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[debug-info] Only hoist the first dbg inst associated with an async debug variable.
Otherwise, we may hoist a llvm.dbg.addr over another llvm.dbg.addr or llvm.dbg.value, changing observable debugging state. As an additional benefit, this finally lets me add straight line end to end lldb tests for async var and lets. This was the last thing stopping me from doing that.
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‎lldb/test/API/lang/swift/variables/move_function_async/Makefile

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SWIFT_SOURCES := main.swift
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SWIFTFLAGS_EXTRAS := -parse-as-library
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include Makefile.rules

‎lldb/test/API/lang/swift/variables/move_function_async/TestSwiftMoveFunctionAsync.py

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# TestSwiftMoveFunctionAsync.py
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#
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# This source file is part of the Swift.org open source project
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#
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# Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
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# Licensed under Apache License v2.0 with Runtime Library Exception
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#
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# See https://swift.org/LICENSE.txt for license information
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# See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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#
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# ------------------------------------------------------------------------------
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"""
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Check that we properly show variables at various points of the CFG while
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stepping with the move function.
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"""
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import lldb
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from lldbsuite.test.lldbtest import *
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from lldbsuite.test.decorators import *
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import lldbsuite.test.lldbutil as lldbutil
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import os
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import sys
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import unittest2
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def stderr_print(line):
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sys.stderr.write(line + "\n")
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class TestSwiftMoveFunctionAsyncType(TestBase):
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mydir = TestBase.compute_mydir(__file__)
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@swiftTest
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def test_swift_move_function_async(self):
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"""Check that we properly show variables at various points of the CFG while
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stepping with the move function.
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"""
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self.build()
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self.target, self.process, self.thread, self.bkpt = \
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lldbutil.run_to_source_breakpoint(
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self, 'Set breakpoint', lldb.SBFileSpec('main.swift'))
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# We setup a single breakpoint in copyable var test so we can disable it
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# after we hit it.
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self.do_setup_breakpoints()
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self.do_check_copyable_value_test()
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self.do_check_copyable_var_test()
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def setUp(self):
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TestBase.setUp(self)
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self.main_source = "main.swift"
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self.main_source_spec = lldb.SBFileSpec(self.main_source)
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self.exec_name = "a.out"
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def get_var(self, name):
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frame = self.thread.frames[0]
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return frame.FindVariable(name)
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def do_setup_breakpoints(self):
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self.breakpoints = []
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pattern = 'Special breakpoint'
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brk = self.target.BreakpointCreateBySourceRegex(
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pattern, self.main_source_spec)
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self.assertGreater(brk.GetNumLocations(), 0, VALID_BREAKPOINT)
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self.breakpoints.append(brk)
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def do_check_copyable_value_test(self):
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# We haven't defined varK yet.
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varK = self.get_var('k')
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self.assertEqual(varK.unsigned, 0, "varK initialized too early?!")
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# Go to break point 2.1. k should be valid.
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self.process.Continue()
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varK = self.get_var('k')
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self.assertGreater(varK.unsigned, 0, "varK not initialized?!")
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# Go to breakpoint 2.2. k should still be valid. And we should be on the
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# other side of the force split.
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self.process.Continue()
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varK = self.get_var('k')
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self.assertGreater(varK.unsigned, 0, "varK not initialized?!")
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# Go to breakpoint 3. k should still be valid. We should be at the move
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# on the other side of the forceSplit.
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self.process.Continue()
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varK = self.get_var('k')
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self.assertGreater(varK.unsigned, 0, "varK not initialized?!")
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# We are now at break point 4. We have moved k, it should be empty.
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self.process.Continue()
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varK = self.get_var('k')
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self.assertIsNone(varK.value, "K is live but was moved?!")
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# Finally, we are on the other side of the final force split. Make sure
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# the value still isn't available.
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self.process.Continue()
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varK = self.get_var('k')
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self.assertIsNone(varK.value, "K is live but was moved?!")
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# Run so we hit the next breakpoint to jump to the next test's
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# breakpoint.
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self.process.Continue()
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def do_check_copyable_var_test(self):
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# We haven't defined varK yet.
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varK = self.get_var('k')
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self.assertEqual(varK.unsigned, 0, "varK initialized too early?!")
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# Go to break point 2.1. k should be valid.
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self.process.Continue()
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varK = self.get_var('k')
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self.assertGreater(varK.unsigned, 0, "varK not initialized?!")
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# Go to breakpoint 2.2. k should still be valid. And we should be on the
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# other side of the force split.
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self.process.Continue()
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varK = self.get_var('k')
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self.assertGreater(varK.unsigned, 0, "varK not initialized?!")
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# Go to breakpoint 3. k should still be valid. We should be at the move
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# on the other side of the forceSplit.
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self.process.Continue()
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varK = self.get_var('k')
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self.assertGreater(varK.unsigned, 0, "varK not initialized?!")
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# There is an instruction with the wrong debug location on Linux,
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# causing us to jump back to 'step backwards' to an earlier location
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# before we have run the move. So disable that breakpoint so when we
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# continue, we get to the appropriate location on Linux and other
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# platforms.
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#
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# TODO: Investigate why this is happening!
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self.runCmd('# Skipping bad loc by disabling earlier break point 6')
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self.runCmd('break dis 2')
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# We are now at break point 4. We have moved k, it should be empty.
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self.process.Continue()
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varK = self.get_var('k')
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self.assertIsNone(varK.value, "K is live but was moved?!")
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# Now, we are on the other side of the final force split. Make sure
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# the value still isn't available.
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self.process.Continue()
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self.runCmd('# On other side of force split')
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varK = self.get_var('k')
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self.assertIsNone(varK.value, "K is live but was moved?!")
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# Finally, we have reinitialized k, look for k.
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self.process.Continue()
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self.runCmd('# After var reinit')
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varK = self.get_var('k')
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self.assertGreater(varK.unsigned, 0, "varK not initialized?!")
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# Run so we hit the next breakpoint to jump to the next test's
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# breakpoint.
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self.runCmd('# At end of routine!')
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self.process.Continue()

‎lldb/test/API/lang/swift/variables/move_function_async/main.swift

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// main.swift
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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// -----------------------------------------------------------------------------
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public class Klass {
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public func doSomething() {}
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}
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public func forceSplit() async {}
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//////////////////
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// Simple Tests //
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//////////////////
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public func copyableValueTest() async {
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print("stop here") // Set breakpoint
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let k = Klass()
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k.doSomething()
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await forceSplit() // Set breakpoint
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let m = _move(k) // Set breakpoint
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m.doSomething() // Set breakpoint
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await forceSplit()
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m.doSomething() // Set breakpoint
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}
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public func copyableVarTest() async {
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print("stop here")
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var k = Klass() // Special breakpoint
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k.doSomething()
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await forceSplit() // Set breakpoint
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let m = _move(k) // Set breakpoint
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m.doSomething() // Set breakpoint
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await forceSplit()
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k = Klass() // Set breakpoint
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k.doSomething() // Set breakpoint
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print("stop here")
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}
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//////////////////////////
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// Top Level Entrypoint //
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//////////////////////////
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@main struct Main {
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static func main() async {
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await copyableValueTest()
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await copyableVarTest()
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}
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}

‎llvm/lib/CodeGen/LiveDebugValues/VarLocBasedImpl.cpp

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@@ -2197,12 +2197,19 @@ bool VarLocBasedLDV::ExtendRanges(MachineFunction &MF,
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// function parameters in order to generate debug entry values for them.
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SmallVector<MachineInstr *, 8> AsyncDbgValues;
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MachineBasicBlock &First_MBB = *(MF.begin());
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// Use a cache so that we only hoist the first swift async context debug inst
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// for a specific DBG_VALUE. Otherwise, we may hoist inappropriately over a
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// llvm.dbg.value.
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SmallDenseSet<DebugVariable, 8> SeenDebugVars;
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for (auto &MI : First_MBB) {
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collectRegDefs(MI, DefinedRegs, TRI);
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if (MI.isDebugValue()) {
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// In Swift async functions entry values are preferred, since they
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// can be evaluated in both live frames and virtual backtraces.
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if (isSwiftAsyncContext(MI)) {
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if (SeenDebugVars.insert(DebugVariable(MI.getDebugVariable(),
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MI.getDebugExpression(),
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MI.getDebugLoc()->getInlinedAt())).second &&
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isSwiftAsyncContext(MI)) {
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// If our instruction is not an entry value yet, make it an entry value.
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if (!MI.getDebugExpression()->isEntryValue()) {
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MI.getOperand(3).setMetadata(DIExpression::prepend(

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