re-use sprintf() optimisation for printf()

Closes phpGH-19658

Author: realFlowControl

UPGRADING

@@ -99,5 +99,10 @@ PHP 8.6 UPGRADE NOTES
 14. Performance Improvements
 ========================================
 
+- Core:
+  . `printf()` using only `%s` and `%d` will be compiled into the equivalent
+    string interpolation, avoiding the overhead of a function call and repeatedly
+    parsing the format string.
+
 - JSON:
   . Improve performance of encoding arrays and objects.

Zend/Optimizer/dce.c

@@ -124,6 +124,7 @@ static inline bool may_have_side_effects(
 		case ZEND_FUNC_NUM_ARGS:
 		case ZEND_FUNC_GET_ARGS:
 		case ZEND_ARRAY_KEY_EXISTS:
+		case ZEND_COPY_TMP:
 			/* No side effects */
 			return false;
 		case ZEND_FREE:
@@ -425,10 +426,12 @@ static bool dce_instr(const context *ctx, zend_op *opline, zend_ssa_op *ssa_op)
 		return false;
 	}
 
-	if ((opline->op1_type & (IS_VAR|IS_TMP_VAR))&& !is_var_dead(ctx, ssa_op->op1_use)) {
+	if ((opline->op1_type & (IS_VAR|IS_TMP_VAR)) && !is_var_dead(ctx, ssa_op->op1_use)) {
 		if (!try_remove_var_def(ctx, ssa_op->op1_use, ssa_op->op1_use_chain, opline)) {
 			if (may_be_refcounted(ssa->var_info[ssa_op->op1_use].type)
-					&& opline->opcode != ZEND_CASE && opline->opcode != ZEND_CASE_STRICT) {
+					&& opline->opcode != ZEND_CASE
+					&& opline->opcode != ZEND_CASE_STRICT
+					&& opline->opcode != ZEND_COPY_TMP) {
 				free_var = ssa_op->op1_use;
 				free_var_type = opline->op1_type;
 			}

Zend/Optimizer/pass1.c

@@ -264,6 +264,16 @@ void zend_optimizer_pass1(zend_op_array *op_array, zend_optimizer_ctx *ctx)
 			collect_constants = false;
 			break;
 		}
+		case ZEND_DO_UCALL:
+		case ZEND_DO_FCALL:
+		case ZEND_DO_FCALL_BY_NAME:
+		case ZEND_FRAMELESS_ICALL_0:
+		case ZEND_FRAMELESS_ICALL_1:
+		case ZEND_FRAMELESS_ICALL_2:
+		case ZEND_FRAMELESS_ICALL_3:
+			/* don't collect constants after any UCALL/FCALL/FRAMELESS ICALL */
+			collect_constants = 0;
+			break;
 		case ZEND_STRLEN:
 			if (opline->op1_type == IS_CONST &&
 					zend_optimizer_eval_strlen(&result, &ZEND_OP1_LITERAL(opline)) == SUCCESS) {

Zend/zend_compile.c

@@ -28,6 +28,7 @@
 #include "zend_API.h"
 #include "zend_exceptions.h"
 #include "zend_interfaces.h"
+#include "zend_types.h"
 #include "zend_virtual_cwd.h"
 #include "zend_multibyte.h"
 #include "zend_language_scanner.h"
@@ -4968,6 +4969,53 @@ static zend_result zend_compile_func_sprintf(znode *result, zend_ast_list *args)
 	return SUCCESS;
 }
 
+static zend_result zend_compile_func_printf(znode *result, zend_ast_list *args) /* {{{ */
+{
+	/* Special case: printf with a single constant string argument and no format specifiers.
+	 * In this case, just emit ECHO and return the string length if needed. */
+	if (args->children == 1) {
+		zend_eval_const_expr(&args->child[0]);
+		if (args->child[0]->kind != ZEND_AST_ZVAL) {
+			return FAILURE;
+		}
+		zval *format_string = zend_ast_get_zval(args->child[0]);
+		if (Z_TYPE_P(format_string) != IS_STRING) {
+			return FAILURE;
+		}
+		/* Check if there are any format specifiers */
+		if (!memchr(Z_STRVAL_P(format_string), '%', Z_STRLEN_P(format_string))) {
+			/* No format specifiers - just emit ECHO and return string length */
+			znode format_node;
+			zend_compile_expr(&format_node, args->child[0]);
+			zend_emit_op(NULL, ZEND_ECHO, &format_node, NULL);
+
+			/* Return the string length as a constant if the result is used */
+			result->op_type = IS_CONST;
+			ZVAL_LONG(&result->u.constant, Z_STRLEN_P(format_string));
+			return SUCCESS;
+		}
+	}
+
+	/* Fall back to sprintf optimization for format strings with specifiers */
+	znode rope_result;
+	if (zend_compile_func_sprintf(&rope_result, args) != SUCCESS) {
+		return FAILURE;
+	}
+
+	/* printf() returns the amount of bytes written, so just an ECHO of the
+	 * resulting sprintf() optimisation might not be enough. At this early
+	 * stage we can't detect if the result is actually used, so we just emit
+	 * the opcodes and let them be cleaned up by the dead code elimination
+	 * pass in the Zend Optimizer if the result of the printf() is in fact
+	 * unused */
+	znode copy;
+	zend_emit_op_tmp(&copy, ZEND_COPY_TMP, &rope_result, NULL);
+	zend_emit_op(NULL, ZEND_ECHO, &rope_result, NULL);
+	zend_emit_op_tmp(result, ZEND_STRLEN, &copy, NULL);
+
+	return SUCCESS;
+}
+
 static zend_result zend_compile_func_clone(znode *result, zend_ast_list *args)
 {
 	znode arg_node;
@@ -5050,6 +5098,8 @@ static zend_result zend_try_compile_special_func_ex(znode *result, zend_string *
 		return zend_compile_func_array_key_exists(result, args);
 	} else if (zend_string_equals_literal(lcname, "sprintf")) {
 		return zend_compile_func_sprintf(result, args);
+	} else if (zend_string_equals_literal(lcname, "printf")) {
+		return zend_compile_func_printf(result, args);
 	} else if (zend_string_equals(lcname, ZSTR_KNOWN(ZEND_STR_CLONE))) {
 		return zend_compile_func_clone(result, args);
 	} else {