[Lldb-commits] [lldb] r257117 - Performance improvement: Change lldb so that it puts a breakpoint
Siva Chandra via lldb-commits
lldb-commits at lists.llvm.org
Thu Jan 7 18:16:33 PST 2016
This broke TestStepNoDebug, atleast on Linux when inferior is compiled
with GCC: http://lab.llvm.org:8011/builders/lldb-x86_64-ubuntu-14.04-cmake/builds/10091
I am able to reproduce this on my machine. Let me know if you need any
help with anything.
On Thu, Jan 7, 2016 at 4:06 PM, Jason Molenda via lldb-commits
<lldb-commits at lists.llvm.org> wrote:
> Author: jmolenda
> Date: Thu Jan 7 18:06:03 2016
> New Revision: 257117
>
> URL: http://llvm.org/viewvc/llvm-project?rev=257117&view=rev
> Log:
> Performance improvement: Change lldb so that it puts a breakpoint
> on the first branch instruction after a function return (or the end
> of a source line), instead of a breakpoint on the return address,
> to skip an extra stop & start of the inferior process.
>
> I changed Process::AdvanceAddressToNextBranchInstruction to not
> take an optional InstructionList argument - no callers are providing
> a cached InstructionList today, and if this function was going to
> do that, the right thing to do would be to fill out / use a
> DisassemblerSP which is a disassembler with the InstructionList for
> this address range.
>
>
> http://reviews.llvm.org/D15708
> <rdar://problem/23309838>
>
>
> Modified:
> lldb/trunk/include/lldb/Target/Process.h
> lldb/trunk/include/lldb/Target/Thread.h
> lldb/trunk/include/lldb/Target/ThreadPlanStepOut.h
> lldb/trunk/source/Target/Process.cpp
> lldb/trunk/source/Target/Thread.cpp
> lldb/trunk/source/Target/ThreadPlanShouldStopHere.cpp
> lldb/trunk/source/Target/ThreadPlanStepOut.cpp
> lldb/trunk/source/Target/ThreadPlanStepOverRange.cpp
>
> Modified: lldb/trunk/include/lldb/Target/Process.h
> URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/include/lldb/Target/Process.h?rev=257117&r1=257116&r2=257117&view=diff
> ==============================================================================
> --- lldb/trunk/include/lldb/Target/Process.h (original)
> +++ lldb/trunk/include/lldb/Target/Process.h Thu Jan 7 18:06:03 2016
> @@ -3149,6 +3149,34 @@ public:
> void
> ResetImageToken(size_t token);
>
> + //------------------------------------------------------------------
> + /// Find the next branch instruction to set a breakpoint on
> + ///
> + /// When instruction stepping through a source line, instead of
> + /// stepping through each instruction, we can put a breakpoint on
> + /// the next branch instruction (within the range of instructions
> + /// we are stepping through) and continue the process to there,
> + /// yielding significant performance benefits over instruction
> + /// stepping.
> + ///
> + /// @param[in] default_stop_addr
> + /// The address of the instruction where lldb would put a
> + /// breakpoint normally.
> + ///
> + /// @param[in] range_bounds
> + /// The range which the breakpoint must be contained within.
> + /// Typically a source line.
> + ///
> + /// @return
> + /// The address of the next branch instruction, or the end of
> + /// the range provided in range_bounds. If there are any
> + /// problems with the disassembly or getting the instructions,
> + /// the original default_stop_addr will be returned.
> + //------------------------------------------------------------------
> + Address
> + AdvanceAddressToNextBranchInstruction (Address default_stop_addr,
> + AddressRange range_bounds);
> +
> protected:
> void
> SetState (lldb::EventSP &event_sp);
>
> Modified: lldb/trunk/include/lldb/Target/Thread.h
> URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/include/lldb/Target/Thread.h?rev=257117&r1=257116&r2=257117&view=diff
> ==============================================================================
> --- lldb/trunk/include/lldb/Target/Thread.h (original)
> +++ lldb/trunk/include/lldb/Target/Thread.h Thu Jan 7 18:06:03 2016
> @@ -888,6 +888,16 @@ public:
> /// @param[in] run_vote
> /// See standard meanings for the stop & run votes in ThreadPlan.h.
> ///
> + /// @param[in] continue_to_next_branch
> + /// Normally this will enqueue a plan that will put a breakpoint on the return address and continue
> + /// to there. If continue_to_next_branch is true, this is an operation not involving the user --
> + /// e.g. stepping "next" in a source line and we instruction stepped into another function --
> + /// so instead of putting a breakpoint on the return address, advance the breakpoint to the
> + /// end of the source line that is doing the call, or until the next flow control instruction.
> + /// If the return value from the function call is to be retrieved / displayed to the user, you must stop
> + /// on the return address. The return value may be stored in volatile registers which are overwritten
> + /// before the next branch instruction.
> + ///
> /// @return
> /// A shared pointer to the newly queued thread plan, or nullptr if the plan could not be queued.
> //------------------------------------------------------------------
> @@ -898,7 +908,8 @@ public:
> bool stop_other_threads,
> Vote stop_vote, // = eVoteYes,
> Vote run_vote, // = eVoteNoOpinion);
> - uint32_t frame_idx);
> + uint32_t frame_idx,
> + bool continue_to_next_branch = false);
>
> //------------------------------------------------------------------
> /// Gets the plan used to step through the code that steps from a function
>
> Modified: lldb/trunk/include/lldb/Target/ThreadPlanStepOut.h
> URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/include/lldb/Target/ThreadPlanStepOut.h?rev=257117&r1=257116&r2=257117&view=diff
> ==============================================================================
> --- lldb/trunk/include/lldb/Target/ThreadPlanStepOut.h (original)
> +++ lldb/trunk/include/lldb/Target/ThreadPlanStepOut.h Thu Jan 7 18:06:03 2016
> @@ -31,7 +31,8 @@ public:
> Vote stop_vote,
> Vote run_vote,
> uint32_t frame_idx,
> - LazyBool step_out_avoids_code_without_debug_info);
> + LazyBool step_out_avoids_code_without_debug_info,
> + bool continue_to_next_branch = false);
>
> ~ThreadPlanStepOut() override;
>
>
> Modified: lldb/trunk/source/Target/Process.cpp
> URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Target/Process.cpp?rev=257117&r1=257116&r2=257117&view=diff
> ==============================================================================
> --- lldb/trunk/source/Target/Process.cpp (original)
> +++ lldb/trunk/source/Target/Process.cpp Thu Jan 7 18:06:03 2016
> @@ -6515,3 +6515,65 @@ Process::ResetImageToken(size_t token)
> if (token < m_image_tokens.size())
> m_image_tokens[token] = LLDB_INVALID_IMAGE_TOKEN;
> }
> +
> +Address
> +Process::AdvanceAddressToNextBranchInstruction (Address default_stop_addr, AddressRange range_bounds)
> +{
> + Target &target = GetTarget();
> + DisassemblerSP disassembler_sp;
> + InstructionList *insn_list = NULL;
> +
> + Address retval = default_stop_addr;
> +
> + if (target.GetUseFastStepping() == false)
> + return retval;
> + if (default_stop_addr.IsValid() == false)
> + return retval;
> +
> + ExecutionContext exe_ctx (this);
> + const char *plugin_name = nullptr;
> + const char *flavor = nullptr;
> + const bool prefer_file_cache = true;
> + disassembler_sp = Disassembler::DisassembleRange(target.GetArchitecture(),
> + plugin_name,
> + flavor,
> + exe_ctx,
> + range_bounds,
> + prefer_file_cache);
> + if (disassembler_sp.get())
> + insn_list = &disassembler_sp->GetInstructionList();
> +
> + if (insn_list == NULL)
> + {
> + return retval;
> + }
> +
> + size_t insn_offset = insn_list->GetIndexOfInstructionAtAddress (default_stop_addr);
> + if (insn_offset == UINT32_MAX)
> + {
> + return retval;
> + }
> +
> + uint32_t branch_index = insn_list->GetIndexOfNextBranchInstruction (insn_offset, target);
> + if (branch_index == UINT32_MAX)
> + {
> + return retval;
> + }
> +
> + if (branch_index > insn_offset)
> + {
> + Address next_branch_insn_address = insn_list->GetInstructionAtIndex (branch_index)->GetAddress();
> + if (next_branch_insn_address.IsValid() && range_bounds.ContainsFileAddress (next_branch_insn_address))
> + {
> + retval = next_branch_insn_address;
> + }
> + }
> +
> + if (disassembler_sp.get())
> + {
> + // FIXME: The DisassemblerLLVMC has a reference cycle and won't go away if it has any active instructions.
> + disassembler_sp->GetInstructionList().Clear();
> + }
> +
> + return retval;
> +}
>
> Modified: lldb/trunk/source/Target/Thread.cpp
> URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Target/Thread.cpp?rev=257117&r1=257116&r2=257117&view=diff
> ==============================================================================
> --- lldb/trunk/source/Target/Thread.cpp (original)
> +++ lldb/trunk/source/Target/Thread.cpp Thu Jan 7 18:06:03 2016
> @@ -1591,7 +1591,7 @@ Thread::QueueThreadPlanForStepOut(bool a
> Vote stop_vote,
> Vote run_vote,
> uint32_t frame_idx,
> - LazyBool step_out_avoids_code_withoug_debug_info)
> + LazyBool step_out_avoids_code_without_debug_info)
> {
> ThreadPlanSP thread_plan_sp (new ThreadPlanStepOut (*this,
> addr_context,
> @@ -1600,7 +1600,7 @@ Thread::QueueThreadPlanForStepOut(bool a
> stop_vote,
> run_vote,
> frame_idx,
> - step_out_avoids_code_withoug_debug_info));
> + step_out_avoids_code_without_debug_info));
>
> if (thread_plan_sp->ValidatePlan(nullptr))
> {
> @@ -1620,7 +1620,8 @@ Thread::QueueThreadPlanForStepOutNoShoul
> bool stop_other_threads,
> Vote stop_vote,
> Vote run_vote,
> - uint32_t frame_idx)
> + uint32_t frame_idx,
> + bool continue_to_next_branch)
> {
> ThreadPlanSP thread_plan_sp(new ThreadPlanStepOut (*this,
> addr_context,
> @@ -1629,7 +1630,8 @@ Thread::QueueThreadPlanForStepOutNoShoul
> stop_vote,
> run_vote,
> frame_idx,
> - eLazyBoolNo));
> + eLazyBoolNo,
> + continue_to_next_branch));
>
> ThreadPlanStepOut *new_plan = static_cast<ThreadPlanStepOut *>(thread_plan_sp.get());
> new_plan->ClearShouldStopHereCallbacks();
>
> Modified: lldb/trunk/source/Target/ThreadPlanShouldStopHere.cpp
> URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Target/ThreadPlanShouldStopHere.cpp?rev=257117&r1=257116&r2=257117&view=diff
> ==============================================================================
> --- lldb/trunk/source/Target/ThreadPlanShouldStopHere.cpp (original)
> +++ lldb/trunk/source/Target/ThreadPlanShouldStopHere.cpp Thu Jan 7 18:06:03 2016
> @@ -135,7 +135,8 @@ ThreadPlanShouldStopHere::DefaultStepFro
> stop_others,
> eVoteNo,
> eVoteNoOpinion,
> - frame_index);
> + frame_index,
> + true);
> return return_plan_sp;
> }
>
>
> Modified: lldb/trunk/source/Target/ThreadPlanStepOut.cpp
> URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Target/ThreadPlanStepOut.cpp?rev=257117&r1=257116&r2=257117&view=diff
> ==============================================================================
> --- lldb/trunk/source/Target/ThreadPlanStepOut.cpp (original)
> +++ lldb/trunk/source/Target/ThreadPlanStepOut.cpp Thu Jan 7 18:06:03 2016
> @@ -18,6 +18,7 @@
> #include "lldb/Core/ValueObjectConstResult.h"
> #include "lldb/Symbol/Block.h"
> #include "lldb/Symbol/Function.h"
> +#include "lldb/Symbol/Symbol.h"
> #include "lldb/Symbol/Type.h"
> #include "lldb/Target/ABI.h"
> #include "lldb/Target/Process.h"
> @@ -44,7 +45,8 @@ ThreadPlanStepOut::ThreadPlanStepOut
> Vote stop_vote,
> Vote run_vote,
> uint32_t frame_idx,
> - LazyBool step_out_avoids_code_without_debug_info
> + LazyBool step_out_avoids_code_without_debug_info,
> + bool continue_to_next_branch
> ) :
> ThreadPlan (ThreadPlan::eKindStepOut, "Step out", thread, stop_vote, run_vote),
> ThreadPlanShouldStopHere (this),
> @@ -86,7 +88,8 @@ ThreadPlanStepOut::ThreadPlanStepOut
> eVoteNoOpinion,
> eVoteNoOpinion,
> frame_idx - 1,
> - eLazyBoolNo));
> + eLazyBoolNo,
> + continue_to_next_branch));
> static_cast<ThreadPlanStepOut *>(m_step_out_to_inline_plan_sp.get())->SetShouldStopHereCallbacks(nullptr, nullptr);
> m_step_out_to_inline_plan_sp->SetPrivate(true);
> }
> @@ -101,7 +104,35 @@ ThreadPlanStepOut::ThreadPlanStepOut
> // Find the return address and set a breakpoint there:
> // FIXME - can we do this more securely if we know first_insn?
>
> - m_return_addr = return_frame_sp->GetFrameCodeAddress().GetLoadAddress(&m_thread.GetProcess()->GetTarget());
> + Address return_address (return_frame_sp->GetFrameCodeAddress());
> + if (continue_to_next_branch)
> + {
> + SymbolContext return_address_sc;
> + AddressRange range;
> + Address return_address_decr_pc = return_address;
> + if (return_address_decr_pc.GetOffset() > 0)
> + return_address_decr_pc.Slide (-1);
> +
> + return_address_decr_pc.CalculateSymbolContext (&return_address_sc, lldb::eSymbolContextLineEntry | lldb::eSymbolContextFunction | lldb::eSymbolContextSymbol);
> + if (return_address_sc.line_entry.IsValid())
> + {
> + range = return_address_sc.line_entry.GetSameLineContiguousAddressRange();
> + }
> + else if (return_address_sc.function)
> + {
> + range = return_address_sc.function->GetAddressRange();
> + }
> + else if (return_address_sc.symbol && return_address_sc.symbol->GetByteSizeIsValid())
> + {
> + range.GetBaseAddress() = return_address_sc.symbol->GetAddress();
> + range.SetByteSize (return_address_sc.symbol->GetByteSize());
> + }
> + if (range.GetByteSize() > 0)
> + {
> + return_address = m_thread.GetProcess()->AdvanceAddressToNextBranchInstruction (return_address, range);
> + }
> + }
> + m_return_addr = return_address.GetLoadAddress(&m_thread.GetProcess()->GetTarget());
>
> if (m_return_addr == LLDB_INVALID_ADDRESS)
> return;
>
> Modified: lldb/trunk/source/Target/ThreadPlanStepOverRange.cpp
> URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Target/ThreadPlanStepOverRange.cpp?rev=257117&r1=257116&r2=257117&view=diff
> ==============================================================================
> --- lldb/trunk/source/Target/ThreadPlanStepOverRange.cpp (original)
> +++ lldb/trunk/source/Target/ThreadPlanStepOverRange.cpp Thu Jan 7 18:06:03 2016
> @@ -185,7 +185,8 @@ ThreadPlanStepOverRange::ShouldStop (Eve
> stop_others,
> eVoteNo,
> eVoteNoOpinion,
> - 0);
> + 0,
> + true);
> break;
> }
> else
>
>
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