Warn when coercing NAN to other types #19573

Girgias · 2025-08-24T13:34:24Z

RFC: https://wiki.php.net/rfc/warnings-php-8-5#coercing_nan_to_other_types

github-actions · 2025-08-29T18:10:25Z

AWS x86_64 (c7i.24xl)

Attribute	Value
Environment	aws
Runner	host
Instance type	c7i.metal-24xl (dedicated)
Architecture	x86_64
CPU	48 cores
CPU settings	disabled deeper C-states, disabled turbo boost, disabled hyper-threading
RAM	188 GB
Kernel	6.1.147-172.266.amzn2023.x86_64
OS	Amazon Linux 2023.8.20250818
GCC	14.2.1
Time	2025-08-29 17:20:09 UTC

Laravel 12.2.0 demo app - 100 consecutive runs, 50 warmups, 100 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skew	P-value	Instr count	Memory
PHP - baseline@fc46	0.46565	0.46818	0.00045	0.10%	0.46637	0.00%	0.46629	0.00%	1.515	0.999	176423932	44.01 MB
PHP - 8.5-warn-nan-coercion	0.45876	0.46679	0.00075	0.16%	0.46494	-0.31%	0.46499	-0.28%	-5.442	0.000	176485965	44.07 MB

Symfony 2.7.0 demo app - 100 consecutive runs, 50 warmups, 100 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skew	P-value	Instr count	Memory
PHP - baseline@fc46	0.72046	0.73259	0.00155	0.21%	0.72261	0.00%	0.72217	0.00%	3.109	0.999	287234974	40.16 MB
PHP - 8.5-warn-nan-coercion	0.72253	0.72854	0.00100	0.14%	0.72405	0.20%	0.72384	0.23%	1.831	0.000	287280133	40.53 MB

Wordpress 6.2 main page - 100 consecutive runs, 20 warmups, 20 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skew	P-value	Instr count	Memory
PHP - baseline@fc46	0.57464	0.58357	0.00228	0.39%	0.58060	0.00%	0.58151	0.00%	-1.225	0.999	1119139470	43.91 MB
PHP - 8.5-warn-nan-coercion	0.57682	0.58512	0.00218	0.37%	0.58209	0.26%	0.58298	0.25%	-1.361	0.000	1119813967	43.91 MB

bench.php - 100 consecutive runs, 10 warmups, 2 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skew	P-value	Instr count	Memory
PHP - baseline@fc46	0.42476	0.55444	0.02724	6.28%	0.43407	0.00%	0.42786	0.00%	4.179	0.999	2020744423	26.98 MB
PHP - 8.5-warn-nan-coercion	0.42534	0.58863	0.03210	7.34%	0.43703	0.68%	0.42765	-0.05%	3.477	0.582	2020694323	27.05 MB

arnaud-lb · 2025-08-25T09:47:46Z

Zend/Optimizer/dce.c

+		case ZEND_CAST: {
+			uint32_t t1 = OP1_INFO();
+			/* Cast from NAN emits warning */
+			if (t1 & MAY_BE_DOUBLE) {
+				return true;
+			}
+			if (t1 & MAY_BE_ARRAY) {
+				/* Array cast to string emits warning */
+				return opline->extended_value == IS_STRING;
+			}
+			return false;
+		}
+		case ZEND_BOOL:
+		case ZEND_BOOL_NOT: {
+			uint32_t t1 = OP1_INFO();
+			/* Cast from NAN emits warning */
+			if (t1 & MAY_BE_DOUBLE) {
+				return true;
+			}
+			return false;
+		}


Only zend_may_throw() needs to be modified:

* * We separate intrinsic side-effects from potential side-effects in the form of notices thrown * by the instruction (in case we want to make this configurable). See may_have_side_effects() and * zend_may_throw().

arnaud-lb · 2025-08-29T17:57:58Z

Zend/zend_compile.c

+		|| opcode == ZEND_BOOL
+		|| opcode == ZEND_BOOL_NOT
+	) {
+		/* BW_NOT on string does not convert the string into an integer. */


This comment should be updated :)

arnaud-lb · 2025-08-29T17:58:50Z

Zend/zend_compile.c

+		opcode == ZEND_IS_EQUAL
+		|| opcode == ZEND_IS_NOT_EQUAL


These are not unary

arnaud-lb · 2025-08-29T18:03:26Z

ext/opcache/jit/zend_jit_helpers.c

@@ -16,6 +16,7 @@
   +----------------------------------------------------------------------+
 */

+#include "../../../Zend/zend_portability.h"


Suggested change

#include "../../../Zend/zend_portability.h"

#include "Zend/zend_portability.h"

arnaud-lb · 2025-08-29T18:23:43Z

ext/opcache/jit/zend_jit_ir.c

@@ -7728,7 +7728,14 @@ static int zend_jit_bool_jmpznz(zend_jit_ctx *jit, const zend_op *opline, uint32
 			if_double = ir_IF(ir_EQ(type, ir_CONST_U8(IS_DOUBLE)));
 			ir_IF_TRUE(if_double);
 		}
-		ref = ir_NE(jit_Z_DVAL(jit, op1_addr), ir_CONST_DOUBLE(0.0));
+


Need to avoid calling zend_is_true() during compilation above when the value is a const nan, otherwise we emit two warnings here: (during tracing, then while compiling the trace)

echo (bool)NAN;

arnaud-lb · 2025-08-29T18:25:33Z

ext/opcache/jit/zend_jit_ir.c

@@ -7728,7 +7728,14 @@ static int zend_jit_bool_jmpznz(zend_jit_ctx *jit, const zend_op *opline, uint32
 			if_double = ir_IF(ir_EQ(type, ir_CONST_U8(IS_DOUBLE)));
 			ir_IF_TRUE(if_double);
 		}
-		ref = ir_NE(jit_Z_DVAL(jit, op1_addr), ir_CONST_DOUBLE(0.0));
+
+		ir_ref dval = jit_Z_DVAL(jit, op1_addr);ir_ref is_nan = ir_NE(dval, dval);


Suggested change

ir_ref dval = jit_Z_DVAL(jit, op1_addr);ir_ref is_nan = ir_NE(dval, dval);

ir_ref dval = jit_Z_DVAL(jit, op1_addr);

ir_ref is_nan = ir_NE(dval, dval);

arnaud-lb · 2025-08-29T18:36:22Z

ext/opcache/jit/zend_jit_helpers.c

@@ -2566,6 +2567,11 @@ static void ZEND_FASTCALL zend_jit_invalid_array_access(zval *container)
 	zend_error(E_WARNING, "Trying to access array offset on %s", zend_zval_value_name(container));
 }

+static void ZEND_FASTCALL zend_jit_check_nan_to_bool_coercion(void)


Suggested change

static void ZEND_FASTCALL zend_jit_check_nan_to_bool_coercion(void)

static void ZEND_FASTCALL zend_jit_nan_coerced_to_type_warning(void)

arnaud-lb · 2025-08-29T18:48:32Z

Zend/Optimizer/block_pass.c

+				 * Those optimizations are not safe if the other operand end up being NAN
+				 * as BOOL/BOOL_NOT will warn which IS_EQUAL/IS_NOT_EQUAL do not.


Triggered a benchmark to check the effect of this: valgrind shows no regression (changes are under 0.0x%).

Girgias added RFC Waiting on RM labels Aug 24, 2025

github-actions bot added Category: Engine Category: Optimizer ABI break labels Aug 24, 2025

Girgias force-pushed the 8.5-warn-nan-coercion branch from d43ae9a to bfb238b Compare August 24, 2025 17:00

github-actions bot added Extension: opcache Extension: standard labels Aug 24, 2025

Girgias force-pushed the 8.5-warn-nan-coercion branch 3 times, most recently from 5cf5f9f to 564b005 Compare August 24, 2025 22:43

Girgias added 2 commits August 29, 2025 10:40

Zend: Add new test for coercions from NAN

53f13be

Warn when coercing NAN to other types

6892199

RFC: https://wiki.php.net/rfc/warnings-php-8-5#coercing_nan_to_other_types

Girgias force-pushed the 8.5-warn-nan-coercion branch from 564b005 to 8da693f Compare August 29, 2025 09:11

try to fix JIT/Optimizations

729488f

Girgias force-pushed the 8.5-warn-nan-coercion branch from 8da693f to 729488f Compare August 29, 2025 15:06

Girgias requested a review from arnaud-lb August 29, 2025 15:38

arnaud-lb reviewed Aug 29, 2025

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Warn when coercing NAN to other types #19573

Warn when coercing NAN to other types #19573

Girgias commented Aug 24, 2025

Uh oh!

github-actions bot commented Aug 29, 2025

Uh oh!

arnaud-lb Aug 25, 2025

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arnaud-lb Aug 29, 2025

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arnaud-lb Aug 29, 2025

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arnaud-lb Aug 29, 2025

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arnaud-lb Aug 29, 2025

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arnaud-lb Aug 29, 2025

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arnaud-lb Aug 29, 2025

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arnaud-lb Aug 29, 2025

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	#include "../../../Zend/zend_portability.h"
	#include "Zend/zend_portability.h"

	ir_ref dval = jit_Z_DVAL(jit, op1_addr);ir_ref is_nan = ir_NE(dval, dval);
	ir_ref dval = jit_Z_DVAL(jit, op1_addr);
	ir_ref is_nan = ir_NE(dval, dval);

	static void ZEND_FASTCALL zend_jit_check_nan_to_bool_coercion(void)
	static void ZEND_FASTCALL zend_jit_nan_coerced_to_type_warning(void)

		* Those optimizations are not safe if the other operand end up being NAN
		* as BOOL/BOOL_NOT will warn which IS_EQUAL/IS_NOT_EQUAL do not.

Warn when coercing NAN to other types #19573

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Warn when coercing NAN to other types #19573

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Girgias commented Aug 24, 2025

Uh oh!

github-actions bot commented Aug 29, 2025

AWS x86_64 (c7i.24xl)

Laravel 12.2.0 demo app - 100 consecutive runs, 50 warmups, 100 requests (sec)

Symfony 2.7.0 demo app - 100 consecutive runs, 50 warmups, 100 requests (sec)

Wordpress 6.2 main page - 100 consecutive runs, 20 warmups, 20 requests (sec)

bench.php - 100 consecutive runs, 10 warmups, 2 requests (sec)

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