[Windows] Add support of watchpoints to `ProcessWindows`

[aleksandr.urakov]

Summary

This patch adds support of watchpoints to the old ProcessWindows plugin.

The ProcessWindows plugin uses the RegisterContext to set and reset watchpoints. The RegisterContext has some interface to access watchpoints, but it is very limited (e.g. it is impossible to retrieve the last triggered watchpoint with it), that's why I have implemented a slightly different interface in the RegisterContextWindows. Moreover, I have made the ProcessWindows plugin responsible for search of a vacant watchpoint slot, because watchpoints exist per-process (not per-thread), then we can place the same watchpoint in the same slot in different threads. With this scheme threads don't need to have their own watchpoint lists, and it simplifies identifying of the last triggered watchpoint.

It looks like it is enough to just implement corresponding methods in the NativeRegisterContextWindows-based classes to support the feature in the new NativeProcessWindows plugin. I'll do it in the next review.

[amccarth]

lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp

397

The names here are a bit confusing: GetTriggeredHardwareBreakpointSlot doesn't return a slot; it returns the index of a slot, so slot also isn't a slot, but the index of a slot. m_watchpoint_slots is not a collection of slots but IDs, that's indexed by an index called a slot.

It may not be possible to completely rationalize this, but doing even a little could help future readers understand. For example, slot could be slot_index, and m_watchpoint_slots could be m_watchpoint_ids (or even just m_watchpoints).

525

This no longer sets the thread ID. Was that intentional?

743

Can you help me why we needed to get rid of the const on the HostThread &?

If native_new_thread were also a const ref, I don't see any conflicting constraint.

832

Should we check if the watchpoint is already enabled? I noticed that DisableWatchpoint has an analogous guard clause.

852

Since you have to explicitly downcast, wouldn't auto *reg_ctx on the left be sufficient and just as clear?

lldb/source/Plugins/Process/Windows/Common/RegisterContextWindows.cpp

82–83

Clever! It took me a minute or two to figure out what the point of that was checking. Perhaps a comment to explain?

[zturner]

lldb/source/Plugins/Process/Windows/Common/RegisterContextWindows.cpp

82–83

Isn't this equivalent to:

switch (size)
{
    case 1:
    case 2:
    case 4:
    case 8:
        break;
    default:
        return false;
}

? That definitely seems much clearer.

I'm also pretty sure that on x86 you can't add a 64-bit watch, So you'd have to do something different depending on the target bitness if you want this to be correct for x86.

[aleksandr.urakov]

Address the requested changes.

[aleksandr.urakov]

Address the requested changes.

[aleksandr.urakov]

Check bitness of the target when checking the watchpoint size.

[aleksandr.urakov]

lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp

397

The most confusing thing here is that watchpoints have two different IDs: ID in LLDB as it is saw by an user, and the number of corresponding debug register in CPU (from 0 to 3). That's why I have selected completely different name for the last one and have called it slot. But you are right, m_watchpoint_slots is a wrong name, changed it to m_watchpoint_ids (because we already have m_watchpoints - it is map from LLDB IDs to watchpoint information).

525

Before this commit m_new_threads kept HostThreads, not ThreadSPs. But a HostThread have no RegisterContext, which we need to set all watchpoints when a new thread is created. That's why we create ThreadSP on thread creation now, so we set the thread ID there (in OnCreateThread function).

743

Oh, I'm sorry, it was left unintentionally after my previous implementation. Fixed it, thanks!

852

Actually, I'm a big fan of auto, and some time ago @zturner have told me that normally it is not used so much in LLVM code, so I have reduced its usage in my patches :) But if it is OK to use auto here, I'll fix it (and in similar places too), thanks!

lldb/source/Plugins/Process/Windows/Common/RegisterContextWindows.cpp

82–83

Yes, it is equivalent, I've chosen the previous form due to its less verbosity. But you are right, clearance is better (especially after adding the architecture check). Fixed it, thanks!

[labath]

lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp

852

Yeah, llvm does not use auto too match, but in this case the type is already explicitly present, so there's no ambiguity, and this is fine. (I would still use auto * instead of plain auto though..)

lldb/source/Plugins/Process/Windows/Common/RegisterContextWindows.cpp

82–83

.... or, you could just use llvm::isPowerOf2_32 from MathExtras.h.

[aleksandr.urakov]

Determine whether 8-byte watchpoints are supported or not statically.

[aleksandr.urakov]

lldb/source/Plugins/Process/Windows/Common/RegisterContextWindows.cpp

82–83

I didn't know about the such function, thanks! But I think that Zachary's approach is better in exactly this case (taking in account the bitness check).

86–88

In the old plugin a required register context is created based on the target architecture check and the bitness of LLDB, but cross-targets (e.g. WoW64) are not supported, and even the type of m_context is determined statically. So we can safely determine the max watchpoint size statically too.

[amccarth]

Thanks for the changes! I think this looks good now.

[aleksandr.urakov]

Thanks all!

lldb/packages/Python/lldbsuite/test/commands/watchpoints/hello_watchlocation/TestWatchLocation.py

def setUp(self):
             self.source, '// Set break point at this line.')
         # This is for verifying that watch location works.
         self.violating_func = "do_bad_thing_with_location"
         # Build dictionary to have unique executable names for each test
         # method.
         self.exe_name = self.testMethodName
         self.d = {'CXX_SOURCES': self.source, 'EXE': self.exe_name}
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Most of the MIPS boards provide only one H/W watchpoints, and S/W
     # watchpoints are not supported yet
     @expectedFailureAll(triple=re.compile('^mips'))
     # SystemZ and PowerPC also currently supports only one H/W watchpoint
     @expectedFailureAll(archs=['powerpc64le', 's390x'])
     @expectedFailureNetBSD
     @skipIfDarwin
     def test_hello_watchlocation(self):

lldb/packages/Python/lldbsuite/test/commands/watchpoints/hello_watchpoint/TestMyFirstWatchpoint.py

def setUp(self):
         self.line = line_number(
             self.source, '// Set break point at this line.')
         # And the watchpoint variable declaration line number.
         self.decl = line_number(self.source,
                                 '// Watchpoint variable declaration.')
         self.exe_name = self.getBuildArtifact('a.out')
         self.d = {'C_SOURCES': self.source, 'EXE': self.exe_name}
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     @add_test_categories(["basic_process"])
     def test_hello_watchpoint_using_watchpoint_set(self):
         """Test a simple sequence of watchpoint creation and watchpoint hit."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)

lldb/packages/Python/lldbsuite/test/commands/watchpoints/multiple_hits/TestMultipleHits.py

 from lldbsuite.test import lldbutil
 
 
 class MultipleHitsTestCase(TestBase):
 
     mydir = TestBase.compute_mydir(__file__)
     NO_DEBUG_INFO_TESTCASE = True
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     @skipIf(bugnumber="llvm.org/pr30758", oslist=["linux"], archs=["arm", "aarch64", "powerpc64le"])
     @skipIfwatchOS
     def test(self):
         self.build()
         exe = self.getBuildArtifact("a.out")
         target = self.dbg.CreateTarget(exe)
         self.assertTrue(target and target.IsValid(), VALID_TARGET)
 

lldb/packages/Python/lldbsuite/test/commands/watchpoints/multiple_threads/TestWatchpointMultipleThreads.py

 
 
 class WatchpointForMultipleThreadsTestCase(TestBase):
 
     mydir = TestBase.compute_mydir(__file__)
     NO_DEBUG_INFO_TESTCASE = True
     main_spec = lldb.SBFileSpec("main.cpp", False)
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     @expectedFailureNetBSD
     def test_watchpoint_before_thread_start(self):
         """Test that we can hit a watchpoint we set before starting another thread"""
         self.do_watchpoint_test("Before running the thread")
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     @expectedFailureNetBSD
     def test_watchpoint_after_thread_start(self):
         """Test that we can hit a watchpoint we set after starting another thread"""
         self.do_watchpoint_test("After running the thread")
 
     def do_watchpoint_test(self, line):
         self.build()
         lldbutil.run_to_source_breakpoint(self, line, self.main_spec)
def do_watchpoint_test(self, line):
         else:
             self.fail("The stop reason should be either break or watchpoint")
 
         # Use the '-v' option to do verbose listing of the watchpoint.
         # The hit count should now be 1.
         self.expect("watchpoint list -v",
                     substrs=['hit_count = 1'])
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     def test_watchpoint_multiple_threads_wp_set_and_then_delete(self):
         """Test that lldb watchpoint works for multiple threads, and after the watchpoint is deleted, the watchpoint event should no longer fires."""
         self.build()
         self.setTearDownCleanup()
 
         lldbutil.run_to_source_breakpoint(self, "After running the thread", self.main_spec)
 
         # Now let's set a write-type watchpoint for variable 'g_val'.

lldb/packages/Python/lldbsuite/test/commands/watchpoints/step_over_watchpoint/TestStepOverWatchpoint.py

class TestStepOverWatchpoint(TestBase):
     mydir = TestBase.compute_mydir(__file__)
 
     @expectedFailureAll(
         oslist=["linux"],
         archs=[
             'aarch64',
             'arm'],
         bugnumber="llvm.org/pr26031")
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
     @expectedFailureAll(oslist=["ios", "watchos", "tvos", "bridgeos"], bugnumber="<rdar://problem/34027183>")  # watchpoint tests aren't working on arm64
     @add_test_categories(["basic_process"])
     def test(self):
         """Test stepping over watchpoints."""
         self.build()
         exe = self.getBuildArtifact("a.out")

lldb/packages/Python/lldbsuite/test/commands/watchpoints/watchpoint_commands/TestWatchpointCommands.py

def setUp(self):
         # And the watchpoint variable declaration line number.
         self.decl = line_number(self.source,
                                 '// Watchpoint variable declaration.')
         # Build dictionary to have unique executable names for each test
         # method.
         self.exe_name = self.testMethodName
         self.d = {'C_SOURCES': self.source, 'EXE': self.exe_name}
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
     def test_rw_watchpoint(self):
         """Test read_write watchpoint and expect to stop two times."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
def test_rw_watchpoint(self):
         self.expect("process status",
                     substrs=['exited'])
 
         # Use the '-v' option to do verbose listing of the watchpoint.
         # The hit count should now be 2.
         self.expect("watchpoint list -v",
                     substrs=['hit_count = 2'])
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
     def test_rw_watchpoint_delete(self):
         """Test delete watchpoint and expect not to stop for watchpoint."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
def test_rw_watchpoint_delete(self):
 
         self.runCmd("process continue")
 
         # There should be no more watchpoint hit and the process status should
         # be 'exited'.
         self.expect("process status",
                     substrs=['exited'])
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
     def test_rw_watchpoint_set_ignore_count(self):
         """Test watchpoint ignore count and expect to not to stop at all."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
def test_rw_watchpoint_set_ignore_count(self):
         self.expect("process status",
                     substrs=['exited'])
 
         # Use the '-v' option to do verbose listing of the watchpoint.
         # Expect to find a hit_count of 2 as well.
         self.expect("watchpoint list -v",
                     substrs=['hit_count = 2', 'ignore_count = 2'])
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
     def test_rw_disable_after_first_stop(self):
         """Test read_write watchpoint but disable it after the first stop."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
def test_rw_disable_after_first_stop(self):
         self.expect("process status",
                     substrs=['exited'])
 
         # Use the '-v' option to do verbose listing of the watchpoint.
         # The hit count should be 1.
         self.expect("watchpoint list -v",
                     substrs=['hit_count = 1'])
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
     def test_rw_disable_then_enable(self):
         """Test read_write watchpoint, disable initially, then enable it."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)

lldb/packages/Python/lldbsuite/test/commands/watchpoints/watchpoint_commands/command/TestWatchpointCommandLLDB.py

def setUp(self):
         self.exe_name = 'a%d.out' % self.test_number
         self.d = {'CXX_SOURCES': self.source, 'EXE': self.exe_name}
 
     @expectedFailureAll(
         oslist=["linux"],
         archs=["aarch64"],
         triple=no_match(".*-android"),
         bugnumber="llvm.org/pr27710") # work on android
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     @expectedFailureNetBSD
     def test_watchpoint_command(self):
         """Test 'watchpoint command'."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
def test_watchpoint_command(self):
         self.expect("frame variable --show-globals cookie",
                     substrs=['(int32_t)', 'cookie = 777'])
 
     @expectedFailureAll(
         oslist=["linux"],
         archs=["aarch64"],
         triple=no_match(".*-android"),
         bugnumber="llvm.org/pr27710") # work on android
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     def test_watchpoint_command_can_disable_a_watchpoint(self):
         """Test that 'watchpoint command' action can disable a watchpoint after it is triggered."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
 

lldb/packages/Python/lldbsuite/test/commands/watchpoints/watchpoint_commands/command/TestWatchpointCommandPython.py

def setUp(self):
                                 '// Watchpoint variable declaration.')
         # Build dictionary to have unique executable names for each test
         # method.
         self.exe_name = self.testMethodName
         self.d = {'CXX_SOURCES': self.source, 'EXE': self.exe_name}
 
     @skipIfFreeBSD  # timing out on buildbot
     @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
-    @expectedFailureAll(
         oslist=["linux"],
         archs=["aarch64"],
         triple=no_match(".*-android"),
         bugnumber="llvm.org/pr27710") # work on android
     @expectedFailureNetBSD
     def test_watchpoint_command(self):
         """Test 'watchpoint command'."""
         self.build(dictionary=self.d)
def test_watchpoint_command(self):
 
         # The watchpoint command "forced" our global variable 'cookie' to
         # become 777.
         self.expect("frame variable --show-globals cookie",
                     substrs=['(int32_t)', 'cookie = 777'])
 
     @skipIfFreeBSD  # timing out on buildbot
     @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
-    @expectedFailureAll(
         oslist=["linux"],
         archs=["aarch64"],
         triple=no_match(".*-android"),
         bugnumber="llvm.org/pr27710") # work on android
     @expectedFailureNetBSD
     def test_continue_in_watchpoint_command(self):
         """Test continue in a watchpoint command."""
         self.build(dictionary=self.d)

lldb/packages/Python/lldbsuite/test/commands/watchpoints/watchpoint_commands/condition/TestWatchpointConditionCmd.py

def setUp(self):
         self.exe_name = self.testMethodName
         self.d = {'CXX_SOURCES': self.source, 'EXE': self.exe_name}
 
     @expectedFailureAll(
         oslist=["linux"],
         archs=["aarch64"],
         triple=no_match(".*-android"),
         bugnumber="llvm.org/pr27710")
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     @expectedFailureNetBSD
     def test_watchpoint_cond(self):
         """Test watchpoint condition."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)

lldb/packages/Python/lldbsuite/test/commands/watchpoints/watchpoint_disable/TestWatchpointDisable.py

 
 class TestWatchpointSetEnable(TestBase):
     mydir = TestBase.compute_mydir(__file__)
 
     def setUp(self):
         # Call super's setUp().
         TestBase.setUp(self)
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     def test_disable_works (self):
         """Set a watchpoint, disable it, and make sure it doesn't get hit."""
         self.build()
         self.do_test(False)
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     def test_disable_enable_works (self):
         """Set a watchpoint, disable it, and make sure it doesn't get hit."""
         self.build()
         self.do_test(True)
 
     def do_test(self, test_enable):
         """Set a watchpoint, disable it and make sure it doesn't get hit."""
 

lldb/packages/Python/lldbsuite/test/commands/watchpoints/watchpoint_events/TestWatchpointEvents.py

def setUp(self):
         self.main_source = "main.c"
 
     @add_test_categories(['pyapi'])
     @expectedFailureAll(
         oslist=["linux"],
         archs=["aarch64"],
         triple=no_match(".*-android"),
         bugnumber="llvm.org/pr27710")
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     def test_with_python_api(self):
         """Test that adding, deleting and modifying watchpoints sends the appropriate events."""
         self.build()
 
         exe = self.getBuildArtifact("a.out")
 
         target = self.dbg.CreateTarget(exe)
         self.assertTrue(target, VALID_TARGET)

lldb/packages/Python/lldbsuite/test/commands/watchpoints/watchpoint_on_vectors/TestValueOfVectorVariable.py

 from lldbsuite.test.lldbtest import *
 from lldbsuite.test import lldbutil
 
 
 class TestValueOfVectorVariableTestCase(TestBase):
 
     mydir = TestBase.compute_mydir(__file__)
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     def test_value_of_vector_variable_using_watchpoint_set(self):
         """Test verify displayed value of vector variable."""
         exe = self.getBuildArtifact("a.out")
         d = {'C_SOURCES': self.source, 'EXE': exe}
         self.build(dictionary=d)
         self.setTearDownCleanup(dictionary=d)
         self.value_of_vector_variable_with_watchpoint_set()
 

lldb/packages/Python/lldbsuite/test/commands/watchpoints/watchpoint_set_command/TestWatchLocationWithWatchSet.py

def setUp(self):
         # method.
 
     @expectedFailureAll(
         oslist=["linux"],
         archs=[
             'aarch64',
             'arm'],
         bugnumber="llvm.org/pr26031")
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     @expectedFailureNetBSD
     def test_watchlocation_using_watchpoint_set(self):
         """Test watching a location with 'watchpoint set expression -w write -s size' option."""
         self.build()
         self.setTearDownCleanup()
 
         exe = self.getBuildArtifact("a.out")
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)

lldb/packages/Python/lldbsuite/test/commands/watchpoints/watchpoint_size/TestWatchpointSizes.py

def setUp(self):
 
         # Source filename.
         self.source = 'main.c'
 
         # Output filename.
         self.exe_name = self.getBuildArtifact("a.out")
         self.d = {'C_SOURCES': self.source, 'EXE': self.exe_name}
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
     def test_byte_size_watchpoints_with_byte_selection(self):
         """Test to selectively watch different bytes in a 8-byte array."""
         self.run_watchpoint_size_test('byteArray', 8, '1')
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
     def test_two_byte_watchpoints_with_word_selection(self):
         """Test to selectively watch different words in an 8-byte word array."""
         self.run_watchpoint_size_test('wordArray', 4, '2')
 
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
     def test_four_byte_watchpoints_with_dword_selection(self):
         """Test to selectively watch two double words in an 8-byte dword array."""
         self.run_watchpoint_size_test('dwordArray', 2, '4')
 
     def run_watchpoint_size_test(self, arrayName, array_size, watchsize):
         self.build(dictionary=self.d)

lldb/packages/Python/lldbsuite/test/python_api/watchpoint/TestSetWatchpoint.py

def setUp(self):
         TestBase.setUp(self)
         # Our simple source filename.
         self.source = 'main.c'
         # Find the line number to break inside main().
         self.line = line_number(
             self.source, '// Set break point at this line.')
 
     @add_test_categories(['pyapi'])
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
     def test_watch_val(self):
         """Exercise SBValue.Watch() API to set a watchpoint."""
         self.build()
         exe = self.getBuildArtifact("a.out")
 
         # Create a target by the debugger.

lldb/packages/Python/lldbsuite/test/python_api/watchpoint/TestWatchpointIgnoreCount.py

def setUp(self):
         TestBase.setUp(self)
         # Our simple source filename.
         self.source = 'main.c'
         # Find the line number to break inside main().
         self.line = line_number(
             self.source, '// Set break point at this line.')
 
     @add_test_categories(['pyapi'])
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
     def test_set_watch_ignore_count(self):
         """Test SBWatchpoint.SetIgnoreCount() API."""
         self.build()
         exe = self.getBuildArtifact("a.out")
 
         # Create a target by the debugger.

lldb/packages/Python/lldbsuite/test/python_api/watchpoint/TestWatchpointIter.py

def setUp(self):
         TestBase.setUp(self)
         # Our simple source filename.
         self.source = 'main.c'
         # Find the line number to break inside main().
         self.line = line_number(
             self.source, '// Set break point at this line.')
 
     @add_test_categories(['pyapi'])
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     def test_watch_iter(self):
         """Exercise SBTarget.watchpoint_iter() API to iterate on the available watchpoints."""
         self.build()
         exe = self.getBuildArtifact("a.out")
 
         # Create a target by the debugger.
         target = self.dbg.CreateTarget(exe)
         self.assertTrue(target, VALID_TARGET)

lldb/packages/Python/lldbsuite/test/python_api/watchpoint/condition/TestWatchpointConditionAPI.py

def setUp(self):
         self.exe_name = self.testMethodName
         self.d = {'CXX_SOURCES': self.source, 'EXE': self.exe_name}
 
     @expectedFailureAll(
         oslist=["linux"],
         archs=["aarch64"],
         triple=no_match(".*-android"),
         bugnumber="llvm.org/pr27710")
-    @skipIfWindows  # Watchpoints not supported on Windows, and this test hangs
     def test_watchpoint_cond_api(self):
         """Test watchpoint condition API."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
         exe = self.getBuildArtifact(self.exe_name)
 
         # Create a target by the debugger.
         target = self.dbg.CreateTarget(exe)

lldb/packages/Python/lldbsuite/test/python_api/watchpoint/watchlocation/TestSetWatchlocation.py

def setUp(self):
         self.source = 'main.cpp'
         # Find the line number to break inside main().
         self.line = line_number(
             self.source, '// Set break point at this line.')
         # This is for verifying that watch location works.
         self.violating_func = "do_bad_thing_with_location"
 
     @add_test_categories(['pyapi'])
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     @expectedFailureNetBSD
     def test_watch_location(self):
         """Exercise SBValue.WatchPointee() API to set a watchpoint."""
         self.build()
         exe = self.getBuildArtifact("a.out")
 
         # Create a target by the debugger.
         target = self.dbg.CreateTarget(exe)

lldb/packages/Python/lldbsuite/test/python_api/watchpoint/watchlocation/TestTargetWatchAddress.py

def setUp(self):
         self.source = 'main.cpp'
         # Find the line number to break inside main().
         self.line = line_number(
             self.source, '// Set break point at this line.')
         # This is for verifying that watch location works.
         self.violating_func = "do_bad_thing_with_location"
 
     @add_test_categories(['pyapi'])
-    @expectedFailureAll(
-        oslist=["windows"],
-        bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     @expectedFailureNetBSD
     def test_watch_address(self):
         """Exercise SBTarget.WatchAddress() API to set a watchpoint."""
         self.build()
         exe = self.getBuildArtifact("a.out")
 
         # Create a target by the debugger.
         target = self.dbg.CreateTarget(exe)

lldb/source/Plugins/Process/Windows/Common/ProcessDebugger.h

public:
   ~ProcessWindowsData() { ::CloseHandle(m_initial_stop_event); }
 
   Status m_launch_error;
   DebuggerThreadSP m_debugger;
   // StopInfoSP m_pending_stop_info;
   HANDLE m_initial_stop_event = nullptr;
   bool m_initial_stop_received = false;
   bool m_stop_at_entry;
-  std::map<lldb::tid_t, HostThread> m_new_threads;
+  std::map<lldb::tid_t, lldb::ThreadSP> m_new_threads;
   std::set<lldb::tid_t> m_exited_threads;
 };
 
 class ProcessDebugger {
 
 public:
   virtual void OnExitProcess(uint32_t exit_code);
   virtual void OnDebuggerConnected(lldb::addr_t image_base);

lldb/source/Plugins/Process/Windows/Common/ProcessWindows.h

ExceptionResult OnDebugException(bool first_chance,
                                    const ExceptionRecord &record) override;
   void OnCreateThread(const HostThread &thread) override;
   void OnExitThread(lldb::tid_t thread_id, uint32_t exit_code) override;
   void OnLoadDll(const ModuleSpec &module_spec,
                  lldb::addr_t module_addr) override;
   void OnUnloadDll(lldb::addr_t module_addr) override;
   void OnDebugString(const std::string &string) override;
   void OnDebuggerError(const Status &error, uint32_t type) override;
+
+  Status GetWatchpointSupportInfo(uint32_t &num) override;
+  Status GetWatchpointSupportInfo(uint32_t &num, bool &after) override;
+  Status EnableWatchpoint(Watchpoint *wp, bool notify = true) override;
+  Status DisableWatchpoint(Watchpoint *wp, bool notify = true) override;
+
+private:
+  struct WatchpointInfo {
+    uint32_t slot_id;
+    lldb::addr_t address;
+    uint32_t size;
+    bool read;
+    bool write;
+  };
+  std::map<lldb::break_id_t, WatchpointInfo> m_watchpoints;
+  std::vector<lldb::break_id_t> m_watchpoint_slot_ids;
 };
 } // namespace lldb_private
 
 #endif // liblldb_Plugins_Process_Windows_Common_ProcessWindows_H_

lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp

 //===-- ProcessWindows.cpp --------------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "ProcessWindows.h"
 
 // Windows includes
 #include "lldb/Host/windows/windows.h"
 #include <psapi.h>
 
+#include "lldb/Breakpoint/Watchpoint.h"
 #include "lldb/Core/Module.h"
 #include "lldb/Core/ModuleSpec.h"
 #include "lldb/Core/PluginManager.h"
 #include "lldb/Core/Section.h"
 #include "lldb/Host/FileSystem.h"
 #include "lldb/Host/HostNativeProcessBase.h"
 #include "lldb/Host/HostProcess.h"
 #include "lldb/Host/windows/HostThreadWindows.h"

 const char *ProcessWindows::GetPluginDescriptionStatic() {
   return "Process plugin for Windows";
 }
 
 // Constructors and destructors.
 
 ProcessWindows::ProcessWindows(lldb::TargetSP target_sp,
                                lldb::ListenerSP listener_sp)
-    : lldb_private::Process(target_sp, listener_sp) {}
+    : lldb_private::Process(target_sp, listener_sp),
+      m_watchpoint_slot_ids(
+          RegisterContextWindows::GetNumHardwareBreakpointSlots(),
+          LLDB_INVALID_BREAK_ID) {}
 
 ProcessWindows::~ProcessWindows() {}
 
 size_t ProcessWindows::GetSTDOUT(char *buf, size_t buf_size, Status &error) {
   error.SetErrorString("GetSTDOUT unsupported on Windows");
   return 0;
 }
 
if (site && site->ValidForThisThread(stop_thread.get())) {
       LLDB_LOG(log,
                "Single-stepped onto a breakpoint in process {0} at "
                "address {1:x} with breakpoint site {2}",
                m_session_data->m_debugger->GetProcess().GetProcessId(), pc,
                site->GetID());
       stop_info = StopInfo::CreateStopReasonWithBreakpointSiteID(*stop_thread,
                                                                  site->GetID());
       stop_thread->SetStopInfo(stop_info);
-    } else {
-      LLDB_LOG(log, "single stepping thread {0}", stop_thread->GetID());
-      stop_info = StopInfo::CreateStopReasonToTrace(*stop_thread);
-      stop_thread->SetStopInfo(stop_info);
-    }
+
+      return;
+    }
+
+    auto reg_ctx = static_cast<RegisterContextWindows *>(
+        stop_thread->GetRegisterContext().get());
+    uint32_t slot_id = reg_ctx->GetTriggeredHardwareBreakpointSlotId();
+    if (slot_id != LLDB_INVALID_INDEX32) {
+      int id = m_watchpoint_slot_ids[slot_id];
+      LLDB_LOG(log,
+               "Single-stepped onto a watchpoint in process {0} at address "
+               "{1:x} with watchpoint {2}",
+               m_session_data->m_debugger->GetProcess().GetProcessId(), pc, id);
+
+      if (lldb::WatchpointSP wp_sp =
+              GetTarget().GetWatchpointList().FindByID(id))
+        wp_sp->SetHardwareIndex(slot_id);
+
+      stop_info = StopInfo::CreateStopReasonWithWatchpointID(
+          *stop_thread, id, m_watchpoints[id].address);
+      stop_thread->SetStopInfo(stop_info);
+
+      return;
+    }
+
+
     return;
   }
 
   case EXCEPTION_BREAKPOINT: {
     RegisterContextSP register_context = stop_thread->GetRegisterContext();
 
     // The current EIP is AFTER the BP opcode, which is one byte.
     uint64_t pc = register_context->GetPC() - 1;
if (exited_thread_iter == m_session_data->m_exited_threads.end()) {
       LLDB_LOGV(log, "Thread {0} was running and has exited.", old_thread_id);
       ++exited_threads;
     }
   }
 
   // Also add all the threads that are new since the last time we broke into
   // the debugger.
   for (const auto &thread_info : m_session_data->m_new_threads) {
-    ThreadSP thread(new TargetThreadWindows(*this, thread_info.second));
-    thread->SetID(thread_info.first);
-    new_thread_list.AddThread(thread);
+    new_thread_list.AddThread(thread_info.second);
     ++new_size;
     ++new_threads;
     LLDB_LOGV(log, "Thread {0} is new since last update.", thread_info.first);
   }
 
   LLDB_LOG(log, "{0} new threads, {1} old threads, {2} exited threads.",
            new_threads, continued_threads, exited_threads);
 
if (target) {
     ModuleList unloaded_modules;
     unloaded_modules.Append(executable_module);
     target->ModulesDidUnload(unloaded_modules, true);
   }
 
   SetProcessExitStatus(GetID(), true, 0, exit_code);
   SetPrivateState(eStateExited);
 
-  // If the process exits before any initial stop then notify the debugger 
+  // If the process exits before any initial stop then notify the debugger
   // of the error otherwise WaitForDebuggerConnection() will be blocked.
-  // An example of this issue is when a process fails to load a dependent DLL. 
+  // An example of this issue is when a process fails to load a dependent DLL.
   if (m_session_data && !m_session_data->m_initial_stop_received) {
     Status error(exit_code, eErrorTypeWin32);
     OnDebuggerError(error, 0);
   }
 
   // Reset the session.
   m_session_data.reset();
 }
if (!module) {
     if (file_name.empty()) {
       return;
     }
 
     FileSpec executable_file(file_name);
     FileSystem::Instance().Resolve(executable_file);
     ModuleSpec module_spec(executable_file);
     Status error;
-    module = GetTarget().GetOrCreateModule(module_spec, 
-                                           true /* notify */, &error);
+    module =
+        GetTarget().GetOrCreateModule(module_spec, true /* notify */, &error);
     if (!module) {
       return;
     }
 
     GetTarget().SetExecutableModule(module, eLoadDependentsNo);
   }
 
   if (auto dyld = GetDynamicLoader())
     dyld->OnLoadModule(module, ModuleSpec(), image_base);
 
   // Add the main executable module to the list of pending module loads.  We
   // can't call GetTarget().ModulesDidLoad() here because we still haven't
   // returned from DoLaunch() / DoAttach() yet so the target may not have set
   // the process instance to `this` yet.
   llvm::sys::ScopedLock lock(m_mutex);
-  const HostThreadWindows &wmain_thread =
-      debugger->GetMainThread().GetNativeThread();
-  m_session_data->m_new_threads[wmain_thread.GetThreadId()] =
-      debugger->GetMainThread();
+
+  const HostThread &host_main_thread = debugger->GetMainThread();
+  ThreadSP main_thread =
+      std::make_shared<TargetThreadWindows>(*this, host_main_thread);
+
+  tid_t id = host_main_thread.GetNativeThread().GetThreadId();
+  main_thread->SetID(id);
+
+  m_session_data->m_new_threads[id] = main_thread;
 }
 
 ExceptionResult
 ProcessWindows::OnDebugException(bool first_chance,
                                  const ExceptionRecord &record) {
   Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_EXCEPTION);
   llvm::sys::ScopedLock lock(m_mutex);
 
if (first_chance)
       result = ExceptionResult::SendToApplication;
     else
       result = ExceptionResult::BreakInDebugger;
   }
 
   return result;
 }
 
 void ProcessWindows::OnCreateThread(const HostThread &new_thread) {
   llvm::sys::ScopedLock lock(m_mutex);
-  const HostThreadWindows &wnew_thread = new_thread.GetNativeThread();
-  m_session_data->m_new_threads[wnew_thread.GetThreadId()] = new_thread;
+
+  ThreadSP thread = std::make_shared<TargetThreadWindows>(*this, new_thread);
+
+  const HostNativeThread &native_new_thread = new_thread.GetNativeThread();
+  tid_t id = native_new_thread.GetThreadId();
+  thread->SetID(id);
+
+  m_session_data->m_new_threads[id] = thread;
+
+  for (const std::map<int, WatchpointInfo>::value_type &p : m_watchpoints) {
+    auto reg_ctx = static_cast<RegisterContextWindows *>(
+        thread->GetRegisterContext().get());
+    reg_ctx->AddHardwareBreakpoint(p.second.slot_id, p.second.address,
+                                   p.second.size, p.second.read,
+                                   p.second.write);
+  }
 }
 
 void ProcessWindows::OnExitThread(lldb::tid_t thread_id, uint32_t exit_code) {
   llvm::sys::ScopedLock lock(m_mutex);
 
   // On a forced termination, we may get exit thread events after the session
   // data has been cleaned up.
   if (!m_session_data)
if (m_session_data->m_initial_stop_received) {
     ::SetEvent(m_session_data->m_initial_stop_event);
     LLDB_LOG(
         log,
         "Error {0} occurred launching the process before the initial stop. {1}",
         error.GetError(), error);
     return;
   }
 }
+
+Status ProcessWindows::GetWatchpointSupportInfo(uint32_t &num) {
+  num = RegisterContextWindows::GetNumHardwareBreakpointSlots();
+  return {};
+}
+
+Status ProcessWindows::GetWatchpointSupportInfo(uint32_t &num, bool &after) {
+  num = RegisterContextWindows::GetNumHardwareBreakpointSlots();
+  after = RegisterContextWindows::DoHardwareBreakpointsTriggerAfter();
+  return {};
+}
+
+Status ProcessWindows::EnableWatchpoint(Watchpoint *wp, bool notify) {
+  Status error;
+
+  if (wp->IsEnabled()) {
+    wp->SetEnabled(true, notify);
+    return error;
+  }
+
+  WatchpointInfo info;
+  for (info.slot_id = 0;
+       info.slot_id < RegisterContextWindows::GetNumHardwareBreakpointSlots();
+       info.slot_id++)
+    if (m_watchpoint_slot_ids[info.slot_id] == LLDB_INVALID_BREAK_ID)
+      break;
+  if (info.slot_id == RegisterContextWindows::GetNumHardwareBreakpointSlots()) {
+    error.SetErrorStringWithFormat("Can't find free slot for watchpoint %i",
+                                   wp->GetID());
+    return error;
+  }
+  info.address = wp->GetLoadAddress();
+  info.size = wp->GetByteSize();
+  info.read = wp->WatchpointRead();
+  info.write = wp->WatchpointWrite();
+
+  for (unsigned i = 0U; i < m_thread_list.GetSize(); i++) {
+    Thread *thread = m_thread_list.GetThreadAtIndex(i).get();
+    auto reg_ctx = static_cast<RegisterContextWindows *>(
+        thread->GetRegisterContext().get());
+    if (!reg_ctx->AddHardwareBreakpoint(info.slot_id, info.address, info.size,
+                                        info.read, info.write)) {
+      error.SetErrorStringWithFormat(
+          "Can't enable watchpoint %i on thread 0x%llx", wp->GetID(),
+          thread->GetID());
+      break;
+    }
+  }
+  if (error.Fail()) {
+    for (unsigned i = 0U; i < m_thread_list.GetSize(); i++) {
+      Thread *thread = m_thread_list.GetThreadAtIndex(i).get();
+      auto reg_ctx = static_cast<RegisterContextWindows *>(
+          thread->GetRegisterContext().get());
+      reg_ctx->RemoveHardwareBreakpoint(info.slot_id);
+    }
+    return error;
+  }
+
+  m_watchpoints[wp->GetID()] = info;
+  m_watchpoint_slot_ids[info.slot_id] = wp->GetID();
+
+  wp->SetEnabled(true, notify);
+
+  return error;
+}
+
+Status ProcessWindows::DisableWatchpoint(Watchpoint *wp, bool notify) {
+  Status error;
+
+  if (!wp->IsEnabled()) {
+    wp->SetEnabled(false, notify);
+    return error;
+  }
+
+  auto it = m_watchpoints.find(wp->GetID());
+  if (it == m_watchpoints.end()) {
+    error.SetErrorStringWithFormat("Info about watchpoint %i is not found",
+                                   wp->GetID());
+    return error;
+  }
+
+  for (unsigned i = 0U; i < m_thread_list.GetSize(); i++) {
+    Thread *thread = m_thread_list.GetThreadAtIndex(i).get();
+    auto reg_ctx = static_cast<RegisterContextWindows *>(
+        thread->GetRegisterContext().get());
+    if (!reg_ctx->RemoveHardwareBreakpoint(it->second.slot_id)) {
+      error.SetErrorStringWithFormat(
+          "Can't disable watchpoint %i on thread 0x%llx", wp->GetID(),
+          thread->GetID());
+      break;
+    }
+  }
+  if (error.Fail())
+    return error;
+
+  m_watchpoint_slot_ids[it->second.slot_id] = LLDB_INVALID_BREAK_ID;
+  m_watchpoints.erase(it);
+
+  wp->SetEnabled(false, notify);
+
+  return error;
+}
 } // namespace lldb_private

lldb/source/Plugins/Process/Windows/Common/RegisterContextWindows.h

public:
 
   bool ReadAllRegisterValues(lldb::DataBufferSP &data_sp) override;
 
   bool WriteAllRegisterValues(const lldb::DataBufferSP &data_sp) override;
 
   uint32_t ConvertRegisterKindToRegisterNumber(lldb::RegisterKind kind,
                                                uint32_t num) override;
 
-  // Subclasses can override these functions if desired
-  uint32_t NumSupportedHardwareBreakpoints() override;
-
-  uint32_t SetHardwareBreakpoint(lldb::addr_t addr, size_t size) override;
-
-  bool ClearHardwareBreakpoint(uint32_t hw_idx) override;
-
-  uint32_t NumSupportedHardwareWatchpoints() override;
+  bool HardwareSingleStep(bool enable) override;
 
-  uint32_t SetHardwareWatchpoint(lldb::addr_t addr, size_t size, bool read,
-                                 bool write) override;
+  static constexpr uint32_t GetNumHardwareBreakpointSlots() {
+    return NUM_HARDWARE_BREAKPOINT_SLOTS;
+  }
+  static constexpr bool DoHardwareBreakpointsTriggerAfter() { return true; }
 
-  bool ClearHardwareWatchpoint(uint32_t hw_index) override;
+  bool AddHardwareBreakpoint(uint32_t slot, lldb::addr_t address, uint32_t size,
+                             bool read, bool write);
+  bool RemoveHardwareBreakpoint(uint32_t slot);
 
-  bool HardwareSingleStep(bool enable) override;
+  uint32_t GetTriggeredHardwareBreakpointSlotId();
 
 protected:
+  static constexpr unsigned NUM_HARDWARE_BREAKPOINT_SLOTS = 4;
+
   virtual bool CacheAllRegisterValues();
+  virtual bool ApplyAllRegisterValues();
 
   CONTEXT m_context;
   bool m_context_stale;
 };
-}
+} // namespace lldb_private
 
 #endif // #ifndef liblldb_RegisterContextWindows_H_

lldb/source/Plugins/Process/Windows/Common/RegisterContextWindows.cpp

bool RegisterContextWindows::ReadAllRegisterValues(
   return true;
 }
 
 bool RegisterContextWindows::WriteAllRegisterValues(
     const lldb::DataBufferSP &data_sp) {
   assert(data_sp->GetByteSize() >= sizeof(m_context));
   memcpy(&m_context, data_sp->GetBytes(), sizeof(m_context));
 
-  TargetThreadWindows &wthread = static_cast<TargetThreadWindows &>(m_thread);
-  if (!::SetThreadContext(
-          wthread.GetHostThread().GetNativeThread().GetSystemHandle(),
-          &m_context))
-    return false;
-
-  return true;
+  return ApplyAllRegisterValues();
 }
 
 uint32_t RegisterContextWindows::ConvertRegisterKindToRegisterNumber(
     lldb::RegisterKind kind, uint32_t num) {
   const uint32_t num_regs = GetRegisterCount();
 
   assert(kind < kNumRegisterKinds);
   for (uint32_t reg_idx = 0; reg_idx < num_regs; ++reg_idx) {
     const RegisterInfo *reg_info = GetRegisterInfoAtIndex(reg_idx);
 
     if (reg_info->kinds[kind] == num)
       return reg_idx;
   }
 
   return LLDB_INVALID_REGNUM;
 }
 
-// Subclasses can these functions if desired
-uint32_t RegisterContextWindows::NumSupportedHardwareBreakpoints() {
-  // Support for hardware breakpoints not yet implemented.
-  return 0;
-}
+bool RegisterContextWindows::HardwareSingleStep(bool enable) { return false; }
 
-uint32_t RegisterContextWindows::SetHardwareBreakpoint(lldb::addr_t addr,
-                                                       size_t size) {
-  return 0;
-}
+bool RegisterContextWindows::AddHardwareBreakpoint(uint32_t slot,
+                                                   lldb::addr_t address,
+                                                   uint32_t size, bool read,
+                                                   bool write) {
+  if (slot >= NUM_HARDWARE_BREAKPOINT_SLOTS)
+    return false;
 
-bool RegisterContextWindows::ClearHardwareBreakpoint(uint32_t hw_idx) {
+  if (!size || size > 8 || size & (size - 1))
     return false;
-}
 
-uint32_t RegisterContextWindows::NumSupportedHardwareWatchpoints() {
-  // Support for hardware watchpoints not yet implemented.
-  return 0;
-}
+  if (!CacheAllRegisterValues())
+    return false;
 
-uint32_t RegisterContextWindows::SetHardwareWatchpoint(lldb::addr_t addr,
-                                                       size_t size, bool read,
-                                                       bool write) {
-  return 0;
+  unsigned shift = 2 * slot;
+  m_context.Dr7 |= 1ULL << shift;
+
+  (&m_context.Dr0)[slot] = address;
+
+  shift = 18 + 4 * slot;
+  m_context.Dr7 &= ~(3ULL << shift);
+  m_context.Dr7 |= (size == 8 ? 2ULL : size - 1) << shift;
+
+  shift = 16 + 4 * slot;
+  m_context.Dr7 &= ~(3ULL << shift);
+  m_context.Dr7 |= (read ? 3ULL : (write ? 1ULL : 0)) << shift;
+
+  return ApplyAllRegisterValues();
 }
 
-bool RegisterContextWindows::ClearHardwareWatchpoint(uint32_t hw_index) {
+bool RegisterContextWindows::RemoveHardwareBreakpoint(uint32_t slot) {
+  if (slot >= NUM_HARDWARE_BREAKPOINT_SLOTS)
+    return false;
+
+  if (!CacheAllRegisterValues())
     return false;
+
+  unsigned shift = 2 * slot;
+  m_context.Dr7 &= ~(1ULL << shift);
+
+  return ApplyAllRegisterValues();
 }
 
-bool RegisterContextWindows::HardwareSingleStep(bool enable) { return false; }
+uint32_t RegisterContextWindows::GetTriggeredHardwareBreakpointSlotId() {
+  if (!CacheAllRegisterValues())
+    return LLDB_INVALID_INDEX32;
+
+  for (unsigned i = 0UL; i < NUM_HARDWARE_BREAKPOINT_SLOTS; i++)
+    if (m_context.Dr6 & (1ULL << i))
+      return i;
+
+  return LLDB_INVALID_INDEX32;
+}
 
 bool RegisterContextWindows::CacheAllRegisterValues() {
   Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_REGISTERS);
   if (!m_context_stale)
     return true;
 
   TargetThreadWindows &wthread = static_cast<TargetThreadWindows &>(m_thread);
   uint8_t buffer[2048];
if (::ResumeThread(
           wthread.GetHostThread().GetNativeThread().GetSystemHandle()) ==
       (DWORD)-1) {
     return false;
   }
   LLDB_LOG(log, "successfully updated the register values.");
   m_context_stale = false;
   return true;
 }
+
+bool RegisterContextWindows::ApplyAllRegisterValues() {
+  TargetThreadWindows &wthread = static_cast<TargetThreadWindows &>(m_thread);
+  return ::SetThreadContext(
+      wthread.GetHostThread().GetNativeThread().GetSystemHandle(), &m_context);
+}

lldb/source/Plugins/Process/Windows/Common/x64/RegisterContextWindows_x64.cpp

case lldb_xmm14_x86_64:
     memcpy(&m_context.Xmm14, reg_value.GetBytes(), 16);
     break;
   case lldb_xmm15_x86_64:
     memcpy(&m_context.Xmm15, reg_value.GetBytes(), 16);
     break;
   }
 
   // Physically update the registers in the target process.
-  TargetThreadWindows &wthread = static_cast<TargetThreadWindows &>(m_thread);
-  return ::SetThreadContext(
-      wthread.GetHostThread().GetNativeThread().GetSystemHandle(), &m_context);
+  return ApplyAllRegisterValues();
 }
 
 #endif // defined(__x86_64__) || defined(_M_X64)

lldb/source/Plugins/Process/Windows/Common/x86/RegisterContextWindows_x86.cpp

case lldb_eflags_i386:
     m_context.EFlags = reg_value.GetAsUInt32();
     break;
   default:
     LLDB_LOG(log, "Write value {0:x} to unknown register {1}",
              reg_value.GetAsUInt32(), reg);
   }
 
   // Physically update the registers in the target process.
-  TargetThreadWindows &wthread = static_cast<TargetThreadWindows &>(m_thread);
-  return ::SetThreadContext(
-      wthread.GetHostThread().GetNativeThread().GetSystemHandle(), &m_context);
+  return ApplyAllRegisterValues();
 }
 
 bool RegisterContextWindows_x86::ReadRegisterHelper(
     DWORD flags_required, const char *reg_name, DWORD value,
     RegisterValue &reg_value) const {
   Log *log = ProcessWindowsLog::GetLogIfAny(WINDOWS_LOG_REGISTERS);
   if ((m_context.ContextFlags & flags_required) != flags_required) {
     LLDB_LOG(log, "Thread context doesn't have {0}", reg_name);
     return false;
   }
   LLDB_LOG(log, "Read value {0:x} from {1}", value, reg_name);
   reg_value.SetUInt32(value);
   return true;
 }
 
 #endif // defined(__i386__) || defined(_M_IX86)