Miscellaneous fixes for big-endian systems

This patch fixes a bunch of issues that show up on big-endian systems:

- The gnu_libstdcpp.py script doesn't follow the way libstdc++ encodes
  bit vectors: it should identify the enclosing *word* and then access
  the appropriate bit within that word.  Instead, the script simply
  operates on bytes.  This gives the same result on little-endian
  systems, but not on big-endian.

- lldb_private::formatters::WCharSummaryProvider always assumes wchar_t
  is UTF16, even though it could also be UTF8 or UTF32.  This is mostly
  not an issue on little-endian systems, but immediately fails on BE.
  Fixed by checking the size of wchar_t like WCharStringSummaryProvider
  already does.

- ClangASTContext::GetChildCompilerTypeAtIndex uses uint32_t to access
  the virtual base offset stored in the vtable, even though the size
  of this field matches the target pointer size according to the C++
  ABI.  Again, this is mostly not visible on LE, but fails on BE.

- Process::ReadStringFromMemory uses strncmp to search for a terminator
  consisting of multiple zero bytes.  This doesn't work since strncmp
  will stop already at the first zero byte.  Use memcmp instead.

Differential Revision: http://reviews.llvm.org/D18983

llvm-svn: 266313

1 files changed, 21 insertions, 1 deletions

diff --git a/lldb/source/Plugins/Language/CPlusPlus/CxxStringTypes.cpp b/lldb/source/Plugins/Language/CPlusPlus/CxxStringTypes.cpp
index 7e8d9582a2b..a2c45fb9989 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/CxxStringTypes.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/CxxStringTypes.cpp
@@ -192,6 +192,14 @@ lldb_private::formatters::WCharSummaryProvider (ValueObject& valobj, Stream& str
     if (error.Fail())
         return false;
     
+    // Get a wchar_t basic type from the current type system
+    CompilerType wchar_compiler_type = valobj.GetCompilerType().GetBasicTypeFromAST(lldb::eBasicTypeWChar);
+
+    if (!wchar_compiler_type)
+        return false;
+
+    const uint32_t wchar_size = wchar_compiler_type.GetBitSize(nullptr); // Safe to pass NULL for exe_scope here
+
     StringPrinter::ReadBufferAndDumpToStreamOptions options(valobj);
     options.SetData(data);
     options.SetStream(&stream);
@@ -200,5 +208,17 @@ lldb_private::formatters::WCharSummaryProvider (ValueObject& valobj, Stream& str
     options.SetSourceSize(1);
     options.SetBinaryZeroIsTerminator(false);
     
-    return StringPrinter::ReadBufferAndDumpToStream<StringPrinter::StringElementType::UTF16>(options);
+    switch (wchar_size)
+    {
+        case 8:
+            return StringPrinter::ReadBufferAndDumpToStream<StringPrinter::StringElementType::UTF8>(options);
+        case 16:
+            return StringPrinter::ReadBufferAndDumpToStream<StringPrinter::StringElementType::UTF16>(options);
+        case 32:
+            return StringPrinter::ReadBufferAndDumpToStream<StringPrinter::StringElementType::UTF32>(options);
+        default:
+            stream.Printf("size for wchar_t is not valid");
+            return true;
+    }
+    return true;
 }