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fb85e6288b
1) Turns out we weren't correctly uniquing types for C++. We would search our repository for "lldb_private::Process", but yet store just "Process" in the unique type map. Now we store things correctly and correctly unique types.
2) SymbolFileDWARF::CompleteType() can be called at any time in order to complete a C++ or Objective C class. All public inquiries into the SymbolFile go through SymbolVendor, and SymbolVendor correctly takes the module lock before it call the SymbolFile API call, but when we let CompilerType objects out in the wild, they can complete themselves at any time from the expression parser, so the ValueObjects or (SBValue objects in the public API), and many more places. So we now take the module lock when completing a type to avoid two threads being in the SymbolFileDWARF at the same time.
3) If a class has a template member function like:
class A
{
<template T>
void Foo(T t);
};
The DWARF will _only_ contain a DW_TAG_subprogram for "Foo" if anyone specialized it. This would cause a class definition for A inside a.cpp that used a "int" and "float" overload to look like:
class A
{
void Foo(int t);
void Foo(double t);
};
And a version from b.cpp that used a "float" overload to look like:
class A
{
void Foo(float t);
};
And a version from c.cpp that use no overloads to look like:
class A
{
};
Then in an expression if you have two variables, one name "a" from a.cpp in liba.dylib, and one named "b" from b.cpp in libb.dylib, you will get conflicting definitions for "A" and your expression will fail. This all stems from the fact that DWARF _only_ emits template specializations, not generic definitions, and they are only emitted if they are used. There are two solutions to this:
a) When ever you run into ANY class, you must say "just because this class doesn't have templatized member functions, it doesn't mean that any other instances might not have any, so when ever I run into ANY class, I must parse all compile units and parse all instances of class "A" just in case it has member functions that are templatized.". That is really bad because it means you always pull in ALL DWARF that contains most likely exact duplicate definitions of the class "A" and you bloat the memory that the SymbolFileDWARF plug-in uses in LLDB (since you pull in all DIEs from all compile units that contain a "A" definition) uses for little value most of the time.
b) Modify DWARF to emit generic template member function definitions so that you know from looking at any instance of class "A" wether it has template member functions or not. In order to do this, we would have to have the ability to correctly parse a member function template, but there is a compiler bug:
<rdar://problem/24515533> [PR 26553] C++ Debug info should reference DW_TAG_template_type_parameter
This bugs means that not all of the info needed to correctly make a template member function is in the DWARF. The main source of the problem is if we have DWARF for a template instantiation for "int" like: "void A::Foo<int>(T)" the DWARF comes out as "void A::Foo<int>(int)" (it doesn't mention type "T", it resolves the type to the specialized type to "int"). But if you actually have your function defined as "<template T> void Foo(int t)" and you only use T for local variables inside the function call, we can't correctly make the function prototype up in the clang::ASTContext.
So the best we can do for now we just omit all member functions that are templatized from the class definition so that "A" never has any template member functions. This means all defintions of "A" look like:
class A
{
};
And our expressions will work. You won't be able to call template member fucntions in expressions (not a regression, we weren't able to do this before) and if you are stopped in a templatized member function, we won't know that are are in a method of class "A". All things we should fix, but we need <rdar://problem/24515533> fixed first, followed by:
<rdar://problem/24515624> Classes should always include a template subprogram definition, even when no template member functions are used
before we can do anything about it in LLDB.
This bug mainly fixed the following Apple radar:
<rdar://problem/24483905>
llvm-svn: 260308