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b816836f02
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Branches: main
Optimize away stack slots storing dummy values; values of the io__state and
store__store types.
compiler/stack_alloc.m:
Allocate distinct negative stack slot numbers to values of dummy types.
We need
compiler/hlds_pred.m:
Add a predicate for testing whether a value is of a dummy type.
compiler/code_into.m:
When constructing the list of live locations after a call, do not
include the negative stack slots containing dummy values. The list
of live locations is used by the (future) native collector, which
should ignore dummy types, and by the debugger. The debugger can't
do anything with these dummy values on the stack except tell the
user about their existence, which doesn't do the debugger user any
good.
We still keep liveness information about dummy values in registers
at calls and returns, since both the procedural and declarative
debuggers need to know procedures' full argument lists.
With respect to the list of live locations before the call, which
was used only by the (now extinct) value numbering optimization,
filter out all dummy types, since their values need not be preserved.
compiler/trace.m:
Do not ask the code generator to preserve values of dummy types,
since doing so would require referring to negative stack slots.
compiler/unify_gen.m:
compiler/var_locn.m:
Fix a couple of situations in which we could refer to the negative
stack slots we now allocate to dummy values.
compiler/call_gen.m:
Reorder some code to make the source match what happens at runtime.
compiler/llds_out.m:
Fix the formatting of the sanity check for negative stack slots.
compiler/handle_options.m:
Since the --debug-opt-pred-id option is useless without --debug-opt,
make --debug-opt-pred-id option imply --debug-opt. This was useful
in debugging this diff.
trace/mercury_trace.c:
Adapt the test for whether a retry is across I/O. We used to base the
test on whether the retried predicate has any I/O state arguments,
and if so, whether the original I/O state variable is still around
on the stack. After this change, the answer to the second half of
that question would always be "no", so we now use only the first half:
whether the retried predicate has any I/O state arguments. This
requires us to consider more retries to be retries across I/O, but
from the point of view of a user who may not remember whether the I/O
predicate has done any I/O so far or not, is arguably more consistent
than our previous policy.
Allow retries even if a value of type store.store is missing, since
store.store is a dummy type just as io.state is.
trace/mercury_trace.c:
compiler/type_util.m:
Document the fact that you need to update both these files if you
want to modify the set of dummy types.
tests/debugger/retry.{inp,exp,exp2}:
Due to the change in mercury_trace.c, one retry in this test case
changes to being retry over I/O. Update the test input to force this
retry over I/O, and expect the expanded input to be echoed in the
output.
tests/debugger/nondet_stack.{exp,exp2}:
Update these expected outputs to account for the fact that we now need
fewer stack slots to hold old I/O states when debugging is enabled.
64 lines
635 B
Plaintext
64 lines
635 B
Plaintext
echo on
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register --quiet
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scroll off
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context none
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goal_paths off
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break det_without_cut_1
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continue -a
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disable 0
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retry
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stack
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finish
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retry 1
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stack
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break det_without_cut_2
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continue -a
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delete *
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retry 2
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finish
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stack
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break det_with_cut_1
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continue -a
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delete *
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finish
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retry 1
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finish
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stack
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retry -f 1
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break det_with_cut_2
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continue -a
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delete *
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break nondet
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continue
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print *
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break nondet_2
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continue
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retry 1
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print *
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delete *
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break fib
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continue
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print *
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continue
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print *
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continue
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continue
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step
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retry 2
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print *
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next
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retry 1
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finish -n
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delete *
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break t
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continue
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table t 1 2
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finish
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table t 1 2
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retry
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table t 1 2
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finish
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table t 1 2
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delete *
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continue -n -S
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