[MsDemangle] Read entire chain of target names in special tables

[Nerixyz]

When there's a deep inheritance hierarchy of multiple C++ classes (see below), then the mangled name of a VFTable can include multiple key nodes in the target name.
For example, in the following code, MSVC will generate mangled names for the VFTables that have up to three key classes in the context.

Code

class Base1 {
  virtual void a() {};
};
class Base2 {
  virtual void b() {}
};

class Ind1 : public Base1 {};
class Ind2 : public Base1 {};

class A : public Ind1, public Ind2 {};

class Ind3 : public A {};
class Ind4 : public A {};

class B : public Ind3, public Ind4 {};

class Ind5 : public B {};
class Ind6 : public B {};

class C : public Ind5, public Ind6 {};

int main() { auto i = new C; }

This will include ??_7C@@6BInd1@@Ind4@@Ind5@@@ (and every other combination). Microsoft's undname will demangle this to "const C::`vftable'{for `Ind1's `Ind4's `Ind5'}". Previously, LLVM would demangle this to "const C::`vftable'{for `Ind1'}".

With this PR, the output of LLVM's undname will be identical to Microsoft's version. This changes SpecialTableSymbolNode::TargetName to a node array which contains each key from the name. Unlike namespaces, these keys are not in reverse order - they are in the same order as in the mangled name.

[Nerixyz]

Ping

[zmodem]

Sorry, I must have missed this before. Thanks for fixing this.

[zmodem]

Instead of building a linked list here, could we just put these into a SmallVector and create the NodeArray from that directly?

[zmodem]

Thanks! I think that's much easier to read.

[zmodem]

lgtm

[dtcxzyw]

I cannot build LLVM with gcc+gnu ld after this patch. It introduces cyclic dependencies (LLVMSupport <-> LLVMDemangle).

FAILED: lib/libLLVMDemangle.so.22.0git 
: && /usr/bin/c++ -fPIC -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-uninitialized -Wno-nonnull -Wno-class-memaccess -Wno-dangling-reference -Wno-redundant-move -Wno-pessimizing-move -Wno-array-bounds -Wno-stringop-overread -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wno-misleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -O2 -g -DNDEBUG  -Wl,-z,defs -Wl,-z,nodelete   -Wl,-rpath-link,/data/zyw/dev/llvm-build/./lib  -Wl,--gc-sections -shared -Wl,-soname,libLLVMDemangle.so.22.0git -o lib/libLLVMDemangle.so.22.0git lib/Demangle/CMakeFiles/LLVMDemangle.dir/Demangle.cpp.o lib/Demangle/CMakeFiles/LLVMDemangle.dir/ItaniumDemangle.cpp.o lib/Demangle/CMakeFiles/LLVMDemangle.dir/MicrosoftDemangle.cpp.o lib/Demangle/CMakeFiles/LLVMDemangle.dir/MicrosoftDemangleNodes.cpp.o lib/Demangle/CMakeFiles/LLVMDemangle.dir/RustDemangle.cpp.o lib/Demangle/CMakeFiles/LLVMDemangle.dir/DLangDemangle.cpp.o  -Wl,-rpath,"\$ORIGIN/../lib:" && :
/usr/bin/ld: lib/Demangle/CMakeFiles/LLVMDemangle.dir/MicrosoftDemangle.cpp.o: in function `llvm::SmallVectorTemplateCommon<llvm::ms_demangle::Node*, void>::grow_pod(unsigned long, unsigned long)':
/data/zyw/dev/llvm-project/llvm/include/llvm/ADT/SmallVector.h:140:(.text._ZN4llvm11ms_demangle9Demangler30demangleSpecialTableSymbolNodeERSt17basic_string_viewIcSt11char_traitsIcEENS0_20SpecialIntrinsicKindE+0x28c): undefined reference to `llvm::SmallVectorBase<unsigned int>::grow_pod(void*, unsigned long, unsigned long)'
collect2: error: ld returned 1 exit status

[Nerixyz]

Sorry, opened #166586 to fix this.

[jplehr]

I believe this one broke a few of our buildbots, e.g., https://lab.llvm.org/buildbot/#/builders/203/builds/28219

From the log

[694/8173] Linking CXX shared library lib/libLLVMDemangle.so.22.0git
FAILED: lib/libLLVMDemangle.so.22.0git 
: && /usr/bin/c++ -fPIC -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-uninitialized -Wno-nonnull -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-array-bounds -Wno-stringop-overread -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wno-misleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG  -Wl,-z,defs -Wl,-z,nodelete   -Wl,-rpath-link,/home/botworker/bbot/amdgpu-offload-ubuntu-22-cmake-build-only/build/./lib  -Wl,--gc-sections -shared -Wl,-soname,libLLVMDemangle.so.22.0git -o lib/libLLVMDemangle.so.22.0git lib/Demangle/CMakeFiles/LLVMDemangle.dir/Demangle.cpp.o lib/Demangle/CMakeFiles/LLVMDemangle.dir/ItaniumDemangle.cpp.o lib/Demangle/CMakeFiles/LLVMDemangle.dir/MicrosoftDemangle.cpp.o lib/Demangle/CMakeFiles/LLVMDemangle.dir/MicrosoftDemangleNodes.cpp.o lib/Demangle/CMakeFiles/LLVMDemangle.dir/RustDemangle.cpp.o lib/Demangle/CMakeFiles/LLVMDemangle.dir/DLangDemangle.cpp.o  -Wl,-rpath,"\$ORIGIN/../lib:" && :
/usr/bin/ld: lib/Demangle/CMakeFiles/LLVMDemangle.dir/MicrosoftDemangle.cpp.o: in function `llvm::ms_demangle::Demangler::demangleSpecialTableSymbolNode(std::basic_string_view<char, std::char_traits<char> >&, llvm::ms_demangle::SpecialIntrinsicKind) [clone .localalias]':
MicrosoftDemangle.cpp:(.text._ZN4llvm11ms_demangle9Demangler30demangleSpecialTableSymbolNodeERSt17basic_string_viewIcSt11char_traitsIcEENS0_20SpecialIntrinsicKindE+0x36c): undefined reference to `llvm::SmallVectorBase<unsigned int>::grow_pod(void*, unsigned long, unsigned long)'
collect2: error: ld returned 1 exit status