[lldb][swift] Disable breakpoint filtering by default

A previous patch had introduced the notion of Language breakpoint
filtering when setting line breakpoints. While this is generally a good
idea, the swift implementation was motivated by statements like this:

```
async let x = ...
await foo()
await x
```

All of these lines have many different breakpoint locations associated
with them, creating many pauses while stepping; the intent behind the
filtering was to provide a smoother stepping experience.

The implementation filters breakpoints by "funclet" numbers,
disabling all but the lowest such funclet. Unfortunately, this fails
when the CFG of an async funclet needs to be cloned in non-trivial ways.
For example:

```
func foo(_ argument: Int) async {
  do {
    switch argument {
    case 1:
      try await willthrow(1)
    case 2:
      try await willthrow(2)
    default:
      return
    }
  } catch {
    print("breakhere")
  }
}
```

The breakpoint in "breakhere" has two funclets associated with it, one
when we throw from case 1, one from case 2. Filtering is incorrect in
this situation.

This patch disables filtering until we can solve this at a compiler
level. While we are disabling this through the TargetProperties setting,
which could affect other languages, Swift is the only such language
using that setting.

Author: felipepiovezan

lldb/source/Target/TargetProperties.td

@@ -380,6 +380,6 @@ let Definition = "thread" in {
 
 let Definition = "language" in {
   def EnableFilterForLineBreakpoints: Property<"enable-filter-for-line-breakpoints", "Boolean">,
-    DefaultTrue,
+    DefaultFalse,
     Desc<"If true, allow Language plugins to filter locations when setting breakpoints by line number or regex.">;
 }

lldb/test/API/lang/swift/async/stepping/step-in/TestSwiftStepInAsync.py

@@ -13,6 +13,7 @@ class TestCase(lldbtest.TestBase):
     def test(self):
         """Test step-in to async functions"""
         self.build()
+        self.runCmd("settings set language.enable-filter-for-line-breakpoints true")
         src = lldb.SBFileSpec('main.swift')
         _, process, _, _ = lldbutil.run_to_source_breakpoint(self, 'await', src)
 

lldb/test/API/lang/swift/async/stepping/step_over/TestSwiftAsyncStepOver.py

@@ -22,6 +22,7 @@ def test(self):
         target, process, thread, bkpt = lldbutil.run_to_source_breakpoint(
             self, "BREAK HERE", source_file
         )
+        bkpt.SetEnabled(False) # avoid hitting multiple locations in async breakpoints
 
         expected_line_nums = [4]  # print(x)
         expected_line_nums += [5, 6, 7, 5, 6, 7, 5]  # two runs over the loop

lldb/test/API/lang/swift/async/unwind/backtrace_locals/TestSwiftAsyncBacktraceLocals.py

@@ -23,6 +23,7 @@ def test(self):
         self.build()
         target, process, thread, main_bkpt = lldbutil.run_to_source_breakpoint(
             self, 'main breakpoint', self.src)
+        main_bkpt.SetEnabled(False) # avoid hitting multiple locations in async breakpoints
         self.run_fibo_tests(target, process)
 
     @swiftTest
@@ -34,6 +35,7 @@ def test_actor(self):
         self.build()
         target, process, thread, main_bkpt = lldbutil.run_to_source_breakpoint(
             self, 'main actor breakpoint', self.src)
+        main_bkpt.SetEnabled(False) # avoid hitting multiple locations in async breakpoints
         self.run_fibo_tests(target, process)
 
 

lldb/test/API/lang/swift/async/unwind/unwind_in_all_instructions/main.swift

@@ -43,7 +43,8 @@ func ASYNC___5___() async -> Int {
 
 @main struct Main {
   static func main() async {
-    let result = await ASYNC___5___() // BREAK HERE
+    print("BREAK HERE")
+    let result = await ASYNC___5___()
     print(result)
   }
 }

lldb/test/API/lang/swift/async_breakpoints/TestSwiftAsyncBreakpoints.py

@@ -13,6 +13,7 @@ class TestSwiftAsyncBreakpoints(lldbtest.TestBase):
     def test(self):
         """Test async breakpoints"""
         self.build()
+        self.runCmd("settings set language.enable-filter-for-line-breakpoints true")
         filespec = lldb.SBFileSpec("main.swift")
         target, process, thread, breakpoint1 = lldbutil.run_to_source_breakpoint(
             self, "Breakpoint1", filespec

lldb/test/API/lang/swift/async_breakpoints_over_many_funclets/Makefile

@@ -0,0 +1,3 @@
+SWIFT_SOURCES := main.swift
+
+include Makefile.rules

lldb/test/API/lang/swift/async_breakpoints_over_many_funclets/TestSwiftAsyncBreakpointsOverManyFunclets.py

@@ -0,0 +1,29 @@
+import lldb
+from lldbsuite.test.decorators import *
+import lldbsuite.test.lldbtest as lldbtest
+import lldbsuite.test.lldbutil as lldbutil
+
+
+class TestSwiftAsyncBreakpoints(lldbtest.TestBase):
+    @swiftTest
+    @skipIfLinux
+    def test(self):
+        """Test async that async breakpoints are not filtered when the same
+        statement is present across multiple funclets"""
+        self.build()
+        filespec = lldb.SBFileSpec("main.swift")
+        target, process, thread, breakpoint1 = lldbutil.run_to_source_breakpoint(
+            self, "breakpoint_start", filespec
+        )
+        breakpoint = target.BreakpointCreateBySourceRegex("breakhere", filespec)
+        self.assertEquals(breakpoint.GetNumLocations(), 2)
+
+        process.Continue()
+        self.assertStopReason(thread.GetStopReason(), lldb.eStopReasonBreakpoint)
+        self.assertEquals(thread.GetStopDescription(128), "breakpoint 2.1")
+        self.expect("expr argument", substrs=["1"])
+
+        process.Continue()
+        self.assertStopReason(thread.GetStopReason(), lldb.eStopReasonBreakpoint)
+        self.assertEquals(thread.GetStopDescription(128), "breakpoint 2.2")
+        self.expect("expr argument", substrs=["2"])

lldb/test/API/lang/swift/async_breakpoints_over_many_funclets/main.swift

@@ -0,0 +1,27 @@
+enum MyError: Error {
+  case MyError1
+  case MyError2
+}
+
+func willthrow(_ arg: Int) async throws {
+  if arg == 1 { throw MyError.MyError1 } else { throw MyError.MyError2 }
+}
+
+func foo(_ argument: Int) async {
+  do {
+    switch argument {
+    case 1:
+      try await willthrow(1)
+    case 2:
+      try await willthrow(2)
+    default:
+      return
+    }
+  } catch {
+    print("breakhere")
+  }
+}
+
+print("breakpoint_start")
+await foo(1)
+await foo(2)

lldb/test/API/lang/swift/protocols/stepping_through_witness/TestSwiftSteppingThroughWitness.py

@@ -22,6 +22,9 @@ def test_step_in_and_out(self):
             self, "break here", lldb.SBFileSpec("main.swift")
         )
 
+        # First, get to the await call.
+        thread.StepOver()
+
         thread.StepInto()
         stop_reason = thread.GetStopReason()
         self.assertStopReason(stop_reason, lldb.eStopReasonPlanComplete)
@@ -48,11 +51,14 @@ def test_step_over(self):
             self, "break here", lldb.SBFileSpec("main.swift")
         )
 
+        # First, get to the await call.
+        thread.StepOver()
+
         thread.StepOver()
         stop_reason = thread.GetStopReason()
         self.assertStopReason(stop_reason, lldb.eStopReasonPlanComplete)
         frame0 = thread.frames[0]
         self.assertIn("doMath", frame0.GetFunctionName())
 
         line_entry = frame0.GetLineEntry()
-        self.assertEqual(14, line_entry.GetLine())
+        self.assertEqual(15, line_entry.GetLine())

lldb/test/API/lang/swift/protocols/stepping_through_witness/main.swift

@@ -10,7 +10,8 @@ class SlowRandomNumberGenerator: RandomNumberGenerator {
 }
 
 func doMath<RNG: RandomNumberGenerator>(with rng: RNG) async {
-    let y = await rng.random(in: 101...200) // break here
+    print("break here")
+    let y = await rng.random(in: 101...200)
     print("Y is \(y)")
 }