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Merge pull request #1269 from primo-ppcg/check-nil-form

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Optimize nil conditions for while and if
This commit is contained in:
Calvin Rose 2023-08-24 09:30:58 -05:00 committed by GitHub
commit d2dd241e6b
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 52 additions and 22 deletions
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74
src/core/specials.c
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@ -530,6 +530,32 @@ static JanetSlot janetc_def(JanetFopts opts, int32_t argn, const Janet *argv) {
return ret;
}
/* Check if a form matches the pattern (= nil _) or (not= nil _) */
static int janetc_check_nil_form(JanetFopts opts, Janet x, Janet *capture, uint32_t fun_tag) {
if (!janet_checktype(x, JANET_TUPLE)) return 0;
JanetTuple tup = janet_unwrap_tuple(x);
if (3 != janet_tuple_length(tup)) return 0;
Janet op1 = tup[0];
if (janet_checktype(op1, JANET_SYMBOL)) {
Janet entry = janet_table_get(opts.compiler->env, op1);
if (janet_checktype(entry, JANET_TABLE)) {
op1 = janet_table_get(janet_unwrap_table(entry), janet_ckeywordv("value"));
}
}
if (!janet_checktype(op1, JANET_FUNCTION)) return 0;
JanetFunction *fun = janet_unwrap_function(op1);
uint32_t tag = fun->def->flags & JANET_FUNCDEF_FLAG_TAG;
if (tag != fun_tag) return 0;
if (janet_checktype(tup[1], JANET_NIL)) {
*capture = tup[2];
return 1;
} else if (janet_checktype(tup[2], JANET_NIL)) {
*capture = tup[1];
return 1;
}
return 0;
}
/*
* :condition
* ...
@ -550,6 +576,7 @@ static JanetSlot janetc_if(JanetFopts opts, int32_t argn, const Janet *argv) {
JanetScope condscope, tempscope;
const int tail = opts.flags & JANET_FOPTS_TAIL;
const int drop = opts.flags & JANET_FOPTS_DROP;
uint8_t ifnjmp = JOP_JUMP_IF_NOT;
if (argn < 2 || argn > 3) {
janetc_cerror(c, "expected 2 or 3 arguments to if");
@ -572,7 +599,16 @@ static JanetSlot janetc_if(JanetFopts opts, int32_t argn, const Janet *argv) {
/* Compile condition */
janetc_scope(&condscope, c, 0, "if");
cond = janetc_value(condopts, argv[0]);
Janet condform = argv[0];
if (janetc_check_nil_form(opts, condform, &condform, JANET_FUN_EQ)) {
ifnjmp = JOP_JUMP_IF_NOT_NIL;
}
if (janetc_check_nil_form(opts, condform, &condform, JANET_FUN_NEQ)) {
ifnjmp = JOP_JUMP_IF_NIL;
}
cond = janetc_value(condopts, condform);
/* Check constant condition. */
/* TODO: Use type info for more short circuits */
@ -595,7 +631,7 @@ static JanetSlot janetc_if(JanetFopts opts, int32_t argn, const Janet *argv) {
}
/* Compile jump to right */
labeljr = janetc_emit_si(c, JOP_JUMP_IF_NOT, cond, 0, 0);
labeljr = janetc_emit_si(c, ifnjmp, cond, 0, 0);
/* Condition left body */
janetc_scope(&tempscope, c, 0, "if-true");
@ -605,7 +641,7 @@ static JanetSlot janetc_if(JanetFopts opts, int32_t argn, const Janet *argv) {
/* Compile jump to done */
labeljd = janet_v_count(c->buffer);
if (!tail) janetc_emit(c, JOP_JUMP);
if (!tail && !(drop && janet_checktype(falsebody, JANET_NIL))) janetc_emit(c, JOP_JUMP);
/* Compile right body */
labelr = janet_v_count(c->buffer);
@ -741,20 +777,6 @@ static JanetSlot janetc_break(JanetFopts opts, int32_t argn, const Janet *argv)
}
}
/* Check if a form matches the pattern (not= nil _) */
static int janetc_check_notnil_form(Janet x, Janet *capture) {
if (!janet_checktype(x, JANET_TUPLE)) return 0;
JanetTuple tup = janet_unwrap_tuple(x);
if (!janet_checktype(tup[0], JANET_FUNCTION)) return 0;
if (3 != janet_tuple_length(tup)) return 0;
JanetFunction *fun = janet_unwrap_function(tup[0]);
uint32_t tag = fun->def->flags & JANET_FUNCDEF_FLAG_TAG;
if (tag != JANET_FUN_NEQ) return 0;
if (!janet_checktype(tup[1], JANET_NIL)) return 0;
*capture = tup[2];
return 1;
}
/*
* :whiletop
* ...
@ -771,6 +793,7 @@ static JanetSlot janetc_while(JanetFopts opts, int32_t argn, const Janet *argv)
JanetScope tempscope;
int32_t labelwt, labeld, labeljt, labelc, i;
int infinite = 0;
int is_nil_form = 0;
int is_notnil_form = 0;
uint8_t ifjmp = JOP_JUMP_IF;
uint8_t ifnjmp = JOP_JUMP_IF_NOT;
@ -784,11 +807,16 @@ static JanetSlot janetc_while(JanetFopts opts, int32_t argn, const Janet *argv)
janetc_scope(&tempscope, c, JANET_SCOPE_WHILE, "while");
/* Check for `(not= nil _)` in condition, and if so, use the
/* Check for `(= nil _)` or `(not= nil _)` in condition, and if so, use the
* jmpnl or jmpnn instructions. This let's us implement `(each ...)`
* more efficiently. */
Janet condform = argv[0];
if (janetc_check_notnil_form(condform, &condform)) {
if (janetc_check_nil_form(opts, condform, &condform, JANET_FUN_EQ)) {
is_nil_form = 1;
ifjmp = JOP_JUMP_IF_NIL;
ifnjmp = JOP_JUMP_IF_NOT_NIL;
}
if (janetc_check_nil_form(opts, condform, &condform, JANET_FUN_NEQ)) {
is_notnil_form = 1;
ifjmp = JOP_JUMP_IF_NOT_NIL;
ifnjmp = JOP_JUMP_IF_NIL;
@ -800,9 +828,11 @@ static JanetSlot janetc_while(JanetFopts opts, int32_t argn, const Janet *argv)
/* Check for constant condition */
if (cond.flags & JANET_SLOT_CONSTANT) {
/* Loop never executes */
int never_executes = is_notnil_form
? janet_checktype(cond.constant, JANET_NIL)
: !janet_truthy(cond.constant);
int never_executes = is_nil_form
? !janet_checktype(cond.constant, JANET_NIL)
: is_notnil_form
? janet_checktype(cond.constant, JANET_NIL)
: !janet_truthy(cond.constant);
if (never_executes) {
janetc_popscope(c);
return janetc_cslot(janet_wrap_nil());