https://llvm.org/bugs/show_bug.cgi?id=27800
Bug ID: 27800
Summary: LLDB step-in misses internal breakpoint and continues
execution
Product: lldb
Version: unspecified
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: All Bugs
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
Created attachment 16383
--> https://llvm.org/bugs/attachment.cgi?id=16383&action=edit
Reproduction test files
lldb-340.4.70
llvm 7.0.0 (clang-700.0.72) (also occurs at trunk@r268813)
Reproduction steps:
1. Compile
g++ -O1 -gdwarf-4 -c TestClass.cpp
g++ -gdwarf-4 lldbBug.cpp TestClass.o -o lldbBug -lm
2. Launch lldb and break at TestSubclass::reproStepBug()
lldb lldbBug
breakpoint set --name TestSubclass::reproStepBug
run
3. Once the breakpoint is hit, try stepping
thread step-in
[bug!!]
The bug is that lldb's internal step breakpoint is skipped over due to
optimizations. Because the optimized code is linked in, there is no warning
about stepping with optimizations.
In multithreaded programs, this bug results in the current thread continuing
out from underneath lldb. From the user's perspective, the thread just becomes
invalid:
Process 37950 stopped ...
(lldb) thread step-in
(lldb) thread step-in
error: invalid thread
(lldb) thread step-in
error: invalid thread
--------------TestClass.cpp--------------
#include "TestClass.h"
__attribute__ ((optnone)) static bool getMember(const TestClass* testObject) {
return testObject->member;
}
void TestClass::callMember() const
{
if (getMember(this))
member->callMember();
}
---------------TestClass.h---------------
class TestClass {
public:
explicit TestClass(TestClass* m) : member(m) { }
void callMember() const;
TestClass* member;
};
class TestSubclass : public TestClass {
public:
explicit TestSubclass() : TestClass(0) { }
// To repro, break at this function and then step through the two calls.
void reproStepBug() {
callMember();
callMember();
}
};
--------------lldbBug.cpp--------------
#include "TestClass.h"
int main(int argc, char *argv[]) {
TestSubclass object;
object.reproStepBug();
return 0;
}
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