3692267ca8
Watchpoints in lldb can be either 'read', 'write', or 'read/write'. This is exposing the actual behavior of hardware watchpoints. gdb has a different behavior: a "write" type watchpoint only stops when the watched memory region *changes*. A user is using a watchpoint for one of three reasons: 1. Want to find what is changing/corrupting this memory. 2. Want to find what is writing to this memory. 3. Want to find what is reading from this memory. I believe (1) is the most common use case for watchpoints, and it currently can't be done in lldb -- the user needs to continue every time the same value is written to the watched-memory manually. I think gdb's behavior is the correct one. There are some use cases where a developer wants to find every function that writes/reads to/from a memory region, regardless of value, I want to still allow that functionality. This is also a bit of groundwork for my large watchpoint support proposal https://discourse.llvm.org/t/rfc-large-watchpoint-support-in-lldb/72116 where I will be adding support for AArch64 MASK watchpoints which watch power-of-2 memory regions. A user might ask to watch 24 bytes, and a MASK watchpoint stub can do this with a 32-byte MASK watchpoint if it is properly aligned. And we need to ignore writes to the final 8 bytes of that watched region, and not show those hits to the user. This patch adds a new 'modify' watchpoint type and it is the default. rdar://108234227
74 lines
2.0 KiB
C++
74 lines
2.0 KiB
C++
//===-- SBWatchpointOptions.cpp -------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "lldb/API/SBWatchpointOptions.h"
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#include "lldb/Breakpoint/Watchpoint.h"
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#include "lldb/Utility/Instrumentation.h"
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#include "Utils.h"
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using namespace lldb;
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using namespace lldb_private;
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class WatchpointOptionsImpl {
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public:
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bool m_read = false;
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bool m_write = false;
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bool m_modify = false;
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};
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SBWatchpointOptions::SBWatchpointOptions()
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: m_opaque_up(new WatchpointOptionsImpl()) {
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LLDB_INSTRUMENT_VA(this);
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}
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SBWatchpointOptions::SBWatchpointOptions(const SBWatchpointOptions &rhs) {
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LLDB_INSTRUMENT_VA(this, rhs);
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m_opaque_up = clone(rhs.m_opaque_up);
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}
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const SBWatchpointOptions &
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SBWatchpointOptions::operator=(const SBWatchpointOptions &rhs) {
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LLDB_INSTRUMENT_VA(this, rhs);
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if (this != &rhs)
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m_opaque_up = clone(rhs.m_opaque_up);
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return *this;
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}
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SBWatchpointOptions::~SBWatchpointOptions() = default;
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void SBWatchpointOptions::SetWatchpointTypeRead(bool read) {
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m_opaque_up->m_read = read;
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}
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bool SBWatchpointOptions::GetWatchpointTypeRead() const {
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return m_opaque_up->m_read;
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}
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void SBWatchpointOptions::SetWatchpointTypeWrite(
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WatchpointWriteType write_type) {
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if (write_type == eWatchpointWriteTypeOnModify) {
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m_opaque_up->m_write = false;
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m_opaque_up->m_modify = true;
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} else if (write_type == eWatchpointWriteTypeAlways) {
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m_opaque_up->m_write = true;
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m_opaque_up->m_modify = false;
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} else
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m_opaque_up->m_write = m_opaque_up->m_modify = false;
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}
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WatchpointWriteType SBWatchpointOptions::GetWatchpointTypeWrite() const {
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if (m_opaque_up->m_modify)
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return eWatchpointWriteTypeOnModify;
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if (m_opaque_up->m_write)
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return eWatchpointWriteTypeAlways;
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return eWatchpointWriteTypeDisabled;
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}
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