5 Commits

Author	SHA1	Message	Date
Simon Taylor	a3819d359c	Fix the handling of purity in the optimization and tabling passes. ... Estimated hours taken: 15 Branches: main Fix the handling of purity in the optimization and tabling passes. Without this change tests/tabling/unused_args.m fails with inter-module optimization. compiler/purity.m: compiler/post_typecheck.m: Allow purity checking to be rerun on a single procedure without requiring an io__state. If the purity is worse (due to inlining a predicate with a `:- pragma promise_pure' declaration), add `promised_pure' or `promised_semipure' to the pred_info. compiler/hlds_out.m: compiler/hlds_pred.m: compiler/intermod.m: compiler/make_hlds.m: compiler/mercury_to_mercury.m: compiler/module_qual.m: compiler/modules.m: compiler/prog_data.m: compiler/prog_io_pragma.m: compiler/purity.m: doc/reference_manual.texi: NEWS: Implement `:- pragma promise_semipure'. This is needed if an predicate marked `promised_pure' which calls impure predicates is inlined into a semipure predicate. compiler/inlining.m: Make sure the purity markers on the goal_infos are correct after inlining predicates which are promised pure. Export a predicate inlining__can_inline_proc which is used by deforestation to determine whether inlining a procedure will change the semantics or will break code generator invariants. compiler/deforest.m: Use the same method as inlining.m to work out whether a procedure can be inlined. Don't inline predicates which are promised pure because the extra impurity which will be propagated through the goal will stop deforestation working on the goal. compiler/simplify.m: Make sure the goal_info resulting from converting a singleton switch into a conjunction has the correct purity. compiler/table_gen.m: Make sure the purity markers on the generated goal_infos are correct. Make sure that call_table_gen goal features cannot be removed by optimization passes. Don't put unnecessary `impure' markers on calls to error/1. tests/debugger/loopcheck.exp: tests/debugger/retry.exp: Adjust the expected output. The change to ensure that `call_table_gen' goal features can't be removed alters the goal paths slightly. tests/invalid/impure_method_impl.m: Adjust the expected output now that predicates can be promised semipure.	2001-03-27 05:23:23 +00:00
Zoltan Somogyi	518e6e46db	Strip away goal paths from exception events in the test cases that ... Estimated hours taken: 0.5 tests/debugger/Mmakefile: tests/debugger/declarative/Mmakefile: Strip away goal paths from exception events in the test cases that generate them, because different optimization levels cause different goals paths to be associated with exceptions. tests/debugger/*.exp{,2}: tests/debugger/declarative/*.exp{,2}: Strip away goal paths from exception events in the expected outputs of those test cases.	2000-11-01 04:26:32 +00:00
Zoltan Somogyi	fdccd65e30	The debugger's retry command at the moment works only from a final port for ... Estimated hours taken: 60 The debugger's retry command at the moment works only from a final port for the call to be retried, the reason being that the RTTI does not have the information required to make sure that the state of the stacks is reset correctly. If you invoke retry from a non-final port, the current implementation skips forward to a final port and then does the retry; this does not work if you get a core dump or a infinite loop during the forward skip. This change adds the required info to the RTTI and thus enables direct retries from the middle of calls. The information added has two components. First, if a procedure that lives on the nondet stack allocates any temporary nondet stack frames, then it must record the old value of maxfr in a stack slot so that retry can restore it. Second, if a procedure is tabled, then it must record the call table tip node corresponding to the actual input arguments, so we can reset this node to uninitialized (if we don't, then the retried call will find the active call marker and report an infinite loop error). The support for retries across minimal model calls is not finished yet. Finding out what the right thing to do in such cases is a research project, one that cannot even be started until minimal model tabling works reliably in the *absence* of retries. However, such retries do grossly wrong things at the moment; this change is a definite improvement. It attempts to perform the retry from the fail port, since that is the only time when the minimal model tabling data structures are quiescent. The "fail" command I added to the debugger command set to let this be done is not complete yet and is therefore undocumented; the problem is that a call to a model_non predicate in a committed choice context will not get to the fail port. I added goal paths to return layouts so that we will eventually be able to tell when execution leaves a committed choice context surrounding an ancestor of a model_non predicate call, but this functionality is not yet implemented. compiler/stack_layout.m: Generate the three new fields: the evaluation method, (maybe) the id of the stack slot containing the saved value of maxfr, and (maybe) the id of the stack slot containing the call table tip. compiler/continuation_info.m: Record the information about the new fields for later use by stack_layout.m. Add a new field to record the goal path of calls for their return layouts. Fix a screwed comment for the continuation_info data structure. compiler/llds.m: Add a new field to call() instructions to hold the goal path of the call. Add a utility function for use by trace.m. compiler/call_gen.m: Fill in this new field. compiler/trace.m: compiler/live_vars.m: Reserve the fixed stack slot for the saved maxfr if necessary, and if the call table tip node is needed, make sure that the variable holding its address is allocated a low-numbered stack slot (otherwise, its number may not fit into the MR_int_least8_t field in the proc_layout). compiler/trace.m: If necessary, fill in the saved maxfr slot. If necessary, initialize the call table tip slot. compiler/hlds_goal.m: Add a goal feature which marks its goal as defining the variable representing the call table tip node. Add a field to the goal path step representing quantification; the field says whether the quantification changes the determinism of the goal (i.e. whether it cuts away solutions). compiler/hlds_pred.m: compiler/hlds_out.m: Add two fields to proc_infos which (a) record which variable, if any, holds the call table tip node, and (b) record whether the procedure's layout structure needs to reserve a slot for the saved value of maxfr. compiler/table_gen.m: Put this feature on the appropriate goal. Also, rename a predicate to make it reflect its purpose better. compiler/code_gen.m: Generate code to put the call table tip variable in its stack slot immediately after it has been generated. Add a sanity check to ensure that if a procedure that lives on the det stack can create a temporary nondet frame, and debugging is enabled, then it did have a stack slot reserved for the saved maxfr. compiler/code_util.m: Add a predicate to make a conservative prediction of whether a procedure may allocate a temporary nondet stack frame. We cannot just generate the code and see, because the code generator needs to know which variables live in which stack slots, and we cannot decide that until we know whether we need a stack slot for the saved value of maxfr. Make an unrelated predicate semidet procedure use a det helper, in order to make it more robust in the face of changes to the HLDS (e.g. it was missing code for handling bi_implications). compiler/code_info.m: Record whether a procedure has in fact created a temporary nondet stack frame. compiler/handle_options.m: Disable hijacks if debugging is enabled. The code we now use to restore the stacks for direct retries works only if the retry does not "backtrack" over a hijacked nondet stack frame whose hijack has not been undone. Note that code compiled without debugging may still hijack nondet stack frames. Execution may reemerge from the nondebugged region in one of two ways. If the nondebugged code returns, then it will have undone hijack, and the retry code will work. If the nondebugged code calls debugged code, there will be a region on the stacks containing no debugging information, and the retry command will refuse to perform retries that go into or beyond this region. Both cases preserve correctness. compiler/*.m: Trivial changes to conform to changes in data structures. runtime/mercury_stack_layout.h: Add three new fields to proc layouts: the numbers of the stack slots (if any) storing the saved maxfr and the call table tip, and a representation of the procedure's evaluation method. runtime/mercury_stack_trace.[ch]: Now that return layouts contain goal paths, print them in stack dumps only if the include_trace_data flag is set (in mdb, this requires the -d flag of the "stack" command). Pass this flag around directly, instead of encoding its value in the NULL vs non-NULL values of sp and curfr. runtime/mercury_regorder.h: Provide a mechanism to access the values of the first few rN registers from a save area, for use in debugging low-level C code in the runtime and the trace directories. trace/mercury_trace.[ch]: Reimplement MR_trace_retry to allow retries from the middle. If the stack segment being retried over contains minimal model procedures, we must still arrange to skip to the end of the retried call. If this call is a minimal model generator, skipping to just any final port is not sufficient to guarantee correctness on retry; to ensure that subgoal is complete, we must skip to a fail port. trace/mercury_trace.[ch]: trace/mercury_trace_internal.c: Implement a debugger command, "fail", which skips to the fail port or the exception port of the specified ancestor. Since procedures that are not model_non are not guaranteed to get to such a port, this command reports an error if the specified call is not model_non. Actually, even calls to model_non procedures may not get to the fail port, as explained above; this is why the command is not yet documented. trace/mercury_trace.c: trace/mercury_trace_util.[ch]: Move some functions to print parts of the Mercury abstract machine state from mercury_trace to mercury_trace_util, so that they are available for use in debugging e.g. mercury_trace_declarative. trace/mercury_trace_internal.c: trace/mercury_trace_external.c: trace/mercury_trace_declarative.c: Use the new implementation of retries. At the moment, only the internal debugger implements the full functionality. The declarative debugger issues retry commands only from situations where the missing functionality is not (yet) needed. The external debugger should continue to work correctly, but Erwan may wish to update it to exploit the availability of the fail command. trace/mercury_trace*.[ch]: Fix MR_prefixes, and a signed/unsigned mismatch. doc/user_guide.texi: Document the new "fail" command, but comment it out for now. tests/debugger/retry.{m,inp,exp,exp2}: A new test case for exercising retry. tests/debugger/Mmakefile: Enable the new test case. tests/debugger/*.exp: Update the expected output, given the extra info now output e.g. for exception events and detailed stack traces.	2000-10-13 04:06:52 +00:00
Zoltan Somogyi	d72a5652c2	Explicitly turn on echoing, to make sure that the results are the same ... Estimated hours taken: 0.1 tests/debugger/loopcheck.{inp,exp}: Explicitly turn on echoing, to make sure that the results are the same with and without readline.	2000-03-22 04:08:10 +00:00
Zoltan Somogyi	a822f78b3c	Add meaningful contexts to the goals inserted into predicates by tabling, ... Estimated hours taken: 4 Add meaningful contexts to the goals inserted into predicates by tabling, for use by the debugger. compiler/table_gen.m: Pass the context of the procedure body through the code, and create new goals with this context. To make this simpler, switch to consistently using combined predmode definitions. In a couple of places, switch to a more reasonable argument ordering. tests/debugger/loopcheck.* Copy this test case here from the tabling directory, and execute it under mdb, as a regression test. The exp2 test case is not final yet. tests/debugger/Mmakefile: Enable the regression test.	1999-12-21 01:23:44 +00:00