Rework tracing for blocks running as methods #4637
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Side note, out of scope for this PR and for fixing the bug, but I did a crude proof of concept for staying in the interpreter (not using |
XrXr
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Jul 10, 2021
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Okay, just pushed V2. I worked through some details about non-local returns and targeting TracePoints. |
XrXr
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Aug 3, 2021
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| define_method(:f_break_defined) do | ||
| return :f_break_defined | ||
| break :f_break_defined |
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Changed this because it was the same as the method above.
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@ko1 review ping. If we want to go with this PR I can try to get it done before release. |
ko1
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Dec 1, 2021
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Sorry for late.
I spend some days to make my patch but it was failed.
I also have some opinion, but we can modify later, so please merge it.
The main impetus for this change is to fix [Bug ruby#13392]. Previously, we fired the "return" TracePoint event after popping the stack frame for the block running as method (BMETHOD). This gave undesirable source location outputs as the return event normally fires right before the frame going away. The iseq for each block can run both as a block and as a method. To accommodate that, this commit makes vm_trace() fire call/return events for instructions that have b_call/b_return events attached when the iseq is running as a BMETHOD. The logic for rewriting to "trace_*" instruction is tweaked so that when the user listens to call/return events, instructions with b_call/b_return become trace variants. To continue to provide the return value for non-local returns done using the "return" or "break" keyword inside BMETHODs, the stack unwinding code is tweaked. b_return events now provide the same return value as return events for these non-local cases. A pre-existing test deemed not providing a return value for these b_return events as a limitation. This commit removes the checks for call/return TracePoint events that happen when calling into BMETHODs when no TracePoints are active. Technically, migrating just the return event is enough to fix the bug, but migrating both call and return removes our reliance on `VM_FRAME_FLAG_FINISH` and re-entering the interpreter when the caller is already in the interpreter.
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Rework tracing for blocks running as methods
The main impetus for this change is to fix [Bug #13392]. Previously, we
fired the "return" TracePoint event after popping the stack frame for
the block running as method (BMETHOD). This gave undesirable source
location outputs as the return event normally fires right before the
frame going away.
The iseq for each block can run both as a block and as a method. To
accommodate that, this commit makes vm_trace() fire call/return events for
instructions that have b_call/b_return events attached when the iseq is
running as a BMETHOD. The logic for rewriting to "trace_*" instruction
is tweaked so that when the user listens to call/return events,
instructions with b_call/b_return become trace variants.
To continue to provide the return value for non-local returns done using
the "return" or "break" keyword inside BMETHODs, the stack unwinding
code is tweaked. b_return events now provide the same return value as
return events for these non-local cases. A pre-existing test deemed not
providing a return value for these b_return events as a limitation.
This commit removes the checks for call/return TracePoint events that
happen when calling into BMETHODs when no TracePoints are active.
Technically, migrating just the return event is enough to fix the bug,
but migrating both call and return removes our reliance on
VM_FRAME_FLAG_FINISHand re-entering the interpreter when the calleris already in the interpreter.