clayborg created this revision.
clayborg added a reviewer: jingham.
Herald added a reviewer: serge-sans-paille.
Herald added a project: LLDB.
Currently when we single step over a source line, we run and stop at every
branch in the source line range. We can reduce the number of times we stop when
stepping over by figuring out if any of these branches are function calls, and
if so, ignore these branches. Since we are stepping over we can safely ignore
these calls since they will return to the next instruction. Currently the step
logic would stop at those branches (1st stop), single step into the branch (2nd
stop), and then set a breakpoint at the return address (3rd stop), and then
continue.
Repository:
rLLDB LLDB
https://reviews.llvm.org/D58678
Files:
include/lldb/Core/Disassembler.h
packages/Python/lldbsuite/test/functionalities/breakpoint/require_hw_breakpoints/TestRequireHWBreakpoints.py
source/Core/Disassembler.cpp
source/Target/Process.cpp
source/Target/ThreadPlanStepRange.cpp
Index: source/Target/ThreadPlanStepRange.cpp
===================================================================
--- source/Target/ThreadPlanStepRange.cpp
+++ source/Target/ThreadPlanStepRange.cpp
@@ -313,9 +313,10 @@
return false;
else {
Target &target = GetThread().GetProcess()->GetTarget();
- uint32_t branch_index;
- branch_index =
- instructions->GetIndexOfNextBranchInstruction(pc_index, target);
+ const bool ignore_calls = GetKind() == eKindStepOverRange;
+ uint32_t branch_index =
+ instructions->GetIndexOfNextBranchInstruction(pc_index, target,
+ ignore_calls);
Address run_to_address;
Index: source/Target/Process.cpp
===================================================================
--- source/Target/Process.cpp
+++ source/Target/Process.cpp
@@ -6019,7 +6019,8 @@
}
uint32_t branch_index =
- insn_list->GetIndexOfNextBranchInstruction(insn_offset, target);
+ insn_list->GetIndexOfNextBranchInstruction(insn_offset, target,
+ false /* ignore_calls*/);
if (branch_index == UINT32_MAX) {
return retval;
}
Index: source/Core/Disassembler.cpp
===================================================================
--- source/Core/Disassembler.cpp
+++ source/Core/Disassembler.cpp
@@ -1087,13 +1087,16 @@
uint32_t
InstructionList::GetIndexOfNextBranchInstruction(uint32_t start,
- Target &target) const {
+ Target &target,
+ bool ignore_calls) const {
size_t num_instructions = m_instructions.size();
uint32_t next_branch = UINT32_MAX;
size_t i;
for (i = start; i < num_instructions; i++) {
if (m_instructions[i]->DoesBranch()) {
+ if (ignore_calls && m_instructions[i]->IsCall())
+ continue;
next_branch = i;
break;
}
Index: packages/Python/lldbsuite/test/functionalities/breakpoint/require_hw_breakpoints/TestRequireHWBreakpoints.py
===================================================================
--- packages/Python/lldbsuite/test/functionalities/breakpoint/require_hw_breakpoints/TestRequireHWBreakpoints.py
+++ packages/Python/lldbsuite/test/functionalities/breakpoint/require_hw_breakpoints/TestRequireHWBreakpoints.py
@@ -79,12 +79,11 @@
self.runCmd("settings set target.require-hardware-breakpoint true")
# Step over doesn't fail immediately but fails later on.
- self.expect("thread step-over")
self.expect(
- "process status",
+ "thread step-over",
+ error=True,
substrs=[
- 'step over failed',
- 'Could not create hardware breakpoint for thread plan'
+ 'error: Could not create hardware breakpoint for thread plan.'
])
@skipIfWindows
Index: include/lldb/Core/Disassembler.h
===================================================================
--- include/lldb/Core/Disassembler.h
+++ include/lldb/Core/Disassembler.h
@@ -292,8 +292,32 @@
lldb::InstructionSP GetInstructionAtIndex(size_t idx) const;
+ //------------------------------------------------------------------
+ /// Get the index of the next branch instruction.
+ ///
+ /// Given a list of instructions, find the next branch instruction
+ /// in the list by returning an index.
+ ///
+ /// @param[in] start
+ /// The instruction index of the first instruction to check.
+ ///
+ /// @param[in] target
+ /// A LLDB target object that is used to resolve addresses.
+ ///
+ /// @param[in] ignore_calls
+ /// It true, then fine the first branch instruction that isn't
+ /// a function call (a branch that calls and returns to the next
+ /// instruction). If false, find the instruction index of any
+ /// branch in the list.
+ ///
+ /// @return
+ /// The instruction index of the first branch that is at or past
+ /// \a start. Returns UINT32_MAX if no matching branches are
+ /// found.
+ //------------------------------------------------------------------
uint32_t GetIndexOfNextBranchInstruction(uint32_t start,
- Target &target) const;
+ Target &target,
+ bool ignore_calls) const;
uint32_t GetIndexOfInstructionAtLoadAddress(lldb::addr_t load_addr,
Target &target);
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