perf(codegen): a store of a value that is never a closure emits no ConstFn admission

[proggeramlug]

Trims the per-site code that #11798 added to every static-key store.

Cause

#11798 gives every static-key store site two ConstFn admission blocks: one on the existing-key hit and one on the key-add memo. Each checks that the stored value is a closure of the site's one body. A site whose value can never be a closure (a literal, an arithmetic or comparison result, an object or array literal) carries both blocks for nothing: a ConstFn lane can never admit its value.

Fix

value_never_closure(value) classifies the store's HIR value. When it holds, the flagged lane branches straight to the miss, which is what a failed admission does, and the admission blocks are not emitted. Values that may be closures keep the full check.

Results

store function (bytes)	morning	main	this PR
o.c = v + 1	915	1,311	957
o.d = "x"	815	1,208	861
o.b = v (any)	834	1,228	1,228

Real workloads (n=5, median instructions:u; main = 5b06d69)

workload	main instr	this PR	delta	full GCs main/PR	RSS KB main/PR	binary bytes main/PR
tsc (transpile x3)	184,902,302,770	184,899,749,498	-0.00%	244/244	323,052/323,912	182,782,336/182,598,016
zod x5000	19,831,886,486	19,831,846,455	-0.00%	0/0	59,396/59,168	24,440,056/24,431,888
qs parse_nested	32,985,522,956	32,989,923,420	+0.01%	0/0	60,144/60,164	27,301,072/27,301,072
commander parse_argv	8,912,561,402	8,912,075,482	-0.01%	0/0	57,528/55,552	34,203,080/34,198,984

Outputs are identical to main's in every run.

Verification

• New codegen test store_ic_emits_no_constfn_admission_for_a_value_that_cannot_be_a_closure: no ConstFn blocks for a number, a string or v + 1, while the F64 lane check stays. A value that may be a closure keeps all three blocks.
• perry-codegen (all) passed on this branch. Gap suite (1254 files) compared with main: 0 regressions. fmt: clean.

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Reviewing files that changed from the base of the PR and between 07e50b1 and ad4ca99.

📒 Files selected for processing (4)

• changelog.d/PENDING-regfix-store-constfn-values.md
• crates/perry-codegen/src/expr/property_set.rs
• crates/perry-codegen/src/expr/put_value_store_ic.rs
• crates/perry-codegen/src/expr/write_pic_barrier_tests.rs

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