SE-0492: Handle top-level @section-annotated globals
#85136
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Currently, normal globals are represented as a PatternBindingDecl and a VarDecl in the AST, directly under the SourceFile:
```
// var variable_name = 42, compiled with -parse-as-library
(source_file ...
(pattern_binding_decl ...
(pattern_entry ...
(pattern_named ... "variable_name") ...
(var_decl "variable_name" ...
```
Top-level globals are represented more like local variables, under a TopLevelCodeDecl. Note that the VarDecl is still at the file scope. In SILGen, this case has some special handling to use the a storage of a global variable, and to avoid cleanups (see `emitInitializationForVarDecl`). Effectively, this means the globals are initialized inside the `main` function.
```
// var variable_name = 42, compiled without -parse-as-library
(source_file ...
(top_level_code_decl ...
(brace_stmt ...
(pattern_binding_decl ...
(pattern_named ... "variable_name") ...
(var_decl "variable_name" ... top_level_global
```
SE-0492 needs top-level globals that have a `@section` annotation to behave like a normal global -- initialization must happen statically, and not in `main`. This PR changes the parsing of those globals to match normal globals, without the TopLevelCodeDecl wrapper. SILGen and IRGen then handles them correctly.
kubamracek
requested review from
CodaFi,
DougGregor,
bnbarham,
hamishknight and
rintaro
as code owners
|
@swift-ci please test |
DougGregor
reviewed
Oct 25, 2025
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Currently, normal globals are represented as a PatternBindingDecl and a VarDecl in the AST, directly under the SourceFile:
Top-level globals are represented more like local variables, under a TopLevelCodeDecl. Note that the VarDecl is still at the file scope. In SILGen, this case has some special handling to use the a storage of a global variable, and to avoid cleanups (see
emitInitializationForVarDecl). Effectively, this means the globals are initialized inside themainfunction.SE-0492 needs top-level globals that have a
@sectionannotation to behave like a normal global -- initialization must happen statically, and not inmain. This PR changes the parsing of those globals to match normal globals, without the TopLevelCodeDecl wrapper. SILGen and IRGen then handles them correctly.