Use rich mangling information in Symtab::InitNameIndexes()
Summary:
I set up a new review, because not all the code I touched was marked as a change in old one anymore.
In preparation for this review, there were two earlier ones:
* https://reviews.llvm.org/D49612 introduced the ItaniumPartialDemangler to LLDB demangling without conceptual changes
* https://reviews.llvm.org/D49909 added a unit test that covers all relevant code paths in the InitNameIndexes() function
Primary goals for this patch are:
(1) Use ItaniumPartialDemangler's rich mangling info for building LLDB's name index.
(2) Provide a uniform interface.
(3) Improve indexing performance.
The central implementation in this patch is our new function for explicit demangling:
```
const RichManglingInfo *
Mangled::DemangleWithRichManglingInfo(RichManglingContext &, SkipMangledNameFn *)
```
It takes a context object and a filter function and provides read-only access to the rich mangling info on success, or otherwise returns null. The two new classes are:
* `RichManglingInfo` offers a uniform interface to query symbol properties like `getFunctionDeclContextName()` or `isCtorOrDtor()` that are forwarded to the respective provider internally (`llvm::ItaniumPartialDemangler` or `lldb_private::CPlusPlusLanguage::MethodName`).
* `RichManglingContext` works a bit like `LLVMContext`, it the actual `RichManglingInfo` returned from `DemangleWithRichManglingInfo()` and handles lifetime and configuration. It is likely stack-allocated and can be reused for multiple queries during batch processing.
The idea here is that `DemangleWithRichManglingInfo()` acts like a gate keeper. It only provides access to `RichManglingInfo` on success, which in turn avoids the need to handle a `NoInfo` state in every single one of its getters. Having it stored within the context, avoids extra heap allocations and aids (3). As instantiations of the IPD the are considered expensive, the context is the ideal place to store it too. An efficient filtering function `SkipMangledNameFn` is another piece in the performance puzzle and it helps to mimic the original behavior of `InitNameIndexes`.
Future potential:
* `DemangleWithRichManglingInfo()` is thread-safe, IFF using different contexts in different threads. This may be exploited in the future. (It's another thing that it has in common with `LLVMContext`.)
* The old implementation only parsed and indexed Itanium mangled names. The new `RichManglingInfo` can be extended for various mangling schemes and languages.
One problem with the implementation of RichManglingInfo is the inaccessibility of class `CPlusPlusLanguage::MethodName` (defined in source/Plugins/Language/..), from within any header in the Core components of LLDB. The rather hacky solution is to store a type erased reference and cast it to the correct type on access in the cpp - see `RichManglingInfo::get<ParserT>()`. At the moment there seems to be no better way to do it. IMHO `CPlusPlusLanguage::MethodName` should be a top-level class in order to enable forward delcarations (but that is a rather big change I guess).
First simple profiling shows a good speedup. `target create clang` now takes 0.64s on average. Before the change I observed runtimes between 0.76s an 1.01s. This is still no bulletproof data (I only ran it on one machine!), but it's a promising indicator I think.
Reviewers: labath, jingham, JDevlieghere, erik.pilkington
Subscribers: zturner, clayborg, mgorny, lldb-commits
Differential Revision: https://reviews.llvm.org/D50071
llvm-svn: 339291
diff --git a/lldb/source/Core/Mangled.cpp b/lldb/source/Core/Mangled.cpp
index b8a43be..64d44958 100644
--- a/lldb/source/Core/Mangled.cpp
+++ b/lldb/source/Core/Mangled.cpp
@@ -16,6 +16,7 @@
#pragma comment(lib, "dbghelp.lib")
#endif
+#include "lldb/Core/RichManglingContext.h"
#include "lldb/Utility/ConstString.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/Logging.h"
@@ -233,6 +234,128 @@
}
//----------------------------------------------------------------------
+// Local helpers for different demangling implementations.
+//----------------------------------------------------------------------
+static char *GetMSVCDemangledStr(const char *M) {
+#if defined(_MSC_VER)
+ const size_t demangled_length = 2048;
+ char *demangled_cstr = static_cast<char *>(::malloc(demangled_length));
+ ::ZeroMemory(demangled_cstr, demangled_length);
+ DWORD result = safeUndecorateName(M, demangled_cstr, demangled_length);
+
+ if (Log *log = lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_DEMANGLE)) {
+ if (demangled_cstr && demangled_cstr[0])
+ log->Printf("demangled msvc: %s -> \"%s\"", M, demangled_cstr);
+ else
+ log->Printf("demangled msvc: %s -> error: 0x%lu", M, result);
+ }
+
+ if (result != 0) {
+ return demangled_cstr;
+ } else {
+ ::free(demangled_cstr);
+ return nullptr;
+ }
+#else
+ return nullptr;
+#endif
+}
+
+static char *GetItaniumDemangledStr(const char *M,
+ llvm::ItaniumPartialDemangler &ipd) {
+ char *demangled_cstr = nullptr;
+ bool err = ipd.partialDemangle(M);
+ if (!err) {
+ // Default buffer and size (will realloc in case it's too small).
+ size_t demangled_size = 80;
+ demangled_cstr = static_cast<char *>(std::malloc(demangled_size));
+ demangled_cstr = ipd.finishDemangle(demangled_cstr, &demangled_size);
+
+ assert(demangled_cstr &&
+ "finishDemangle must always succeed if partialDemangle did");
+ assert(demangled_cstr[demangled_size - 1] == '\0' &&
+ "Expected demangled_size to return length including trailing null");
+ }
+
+ if (Log *log = lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_DEMANGLE)) {
+ if (demangled_cstr)
+ log->Printf("demangled itanium: %s -> \"%s\"", M, demangled_cstr);
+ else
+ log->Printf("demangled itanium: %s -> error: failed to demangle", M);
+ }
+
+ return demangled_cstr;
+}
+
+//----------------------------------------------------------------------
+// Explicit demangling for scheduled requests during batch processing. This
+// makes use of ItaniumPartialDemangler's rich demangle info
+//----------------------------------------------------------------------
+bool Mangled::DemangleWithRichManglingInfo(
+ RichManglingContext &context, SkipMangledNameFn *skip_mangled_name) {
+ // We need to generate and cache the demangled name.
+ static Timer::Category func_cat(LLVM_PRETTY_FUNCTION);
+ Timer scoped_timer(func_cat,
+ "Mangled::DemangleWithRichNameIndexInfo (m_mangled = %s)",
+ m_mangled.GetCString());
+
+ // Others are not meant to arrive here. ObjC names or C's main() for example
+ // have their names stored in m_demangled, while m_mangled is empty.
+ assert(m_mangled);
+
+ // Check whether or not we are interested in this name at all.
+ ManglingScheme scheme = cstring_mangling_scheme(m_mangled.GetCString());
+ if (skip_mangled_name && skip_mangled_name(m_mangled.GetStringRef(), scheme))
+ return false;
+
+ switch (scheme) {
+ case eManglingSchemeNone:
+ // The current mangled_name_filter would allow llvm_unreachable here.
+ return false;
+
+ case eManglingSchemeItanium:
+ // We want the rich mangling info here, so we don't care whether or not
+ // there is a demangled string in the pool already.
+ if (context.FromItaniumName(m_mangled)) {
+ // If we got an info, we have a name. Copy to string pool and connect the
+ // counterparts to accelerate later access in GetDemangledName().
+ context.ParseFullName();
+ m_demangled.SetStringWithMangledCounterpart(context.GetBufferRef(),
+ m_mangled);
+ return true;
+ } else {
+ m_demangled.SetCString("");
+ return false;
+ }
+
+ case eManglingSchemeMSVC: {
+ // We have no rich mangling for MSVC-mangled names yet, so first try to
+ // demangle it if necessary.
+ if (!m_demangled && !m_mangled.GetMangledCounterpart(m_demangled)) {
+ if (char *d = GetMSVCDemangledStr(m_mangled.GetCString())) {
+ // If we got an info, we have a name. Copy to string pool and connect
+ // the counterparts to accelerate later access in GetDemangledName().
+ m_demangled.SetStringWithMangledCounterpart(llvm::StringRef(d),
+ m_mangled);
+ ::free(d);
+ } else {
+ m_demangled.SetCString("");
+ }
+ }
+
+ if (m_demangled.IsEmpty()) {
+ // Cannot demangle it, so don't try parsing.
+ return false;
+ } else {
+ // Demangled successfully, we can try and parse it with
+ // CPlusPlusLanguage::MethodName.
+ return context.FromCxxMethodName(m_demangled);
+ }
+ }
+ }
+}
+
+//----------------------------------------------------------------------
// Generate the demangled name on demand using this accessor. Code in this
// class will need to use this accessor if it wishes to decode the demangled
// name. The result is cached and will be kept until a new string value is
@@ -248,8 +371,6 @@
Timer scoped_timer(func_cat, "Mangled::GetDemangledName (m_mangled = %s)",
m_mangled.GetCString());
- Log *log = lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_DEMANGLE);
-
// Don't bother running anything that isn't mangled
const char *mangled_name = m_mangled.GetCString();
ManglingScheme mangling_scheme{cstring_mangling_scheme(mangled_name)};
@@ -259,56 +380,20 @@
// add it to our map.
char *demangled_name = nullptr;
switch (mangling_scheme) {
- case eManglingSchemeMSVC: {
-#if defined(_MSC_VER)
- if (log)
- log->Printf("demangle msvc: %s", mangled_name);
- const size_t demangled_length = 2048;
- demangled_name = static_cast<char *>(::malloc(demangled_length));
- ::ZeroMemory(demangled_name, demangled_length);
- DWORD result =
- safeUndecorateName(mangled_name, demangled_name, demangled_length);
- if (log) {
- if (demangled_name && demangled_name[0])
- log->Printf("demangled msvc: %s -> \"%s\"", mangled_name,
- demangled_name);
- else
- log->Printf("demangled msvc: %s -> error: 0x%lu", mangled_name,
- result);
- }
-
- if (result == 0) {
- free(demangled_name);
- demangled_name = nullptr;
- }
-#endif
+ case eManglingSchemeMSVC:
+ demangled_name = GetMSVCDemangledStr(mangled_name);
break;
- }
case eManglingSchemeItanium: {
- llvm::ItaniumPartialDemangler IPD;
- bool demangle_err = IPD.partialDemangle(mangled_name);
- if (!demangle_err) {
- // Default buffer and size (realloc is used in case it's too small).
- size_t demangled_size = 80;
- demangled_name = static_cast<char *>(::malloc(demangled_size));
- demangled_name = IPD.finishDemangle(demangled_name, &demangled_size);
- }
-
- if (log) {
- if (demangled_name)
- log->Printf("demangled itanium: %s -> \"%s\"", mangled_name,
- demangled_name);
- else
- log->Printf("demangled itanium: %s -> error: failed to demangle",
- mangled_name);
- }
+ llvm::ItaniumPartialDemangler ipd;
+ demangled_name = GetItaniumDemangledStr(mangled_name, ipd);
break;
}
case eManglingSchemeNone:
- break;
+ llvm_unreachable("eManglingSchemeNone was handled already");
}
if (demangled_name) {
- m_demangled.SetStringWithMangledCounterpart(demangled_name, m_mangled);
+ m_demangled.SetStringWithMangledCounterpart(
+ llvm::StringRef(demangled_name), m_mangled);
free(demangled_name);
}
}