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953ea7667f
The crash that this diff fixes occurred when giving a command such as
"print Var^1" to mdb, where the first argument of Var is a direct arg.
runtime/mercury_ml_expand_body.h:
When deconstructing a term with a direct arg, return NULL
as the value of expand_info->chosen_arg_word_sized_ptr.
The crash occurred when we returned a non-null pointer,
which violated the expectations of trace/mercury_trace_vars.c
and its callers. (Not surprising, since those that function and
its callers were written long before the direct_arg optimization
was added to the system.)
runtime/mercury_deconstruct.h:
Document the rationale behind the above changes. (The contents of
mercury_ml_expand_body.h are #included in mercury_deconstruct.c.)
trace/mercury_trace_vars.c:
Add the debugging code I used to track down this issue, in disabled form.
Fix missing copyright year.
trace/mercury_trace_browse.c:
Delete obsolete comment.
Fix missing copyright years.
tests/debugger/direct_arg_test.{m,inp,exp}:
A test case for this bug.
tests/debugger/Mmakefile:
Enable the new test case.
compiler/hlds_out_type_table.m:
When dumping out the data constructors in the type table,
if a constructor has names for some of its fields,
put the name and the type of each field on different lines.
In the original test case for this bug, of which direct_arg_test.m
is an extreme simplification, pretty much every line overflows
without this.
Also, factor out some duplicated code, and replace bools with values
of a bespoke type.
163 lines
6.4 KiB
C
163 lines
6.4 KiB
C
// vim: ts=4 sw=4 expandtab ft=c
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// Copyright (C) 2002, 2005, 2007, 2011 The University of Melbourne.
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// Copyright (C) 2015-2016, 2018, 2026 The Mercury team.
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// This file is distributed under the terms specified in COPYING.LIB.
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// mercury_deconstruct.h
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//
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// This file declares utility functions for deconstructing terms,
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// for use by the standard library and the debugger.
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#ifndef MERCURY_DECONSTRUCT_H
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#define MERCURY_DECONSTRUCT_H
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#include "mercury_imp.h"
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#include <stdio.h>
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typedef struct {
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int arity;
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int functor_number;
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MR_ConstString functor;
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MR_Word arg_univs_list;
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} MR_ExpandFunctorArgsInfo;
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typedef struct {
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int arity;
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int functor_number;
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MR_ConstString functor;
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MR_Word arg_univs_list;
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MR_bool limit_reached;
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} MR_ExpandFunctorArgsLimitInfo;
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typedef struct {
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int arity;
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int functor_number;
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MR_ConstString functor_only;
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} MR_ExpandFunctorOnlyInfo;
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typedef struct {
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int arity;
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MR_Word arg_univs_list;
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} MR_ExpandArgsOnlyInfo;
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typedef struct {
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int arity;
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MR_bool chosen_index_exists;
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MR_TypeInfo chosen_arg_type_info;
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MR_Word chosen_arg_term;
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MR_Word *chosen_arg_word_sized_ptr;
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} MR_ExpandChosenArgOnlyInfo;
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// MR_NONCANON_ABORT asks that deconstructions of noncanonical types should
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// cause a runtime abort.
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//
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// MR_NONCANON_ALLOW asks that deconstructions of noncanonical types should
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// return a constant that indicates this fact.
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//
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// MR_NONCANON_CC asks that deconstruction of noncanonical types should
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// deconstruct the term as if it were canonical. Since by definition,
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// noncanonical types may have more than one representation for the same value,
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// this requires the caller to be in a committed choice context.
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typedef enum {
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MR_NONCANON_ABORT,
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MR_NONCANON_ALLOW,
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MR_NONCANON_CC
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} MR_noncanon_handling;
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// The MR_expand_* functions do the heavy lifting in the implementation
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// of the main predicates of library/deconstruct.m. Given a term and its type,
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// they can find out and return the name and the arity of the term's top
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// function symbol, a list of the values of all its arguments, or the value
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// of just one argument, chosen by index or by field name. Each variant
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// returns some subset of this information. The subset is given by the fields
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// of the MR_Expand* type referred to by its last argument.
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// XXX In each of these functions, the name of the argument that represents
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// the whole term is
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//
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// - Term in deconstruct.m in the library,
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// - term_ptr in mercury_deconstruct.c, and
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// - data_word_ptr here and in mercury_ml_expand_body.h.
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//
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// It would be nice if the terminology was consistent.
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extern void MR_expand_functor_args(MR_TypeInfo type_info,
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MR_Word *data_word_ptr, MR_noncanon_handling noncanon,
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MR_ExpandFunctorArgsInfo *expand_info);
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extern void MR_expand_functor_args_limit(MR_TypeInfo type_info,
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MR_Word *data_word_ptr, MR_noncanon_handling noncanon,
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int max_arity,
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MR_ExpandFunctorArgsLimitInfo *expand_info);
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extern void MR_expand_functor_only(MR_TypeInfo type_info,
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MR_Word *data_word_ptr, MR_noncanon_handling noncanon,
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MR_ExpandFunctorOnlyInfo *expand_info);
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extern void MR_expand_args_only(MR_TypeInfo type_info,
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MR_Word *data_word_ptr, MR_noncanon_handling noncanon,
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MR_ExpandArgsOnlyInfo *expand_info);
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extern void MR_expand_chosen_arg_only(MR_TypeInfo type_info,
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MR_Word *data_word_ptr, MR_noncanon_handling noncanon,
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int chosen, MR_ExpandChosenArgOnlyInfo *expand_info);
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extern void MR_expand_named_arg_only(MR_TypeInfo type_info,
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MR_Word *data_word_ptr, MR_noncanon_handling noncanon,
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MR_ConstString chosen_name,
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MR_ExpandChosenArgOnlyInfo *expand_info);
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// MR_arg() takes the address of a term, its type, and an argument position
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// (the first argument being at position 1), as well as an indication
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// of the desired `canonicality' of the decomposition.
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//
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// If the given term has an argument at the specified position, MR_arg returns
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// MR_TRUE, and fills in *arg_type_info_ptr and *arg_term_ptr with the
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// type_info and value of that argument at the selected position. It also
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// fills in *word_sized_arg_ptr. It sets *word_sized_arg_ptr
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//
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// - to the address of the argument if the argument's size in the argument
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// vector is exactly one word, or
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//
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// - to NULL, if the size is anything else (double word, subword, or nothing
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// for dummies), or if the argument is not IN the argument vector
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// (as with direct_args, where the argument is in what would usually be
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// the *pointer* to the argument vector).
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//
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// If the given term does not have an argument at the specified position,
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// MR_arg fails, i.e. it returns MR_FALSE.
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//
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// You need to wrap MR_{save/restore}_transient_hp() around
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// calls to this function.
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extern MR_bool MR_arg(MR_TypeInfo type_info, MR_Word *term,
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MR_noncanon_handling noncanon, int arg_index,
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MR_TypeInfo *arg_type_info_ptr, MR_Word *arg_term_ptr,
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MR_Word **word_sized_arg_ptr);
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// MR_named_arg() is just like MR_arg, except the argument is selected by name,
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// not by position.
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//
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// You need to wrap MR_{save/restore}_transient_hp() around
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// calls to this function.
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extern MR_bool MR_named_arg(MR_TypeInfo type_info, MR_Word *term,
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MR_noncanon_handling noncanon, MR_ConstString arg_name,
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MR_TypeInfo *arg_type_info_ptr, MR_Word *arg_term_ptr,
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MR_Word **word_sized_arg_ptr);
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// MR_named_arg_num() takes the address of a term, its type, and an argument
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// name. If the given term has an argument with the given name, it succeeds
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// and returns the argument number (counted starting from 0) of the argument.
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// If it doesn't, it fails, i.e. returns MR_FALSE.
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//
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// You need to wrap MR_{save/restore}_transient_hp() around
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// calls to this function.
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extern MR_bool MR_named_arg_num(MR_TypeInfo type_info, MR_Word *term_ptr,
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const char *arg_name, int *arg_num_ptr);
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#endif // MERCURY_DECONSTRUCT_H
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