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SIL: Record whether vtable entries are inherited or overridden

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Consider a class hierarchy like the following:

class Base {
  func m1() {}
  func m2() {}
}

class Derived : Base {
  override func m2() {}
  func m3() {}
}

The SIL vtable for 'Derived' now records that the entry for m1
is inherited, the entry for m2 is an override, and the entry
for m3 is a new entry:

sil_vtable Derived {
  #Base.m1!1: (Base) -> () -> () : _T01a4BaseC2m1yyF [inherited]
  #Base.m2!1: (Base) -> () -> () : _T01a7DerivedC2m2yyF [override]
  #Derived.m3!1: (Derived) -> () -> () : _T01a7DerivedC2m3yyF
}

This additional information will allow IRGen to emit the vtable
for Derived resiliently, without referencing the symbol for
the inherited method m1() directly.
This commit is contained in:
Slava Pestov
2017-08-14 17:57:17 -04:00
parent fd253dabaf
commit 556d35d9b1
17 changed files with 349 additions and 170 deletions
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26
lib/ParseSIL/ParseSIL.cpp
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@@ -5058,7 +5058,31 @@ bool SILParserTUState::parseSILVTable(Parser &P) {
if (!Linkage)
Linkage = stripExternalFromLinkage(Func->getLinkage());
}
vtableEntries.emplace_back(Ref, Func, Linkage.getValue());
auto Kind = SILVTable::Entry::Kind::Normal;
if (P.Tok.is(tok::l_square)) {
P.consumeToken(tok::l_square);
if (P.Tok.isNot(tok::identifier)) {
P.diagnose(P.Tok.getLoc(), diag::sil_vtable_bad_entry_kind);
return true;
}
if (P.Tok.getText() == "override") {
P.consumeToken();
Kind = SILVTable::Entry::Kind::Override;
} else if (P.Tok.getText() == "inherited") {
P.consumeToken();
Kind = SILVTable::Entry::Kind::Inherited;
} else {
P.diagnose(P.Tok.getLoc(), diag::sil_vtable_bad_entry_kind);
return true;
}
if (P.parseToken(tok::r_square, diag::sil_vtable_expect_rsquare))
return true;
}
vtableEntries.emplace_back(Ref, Func, Kind, Linkage.getValue());
} while (P.Tok.isNot(tok::r_brace) && P.Tok.isNot(tok::eof));
}