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Fix handling of declarative segments #7660

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Fix handling of declarative segments #7660

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7a948aa
Fix handling of declarative segments
osa1 Jun 17, 2025
cd9e67b
Update lit tests -- not final!
osa1 Jun 17, 2025
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1 change: 0 additions & 1 deletion scripts/test/shared.py
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Original file line number Diff line number Diff line change
Expand Up @@ -421,7 +421,6 @@ def get_tests(test_dir, extensions=[], recursive=False):
'const.wast', # Hex float constant not recognized as out of range
'conversions.wast', # Promoted NaN should be canonical
'data.wast', # Constant global references allowed by GC
'elem.wast', # Requires modeling empty declarative segments
'f32.wast', # Adding -0 and -nan should give a canonical NaN
'f64.wast', # Adding -0 and -nan should give a canonical NaN
'float_exprs.wast', # Adding 0 and NaN should give canonical NaN
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13 changes: 13 additions & 0 deletions src/parser/context-decls.cpp
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Expand Up @@ -241,6 +241,19 @@ Result<> ParseDeclsCtx::addElem(
return Ok{};
}

Result<> ParseDeclsCtx::addDeclareElem(Name name, ElemListT&&, Index) {
auto e = std::make_unique<ElementSegment>();
if (name) {
e->setExplicitName(name);
} else {
name = std::to_string(elemCounter++);
name = Names::getValidElementSegmentName(wasm, name);
e->name = name;
}
wasm.addElementSegment(std::move(e));
return Ok{};
}

Result<> ParseDeclsCtx::addData(Name name,
MemoryIdxT*,
std::optional<ExprT>,
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2 changes: 1 addition & 1 deletion src/parser/contexts.h
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Expand Up @@ -1116,7 +1116,7 @@ struct ParseDeclsCtx : NullTypeParserCtx, NullInstrParserCtx {

Result<> addElem(Name, TableIdxT*, std::optional<ExprT>, ElemListT&&, Index);

Result<> addDeclareElem(Name, ElemListT&&, Index) { return Ok{}; }
Result<> addDeclareElem(Name, ElemListT&&, Index);

Result<> addData(Name name,
MemoryIdxT*,
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6 changes: 5 additions & 1 deletion test/lit/basic/multi-table.wast
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Expand Up @@ -76,6 +76,8 @@
;; CHECK-TEXT: (elem $empty func)
;; CHECK-BIN: (elem $empty func)
(elem $empty func)
;; CHECK-TEXT: (elem $declarative func)
;; CHECK-BIN: (elem $declarative func)
(elem $declarative declare func $h)

;; This elem will be emitted as usesExpressions because of the type of the
Expand Down Expand Up @@ -142,7 +144,9 @@

;; CHECK-BIN-NODEBUG: (elem $8 func)

;; CHECK-BIN-NODEBUG: (elem $9 (table $3) (i32.const 0) (ref null $0) (item (ref.func $0)) (item (ref.func $2)))
;; CHECK-BIN-NODEBUG: (elem $9 func)

;; CHECK-BIN-NODEBUG: (elem $10 (table $3) (i32.const 0) (ref null $0) (item (ref.func $0)) (item (ref.func $2)))
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It would be good if the binary writer searched for an empty segment with an appropriate type to reuse as the declarative segment to avoid having round trips increase the number of segments like this.


;; CHECK-BIN-NODEBUG: (func $0 (type $0)
;; CHECK-BIN-NODEBUG-NEXT: (drop
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