[PFA 4/n] Optimize constant pre-bound arguments

Zend/Optimizer/compact_literals.c

@@ -26,6 +26,7 @@
 #include "zend_execute.h"
 #include "zend_vm.h"
 #include "zend_extensions.h"
+#include "zend_partial.h"
 
 #define DEBUG_COMPACT_LITERALS 0
 
@@ -747,7 +748,7 @@ void zend_optimizer_compact_literals(zend_op_array *op_array, zend_optimizer_ctx
 					}
 					break;
 				case ZEND_CALLABLE_CONVERT_PARTIAL:
-					opline->op1.num = cache_size;
+					opline->extended_value = cache_size | (opline->extended_value & ZEND_PARTIAL_FLAGS);
 					cache_size += 2 * sizeof(void *);
 					break;
 			}

Zend/Optimizer/dfa_pass.c

@@ -469,6 +469,34 @@ static uint32_t zend_dfa_optimize_calls(zend_op_array *op_array, zend_ssa *ssa)
 					}
 				}
 			}
+
+			if (call_info->caller_call_opline && call_info->caller_call_opline->opcode == ZEND_CALLABLE_CONVERT_PARTIAL) {
+				/* Build a bitset of constant pre-bound PFA args: These are args whose value is alway the same for all
+				 * instances of a PFA. */
+				uint32_t const_args = 0;
+				for (uint32_t i = 0, l = MIN(sizeof(const_args)*CHAR_BIT, call_info->num_args); i < l; i++) {
+					zend_op *send_opline = call_info->arg_info[i].opline;
+					if (send_opline->op1_type == IS_CONST) {
+						zval *value = CT_CONSTANT_EX(op_array, send_opline->op1.constant);
+						if (Z_TYPE_P(value) == IS_CONSTANT_AST) {
+							/* Const exprs can evaluate to non-const zvals (e.g. objects), and are not idempotent */
+							continue;
+						}
+						const_args |= (UINT32_C(1) << i);
+					}
+				}
+
+				/* Pass the bitset to the ZEND_CALLABLE_CONVERT_PARTIAL opline. */
+				zend_op *call_opline = call_info->caller_call_opline;
+				if (call_opline->op2_type == IS_UNUSED) {
+					call_opline->op2.num = const_args;
+				} else {
+					ZEND_ASSERT(call_opline->op2_type == IS_CONST);
+					zval *zv = CT_CONSTANT_EX(op_array, call_opline->op2.constant);
+					Z_EXTRA_P(zv) = const_args;
+				}
+			}
+
 			call_info = call_info->next_callee;
 		} while (call_info);
 	}

Zend/tests/partial_application/const_arg_opt.phpt

@@ -0,0 +1,162 @@
+--TEST--
+Constant argument optimization
+--DESCRIPTION--
+Pre-bound arguments that are constant can be burned into the generated
+op_array instead of being passed via the Closure's lexical vars.
+--ENV--
+A=1
+--INI--
+opcache.enable=1
+opcache.enable_cli=1
+opcache.optimization_level=-1
+--FILE--
+<?php
+
+function f($a, $b) {
+    var_dump([$a, $b]);
+}
+
+function g() {
+    return 3;
+}
+
+function h($a, $b, $c) {
+    var_dump([$a, $b, $c]);
+}
+
+function i($a1, $a2, $a3, $a4, $a5, $a6, $a7, $a8, $a9, $a10, $a11, $a12, $a13, $a14, $a15, $a16, $a17, $a18, $a19, $a20, $a21, $a22, $a23, $a24, $a25, $a26, $a27, $a28, $a29, $a30, $a31, $a32, $a33) {
+    var_dump($a33);
+}
+
+function print_lexical_vars($f) {
+    $vars = new ReflectionFunction($f)->getClosureUsedVariables();
+    if ($vars === []) {
+        echo "no lexical vars\n";
+    } else {
+        $varNames = array_keys($vars);
+        echo 'lexical vars: ', implode(', ', $varNames), "\n";
+    }
+}
+
+echo "# Non-constant pre-bound argument:\n";
+$f = f(getenv('A'), ?);
+print_lexical_vars($f);
+$f(2);
+
+echo "# Constant pre-bound argument:\n";
+$f = f(2, ?);
+print_lexical_vars($f);
+$f(2);
+
+echo "# Constant pre-bound argument (inverted):\n";
+$f = f(?, 2);
+print_lexical_vars($f);
+$f(1);
+
+echo "# Inlined pre-bound argument:\n";
+$f = f(g(), ?);
+print_lexical_vars($f);
+$f(2);
+
+echo "# Constexpr pre-bound argument:\n";
+const B = 4;
+$f = f(B, ?);
+print_lexical_vars($f);
+$f(2);
+
+echo "# Mixed arguments:\n";
+$f = h(5, getenv('A'), ?);
+print_lexical_vars($f);
+$f(2);
+
+echo "# Constant array pre-bound argument:\n";
+$f = f(['foo' => 'bar'], ?);
+print_lexical_vars($f);
+$f(2);
+
+echo "# Named arguments:\n";
+$f = h(1, c: ?, b: ?);
+print_lexical_vars($f);
+$f(2, 3);
+
+echo "# Many arguments (optimization can not be applied for all args) :\n";
+$f = i(?, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33);
+print_lexical_vars($f);
+$f(33);
+
+?>
+--EXPECT--
+# Non-constant pre-bound argument:
+lexical vars: a
+array(2) {
+  [0]=>
+  string(1) "1"
+  [1]=>
+  int(2)
+}
+# Constant pre-bound argument:
+no lexical vars
+array(2) {
+  [0]=>
+  int(2)
+  [1]=>
+  int(2)
+}
+# Constant pre-bound argument (inverted):
+no lexical vars
+array(2) {
+  [0]=>
+  int(1)
+  [1]=>
+  int(2)
+}
+# Inlined pre-bound argument:
+no lexical vars
+array(2) {
+  [0]=>
+  int(3)
+  [1]=>
+  int(2)
+}
+# Constexpr pre-bound argument:
+lexical vars: a
+array(2) {
+  [0]=>
+  int(4)
+  [1]=>
+  int(2)
+}
+# Mixed arguments:
+lexical vars: b
+array(3) {
+  [0]=>
+  int(5)
+  [1]=>
+  string(1) "1"
+  [2]=>
+  int(2)
+}
+# Constant array pre-bound argument:
+no lexical vars
+array(2) {
+  [0]=>
+  array(1) {
+    ["foo"]=>
+    string(3) "bar"
+  }
+  [1]=>
+  int(2)
+}
+# Named arguments:
+no lexical vars
+array(3) {
+  [0]=>
+  int(1)
+  [1]=>
+  int(3)
+  [2]=>
+  int(2)
+}
+# Many arguments (optimization can not be applied for all args) :
+lexical vars: a33
+int(33)

Zend/tests/partial_application/constexpr_001.phpt

@@ -0,0 +1,30 @@
+--TEST--
+PFA in constexpr 001
+--FILE--
+<?php
+
+function f($a = g("foo", ?)) {
+    return $a(1);
+}
+
+function g(string $a, int $b) {
+    return [$a, $b];
+}
+
+var_dump(f());
+var_dump(f());
+
+?>
+--EXPECT--
+array(2) {
+  [0]=>
+  string(3) "foo"
+  [1]=>
+  int(1)
+}
+array(2) {
+  [0]=>
+  string(3) "foo"
+  [1]=>
+  int(1)
+}

Zend/tests/partial_application/constexpr_002.phpt

@@ -0,0 +1,22 @@
+--TEST--
+PFA in constexpr: non-constexpr arg
+--FILE--
+<?php
+
+function f($a = g(new stdClass, $x, ?)) {
+    return $a(1);
+}
+
+function g(string $a, int $b) {
+    return [$a, $b];
+}
+
+try {
+    var_dump(f());
+} catch (Error $e) {
+    echo $e::class, ": ", $e->getMessage(), " on line ", $e->getLine();
+}
+
+?>
+--EXPECTF--
+Fatal error: Constant expression contains invalid operations in %s on line %d

Zend/tests/partial_application/constexpr_003.phpt

@@ -0,0 +1,25 @@
+--TEST--
+PFA in constexpr: named args
+--FILE--
+<?php
+
+function f($a = g(c: ?, ...)) {
+    return $a(1.5, b: 3);
+}
+
+function g(string $a = 'hello', int $b = 2, float $c = 0) {
+    return [$a, $b, $c];
+}
+
+var_dump(f());
+
+?>
+--EXPECT--
+array(3) {
+  [0]=>
+  string(5) "hello"
+  [1]=>
+  int(3)
+  [2]=>
+  float(1.5)
+}

Zend/tests/partial_application/constexpr_004.phpt

@@ -0,0 +1,28 @@
+--TEST--
+PFA in constexpr: extra named args
+--FILE--
+<?php
+
+function f($a = g(?, foo: 'bar', ...)) {
+    return $a(1, bar: 'baz');
+}
+
+function g(...$args) {
+    return [$args];
+}
+
+var_dump(f());
+
+?>
+--EXPECT--
+array(1) {
+  [0]=>
+  array(3) {
+    [0]=>
+    int(1)
+    ["foo"]=>
+    string(3) "bar"
+    ["bar"]=>
+    string(3) "baz"
+  }
+}

Zend/tests/partial_application/constexpr_005.phpt

@@ -0,0 +1,13 @@
+--TEST--
+PFA in constexpr: variadic placeholder must be after positional params
+--FILE--
+<?php
+
+function f($a = g(..., 1)) {
+}
+
+f();
+
+?>
+--EXPECTF--
+Fatal error: Variadic placeholder must be last in %s on line %d

Zend/tests/partial_application/constexpr_006.phpt

@@ -0,0 +1,13 @@
+--TEST--
+PFA in constexpr: variadic placeholder must be after named params
+--FILE--
+<?php
+
+function f($a = g(..., foo: 1)) {
+}
+
+f();
+
+?>
+--EXPECTF--
+Fatal error: Variadic placeholder must be last in %s on line %d

Zend/tests/partial_application/constexpr_007.phpt

@@ -0,0 +1,13 @@
+--TEST--
+PFA in constexpr: variadic placeholder may only appear once
+--FILE--
+<?php
+
+function f($a = g(..., ...)) {
+}
+
+f();
+
+?>
+--EXPECTF--
+Fatal error: Variadic placeholder may only appear once in %s on line %d

Zend/tests/partial_application/constexpr_008.phpt

@@ -0,0 +1,13 @@
+--TEST--
+PFA in constexpr: variadic placeholder not allowed to be named
+--FILE--
+<?php
+
+function f($a = g(foo: ...)) {
+}
+
+f();
+
+?>
+--EXPECTF--
+Parse error: syntax error, unexpected token "..." in %s on line %d