JIT: Avoid object type check if the object is known to be a type

[ndossche]

Follow-up for #24052

Before:

	mov    %r15,%r14
	lea    0x50(%r14),%rdi       ; &CV0($o)
	cmpb   $0x8,0x58(%r14)       ; Check IS_OBJECT
	jne    not_an_object         ; ...
	mov    (%rdi),%rax           ; Z_OBJ_P($o)
	lea    -0x77280f9(%rip),%rcx ; ce to compare against
	cmp    0x10(%rax),%rcx       ; Z_OBJ_P($o)->ce == ce
	je     wrong_ce
	...

After:

	mov    %r15,%r14
	lea    0x50(%r14),%rdi       ; &CV0($o)
	mov    (%rdi),%rax           ; Z_OBJ_P($o) (known to be an object)
	lea    -0x77280f9(%rip),%rcx ; ce to compare against
	cmp    0x10(%rax),%rcx       ; Z_OBJ_P($o)->ce == ce
	je     wrong_ce
	...

This also helps with an ?Foo type check: it can skip the IS_OBJECT and IS_NULL check.

This also simplifies zend_jit_verify_arg_type: the (type == IS_UNKNOWN || type == IS_OBJECT) check becomes always-true.

[github-actions]

AWS x86_64 (c6id.metal)

Attribute	Value
Environment	aws
Instance type	c6id.metal
Architecture	x86_64
CPU	Intel(R) Xeon(R) Platinum 8375C CPU @ 2.90GHz, 64 cores @ 2900 MHz
CPU settings	disabled deeper C-states, disabled turbo boost, disabled hyper-threading
RAM	251 GB
Kernel	6.18.38-76.139.amzn2023.x86_64
OS	Amazon Linux 2023.12.20260727
GCC	14.2.1
Binary layout strategy	none
Time	2026-10-03 09:45:00 UTC
Job details	https://github.com/php/php-src/actions/runs/37114074071 (Artifacts)
Changeset	https://github.com/php/php-src/compare/cd8312e052..30f0cf6e6b

Laravel 12.11.0 demo app - 50 iterations, 50 warmups, 100 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skewness	Z-stat	P-value	Memory
PHP - baseline@cd8312e	0.38119	0.38301	0.00040	0.11%	0.38173	0.00%	0.38158	0.00%	1.493	0.000	1.000	25.90 MB
PHP - baseline@cd8312e (JIT)	0.35689	0.35776	0.00021	0.06%	0.35726	-6.41%	0.35723	-6.38%	0.576	8.614	0.000	25.98 MB
PHP - jit-recv-known-object	0.38100	0.38265	0.00029	0.08%	0.38145	-0.07%	0.38142	-0.04%	1.882	4.171	0.000	25.90 MB
PHP - jit-recv-known-object (JIT)	0.35705	0.35848	0.00027	0.08%	0.35747	-6.35%	0.35744	-6.33%	1.471	8.614	0.000	25.98 MB

Symfony 2.8.0 demo app - 50 iterations, 50 warmups, 100 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skewness	Z-stat	P-value	Memory
PHP - baseline@cd8312e	0.67723	0.67940	0.00049	0.07%	0.67779	0.00%	0.67762	0.00%	1.624	0.000	1.000	26.25 MB
PHP - baseline@cd8312e (JIT)	0.64253	0.64622	0.00066	0.10%	0.64323	-5.10%	0.64303	-5.11%	2.625	8.614	0.000	26.23 MB
PHP - jit-recv-known-object	0.67736	0.68170	0.00077	0.11%	0.67798	0.03%	0.67777	0.02%	3.152	-1.868	0.062	26.21 MB
PHP - jit-recv-known-object (JIT)	0.64236	0.67301	0.00562	0.87%	0.64395	-4.99%	0.64264	-5.16%	4.799	8.614	0.000	26.22 MB

Wordpress 6.9 main page - 50 iterations, 20 warmups, 20 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skewness	Z-stat	P-value	Memory
PHP - baseline@cd8312e	0.59640	0.60098	0.00070	0.12%	0.59735	0.00%	0.59725	0.00%	3.010	0.000	1.000	26.28 MB
PHP - baseline@cd8312e (JIT)	0.52281	0.52599	0.00065	0.12%	0.52373	-12.33%	0.52355	-12.34%	2.096	8.614	0.000	26.33 MB
PHP - jit-recv-known-object	0.59642	0.60001	0.00094	0.16%	0.59755	0.03%	0.59733	0.01%	1.699	-0.465	0.642	26.25 MB
PHP - jit-recv-known-object (JIT)	0.52306	0.53413	0.00162	0.31%	0.52434	-12.22%	0.52395	-12.27%	4.817	8.614	0.000	26.33 MB

bench.php - 50 iterations, 20 warmups, 2 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skewness	Z-stat	P-value	Memory
PHP - baseline@cd8312e	0.45144	0.45483	0.00078	0.17%	0.45291	0.00%	0.45289	0.00%	0.167	0.000	1.000	26.28 MB
PHP - baseline@cd8312e (JIT)	0.14386	0.14473	0.00022	0.15%	0.14431	-68.14%	0.14430	-68.14%	-0.067	8.614	0.000	26.33 MB
PHP - jit-recv-known-object	0.45137	0.45542	0.00079	0.17%	0.45288	-0.01%	0.45283	-0.01%	0.669	0.358	0.720	26.25 MB
PHP - jit-recv-known-object (JIT)	0.14365	0.14517	0.00026	0.18%	0.14433	-68.13%	0.14432	-68.13%	0.461	8.614	0.000	26.33 MB