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compile.c
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compile.c
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#ifndef _GNU_SOURCE
#define _GNU_SOURCE // for strdup
#endif
#include <assert.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include "compile.h"
#include "bytecode.h"
#include "locfile.h"
#include "jv_alloc.h"
#include "linker.h"
/*
The intermediate representation for jq filters is as a sequence of
struct inst, which form a doubly-linked list via the next and prev
pointers.
A "block" represents a sequence of "struct inst", which may be
empty.
Blocks are generated by the parser bottom-up, so may have free
variables (refer to things not defined). See inst.bound_by and
inst.symbol.
*/
struct inst {
struct inst* next;
struct inst* prev;
opcode op;
struct {
uint16_t intval;
struct inst* target;
jv constant;
const struct cfunction* cfunc;
} imm;
struct locfile* locfile;
location source;
// Binding
// An instruction requiring binding (for parameters/variables/functions)
// is in one of three states:
// inst->bound_by = NULL - Unbound free variable
// inst->bound_by = inst - This instruction binds a variable
// inst->bound_by = other - Uses variable bound by other instruction
// Unbound instructions (references to other things that may or may not
// exist) are created by "gen_foo_unbound", and bindings are created by
// block_bind(definition, body), which binds all instructions in
// body which are unbound and refer to "definition" by name.
struct inst* bound_by;
char* symbol;
int any_unbound;
int referenced;
int nformals;
int nactuals;
block subfn; // used by CLOSURE_CREATE (body of function)
block arglist; // used by CLOSURE_CREATE (formals) and CALL_JQ (arguments)
// This instruction is compiled as part of which function?
// (only used during block_compile)
struct bytecode* compiled;
int bytecode_pos; // position just after this insn
};
static inst* inst_new(opcode op) {
inst* i = jv_mem_alloc(sizeof(inst));
i->next = i->prev = 0;
i->op = op;
i->bytecode_pos = -1;
i->bound_by = 0;
i->symbol = 0;
i->any_unbound = 0;
i->referenced = 0;
i->nformals = -1;
i->nactuals = -1;
i->subfn = gen_noop();
i->arglist = gen_noop();
i->source = UNKNOWN_LOCATION;
i->locfile = 0;
return i;
}
static void inst_free(struct inst* i) {
jv_mem_free(i->symbol);
block_free(i->subfn);
block_free(i->arglist);
if (i->locfile)
locfile_free(i->locfile);
if (opcode_describe(i->op)->flags & OP_HAS_CONSTANT) {
jv_free(i->imm.constant);
}
jv_mem_free(i);
}
static block inst_block(inst* i) {
block b = {i,i};
return b;
}
int block_is_single(block b) {
return b.first && b.first == b.last;
}
static inst* block_take(block* b) {
if (b->first == 0) return 0;
inst* i = b->first;
if (i->next) {
i->next->prev = 0;
b->first = i->next;
i->next = 0;
} else {
b->first = 0;
b->last = 0;
}
return i;
}
block gen_location(location loc, struct locfile* l, block b) {
for (inst* i = b.first; i; i = i->next) {
if (i->source.start == UNKNOWN_LOCATION.start &&
i->source.end == UNKNOWN_LOCATION.end) {
i->source = loc;
i->locfile = locfile_retain(l);
}
}
return b;
}
block gen_noop() {
block b = {0,0};
return b;
}
int block_is_noop(block b) {
return (b.first == 0 && b.last == 0);
}
block gen_op_simple(opcode op) {
assert(opcode_describe(op)->length == 1);
return inst_block(inst_new(op));
}
block gen_const(jv constant) {
assert(opcode_describe(LOADK)->flags & OP_HAS_CONSTANT);
inst* i = inst_new(LOADK);
i->imm.constant = constant;
return inst_block(i);
}
block gen_const_global(jv constant, const char *name) {
assert((opcode_describe(STORE_GLOBAL)->flags & (OP_HAS_CONSTANT | OP_HAS_VARIABLE | OP_HAS_BINDING)) ==
(OP_HAS_CONSTANT | OP_HAS_VARIABLE | OP_HAS_BINDING));
inst* i = inst_new(STORE_GLOBAL);
i->imm.constant = constant;
i->symbol = strdup(name);
i->any_unbound = 0;
return inst_block(i);
}
block gen_op_pushk_under(jv constant) {
assert(opcode_describe(PUSHK_UNDER)->flags & OP_HAS_CONSTANT);
inst* i = inst_new(PUSHK_UNDER);
i->imm.constant = constant;
return inst_block(i);
}
int block_is_const(block b) {
return (block_is_single(b) && (b.first->op == LOADK || b.first->op == PUSHK_UNDER));
}
int block_is_const_inf(block b) {
return (block_is_single(b) && b.first->op == LOADK &&
jv_get_kind(b.first->imm.constant) == JV_KIND_NUMBER &&
isinf(jv_number_value(b.first->imm.constant)));
}
jv_kind block_const_kind(block b) {
assert(block_is_const(b));
return jv_get_kind(b.first->imm.constant);
}
jv block_const(block b) {
assert(block_is_const(b));
return jv_copy(b.first->imm.constant);
}
block gen_op_target(opcode op, block target) {
assert(opcode_describe(op)->flags & OP_HAS_BRANCH);
assert(target.last);
inst* i = inst_new(op);
i->imm.target = target.last;
return inst_block(i);
}
block gen_op_targetlater(opcode op) {
assert(opcode_describe(op)->flags & OP_HAS_BRANCH);
inst* i = inst_new(op);
i->imm.target = 0;
return inst_block(i);
}
void inst_set_target(block b, block target) {
assert(block_is_single(b));
assert(opcode_describe(b.first->op)->flags & OP_HAS_BRANCH);
assert(target.last);
b.first->imm.target = target.last;
}
block gen_op_unbound(opcode op, const char* name) {
assert(opcode_describe(op)->flags & OP_HAS_BINDING);
inst* i = inst_new(op);
i->symbol = strdup(name);
i->any_unbound = 1;
return inst_block(i);
}
block gen_op_var_fresh(opcode op, const char* name) {
assert(opcode_describe(op)->flags & OP_HAS_VARIABLE);
block b = gen_op_unbound(op, name);
b.first->bound_by = b.first;
return b;
}
block gen_op_bound(opcode op, block binder) {
assert(block_is_single(binder));
block b = gen_op_unbound(op, binder.first->symbol);
b.first->bound_by = binder.first;
b.first->any_unbound = 0;
return b;
}
block gen_dictpair(block k, block v) {
return BLOCK(gen_subexp(k), gen_subexp(v), gen_op_simple(INSERT));
}
static void inst_join(inst* a, inst* b) {
assert(a && b);
assert(!a->next);
assert(!b->prev);
a->next = b;
b->prev = a;
}
void block_append(block* b, block b2) {
if (b2.first) {
if (b->last) {
inst_join(b->last, b2.first);
} else {
b->first = b2.first;
}
b->last = b2.last;
}
}
block block_join(block a, block b) {
block c = a;
block_append(&c, b);
return c;
}
int block_has_only_binders_and_imports(block binders, int bindflags) {
bindflags |= OP_HAS_BINDING;
for (inst* curr = binders.first; curr; curr = curr->next) {
if ((opcode_describe(curr->op)->flags & bindflags) != bindflags && curr->op != DEPS && curr->op != MODULEMETA) {
return 0;
}
}
return 1;
}
static int inst_is_binder(inst *i, int bindflags) {
return !((opcode_describe(i->op)->flags & bindflags) != bindflags && i->op != MODULEMETA);
}
int block_has_only_binders(block binders, int bindflags) {
bindflags |= OP_HAS_BINDING;
bindflags &= ~OP_BIND_WILDCARD;
for (inst* curr = binders.first; curr; curr = curr->next) {
if ((opcode_describe(curr->op)->flags & bindflags) != bindflags && curr->op != MODULEMETA) {
return 0;
}
}
return 1;
}
// Count a call site's actual params
static int block_count_actuals(block b) {
int args = 0;
for (inst* i = b.first; i; i = i->next) {
switch (i->op) {
default: assert(0 && "Unknown function type"); break;
case CLOSURE_CREATE:
case CLOSURE_PARAM:
case CLOSURE_CREATE_C:
args++;
break;
}
}
return args;
}
static int block_bind_subblock_inner(int* any_unbound, block binder, block body, int bindflags, int break_distance) {
assert(block_is_single(binder));
assert((opcode_describe(binder.first->op)->flags & bindflags) == (bindflags & ~OP_BIND_WILDCARD));
assert(binder.first->symbol);
assert(binder.first->bound_by == 0 || binder.first->bound_by == binder.first);
assert(break_distance >= 0);
binder.first->bound_by = binder.first;
int nrefs = 0;
for (inst* i = body.first; i; i = i->next) {
if (i->any_unbound == 0)
continue;
int flags = opcode_describe(i->op)->flags;
if ((flags & bindflags) == (bindflags & ~OP_BIND_WILDCARD) && i->bound_by == 0 &&
(!strcmp(i->symbol, binder.first->symbol) ||
// Check for break/break2/break3; see parser.y
((bindflags & OP_BIND_WILDCARD) && i->symbol[0] == '*' &&
break_distance <= 3 && (i->symbol[1] == '1' + break_distance) &&
i->symbol[2] == '\0'))) {
// bind this instruction
if (i->nactuals == -1 || i->nactuals == binder.first->nformals) {
i->bound_by = binder.first;
nrefs++;
}
} else if ((flags & bindflags) == (bindflags & ~OP_BIND_WILDCARD) && i->bound_by != 0 &&
!strncmp(binder.first->symbol, "*anonlabel", sizeof("*anonlabel") - 1) &&
!strncmp(i->symbol, "*anonlabel", sizeof("*anonlabel") - 1)) {
// Increment the break distance required for this binder to match
// a break whenever we come across a STOREV of *anonlabel...
break_distance++;
}
i->any_unbound = (i->symbol && !i->bound_by);
// binding recurses into closures
nrefs += block_bind_subblock_inner(&i->any_unbound, binder, i->subfn, bindflags, break_distance);
// binding recurses into argument list
nrefs += block_bind_subblock_inner(&i->any_unbound, binder, i->arglist, bindflags, break_distance);
if (i->any_unbound)
*any_unbound = 1;
}
return nrefs;
}
static int block_bind_subblock(block binder, block body, int bindflags, int break_distance) {
int any_unbound;
return block_bind_subblock_inner(&any_unbound, binder, body, bindflags, break_distance);
}
static int block_bind_each(block binder, block body, int bindflags) {
assert(block_has_only_binders(binder, bindflags));
bindflags |= OP_HAS_BINDING;
int nrefs = 0;
for (inst* curr = binder.first; curr; curr = curr->next) {
nrefs += block_bind_subblock(inst_block(curr), body, bindflags, 0);
}
return nrefs;
}
static block block_bind(block binder, block body, int bindflags) {
block_bind_each(binder, body, bindflags);
return block_join(binder, body);
}
block block_bind_library(block binder, block body, int bindflags, const char *libname) {
bindflags |= OP_HAS_BINDING;
int nrefs = 0;
int matchlen = (libname == NULL) ? 0 : strlen(libname);
char *matchname = jv_mem_alloc(matchlen+2+1);
matchname[0] = '\0';
if (libname != NULL && libname[0] != '\0') {
strcpy(matchname,libname);
strcpy(matchname+matchlen, "::");
matchlen += 2;
}
assert(block_has_only_binders(binder, bindflags));
for (inst *curr = binder.last; curr; curr = curr->prev) {
int bindflags2 = bindflags;
char* cname = curr->symbol;
char* tname = jv_mem_alloc(strlen(curr->symbol)+matchlen+1);
strcpy(tname, matchname);
strcpy(tname+matchlen, curr->symbol);
// Ew
if ((opcode_describe(curr->op)->flags & (OP_HAS_VARIABLE | OP_HAS_CONSTANT)))
bindflags2 = OP_HAS_VARIABLE | OP_HAS_BINDING;
// This mutation is ugly, even if we undo it
curr->symbol = tname;
nrefs += block_bind_subblock(inst_block(curr), body, bindflags2, 0);
curr->symbol = cname;
free(tname);
}
free(matchname);
return body; // We don't return a join because we don't want those sticking around...
}
static inst* block_take_last(block* b) {
inst* i = b->last;
if (i == 0)
return 0;
if (i->prev) {
i->prev->next = i->next;
b->last = i->prev;
i->prev = 0;
} else {
b->first = 0;
b->last = 0;
}
return i;
}
// Binds a sequence of binders, which *must not* alrady be bound to each other,
// to body, throwing away unreferenced defs
block block_bind_referenced(block binder, block body, int bindflags) {
assert(block_has_only_binders(binder, bindflags));
bindflags |= OP_HAS_BINDING;
inst* curr;
while ((curr = block_take_last(&binder))) {
block b = inst_block(curr);
if (block_bind_subblock(b, body, bindflags, 0) == 0) {
block_free(b);
} else {
body = BLOCK(b, body);
}
}
return body;
}
block block_bind_self(block binder, int bindflags) {
assert(block_has_only_binders(binder, bindflags));
bindflags |= OP_HAS_BINDING;
block body = gen_noop();
inst* curr;
while ((curr = block_take_last(&binder))) {
block b = inst_block(curr);
block_bind_subblock(b, body, bindflags, 0);
body = BLOCK(b, body);
}
return body;
}
static void block_mark_referenced(block body) {
int saw_top = 0;
for (inst* i = body.last; i; i = i->prev) {
if (saw_top && i->bound_by == i && !i->referenced)
continue;
if (i->op == TOP) {
saw_top = 1;
}
if (i->bound_by) {
i->bound_by->referenced = 1;
}
block_mark_referenced(i->arglist);
block_mark_referenced(i->subfn);
}
}
block block_drop_unreferenced(block body) {
block_mark_referenced(body);
block refd = gen_noop();
inst* curr;
while ((curr = block_take(&body))) {
if (curr->bound_by == curr && !curr->referenced) {
inst_free(curr);
} else {
refd = BLOCK(refd, inst_block(curr));
}
}
return refd;
}
jv block_take_imports(block* body) {
jv imports = jv_array();
/* Parser should never generate TOP before imports */
assert(!(body->first && body->first->op == TOP && body->first->next &&
(body->first->next->op == MODULEMETA || body->first->next->op == DEPS)));
while (body->first && (body->first->op == MODULEMETA || body->first->op == DEPS)) {
inst* dep = block_take(body);
if (dep->op == DEPS) {
imports = jv_array_append(imports, jv_copy(dep->imm.constant));
}
inst_free(dep);
}
return imports;
}
jv block_list_funcs(block body, int omit_underscores) {
jv funcs = jv_object(); // Use the keys for set semantics.
for (inst *pos = body.first; pos != NULL; pos = pos->next) {
if (pos->op == CLOSURE_CREATE || pos->op == CLOSURE_CREATE_C) {
if (pos->symbol != NULL && (!omit_underscores || pos->symbol[0] != '_')) {
funcs = jv_object_set(funcs, jv_string_fmt("%s/%i", pos->symbol, pos->nformals), jv_null());
}
}
}
return jv_keys_unsorted(funcs);
}
block gen_module(block metadata) {
inst* i = inst_new(MODULEMETA);
i->imm.constant = block_const(metadata);
if (jv_get_kind(i->imm.constant) != JV_KIND_OBJECT)
i->imm.constant = jv_object_set(jv_object(), jv_string("metadata"), i->imm.constant);
block_free(metadata);
return inst_block(i);
}
jv block_module_meta(block b) {
if (b.first != NULL && b.first->op == MODULEMETA)
return jv_copy(b.first->imm.constant);
return jv_null();
}
block gen_import(const char* name, const char* as, int is_data) {
inst* i = inst_new(DEPS);
jv meta = jv_object();
if (as != NULL)
meta = jv_object_set(meta, jv_string("as"), jv_string(as));
meta = jv_object_set(meta, jv_string("is_data"), is_data ? jv_true() : jv_false());
meta = jv_object_set(meta, jv_string("relpath"), jv_string(name));
i->imm.constant = meta;
return inst_block(i);
}
block gen_import_meta(block import, block metadata) {
assert(block_is_single(import) && import.first->op == DEPS);
assert(block_is_const(metadata) && block_const_kind(metadata) == JV_KIND_OBJECT);
inst *i = import.first;
i->imm.constant = jv_object_merge(block_const(metadata), i->imm.constant);
block_free(metadata);
return import;
}
block gen_function(const char* name, block formals, block body) {
inst* i = inst_new(CLOSURE_CREATE);
int nformals = 0;
for (inst* i = formals.last; i; i = i->prev) {
nformals++;
i->nformals = 0;
if (i->op == CLOSURE_PARAM_REGULAR) {
i->op = CLOSURE_PARAM;
body = gen_var_binding(gen_call(i->symbol, gen_noop()), i->symbol, body);
}
block_bind_subblock(inst_block(i), body, OP_IS_CALL_PSEUDO | OP_HAS_BINDING, 0);
}
i->subfn = body;
i->symbol = strdup(name);
i->any_unbound = -1;
i->nformals = nformals;
i->arglist = formals;
block b = inst_block(i);
block_bind_subblock(b, b, OP_IS_CALL_PSEUDO | OP_HAS_BINDING, 0);
return b;
}
block gen_param_regular(const char* name) {
return gen_op_unbound(CLOSURE_PARAM_REGULAR, name);
}
block gen_param(const char* name) {
return gen_op_unbound(CLOSURE_PARAM, name);
}
block gen_lambda(block body) {
return gen_function("@lambda", gen_noop(), body);
}
block gen_call(const char* name, block args) {
block b = gen_op_unbound(CALL_JQ, name);
b.first->arglist = args;
b.first->nactuals = block_count_actuals(b.first->arglist);
return b;
}
block gen_subexp(block a) {
if (block_is_noop(a)) {
return gen_op_simple(DUP);
}
if (block_is_single(a) && a.first->op == LOADK) {
jv c = block_const(a);
block_free(a);
return gen_op_pushk_under(c);
}
return BLOCK(gen_op_simple(SUBEXP_BEGIN), a, gen_op_simple(SUBEXP_END));
}
block gen_both(block a, block b) {
block jump = gen_op_targetlater(JUMP);
block fork = gen_op_target(FORK, jump);
block c = BLOCK(fork, a, jump, b);
inst_set_target(jump, c);
return c;
}
block gen_const_object(block expr) {
int is_const = 1;
jv o = jv_object();
jv k = jv_null();
jv v = jv_null();
for (inst *i = expr.first; i; i = i->next) {
if (i->op == PUSHK_UNDER) {
k = jv_copy(i->imm.constant);
i = i->next;
} else if (i->op != SUBEXP_BEGIN ||
i->next == NULL ||
i->next->op != LOADK ||
i->next->next == NULL ||
i->next->next->op != SUBEXP_END) {
is_const = 0;
break;
} else {
k = jv_copy(i->next->imm.constant);
i = i->next->next->next;
}
if (i != NULL && i->op == PUSHK_UNDER) {
v = jv_copy(i->imm.constant);
i = i->next;
} else if (i == NULL ||
i->op != SUBEXP_BEGIN ||
i->next == NULL ||
i->next->op != LOADK ||
i->next->next == NULL ||
i->next->next->op != SUBEXP_END) {
is_const = 0;
break;
} else {
v = jv_copy(i->next->imm.constant);
i = i->next->next->next;
}
if (i == NULL || i->op != INSERT) {
is_const = 0;
break;
}
if (jv_get_kind(k) != JV_KIND_STRING) {
is_const = 0;
break;
}
o = jv_object_set(o, k, v);
k = jv_null();
v = jv_null();
}
if (!is_const) {
jv_free(o);
jv_free(k);
jv_free(v);
block b = {0,0};
return b;
}
block_free(expr);
return gen_const(o);
}
static block gen_const_array(block expr) {
/*
* An expr of all constant elements looks like this:
*
* 0009 FORK 0027
* 0011 FORK 0023
* 0013 FORK 0019
* 0015 LOADK 1
* 0017 JUMP 0021
* 0019 LOADK 2
* 0021 JUMP 0025
* 0023 LOADK 3
* 0025 JUMP 0029
* 0027 LOADK 4
*
* That's: N-1 commas for N elements, N LOADKs, and a JUMP between
* every LOADK. The sequence ends in a LOADK. Any deviation and it's
* not a list of constants.
*
* Here we check for this pattern almost exactly. We don't check that
* the targets of the FORK and JUMP instructions are in the right
* sequence.
*/
int all_const = 1;
int commas = 0;
int normal = 1;
jv a = jv_array();
for (inst *i = expr.first; i; i = i->next) {
if (i->op == FORK) {
commas++;
if (i->imm.target == NULL || i->imm.target->op != JUMP ||
jv_array_length(jv_copy(a)) > 0) {
normal = 0;
break;
}
} else if (all_const && i->op == LOADK) {
if (i->next != NULL && i->next->op != JUMP) {
normal = 0;
break;
}
a = jv_array_append(a, jv_copy(i->imm.constant));
} else if (i->op != JUMP || i->imm.target == NULL ||
i->imm.target->op != LOADK) {
all_const = 0;
}
}
if (all_const && normal &&
(expr.last == NULL || expr.last->op == LOADK) &&
jv_array_length(jv_copy(a)) == commas + 1) {
block_free(expr);
return gen_const(a);
}
jv_free(a);
block b = {0,0};
return b;
}
block gen_collect(block expr) {
block const_array = gen_const_array(expr);
if (const_array.first != NULL)
return const_array;
block array_var = gen_op_var_fresh(STOREV, "collect");
block c = BLOCK(gen_op_simple(DUP), gen_const(jv_array()), array_var);
block tail = BLOCK(gen_op_bound(APPEND, array_var),
gen_op_simple(BACKTRACK));
return BLOCK(c,
gen_op_target(FORK, tail),
expr,
tail,
gen_op_bound(LOADVN, array_var));
}
static block bind_matcher(block matcher, block body) {
// cannot call block_bind(matcher, body) because that requires
// block_has_only_binders(matcher), which is not true here as matchers
// may also contain code to extract the correct elements
for (inst* i = matcher.first; i; i = i->next) {
if ((i->op == STOREV || i->op == STOREVN) && !i->bound_by)
block_bind_subblock(inst_block(i), body, OP_HAS_VARIABLE, 0);
}
return BLOCK(matcher, body);
}
// Extract destructuring var names from the block
// *vars should be a jv_object (for set semantics)
static void block_get_unbound_vars(block b, jv *vars) {
assert(vars != NULL);
assert(jv_get_kind(*vars) == JV_KIND_OBJECT);
for (inst* i = b.first; i; i = i->next) {
if (i->subfn.first) {
block_get_unbound_vars(i->subfn, vars);
continue;
}
if ((i->op == STOREV || i->op == STOREVN) && i->bound_by == NULL) {
*vars = jv_object_set(*vars, jv_string(i->symbol), jv_true());
}
}
}
/* Build wrappers around destructuring matchers so that we can chain them
* when we have errors. The approach is as follows:
* DESTRUCTURE_ALT NEXT_MATCHER (unless last matcher)
* existing_matcher_block
* JUMP BODY
*/
static block bind_alternation_matchers(block matchers, block body) {
block preamble = {0};
block altmatchers = {0};
block mb = {0};
block final_matcher = matchers;
// Pass through the matchers to find all destructured names.
while (final_matcher.first && final_matcher.first->op == DESTRUCTURE_ALT) {
block_append(&altmatchers, inst_block(block_take(&final_matcher)));
}
// We don't have any alternations here, so we can use the simplest case.
if (altmatchers.first == NULL) {
return bind_matcher(final_matcher, body);
}
// Collect var names
jv all_vars = jv_object();
block_get_unbound_vars(altmatchers, &all_vars);
block_get_unbound_vars(final_matcher, &all_vars);
// We need a preamble of STOREVs to which to bind the matchers and the body.
jv_object_keys_foreach(all_vars, key) {
preamble = BLOCK(preamble,
gen_op_simple(DUP),
gen_const(jv_null()),
gen_op_unbound(STOREV, jv_string_value(key)));
jv_free(key);
}
jv_free(all_vars);
// Now we build each matcher in turn
for (inst *i = altmatchers.first; i; i = i->next) {
block submatcher = i->subfn;
// If we're successful, jump to the end of the matchers
submatcher = BLOCK(submatcher, gen_op_target(JUMP, final_matcher));
// DESTRUCTURE_ALT to the end of this submatcher so we can skip to the next one on error
mb = BLOCK(mb, gen_op_target(DESTRUCTURE_ALT, submatcher), submatcher);
// We're done with this inst and we don't want it anymore
// But we can't let it free the submatcher block.
i->subfn.first = i->subfn.last = NULL;
}
// We're done with these insts now.
block_free(altmatchers);
return bind_matcher(preamble, BLOCK(mb, final_matcher, body));
}
block gen_reduce(block source, block matcher, block init, block body) {
block res_var = gen_op_var_fresh(STOREV, "reduce");
block loop = BLOCK(gen_op_simple(DUPN),
source,
bind_alternation_matchers(matcher,
BLOCK(gen_op_bound(LOADVN, res_var),
body,
gen_op_bound(STOREV, res_var))),
gen_op_simple(BACKTRACK));
return BLOCK(gen_op_simple(DUP),
init,
res_var,
gen_op_target(FORK, loop),
loop,
gen_op_bound(LOADVN, res_var));
}
block gen_foreach(block source, block matcher, block init, block update, block extract) {
block output = gen_op_targetlater(JUMP);
block state_var = gen_op_var_fresh(STOREV, "foreach");
block loop = BLOCK(gen_op_simple(DUPN),
// get a value from the source expression:
source,
// destructure the value into variable(s) for all the code
// in the body to see
bind_alternation_matchers(matcher,
// load the loop state variable
BLOCK(gen_op_bound(LOADVN, state_var),
// generate updated state
update,
// save the updated state for value extraction
gen_op_simple(DUP),
// save new state
gen_op_bound(STOREV, state_var),
// extract an output...
extract,
// ...and output it by jumping
// past the BACKTRACK that comes
// right after the loop body,
// which in turn is there
// because...
//
// (Incidentally, extract can also
// backtrack, e.g., if it calls
// empty, in which case we don't
// get here.)
output)));
block foreach = BLOCK(gen_op_simple(DUP),
init,
state_var,
gen_op_target(FORK, loop),
loop,
// ...at this point `foreach`'s original input
// will be on top of the stack, and we don't
// want to output it, so we backtrack.
gen_op_simple(BACKTRACK));
inst_set_target(output, foreach); // make that JUMP go bast the BACKTRACK at the end of the loop
return foreach;
}
block gen_definedor(block a, block b) {
// var found := false
block found_var = gen_op_var_fresh(STOREV, "found");
block init = BLOCK(gen_op_simple(DUP), gen_const(jv_false()), found_var);
// if found, backtrack. Otherwise execute b
block backtrack = gen_op_simple(BACKTRACK);
block tail = BLOCK(gen_op_simple(DUP),
gen_op_bound(LOADV, found_var),
gen_op_target(JUMP_F, backtrack),
backtrack,
gen_op_simple(POP),
b);
// try again
block if_notfound = gen_op_simple(BACKTRACK);
// found := true, produce result
block if_found = BLOCK(gen_op_simple(DUP),
gen_const(jv_true()),
gen_op_bound(STOREV, found_var),
gen_op_target(JUMP, tail));
return BLOCK(init,
gen_op_target(FORK, if_notfound),
a,
gen_op_target(JUMP_F, if_found),
if_found,
if_notfound,
tail);
}
int block_has_main(block top) {
for (inst *c = top.first; c; c = c->next) {
if (c->op == TOP)
return 1;
}
return 0;
}
int block_is_funcdef(block b) {
if (b.first != NULL && b.first->op == CLOSURE_CREATE)
return 1;
return 0;
}
block gen_condbranch(block iftrue, block iffalse) {
iftrue = BLOCK(iftrue, gen_op_target(JUMP, iffalse));
return BLOCK(gen_op_target(JUMP_F, iftrue), iftrue, iffalse);
}
block gen_and(block a, block b) {
// a and b = if a then (if b then true else false) else false
return BLOCK(gen_op_simple(DUP), a,
gen_condbranch(BLOCK(gen_op_simple(POP),
b,
gen_condbranch(gen_const(jv_true()),
gen_const(jv_false()))),
BLOCK(gen_op_simple(POP), gen_const(jv_false()))));
}
block gen_or(block a, block b) {
// a or b = if a then true else (if b then true else false)
return BLOCK(gen_op_simple(DUP), a,
gen_condbranch(BLOCK(gen_op_simple(POP), gen_const(jv_true())),
BLOCK(gen_op_simple(POP),
b,
gen_condbranch(gen_const(jv_true()),
gen_const(jv_false())))));
}
block gen_destructure_alt(block matcher) {
for (inst *i = matcher.first; i; i = i->next) {
if (i->op == STOREV) {
i->op = STOREVN;
}
}
inst* i = inst_new(DESTRUCTURE_ALT);
i->subfn = matcher;
return inst_block(i);
}
block gen_var_binding(block var, const char* name, block body) {
return gen_destructure(var, gen_op_unbound(STOREV, name), body);
}
block gen_array_matcher(block left, block curr) {
int index;
if (block_is_noop(left))
index = 0;
else {
// `left` was returned by this function, so the third inst is the
// constant containing the previously used index
assert(left.first->op == DUP);
assert(left.first->next != NULL);
inst *i = NULL;
if (left.first->next->op == PUSHK_UNDER) {
i = left.first->next;
} else {
assert(left.first->next->op == SUBEXP_BEGIN);
assert(left.first->next->next->op == LOADK);
i = left.first->next->next;
}
index = 1 + (int) jv_number_value(i->imm.constant);
}
// `left` goes at the end so that the const index is in a predictable place
return BLOCK(gen_op_simple(DUP), gen_subexp(gen_const(jv_number(index))),
gen_op_simple(INDEX), curr, left);