vsk updated this revision to Diff 160666.
vsk retitled this revision from "WIP: Basic tail call frame support" to "Add
support for artificial tail call frames".
vsk edited the summary of this revision.
vsk added reviewers: aprantl, probinson, JDevlieghere, jingham, friss, zturner.
vsk removed subscribers: JDevlieghere, jingham, probinson, aprantl.
vsk added a dependency: D49887: [DebugInfo] Add support for DWARF5 call
site-related attributes.
https://reviews.llvm.org/D50478
Files:
lldb/include/lldb/Symbol/Block.h
lldb/include/lldb/Symbol/Function.h
lldb/include/lldb/Symbol/SymbolFile.h
lldb/include/lldb/Target/StackFrame.h
lldb/include/lldb/Target/StackFrameList.h
lldb/packages/Python/lldbsuite/test/decorators.py
lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq1/Makefile
lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq1/TestAmbiguousTailCallSeq1.py
lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq1/main.cpp
lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq2/Makefile
lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq2/TestAmbiguousTailCallSeq2.py
lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq2/main.cpp
lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_call_site/Makefile
lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_call_site/TestDisambiguateCallSite.py
lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_call_site/main.cpp
lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_tail_call_seq/Makefile
lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_tail_call_seq/TestDisambiguateTailCallSeq.py
lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_tail_call_seq/main.cpp
lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/unambiguous_sequence/Makefile
lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/unambiguous_sequence/TestUnambiguousTailCalls.py
lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/unambiguous_sequence/main.cpp
lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
lldb/source/Symbol/Block.cpp
lldb/source/Symbol/Function.cpp
lldb/source/Target/StackFrameList.cpp
Index: lldb/source/Target/StackFrameList.cpp
===================================================================
--- lldb/source/Target/StackFrameList.cpp
+++ lldb/source/Target/StackFrameList.cpp
@@ -27,6 +27,7 @@
#include "lldb/Target/Thread.h"
#include "lldb/Target/Unwind.h"
#include "lldb/Utility/Log.h"
+#include "llvm/ADT/SmallPtrSet.h"
//#define DEBUG_STACK_FRAMES 1
@@ -240,6 +241,152 @@
m_frames.resize(num_frames);
}
+/// Find the unique path through the call graph from \p begin (at PC offset
+/// \p call_pc) to \p end. On success this path is stored into \p path, and on
+/// failure \p path is unchanged.
+static void FindInterveningFrames(Function &begin, Function &end,
+ Target &target, addr_t call_pc,
+ std::vector<Function *> &path,
+ ModuleList &images, Log *log) {
+ LLDB_LOG(log, "Finding frames between {0} and {1}, call-pc={2:x}",
+ begin.GetDisplayName(), end.GetDisplayName(), call_pc);
+
+ // Find a non-tail calling edge with the first return PC greater than the
+ // call PC.
+ auto first_level_edges = begin.GetCallEdges();
+ auto first_edge_it = std::lower_bound(
+ first_level_edges.begin(), first_level_edges.end(), call_pc,
+ [&](const CallEdge &edge, addr_t target_pc) {
+ return edge.GetReturnPCAddress(begin, target) < target_pc;
+ });
+ if (first_edge_it == first_level_edges.end())
+ return;
+ CallEdge &first_edge = const_cast<CallEdge &>(*first_edge_it);
+ if (first_edge.GetReturnPCAddress(begin, target) == LLDB_INVALID_ADDRESS)
+ return;
+
+ // The first callee may not be resolved, or there may be nothing to fill in.
+ Function *first_callee = first_edge.GetCallee(images);
+ if (!first_callee || first_callee == &end)
+ return;
+
+ // Run DFS on the tail-calling edges out of the first callee to find \p end.
+ // Fully explore the set of functions reachable from the first edge via tail
+ // calls in order to detect ambiguous executions.
+ struct DFS {
+ std::vector<Function *> active_path = {};
+ std::vector<Function *> solution_path = {};
+ llvm::SmallPtrSet<Function *, 2> visited_nodes = {};
+ bool ambiguous = false;
+ Function *end;
+ ModuleList &images;
+
+ DFS(Function *end, ModuleList &images) : end(end), images(images) {}
+
+ void search(Function *first_callee, std::vector<Function *> &path) {
+ dfs(first_callee);
+ if (!ambiguous)
+ path = std::move(solution_path);
+ }
+
+ void dfs(Function *callee) {
+ // Found a path to the target function.
+ if (callee == end) {
+ if (solution_path.empty())
+ solution_path = active_path;
+ else
+ ambiguous = true;
+ return;
+ }
+
+ // Terminate the search if tail recursion is found, or more generally if
+ // there's more than one way to reach a target. This errs on the side of
+ // caution: it conservatively stops searching when some solutions are
+ // still possible to save time in the average case.
+ if (!visited_nodes.insert(callee).second) {
+ ambiguous = true;
+ return;
+ }
+
+ // Search the calls made from this callee.
+ active_path.push_back(callee);
+ for (CallEdge &edge : callee->GetTailCallingEdges()) {
+ Function *next_callee = edge.GetCallee(images);
+ if (!next_callee)
+ continue;
+
+ dfs(next_callee);
+ if (ambiguous)
+ return;
+ }
+ active_path.pop_back();
+ }
+ };
+
+ DFS(&end, images).search(first_callee, path);
+}
+
+/// Given that \p next_frame will be appended to the frame list, synthesize
+/// tail call frames between the current end of the list and \p next_frame.
+/// If any frames are added, adjust the frame index of \p next_frame.
+void StackFrameList::SynthesizeTailCallFrames(StackFrame &next_frame) {
+ TargetSP target_sp = next_frame.CalculateTarget();
+ if (!target_sp)
+ return;
+
+ lldb::RegisterContextSP next_reg_ctx_sp = next_frame.GetRegisterContext();
+ if (!next_reg_ctx_sp)
+ return;
+
+ Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
+
+ assert(!m_frames.empty() && "Cannot synthesize frames in an empty stack");
+ StackFrame &prev_frame = *m_frames.back().get();
+
+ // Find the functions prev_frame and next_frame are stopped in. The function
+ // objects are needed to search the lazy call graph for intervening frames.
+ Function *prev_func =
+ prev_frame.GetSymbolContext(eSymbolContextFunction).function;
+ if (!prev_func)
+ return;
+ Function *next_func =
+ next_frame.GetSymbolContext(eSymbolContextFunction).function;
+ if (!next_func)
+ return;
+
+ // Try to find the unique sequence of (tail) calls which led from next_frame
+ // to prev_frame.
+ std::vector<Function *> path;
+ addr_t call_pc = next_reg_ctx_sp->GetPC();
+ Target &target = *target_sp.get();
+ ModuleList &images = next_frame.CalculateTarget()->GetImages();
+ FindInterveningFrames(*next_func, *prev_func, target, call_pc, path, images,
+ log);
+
+ // Push synthetic tail call frames.
+ for (Function *callee : llvm::reverse(path)) {
+ uint32_t frame_idx = m_frames.size();
+ uint32_t concrete_frame_idx = next_frame.GetConcreteFrameIndex();
+ addr_t cfa = LLDB_INVALID_ADDRESS;
+ bool cfa_is_valid = false;
+ addr_t pc = LLDB_INVALID_ADDRESS;
+ uint32_t stop_id = 0;
+ bool stop_id_is_valid = false;
+ bool is_history_frame = false;
+ SymbolContext sc;
+ callee->CalculateSymbolContext(&sc);
+ StackFrameSP synth_frame{new StackFrame(
+ m_thread.shared_from_this(), frame_idx, concrete_frame_idx, cfa,
+ cfa_is_valid, pc, stop_id, stop_id_is_valid, is_history_frame, &sc)};
+ m_frames.push_back(synth_frame);
+ LLDB_LOG(log, "Pushed frame {0}", callee->GetDisplayName());
+ }
+
+ // If any frames were created, adjust next_frame's index.
+ if (!path.empty())
+ next_frame.SetFrameIndex(m_frames.size());
+}
+
void StackFrameList::GetFramesUpTo(uint32_t end_idx) {
// Do not fetch frames for an invalid thread.
if (!m_thread.IsValid())
@@ -320,6 +467,12 @@
unwind_frame_sp.reset(new StackFrame(
m_thread.shared_from_this(), m_frames.size(), idx, cfa, cfa_is_valid,
pc, 0, stop_id_is_valid, is_history_frame, nullptr));
+
+ // Create synthetic tail call frames between the previous frame and the
+ // newly-found frame. The new frame's index may change after this call,
+ // although its concrete index will stay the same.
+ SynthesizeTailCallFrames(*unwind_frame_sp.get());
+
m_frames.push_back(unwind_frame_sp);
}
Index: lldb/source/Symbol/Function.cpp
===================================================================
--- lldb/source/Symbol/Function.cpp
+++ lldb/source/Symbol/Function.cpp
@@ -10,14 +10,16 @@
#include "lldb/Symbol/Function.h"
#include "lldb/Core/Disassembler.h"
#include "lldb/Core/Module.h"
+#include "lldb/Core/ModuleList.h"
#include "lldb/Core/Section.h"
#include "lldb/Host/Host.h"
#include "lldb/Symbol/CompileUnit.h"
#include "lldb/Symbol/CompilerType.h"
#include "lldb/Symbol/LineTable.h"
#include "lldb/Symbol/SymbolFile.h"
#include "lldb/Symbol/SymbolVendor.h"
#include "lldb/Target/Language.h"
+#include "lldb/Utility/Log.h"
#include "llvm/Support/Casting.h"
using namespace lldb;
@@ -128,6 +130,59 @@
return FunctionInfo::MemorySize() + m_mangled.MemorySize();
}
+//----------------------------------------------------------------------
+//
+//----------------------------------------------------------------------
+CallEdge::CallEdge(const char *mangled_name, lldb::addr_t return_pc)
+ : resolved(false), return_pc(return_pc) {
+ lazy_callee.mangled_name = mangled_name;
+}
+
+void CallEdge::ParseSymbolFileAndResolve(ModuleList &images) {
+ if (resolved)
+ return;
+
+ Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
+ LLDB_LOG(log, "CallEdge: Lazily parsing the call graph for {0}",
+ lazy_callee.mangled_name);
+
+ lazy_callee.def = [&]() -> Function * {
+ ConstString callee_name{lazy_callee.mangled_name};
+ SymbolContextList sc_list;
+ size_t num_matches =
+ images.FindFunctionSymbols(callee_name, eFunctionNameTypeAuto, sc_list);
+ if (num_matches != 1 || !sc_list[0].symbol) {
+ LLDB_LOG(log, "CallEdge: Found {0} symbols for {1}, cannot resolve it",
+ num_matches, callee_name);
+ return nullptr;
+ }
+ Address callee_addr = sc_list[0].symbol->GetAddress();
+ if (!callee_addr.IsValid()) {
+ LLDB_LOG(log, "CallEdge: Invalid symbol address");
+ return nullptr;
+ }
+ Function *f = callee_addr.CalculateSymbolContextFunction();
+ if (!f) {
+ LLDB_LOG(log, "CallEdge: Could not find complete function");
+ return nullptr;
+ }
+ return f;
+ }();
+ resolved = true;
+}
+
+Function *CallEdge::GetCallee(ModuleList &images) {
+ ParseSymbolFileAndResolve(images);
+ return lazy_callee.def;
+}
+
+lldb::addr_t CallEdge::GetReturnPCAddress(Function &caller,
+ Target &target) const {
+ const Address &base = caller.GetAddressRange().GetBaseAddress();
+ Address return_pc_addr{base.GetSection(), return_pc};
+ return return_pc_addr.GetLoadAddress(&target);
+}
+
//----------------------------------------------------------------------
//
//----------------------------------------------------------------------
@@ -192,6 +247,43 @@
}
}
+llvm::MutableArrayRef<CallEdge> Function::GetCallEdges() {
+ if (m_call_edges_resolved)
+ return m_call_edges;
+
+ Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
+ LLDB_LOG(log, "GetCallEdges: Attempting to parse call site info for {0}",
+ GetDisplayName());
+
+ m_call_edges_resolved = true;
+
+ // Find the SymbolFile which provided this function's definition.
+ Block &block = GetBlock(/*can_create*/true);
+ SymbolFile *sym_file = block.GetSymbolFile();
+ if (!sym_file)
+ return llvm::None;
+
+ // Lazily read call site information from the SymbolFile.
+ m_call_edges = sym_file->ParseCallEdgesInFunction(GetID());
+
+ // Sort the call edges to speed up return_pc lookups.
+ std::sort(m_call_edges.begin(), m_call_edges.end(),
+ [](const CallEdge &LHS, const CallEdge &RHS) {
+ return LHS.GetUnresolvedReturnPCAddress() <
+ RHS.GetUnresolvedReturnPCAddress();
+ });
+
+ return m_call_edges;
+}
+
+llvm::MutableArrayRef<CallEdge> Function::GetTailCallingEdges() {
+ // Call edges are sorted by return PC, and tail calling edges have invalid
+ // return PCs. Find them at the end of the list.
+ return GetCallEdges().drop_until([](const CallEdge &edge) {
+ return edge.GetUnresolvedReturnPCAddress() == LLDB_INVALID_ADDRESS;
+ });
+}
+
Block &Function::GetBlock(bool can_create) {
if (!m_block.BlockInfoHasBeenParsed() && can_create) {
SymbolContext sc;
Index: lldb/source/Symbol/Block.cpp
===================================================================
--- lldb/source/Symbol/Block.cpp
+++ lldb/source/Symbol/Block.cpp
@@ -444,19 +444,16 @@
return num_variables_added;
}
-CompilerDeclContext Block::GetDeclContext() {
- ModuleSP module_sp = CalculateSymbolContextModule();
-
- if (module_sp) {
- SymbolVendor *sym_vendor = module_sp->GetSymbolVendor();
-
- if (sym_vendor) {
- SymbolFile *sym_file = sym_vendor->GetSymbolFile();
+SymbolFile *Block::GetSymbolFile() {
+ if (ModuleSP module_sp = CalculateSymbolContextModule())
+ if (SymbolVendor *sym_vendor = module_sp->GetSymbolVendor())
+ return sym_vendor->GetSymbolFile();
+ return nullptr;
+}
- if (sym_file)
- return sym_file->GetDeclContextForUID(GetID());
- }
- }
+CompilerDeclContext Block::GetDeclContext() {
+ if (SymbolFile *sym_file = GetSymbolFile())
+ return sym_file->GetDeclContextForUID(GetID());
return CompilerDeclContext();
}
Index: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
+++ lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
@@ -122,6 +122,8 @@
size_t GetTypes(lldb_private::SymbolContextScope *sc_scope,
uint32_t type_mask,
lldb_private::TypeList &type_list) override;
+ std::vector<lldb_private::CallEdge>
+ ParseCallEdgesInFunction(lldb_private::UserID func_id) override;
//------------------------------------------------------------------
// PluginInterface protocol
Index: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
+++ lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
@@ -1060,6 +1060,15 @@
return type_list.GetSize() - initial_size;
}
+std::vector<lldb_private::CallEdge>
+SymbolFileDWARFDebugMap::ParseCallEdgesInFunction(UserID func_id) {
+ uint32_t oso_idx = GetOSOIndexFromUserID(func_id.GetID());
+ SymbolFileDWARF *oso_dwarf = GetSymbolFileByOSOIndex(oso_idx);
+ if (oso_dwarf)
+ return oso_dwarf->ParseCallEdgesInFunction(func_id);
+ return {};
+}
+
TypeSP SymbolFileDWARFDebugMap::FindDefinitionTypeForDWARFDeclContext(
const DWARFDeclContext &die_decl_ctx) {
TypeSP type_sp;
Index: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
+++ lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
@@ -316,6 +316,9 @@
DIEInDeclContext(const lldb_private::CompilerDeclContext *parent_decl_ctx,
const DWARFDIE &die);
+ std::vector<lldb_private::CallEdge>
+ ParseCallEdgesInFunction(UserID func_id) override;
+
void Dump(lldb_private::Stream &s) override;
protected:
Index: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -3736,6 +3736,59 @@
return vars_added;
}
+/// Collect call graph edges present in a function DIE.
+static std::vector<lldb_private::CallEdge>
+CollectCallEdges(DWARFDIE function_die) {
+ // Check if the function has a supported call site-related attribute.
+ // TODO: In the future it may be worthwhile to support call_all_source_calls.
+ uint64_t has_call_edges =
+ function_die.GetAttributeValueAsUnsigned(DW_AT_call_all_calls, 0);
+ if (!has_call_edges)
+ return {};
+
+ Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
+ LLDB_LOG(log, "CollectCallEdges: Found call site info in {0}",
+ function_die.GetPubname());
+
+ // Scan the DIE for TAG_call_site entries.
+ // TODO: A recursive scan of all blocks in the subprogram is needed in order
+ // to be DWARF5-compliant. This may need to be done lazily to be performant.
+ // For now, assume that all entries are nested directly under the subprogram
+ // (this is the kind of DWARF LLVM produces) and parse them eagerly.
+ std::vector<CallEdge> call_edges;
+ for (DWARFDIE child = function_die.GetFirstChild(); child.IsValid();
+ child = child.GetSibling()) {
+ if (child.Tag() != DW_TAG_call_site)
+ continue;
+
+ // Extract DW_AT_call_origin (the call target's DIE).
+ DWARFDIE call_origin = child.GetReferencedDIE(DW_AT_call_origin);
+ if (!call_origin.IsValid()) {
+ LLDB_LOG(log, "CollectCallEdges: Invalid call origin in {0}",
+ function_die.GetPubname());
+ continue;
+ }
+
+ // Extract DW_AT_call_return_pc (the PC the call returns to) if it's
+ // available.
+ addr_t return_pc = child.GetAttributeValueAsAddress(DW_AT_call_return_pc,
+ LLDB_INVALID_ADDRESS);
+
+ LLDB_LOG(log, "CollectCallEdges: Found call origin: {0} (return PC = {1})",
+ call_origin.GetPubname(), return_pc);
+ call_edges.emplace_back(call_origin.GetMangledName(), return_pc);
+ }
+ return call_edges;
+}
+
+std::vector<lldb_private::CallEdge>
+SymbolFileDWARF::ParseCallEdgesInFunction(UserID func_id) {
+ DWARFDIE func_die = GetDIEFromUID(func_id.GetID());
+ if (func_die.IsValid())
+ return CollectCallEdges(func_die);
+ return {};
+}
+
//------------------------------------------------------------------
// PluginInterface protocol
//------------------------------------------------------------------
Index: lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/unambiguous_sequence/main.cpp
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/unambiguous_sequence/main.cpp
@@ -0,0 +1,25 @@
+//===-- main.cpp ------------------------------------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+volatile int x;
+
+void __attribute__((noinline)) sink() {
+ x++; //% self.expect("bt", substrs = ['main', 'func1', 'func2', 'func3', 'sink'])
+}
+
+void __attribute__((noinline)) func3() { sink(); /* tail */ }
+
+void __attribute__((disable_tail_calls, noinline)) func2() { func3(); /* regular */ }
+
+void __attribute__((noinline)) func1() { func2(); /* tail */ }
+
+int __attribute__((disable_tail_calls)) main() {
+ func1(); /* regular */
+ return 0;
+}
Index: lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/unambiguous_sequence/TestUnambiguousTailCalls.py
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/unambiguous_sequence/TestUnambiguousTailCalls.py
@@ -0,0 +1,5 @@
+from lldbsuite.test import lldbinline
+from lldbsuite.test import decorators
+
+lldbinline.MakeInlineTest(__file__, globals(),
+ [decorators.skipUnlessHasCallSiteInfo])
Index: lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/unambiguous_sequence/Makefile
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/unambiguous_sequence/Makefile
@@ -0,0 +1,4 @@
+LEVEL = ../../../make
+CXX_SOURCES := main.cpp
+include $(LEVEL)/Makefile.rules
+CXXFLAGS += -mllvm -callsite-debuginfo-experimental=true -g -O1 -glldb
Index: lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_tail_call_seq/main.cpp
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_tail_call_seq/main.cpp
@@ -0,0 +1,27 @@
+//===-- main.cpp ------------------------------------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+volatile int x;
+
+void __attribute__((noinline)) sink() {
+ x++; //% self.expect("bt", substrs = ['main', 'func1', 'func3', 'sink'])
+}
+
+void __attribute__((noinline)) func3() { sink(); /* tail */ }
+
+void __attribute__((noinline)) func2() { sink(); /* tail */ }
+
+void __attribute__((noinline)) func1() { func3(); /* tail */ }
+
+int __attribute__((disable_tail_calls)) main(int argc, char **) {
+ // The sequences `main -> func1 -> f{2,3} -> sink` are both plausible. Test that
+ // lldb picks the latter sequence.
+ func1();
+ return 0;
+}
Index: lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_tail_call_seq/TestDisambiguateTailCallSeq.py
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_tail_call_seq/TestDisambiguateTailCallSeq.py
@@ -0,0 +1,5 @@
+from lldbsuite.test import lldbinline
+from lldbsuite.test import decorators
+
+lldbinline.MakeInlineTest(__file__, globals(),
+ [decorators.skipUnlessHasCallSiteInfo])
Index: lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_tail_call_seq/Makefile
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_tail_call_seq/Makefile
@@ -0,0 +1,4 @@
+LEVEL = ../../../make
+CXX_SOURCES := main.cpp
+include $(LEVEL)/Makefile.rules
+CXXFLAGS += -mllvm -callsite-debuginfo-experimental=true -g -O1 -glldb
Index: lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_call_site/main.cpp
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_call_site/main.cpp
@@ -0,0 +1,27 @@
+//===-- main.cpp ------------------------------------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+volatile int x;
+
+void __attribute__((noinline)) sink() {
+ x++; //% self.expect("bt", substrs = ['main', 'func2', 'sink'])
+}
+
+void __attribute__((noinline)) func2() { sink(); /* tail */ }
+
+void __attribute__((noinline)) func1() { sink(); /* tail */ }
+
+int __attribute__((disable_tail_calls)) main(int argc, char **) {
+ // The sequences `main -> f{1,2} -> sink` are both plausible. Test that
+ // return-pc call site info allows lldb to pick the correct sequence.
+ func2();
+ if (argc == 100)
+ func1();
+ return 0;
+}
Index: lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_call_site/TestDisambiguateCallSite.py
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_call_site/TestDisambiguateCallSite.py
@@ -0,0 +1,5 @@
+from lldbsuite.test import lldbinline
+from lldbsuite.test import decorators
+
+lldbinline.MakeInlineTest(__file__, globals(),
+ [decorators.skipUnlessHasCallSiteInfo])
Index: lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_call_site/Makefile
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/disambiguate_call_site/Makefile
@@ -0,0 +1,4 @@
+LEVEL = ../../../make
+CXX_SOURCES := main.cpp
+include $(LEVEL)/Makefile.rules
+CXXFLAGS += -mllvm -callsite-debuginfo-experimental=true -g -O1 -glldb
Index: lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq2/main.cpp
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq2/main.cpp
@@ -0,0 +1,37 @@
+//===-- main.cpp ------------------------------------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+volatile int x;
+
+void __attribute__((noinline)) sink() {
+ x++; //% self.expect("bt", substrs = ["func1", "func2"], matching = False)
+}
+
+void func2();
+
+void __attribute__((noinline)) func1() {
+ if (x < 1)
+ func2();
+ else
+ sink();
+}
+
+void __attribute__((noinline)) func2() {
+ if (x < 1)
+ sink();
+ else
+ func1();
+}
+
+int main() {
+ // Tail recursion creates ambiguous execution histories.
+ x = 0;
+ func1();
+ return 0;
+}
Index: lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq2/TestAmbiguousTailCallSeq2.py
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq2/TestAmbiguousTailCallSeq2.py
@@ -0,0 +1,5 @@
+from lldbsuite.test import lldbinline
+from lldbsuite.test import decorators
+
+lldbinline.MakeInlineTest(__file__, globals(),
+ [decorators.skipUnlessHasCallSiteInfo])
Index: lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq2/Makefile
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq2/Makefile
@@ -0,0 +1,4 @@
+LEVEL = ../../../make
+CXX_SOURCES := main.cpp
+include $(LEVEL)/Makefile.rules
+CXXFLAGS += -mllvm -callsite-debuginfo-experimental=true -g -O1 -glldb
Index: lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq1/main.cpp
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq1/main.cpp
@@ -0,0 +1,32 @@
+//===-- main.cpp ------------------------------------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+volatile int x;
+
+void __attribute__((noinline)) sink() {
+ x++; //% self.expect("bt", substrs = ["_amb"], matching = False)
+}
+
+void __attribute__((noinline)) func3_amb() { sink(); /* tail */ }
+
+void __attribute__((noinline)) func2_amb() { sink(); /* tail */ }
+
+void __attribute__((noinline)) func1() {
+ if (x > 0)
+ func2_amb(); /* tail */
+ else
+ func3_amb(); /* tail */
+}
+
+int __attribute__((disable_tail_calls)) main(int argc, char **) {
+ // The sequences `main -> func1 -> f{2,3}_amb -> sink` are both plausible. Test
+ // that lldb doesn't attempt to guess which one occurred.
+ func1();
+ return 0;
+}
Index: lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq1/TestAmbiguousTailCallSeq1.py
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq1/TestAmbiguousTailCallSeq1.py
@@ -0,0 +1,5 @@
+from lldbsuite.test import lldbinline
+from lldbsuite.test import decorators
+
+lldbinline.MakeInlineTest(__file__, globals(),
+ [decorators.skipUnlessHasCallSiteInfo])
Index: lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq1/Makefile
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/ambiguous_tail_call_seq1/Makefile
@@ -0,0 +1,4 @@
+LEVEL = ../../../make
+CXX_SOURCES := main.cpp
+include $(LEVEL)/Makefile.rules
+CXXFLAGS += -mllvm -callsite-debuginfo-experimental=true -g -O1 -glldb
Index: lldb/packages/Python/lldbsuite/test/decorators.py
===================================================================
--- lldb/packages/Python/lldbsuite/test/decorators.py
+++ lldb/packages/Python/lldbsuite/test/decorators.py
@@ -687,6 +687,30 @@
return None
return skipTestIfFn(compiler_doesnt_support_struct_attribute)
+def skipUnlessHasCallSiteInfo(func):
+ "Decorate the function to skip testing unless call site info from clang is available."""
+
+ def is_compiler_clang_with_call_site_info(self):
+ compiler_path = self.getCompiler()
+ compiler = os.path.basename(compiler_path)
+ if not compiler.startswith("clang"):
+ return "Test requires clang as compiler"
+
+ f = tempfile.NamedTemporaryFile()
+ cmd = "echo 'int main() {}' | " \
+ "%s -g -O1 -S -emit-llvm -mllvm -callsite-debuginfo-experimental=true -x c -o %s -" % (compiler_path, f.name)
+ if os.popen(cmd).close() is not None:
+ return "Compiler can't compile with call site info enabled"
+
+ with open(f.name, 'r') as ir_output_file:
+ buf = ir_output_file.read()
+
+ if 'DIFlagAllCallsDescribed' not in buf:
+ return "Compiler did not introduce DIFlagAllCallsDescribed IR flag"
+
+ return None
+ return skipTestIfFn(is_compiler_clang_with_call_site_info)(func)
+
def skipUnlessThreadSanitizer(func):
"""Decorate the item to skip test unless Clang -fsanitize=thread is supported."""
Index: lldb/include/lldb/Target/StackFrameList.h
===================================================================
--- lldb/include/lldb/Target/StackFrameList.h
+++ lldb/include/lldb/Target/StackFrameList.h
@@ -99,6 +99,8 @@
void GetOnlyConcreteFramesUpTo(uint32_t end_idx, Unwind *unwinder);
+ void SynthesizeTailCallFrames(StackFrame &next_frame);
+
bool GetAllFramesFetched() { return m_concrete_frames_fetched == UINT32_MAX; }
void SetAllFramesFetched() { m_concrete_frames_fetched = UINT32_MAX; }
Index: lldb/include/lldb/Target/StackFrame.h
===================================================================
--- lldb/include/lldb/Target/StackFrame.h
+++ lldb/include/lldb/Target/StackFrame.h
@@ -412,6 +412,11 @@
//------------------------------------------------------------------
uint32_t GetFrameIndex() const;
+ //------------------------------------------------------------------
+ /// Set this frame's synthetic frame index.
+ //------------------------------------------------------------------
+ void SetFrameIndex(uint32_t index) { m_frame_index = index; }
+
//------------------------------------------------------------------
/// Query this frame to find what frame it is in this Thread's
/// StackFrameList, not counting inlined frames.
Index: lldb/include/lldb/Symbol/SymbolFile.h
===================================================================
--- lldb/include/lldb/Symbol/SymbolFile.h
+++ lldb/include/lldb/Symbol/SymbolFile.h
@@ -14,6 +14,7 @@
#include "lldb/Symbol/CompilerDecl.h"
#include "lldb/Symbol/CompilerDeclContext.h"
#include "lldb/Symbol/CompilerType.h"
+#include "lldb/Symbol/Function.h"
#include "lldb/Symbol/Type.h"
#include "lldb/lldb-private.h"
@@ -194,6 +195,10 @@
ObjectFile *GetObjectFile() { return m_obj_file; }
const ObjectFile *GetObjectFile() const { return m_obj_file; }
+ virtual std::vector<CallEdge> ParseCallEdgesInFunction(UserID func_id) {
+ return {};
+ }
+
//------------------------------------------------------------------
/// Notify the SymbolFile that the file addresses in the Sections
/// for this module have been changed.
Index: lldb/include/lldb/Symbol/Function.h
===================================================================
--- lldb/include/lldb/Symbol/Function.h
+++ lldb/include/lldb/Symbol/Function.h
@@ -16,6 +16,7 @@
#include "lldb/Symbol/Block.h"
#include "lldb/Symbol/Declaration.h"
#include "lldb/Utility/UserID.h"
+#include "llvm/ADT/ArrayRef.h"
namespace lldb_private {
@@ -290,6 +291,55 @@
Declaration m_call_decl;
};
+class Function;
+
+//----------------------------------------------------------------------
+/// @class CallEdge Function.h "lldb/Symbol/Function.h"
+///
+/// Represent a call made within a Function. This can be used to find a path
+/// in the call graph between two functions.
+//----------------------------------------------------------------------
+class CallEdge {
+public:
+ CallEdge(const char *mangled_name, lldb::addr_t return_pc);
+
+ CallEdge(CallEdge &&) = default;
+ CallEdge &operator=(CallEdge &&) = default;
+
+ /// Get the callee's definition.
+ ///
+ /// Note that this might lazily invoke the DWARF parser.
+ Function *GetCallee(ModuleList &images);
+
+ /// Get the load PC address of the instruction which executes after the call
+ /// returns. Returns LLDB_INVALID_ADDRESS iff this is a tail call. \p caller
+ /// is the Function containing this call, and \p target is the Target which
+ /// made the call.
+ lldb::addr_t GetReturnPCAddress(Function &caller, Target &target) const;
+
+ /// Like \ref GetReturnPCAddress, but returns an unresolved file address.
+ lldb::addr_t GetUnresolvedReturnPCAddress() const { return return_pc; }
+
+private:
+ void ParseSymbolFileAndResolve(ModuleList &images);
+
+ /// Whether or not an attempt was made to find the callee's definition.
+ bool resolved;
+
+ /// Either the callee's mangled name or its definition, discriminated by
+ /// \ref resolved.
+ union {
+ const char *mangled_name;
+ Function *def;
+ } lazy_callee;
+
+ /// An invalid address if this is a tail call. Otherwise, the return PC for
+ /// the call. Note that this is a file address which must be resolved.
+ lldb::addr_t return_pc;
+
+ DISALLOW_COPY_AND_ASSIGN(CallEdge);
+};
+
//----------------------------------------------------------------------
/// @class Function Function.h "lldb/Symbol/Function.h"
/// A class that describes a function.
@@ -396,6 +446,18 @@
//------------------------------------------------------------------
void GetEndLineSourceInfo(FileSpec &source_file, uint32_t &line_no);
+ //------------------------------------------------------------------
+ /// Get the outgoing call edges from this function, sorted by their return
+ /// PC addresses (in increasing order).
+ //------------------------------------------------------------------
+ llvm::MutableArrayRef<CallEdge> GetCallEdges();
+
+ //------------------------------------------------------------------
+ /// Get the outgoing tail-callling edges from this function. If none exist,
+ /// return None.
+ //------------------------------------------------------------------
+ llvm::MutableArrayRef<CallEdge> GetTailCallingEdges();
+
//------------------------------------------------------------------
/// Get accessor for the block list.
///
@@ -587,6 +649,10 @@
Flags m_flags;
uint32_t
m_prologue_byte_size; ///< Compute the prologue size once and cache it
+
+ bool m_call_edges_resolved = false; ///< Whether call site info has been
+ /// parsed.
+ std::vector<CallEdge> m_call_edges; ///< Outgoing call edges.
private:
DISALLOW_COPY_AND_ASSIGN(Function);
};
Index: lldb/include/lldb/Symbol/Block.h
===================================================================
--- lldb/include/lldb/Symbol/Block.h
+++ lldb/include/lldb/Symbol/Block.h
@@ -327,6 +327,14 @@
return m_inlineInfoSP.get();
}
+ //------------------------------------------------------------------
+ /// Get the symbol file which contains debug info for this block's
+ /// symbol context module.
+ ///
+ /// @return A pointer to the symbol file or nullptr.
+ //------------------------------------------------------------------
+ SymbolFile *GetSymbolFile();
+
CompilerDeclContext GetDeclContext();
//------------------------------------------------------------------
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