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ffi 1.5: intern Obj-C selectors — one static SEL slot per unique name

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101/101 regression tests pass; the IR snapshot for the selector-
sharing test diff flips from four per-call `sel_registerName` calls
to two (one per unique selector) routed through a module-init
constructor — matching what clang emits for `@selector(...)`.

Hot-path cost collapses from a libobjc hashtable lookup per call to
a single load of a static `SEL*` slot:

  Before (Phase 1.3):
    %sel = call ptr @sel_registerName(<"init">)
    call ptr @objc_msgSend(<recv>, %sel)

  After (Phase 1.5):
    %sel = load ptr, ptr @OBJC_SELECTOR_REFERENCES_init
    call ptr @objc_msgSend(<recv>, %sel)

  +  @OBJC_SELECTOR_REFERENCES_init    = internal global ptr null
  +  @OBJC_SELECTOR_REFERENCES_release = internal global ptr null
  +  define internal void @__sx_objc_selector_init() {
  +    %sel  = call ptr @sel_registerName(ptr @OBJC_METH_VAR_NAME_)
  +    store ptr %sel, ptr @OBJC_SELECTOR_REFERENCES_init
  +    %sel1 = call ptr @sel_registerName(ptr @OBJC_METH_VAR_NAME_.2)
  +    store ptr %sel1, ptr @OBJC_SELECTOR_REFERENCES_release
  +    ret void
  +  }
  +  @llvm.global_ctors = appending global [1 x { i32, ptr, ptr }]
  +    [{ ..., ptr @__sx_objc_selector_init, ptr null }]

Implementation:
  module.zig    | new `objc_selector_cache: ArrayList(ObjcSelectorEntry)`
                  with `lookupObjcSelector` / `appendObjcSelector`. List
                  (not hashmap) keeps emit order stable across builds so
                  the IR snapshot doesn't flicker on rehash.
  lower.zig     | `internObjcSelector(sel)` creates the slot on first
                  use, returns the same `GlobalId` on every subsequent
                  call to the same selector. lowerFfiIntrinsicCall now
                  emits `global_addr + load` for literal selectors.
                  Non-literal selectors keep the `sel_registerName`
                  fallback. Declaring `sel_registerName` lazily on
                  first intern so emit_llvm finds it for the
                  constructor body.
  emit_llvm.zig | new `emitObjcSelectorInit` pass synthesizes a void
                  constructor that loops over the cache, calls
                  `sel_registerName` for each unique selector string,
                  stores the result in the slot. Constructor is
                  registered in `@llvm.global_ctors` with default
                  priority (65535) so dyld runs it before main.

The `@OBJC_METH_VAR_NAME_` private string globals and unnamed-addr
flag match clang's exact emission shape — picked up by the system
linker into the right Mach-O sections on macOS / iOS. Chess
Android + iOS-sim still build clean (no `#objc_call` in chess yet —
phase-3 migration will start exercising this).
This commit is contained in:
agra
2026-05-19 13:09:34 +03:00
parent 26a04e49d0
commit b8a412ddc7
4 changed files with 189 additions and 31 deletions
Download Patch File Download Diff File Expand all files Collapse all files

46
tests/expected/ffi-objc-call-03-selector-sharing.ir
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@@ -3,12 +3,13 @@
@OS = internal global i64 0
@ARCH = internal global i64 0
@POINTER_SIZE = internal global i64 8
@str = private unnamed_addr constant [5 x i8] c"init\00", align 1
@str.1 = private unnamed_addr constant [5 x i8] c"init\00", align 1
@str.2 = private unnamed_addr constant [5 x i8] c"init\00", align 1
@str.3 = private unnamed_addr constant [8 x i8] c"release\00", align 1
@str.4 = private unnamed_addr constant [4 x i8] c"ok\0A\00", align 1
@str.5 = private unnamed_addr constant [1 x i8] zeroinitializer, align 1
@OBJC_SELECTOR_REFERENCES_init = internal global ptr null
@OBJC_SELECTOR_REFERENCES_release = internal global ptr null
@str = private unnamed_addr constant [4 x i8] c"ok\0A\00", align 1
@str.1 = private unnamed_addr constant [1 x i8] zeroinitializer, align 1
@OBJC_METH_VAR_NAME_ = private unnamed_addr constant [5 x i8] c"init\00"
@OBJC_METH_VAR_NAME_.2 = private unnamed_addr constant [8 x i8] c"release\00"
@llvm.global_ctors = appending global [1 x { i32, ptr, ptr }] [{ i32, ptr, ptr } { i32 65535, ptr @__sx_objc_selector_init, ptr null }]
; Function Attrs: nounwind
declare void @out(ptr) #0
@@ -225,27 +226,27 @@ entry:
%siN = insertvalue { { ptr, ptr, ptr }, ptr } undef, { ptr, ptr, ptr } %siN, 0
%siN = insertvalue { { ptr, ptr, ptr }, ptr } %siN, ptr null, 1
store { { ptr, ptr, ptr }, ptr } %siN, ptr @context, align 8
%call = call ptr @sel_registerName(ptr @str)
%callN = call ptr @objc_msgSend(ptr null, ptr %call)
%callN = call ptr @sel_registerName(ptr @str.1)
%callN = call ptr @objc_msgSend(ptr null, ptr %callN)
%callN = call ptr @sel_registerName(ptr @str.2)
%callN = call ptr @objc_msgSend(ptr null, ptr %callN)
%callN = call ptr @sel_registerName(ptr @str.3)
%callN = call ptr @objc_msgSend(ptr null, ptr %callN)
%load = load ptr, ptr @OBJC_SELECTOR_REFERENCES_init, align 8
%call = call ptr @objc_msgSend(ptr null, ptr %load)
%loadN = load ptr, ptr @OBJC_SELECTOR_REFERENCES_init, align 8
%callN = call ptr @objc_msgSend(ptr null, ptr %loadN)
%loadN = load ptr, ptr @OBJC_SELECTOR_REFERENCES_init, align 8
%callN = call ptr @objc_msgSend(ptr null, ptr %loadN)
%loadN = load ptr, ptr @OBJC_SELECTOR_REFERENCES_release, align 8
%callN = call ptr @objc_msgSend(ptr null, ptr %loadN)
%allocaN = alloca { ptr, i64 }, align 8
%gep = getelementptr inbounds { ptr, i64 }, ptr %allocaN, i32 0, i32 0
store ptr null, ptr %gep, align 8
%gepN = getelementptr inbounds { ptr, i64 }, ptr %allocaN, i32 0, i32 1
store i64 0, ptr %gepN, align 8
%allocaN = alloca { ptr, i64 }, align 8
store { ptr, i64 } { ptr @str.4, i64 3 }, ptr %allocaN, align 8
store { ptr, i64 } { ptr @str, i64 3 }, ptr %allocaN, align 8
%allocaN = alloca { ptr, i64 }, align 8
store { ptr, i64 } { ptr @str.5, i64 0 }, ptr %allocaN, align 8
%load = load { ptr, i64 }, ptr %allocaN, align 8
store { ptr, i64 } { ptr @str.1, i64 0 }, ptr %allocaN, align 8
%loadN = load { ptr, i64 }, ptr %allocaN, align 8
%loadN = load { ptr, i64 }, ptr %allocaN, align 8
%callN = call { ptr, i64 } @substr({ ptr, i64 } %loadN, i64 0, i64 3)
%callN = call { ptr, i64 } @concat({ ptr, i64 } %load, { ptr, i64 } %callN)
%callN = call { ptr, i64 } @concat({ ptr, i64 } %loadN, { ptr, i64 } %callN)
store { ptr, i64 } %callN, ptr %allocaN, align 8
%loadN = load { ptr, i64 }, ptr %allocaN, align 8
%str.ptr = extractvalue { ptr, i64 } %loadN, 0
@@ -275,3 +276,12 @@ declare ptr @sel_registerName(ptr) #0
declare ptr @objc_msgSend(ptr, ptr) #0
declare i64 @write(i32, ptr, i64)
define internal void @__sx_objc_selector_init() {
entry:
%sel = call ptr @sel_registerName(ptr @OBJC_METH_VAR_NAME_)
store ptr %sel, ptr @OBJC_SELECTOR_REFERENCES_init, align 8
%selN = call ptr @sel_registerName(ptr @OBJC_METH_VAR_NAME_.2)
store ptr %selN, ptr @OBJC_SELECTOR_REFERENCES_release, align 8
ret void
}