
+            error=True,
+            substrs=['array index 4 is not valid for "(valarray<int>) va_int"'],
+        )
+
+        self.expect(
+            "frame variable va_double",
+            substrs=[
+                "va_double = size=4",
+                "[0] = 1",
+                "[1] = 0.5",
+                "[2] = 0.25",
+                "[3] = 0.125",
+                "}",
+            ],
+        )
+
+        # check access-by-index
+        self.expect("frame variable va_double[0]", substrs=["1"])
+        self.expect("frame variable va_double[1]", substrs=["0.5"])
+        self.expect("frame variable va_double[2]", substrs=["0.25"])
+        self.expect("frame variable va_double[3]", substrs=["0.125"])
+        self.expect(
+            "frame variable va_double[4]",
+            error=True,
+            substrs=['array index 4 is not valid for "(valarray<double>) va_double"'],
+        )

lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/valarray/main.cpp

@@ -0,0 +1,17 @@
+#include <iostream>
+#include <valarray>
+
+int main() {
+
+  std::valarray<int> va_int(4);
+  std::cout << "break here";
+
+  va_int[0] = 1;
+  va_int[1] = 12;
+  va_int[2] = 123;
+  va_int[3] = 1234;
+
+  std::valarray<double> va_double({1.0, 0.5, 0.25, 0.125});
+
+  std::cout << "break here\n";
+}