https://github.com/b0gdnv updated
https://github.com/llvm/llvm-project/pull/147853
>From cf6278f92b32106a406aab92f66d66ce992cc04d Mon Sep 17 00:00:00 2001
From: Bogdan Vetrenko <b.vetre...@yandex.ru>
Date: Thu, 10 Jul 2025 02:30:27 +0300
Subject: [PATCH] [clang] Use SmallString in CommentBriefParser to eliminate
per-token heap allocations
---
clang/lib/AST/CommentBriefParser.cpp | 38 +++++++++++++---------------
1 file changed, 18 insertions(+), 20 deletions(-)
diff --git a/clang/lib/AST/CommentBriefParser.cpp
b/clang/lib/AST/CommentBriefParser.cpp
index bf9e179934976..5a5217583cafc 100644
--- a/clang/lib/AST/CommentBriefParser.cpp
+++ b/clang/lib/AST/CommentBriefParser.cpp
@@ -9,6 +9,7 @@
#include "clang/AST/CommentBriefParser.h"
#include "clang/AST/CommentCommandTraits.h"
#include "clang/Basic/CharInfo.h"
+#include "llvm/ADT/SmallString.h"
namespace clang {
namespace comments {
@@ -17,12 +18,11 @@ namespace {
/// Convert all whitespace into spaces, remove leading and trailing spaces,
/// compress multiple spaces into one.
-void cleanupBrief(std::string &S) {
+void cleanupBrief(llvm::SmallVectorImpl<char> &S) {
bool PrevWasSpace = true;
- std::string::iterator O = S.begin();
- for (std::string::iterator I = S.begin(), E = S.end();
- I != E; ++I) {
- const char C = *I;
+ auto O = S.begin();
+ for (auto I = S.begin(), E = S.end(); I != E; ++I) {
+ char C = *I;
if (clang::isWhitespace(C)) {
if (!PrevWasSpace) {
*O++ = ' ';
@@ -35,8 +35,7 @@ void cleanupBrief(std::string &S) {
}
if (O != S.begin() && *(O - 1) == ' ')
--O;
-
- S.resize(O - S.begin());
+ S.truncate(O - S.begin());
}
bool isWhitespace(StringRef Text) {
@@ -44,15 +43,15 @@ bool isWhitespace(StringRef Text) {
}
} // unnamed namespace
-BriefParser::BriefParser(Lexer &L, const CommandTraits &Traits) :
- L(L), Traits(Traits) {
+BriefParser::BriefParser(Lexer &L, const CommandTraits &Traits)
+ : L(L), Traits(Traits) {
// Get lookahead token.
ConsumeToken();
}
std::string BriefParser::Parse() {
- std::string FirstParagraphOrBrief;
- std::string ReturnsParagraph;
+ llvm::SmallString<128> FirstParagraphOrBrief;
+ llvm::SmallString<64> ReturnsParagraph;
bool InFirstParagraph = true;
bool InBrief = false;
bool InReturns = false;
@@ -60,9 +59,9 @@ std::string BriefParser::Parse() {
while (Tok.isNot(tok::eof)) {
if (Tok.is(tok::text)) {
if (InFirstParagraph || InBrief)
- FirstParagraphOrBrief += Tok.getText();
+ FirstParagraphOrBrief.append(Tok.getText());
else if (InReturns)
- ReturnsParagraph += Tok.getText();
+ ReturnsParagraph.append(Tok.getText());
ConsumeToken();
continue;
}
@@ -79,7 +78,7 @@ std::string BriefParser::Parse() {
InReturns = true;
InBrief = false;
InFirstParagraph = false;
- ReturnsParagraph += "Returns ";
+ ReturnsParagraph.append("Returns ");
ConsumeToken();
continue;
}
@@ -94,9 +93,9 @@ std::string BriefParser::Parse() {
if (Tok.is(tok::newline)) {
if (InFirstParagraph || InBrief)
- FirstParagraphOrBrief += ' ';
+ FirstParagraphOrBrief.push_back(' ');
else if (InReturns)
- ReturnsParagraph += ' ';
+ ReturnsParagraph.push_back(' ');
ConsumeToken();
// If the next token is a whitespace only text, ignore it. Thus we allow
@@ -132,13 +131,12 @@ std::string BriefParser::Parse() {
cleanupBrief(FirstParagraphOrBrief);
if (!FirstParagraphOrBrief.empty())
- return FirstParagraphOrBrief;
+ return std::string(FirstParagraphOrBrief.begin(),
+ FirstParagraphOrBrief.end());
cleanupBrief(ReturnsParagraph);
- return ReturnsParagraph;
+ return std::string(ReturnsParagraph.begin(), ReturnsParagraph.end());
}
} // end namespace comments
} // end namespace clang
-
-
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