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StringLowering: Properly handle nullable inputs to StringAs #6307

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Merged
merged 4 commits into from
Feb 14, 2024
Merged

StringLowering: Properly handle nullable inputs to StringAs #6307

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c3a63ab
fix
kripken Feb 14, 2024
9f52cd1
fix
kripken Feb 14, 2024
4b2c574
fix
kripken Feb 14, 2024
6d40ef4
test the case that needs no cast
kripken Feb 14, 2024
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12 changes: 11 additions & 1 deletion src/passes/StringLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@
#include "ir/module-utils.h"
#include "ir/names.h"
#include "ir/type-updating.h"
#include "ir/utils.h"
#include "pass.h"
#include "support/json.h"
#include "wasm-builder.h"
Expand Down Expand Up @@ -360,7 +361,13 @@ struct StringLowering : public StringGathering {
void visitStringAs(StringAs* curr) {
// There is no difference between strings and views with imported
// strings: they are all just JS strings, so no conversion is needed.
replaceCurrent(curr->ref);
// However, we must keep the same nullability: the output of StringAs
// must be non-nullable.
auto* ref = curr->ref;
if (ref->type.isNullable()) {
ref = Builder(*getModule()).makeRefAs(RefAsNonNull, ref);
}
replaceCurrent(ref);
}

void visitStringEncode(StringEncode* curr) {
Expand Down Expand Up @@ -468,6 +475,9 @@ struct StringLowering : public StringGathering {
Replacer replacer(*this);
replacer.run(getPassRunner(), module);
replacer.walkModuleCode(module);

// ReFinalize to apply changes to parents.
ReFinalize().run(getPassRunner(), module);
}
};

Expand Down
41 changes: 36 additions & 5 deletions test/lit/passes/string-lowering-instructions.wast
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Original file line number Diff line number Diff line change
Expand Up @@ -49,7 +49,7 @@

;; CHECK: (type $17 (func (param (ref $0))))

;; CHECK: (type $18 (func (param externref externref externref externref)))
;; CHECK: (type $18 (func (param externref (ref extern) externref externref externref (ref extern))))

;; CHECK: (type $19 (func (param (ref null $0) i32 i32) (result (ref extern))))

Expand Down Expand Up @@ -90,22 +90,38 @@

;; CHECK: (export "export.2" (func $exported-string-receiver))

;; CHECK: (func $string.as (type $18) (param $a externref) (param $b externref) (param $c externref) (param $d externref)
;; CHECK: (func $string.as (type $18) (param $a externref) (param $a_nn (ref extern)) (param $b externref) (param $c externref) (param $d externref) (param $nn_view (ref extern))
;; CHECK-NEXT: (local.set $b
;; CHECK-NEXT: (local.get $a)
;; CHECK-NEXT: (ref.as_non_null
;; CHECK-NEXT: (local.get $a)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (local.set $c
;; CHECK-NEXT: (local.get $a)
;; CHECK-NEXT: (ref.as_non_null
;; CHECK-NEXT: (local.get $a)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (local.set $d
;; CHECK-NEXT: (local.get $a)
;; CHECK-NEXT: (ref.as_non_null
;; CHECK-NEXT: (local.get $a)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (local.set $nn_view
;; CHECK-NEXT: (ref.as_non_null
;; CHECK-NEXT: (local.get $a)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (local.set $nn_view
;; CHECK-NEXT: (local.get $a_nn)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $string.as
(param $a stringref)
(param $a_nn (ref string))
(param $b stringview_wtf8)
(param $c stringview_wtf16)
(param $d stringview_iter)
(param $nn_view (ref stringview_wtf16))
;; These operations all vanish in the lowering, as they all become extref
;; (JS strings).
(local.set $b
Expand All @@ -123,6 +139,21 @@
(local.get $a)
)
)
;; The input is nullable, and string.as casts to non-null, so we will need
;; to keep a cast here in order to validate. (We also add a cast in all the
;; above as the inputs are nullable, but this is the only one that will
;; fail to validate. Other opts can remove the above ones.)
(local.set $nn_view
(string.as_wtf16
(local.get $a)
)
)
;; The input is already non-nullable here, so no cast is needed.
(local.set $nn_view
(string.as_wtf16
(local.get $a_nn)
)
)
)

;; CHECK: (func $string.new.gc (type $17) (param $array16 (ref $0))
Expand Down