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[lldb] If the function cannot be found, use the symbol to get instructions. #7114

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[lldb] If the function cannot be found, use the symbol to get instructions. #7114

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20 changes: 17 additions & 3 deletions lldb/test/API/lang/swift/async/stepping/step-in/task-switch/TestSwiftTaskSwitch.py
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Original file line number Diff line number Diff line change
Expand Up @@ -15,11 +15,25 @@ def test(self):
target, _, thread, _ = lldbutil.run_to_source_breakpoint(self, "await f()", src)
self.assertEqual(thread.frame[0].function.mangled, "$s1a5entryO4mainyyYaFZ")

function = target.FindFunctions("$s1a5entryO4mainyyYaFZTQ0_")[0].function
instructions = list(function.GetInstructions(target))
sym_ctx_list = target.FindFunctions("$s1a5entryO4mainyyYaFZTQ0_", lldb.eFunctionNameTypeAuto)
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eFunctionNameTypeAuto is effectively the default parameter value, so it seems it can be left off.

self.assertEquals(sym_ctx_list.GetSize(), 1)
symbolContext = sym_ctx_list.GetContextAtIndex(0)
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for consistency, could you name this symbol_context or symbol_ctx, thanks.

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Sorry, my mistake.
I will update if this PR is still needed.

function = symbolContext.GetFunction()
if function:
instructions = list(function.GetInstructions(target))
else:
symbol = symbolContext.GetSymbol()
self.assertIsNotNone(symbol)
instructions = list(symbol.GetInstructions(target))
Comment on lines +24 to +27
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this seems like the crux of the change, is that correct? Does this mean the test is being run without debug info? Or does it mean that even with debug info, somehow GetFunction returns None? If the reason for this else case is understood, then could you add a comment explaining?

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Yes.

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I may know what the problem is. If I understand correctly, GetFunction is taken from the debuginfo.
An incorrect DW_TAG_subprogram caused the GetFunction returns None.


# Expected to be a trampoline that tail calls `swift_task_switch`.
self.assertIn("swift_task_switch", instructions[-1].GetComment(target))
for inst in reversed(instructions):
control_flow_kind = inst.GetControlFlowKind(target)
if control_flow_kind == lldb.eInstructionControlFlowKindOther:
continue
Comment on lines +31 to +33
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can you say why some instructions need to be skipped? Padding instructions?

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Yes. Getting from the symbol will include the padding directive at the end.
But I'm not clear on lldb's difference between GetSymbol and GetFunction.

self.assertEqual(control_flow_kind, lldb.eInstructionControlFlowKindJump)
self.assertIn("swift_task_switch", inst.GetComment(target))
break

# Using the line table, build a set of the non-zero line numbers for
# this this function - and verify that there is exactly one line.
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