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[clangd][Hover] Suppress initializers with many tokens 

This results in excessive memory usage and eats a lot of screen estate.
Especially in the cases with lots of nested macro calls.

This patch tries to remedy it before the release cut by suppressing the
initializers. For better UX we should probably update the expression printer to
truncate those (behind some policy).

Fixes https://github.com/clangd/clangd/issues/917

Differential Revision: https://reviews.llvm.org/D118260
This commit is contained in:
Kadir Cetinkaya 2022-01-26 17:55:52 +01:00
parent 97916673d4
commit c4e68953f6
No known key found for this signature in database
GPG Key ID: E39E36B8D2057ED6
2 changed files with 29 additions and 4 deletions
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19
clang-tools-extra/clangd/Hover.cpp
View File

@ -126,7 +126,17 @@ std::string getNamespaceScope(const Decl *D) {
return "";
}
std::string printDefinition(const Decl *D, const PrintingPolicy &PP) {
std::string printDefinition(const Decl *D, PrintingPolicy PP,
const syntax::TokenBuffer &TB) {
if (auto *VD = llvm::dyn_cast<VarDecl>(D)) {
if (auto *IE = VD->getInit()) {
// Initializers might be huge and result in lots of memory allocations in
// some catostrophic cases. Such long lists are not useful in hover cards
// anyway.
if (200 < TB.expandedTokens(IE->getSourceRange()).size())
PP.SuppressInitializers = true;
}
}
std::string Definition;
llvm::raw_string_ostream OS(Definition);
D->print(OS, PP);
@ -568,7 +578,8 @@ std::string synthesizeDocumentation(const NamedDecl *ND) {
/// Generate a \p Hover object given the declaration \p D.
HoverInfo getHoverContents(const NamedDecl *D, const PrintingPolicy &PP,
const SymbolIndex *Index) {
const SymbolIndex *Index,
const syntax::TokenBuffer &TB) {
HoverInfo HI;
const ASTContext &Ctx = D->getASTContext();
@ -630,7 +641,7 @@ HoverInfo getHoverContents(const NamedDecl *D, const PrintingPolicy &PP,
HI.Value = toString(ECD->getInitVal(), 10);
}
HI.Definition = printDefinition(D, PP);
HI.Definition = printDefinition(D, PP, TB);
return HI;
}
@ -1029,7 +1040,7 @@ llvm::Optional<HoverInfo> getHover(ParsedAST &AST, Position Pos,
auto Decls = explicitReferenceTargets(N->ASTNode, DeclRelation::Alias,
AST.getHeuristicResolver());
if (!Decls.empty()) {
HI = getHoverContents(Decls.front(), PP, Index);
HI = getHoverContents(Decls.front(), PP, Index, TB);
// Layout info only shown when hovering on the field/class itself.
if (Decls.front() == N->ASTNode.get<Decl>())
addLayoutInfo(*Decls.front(), *HI);

14
clang-tools-extra/clangd/unittests/HoverTests.cpp
View File

@ -3172,6 +3172,20 @@ TEST(Hover, DisableShowAKA) {
EXPECT_EQ(H->Type, HoverInfo::PrintedType("m_int"));
}
TEST(Hover, HideBigInitializers) {
Annotations T(R"cpp(
#define A(x) x, x, x, x
#define B(x) A(A(A(A(x))))
int a^rr[] = {B(0)};
)cpp");
TestTU TU = TestTU::withCode(T.code());
auto AST = TU.build();
auto H = getHover(AST, T.point(), format::getLLVMStyle(), nullptr);
ASSERT_TRUE(H);
EXPECT_EQ(H->Definition, "int arr[]");
}
} // namespace
} // namespace clangd
} // namespace clang