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[llvm][mustache] Use BumpPtrAllocator to save ASTNodes #159194

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Merged
merged 1 commit into from
Oct 9, 2025
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[llvm][mustache] Use BumpPtrAllocator to save ASTNodes #159194

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22 changes: 15 additions & 7 deletions clang-tools-extra/clang-doc/HTMLMustacheGenerator.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -46,18 +46,22 @@ class MustacheHTMLGenerator : public Generator {
const ClangDocContext &CDCtx) override;
};

class MustacheTemplateFile : public Template {
class MustacheTemplateFile {
BumpPtrAllocator Allocator;
StringSaver Saver;
MustacheContext Ctx;
Template T;
std::unique_ptr<MemoryBuffer> Buffer;

public:
static Expected<std::unique_ptr<MustacheTemplateFile>>
createMustacheFile(StringRef FileName) {
ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrError =
MemoryBuffer::getFile(FileName);
if (auto EC = BufferOrError.getError())
return createFileOpenError(FileName, EC);

std::unique_ptr<MemoryBuffer> Buffer = std::move(BufferOrError.get());
StringRef FileContent = Buffer->getBuffer();
return std::make_unique<MustacheTemplateFile>(FileContent);
return std::make_unique<MustacheTemplateFile>(
std::move(BufferOrError.get()));
}

Error registerPartialFile(StringRef Name, StringRef FileName) {
Expand All @@ -68,11 +72,15 @@ class MustacheTemplateFile : public Template {

std::unique_ptr<MemoryBuffer> Buffer = std::move(BufferOrError.get());
StringRef FileContent = Buffer->getBuffer();
registerPartial(Name.str(), FileContent.str());
T.registerPartial(Name.str(), FileContent.str());
return Error::success();
}

MustacheTemplateFile(StringRef TemplateStr) : Template(TemplateStr) {}
void render(json::Value &V, raw_ostream &OS) { T.render(V, OS); }

MustacheTemplateFile(std::unique_ptr<MemoryBuffer> &&B)
: Saver(Allocator), Ctx(Allocator, Saver), T(B->getBuffer(), Ctx),
Buffer(std::move(B)) {}
};

static std::unique_ptr<MustacheTemplateFile> NamespaceTemplate = nullptr;
Expand Down
51 changes: 42 additions & 9 deletions llvm/benchmarks/Mustache.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@
static const std::string LongHtmlString = [] {
std::string S;
S.reserve(500000);
for (int i = 0; i < 50000; ++i) {
for (int Idx = 0; Idx < 50000; ++Idx) {
S += "<script>alert('xss');</script>";
}
return S;
Expand Down Expand Up @@ -153,7 +153,11 @@ static const std::string LargeOutputStringTemplate = "{{long_string}}";
// syntaxes.
static void BM_Mustache_StringRendering(benchmark::State &state,
const std::string &TplStr) {
llvm::mustache::Template Tpl(TplStr);
llvm::BumpPtrAllocator Allocator;
llvm::StringSaver Saver(Allocator);
llvm::mustache::MustacheContext Ctx(Allocator, Saver);

llvm::mustache::Template Tpl(TplStr, Ctx);
llvm::json::Value Data =
llvm::json::Object({{"content", llvm::json::Value(LongHtmlString)}});
for (auto _ : state) {
Expand All @@ -172,7 +176,11 @@ BENCHMARK_CAPTURE(BM_Mustache_StringRendering, Unescaped_Ampersand,
// Tests the "hot render" cost of repeatedly traversing a deep and wide
// JSON object.
static void BM_Mustache_DeepTraversal(benchmark::State &state) {
llvm::mustache::Template Tpl(DeepTraversalTemplate);
llvm::BumpPtrAllocator Allocator;
llvm::StringSaver Saver(Allocator);
llvm::mustache::MustacheContext Ctx(Allocator, Saver);

llvm::mustache::Template Tpl(DeepTraversalTemplate, Ctx);
for (auto _ : state) {
std::string Result;
llvm::raw_string_ostream OS(Result);
Expand All @@ -184,7 +192,12 @@ BENCHMARK(BM_Mustache_DeepTraversal);

// Tests the "hot render" cost of pushing and popping a deep context stack.
static void BM_Mustache_DeeplyNestedRendering(benchmark::State &state) {
llvm::mustache::Template Tpl(DeeplyNestedRenderingTemplate);

llvm::BumpPtrAllocator Allocator;
llvm::StringSaver Saver(Allocator);
llvm::mustache::MustacheContext Ctx(Allocator, Saver);

llvm::mustache::Template Tpl(DeeplyNestedRenderingTemplate, Ctx);
for (auto _ : state) {
std::string Result;
llvm::raw_string_ostream OS(Result);
Expand All @@ -197,7 +210,11 @@ BENCHMARK(BM_Mustache_DeeplyNestedRendering);
// Tests the performance of the loop logic when iterating over a huge number of
// items.
static void BM_Mustache_HugeArrayIteration(benchmark::State &state) {
llvm::mustache::Template Tpl(HugeArrayIterationTemplate);
llvm::BumpPtrAllocator Allocator;
llvm::StringSaver Saver(Allocator);
llvm::mustache::MustacheContext Ctx(Allocator, Saver);

llvm::mustache::Template Tpl(HugeArrayIterationTemplate, Ctx);
for (auto _ : state) {
std::string Result;
llvm::raw_string_ostream OS(Result);
Expand All @@ -209,25 +226,37 @@ BENCHMARK(BM_Mustache_HugeArrayIteration);

// Tests the performance of the parser on a large, "wide" template.
static void BM_Mustache_ComplexTemplateParsing(benchmark::State &state) {
llvm::BumpPtrAllocator Allocator;
llvm::StringSaver Saver(Allocator);
llvm::mustache::MustacheContext Ctx(Allocator, Saver);

for (auto _ : state) {
llvm::mustache::Template Tpl(ComplexTemplateParsingTemplate);
llvm::mustache::Template Tpl(ComplexTemplateParsingTemplate, Ctx);
benchmark::DoNotOptimize(Tpl);
}
}
BENCHMARK(BM_Mustache_ComplexTemplateParsing);

// Tests the performance of the parser on a small, "deep" template.
static void BM_Mustache_SmallTemplateParsing(benchmark::State &state) {
llvm::BumpPtrAllocator Allocator;
llvm::StringSaver Saver(Allocator);
llvm::mustache::MustacheContext Ctx(Allocator, Saver);

for (auto _ : state) {
llvm::mustache::Template Tpl(SmallTemplateParsingTemplate);
llvm::mustache::Template Tpl(SmallTemplateParsingTemplate, Ctx);
benchmark::DoNotOptimize(Tpl);
}
}
BENCHMARK(BM_Mustache_SmallTemplateParsing);

// Tests the performance of rendering a template that includes a partial.
static void BM_Mustache_PartialsRendering(benchmark::State &state) {
llvm::mustache::Template Tpl(ComplexPartialTemplate);
llvm::BumpPtrAllocator Allocator;
llvm::StringSaver Saver(Allocator);
llvm::mustache::MustacheContext Ctx(Allocator, Saver);

llvm::mustache::Template Tpl(ComplexPartialTemplate, Ctx);
Tpl.registerPartial("item_partial", ItemPartialTemplate);
llvm::json::Value Data = HugeArrayData;

Expand All @@ -243,7 +272,11 @@ BENCHMARK(BM_Mustache_PartialsRendering);
// Tests the performance of the underlying buffer management when generating a
// very large output.
static void BM_Mustache_LargeOutputString(benchmark::State &state) {
llvm::mustache::Template Tpl(LargeOutputStringTemplate);
llvm::BumpPtrAllocator Allocator;
llvm::StringSaver Saver(Allocator);
llvm::mustache::MustacheContext Ctx(Allocator, Saver);

llvm::mustache::Template Tpl(LargeOutputStringTemplate, Ctx);
for (auto _ : state) {
std::string Result;
llvm::raw_string_ostream OS(Result);
Expand Down
15 changes: 11 additions & 4 deletions llvm/include/llvm/Support/Mustache.h
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Original file line number Diff line number Diff line change
Expand Up @@ -71,6 +71,8 @@

#include "Error.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/ilist.h"
#include "llvm/ADT/ilist_node.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/JSON.h"
Expand All @@ -84,10 +86,15 @@ using Lambda = std::function<llvm::json::Value()>;
using SectionLambda = std::function<llvm::json::Value(std::string)>;

class ASTNode;
using AstPtr = std::unique_ptr<ASTNode>;
using AstPtr = ASTNode *;
using EscapeMap = DenseMap<char, std::string>;
using ASTNodeList = iplist<ASTNode>;

struct MustacheContext {
MustacheContext(BumpPtrAllocator &Allocator, StringSaver &Saver)
: Allocator(Allocator), Saver(Saver) {}
BumpPtrAllocator &Allocator;
StringSaver &Saver;
StringMap<AstPtr> Partials;
StringMap<Lambda> Lambdas;
StringMap<SectionLambda> SectionLambdas;
Expand All @@ -98,7 +105,7 @@ struct MustacheContext {
// and Lambdas that are registered with it.
class Template {
public:
LLVM_ABI Template(StringRef TemplateStr);
LLVM_ABI Template(StringRef TemplateStr, MustacheContext &Ctx);

Template(const Template &) = delete;

Expand All @@ -110,7 +117,7 @@ class Template {
// type.
LLVM_ABI ~Template();

LLVM_ABI Template &operator=(Template &&Other) noexcept;
Template &operator=(Template &&) = delete;

LLVM_ABI void render(const llvm::json::Value &Data, llvm::raw_ostream &OS);

Expand All @@ -126,7 +133,7 @@ class Template {
LLVM_ABI void overrideEscapeCharacters(DenseMap<char, std::string> Escapes);

private:
MustacheContext Ctx;
MustacheContext &Ctx;
AstPtr Tree;
};
} // namespace llvm::mustache
Expand Down
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