From 6cc79ad9947bc353dbc7decd91c462c9b104cf92 Mon Sep 17 00:00:00 2001 From: Milian Wolff Date: Sat, 30 May 2015 23:10:00 +0200 Subject: [PATCH] Optimize moc: Preallocate space for list of preprocessed symbols. Without this, the symbol list is frequently reallocated. The value is a guestimate. It corresponds to a block of memory with the size 262144 * 3 * 8 byte = ca. 6.3 megabytes on a 64 bit machine. Looking at the final size of the symbol list, this seems to fit the common case nicely. Change-Id: Ib546a1ea479f2c6d8ab57be783cdf630f9b54f77 Reviewed-by: Marc Mutz --- src/tools/moc/preprocessor.cpp | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/src/tools/moc/preprocessor.cpp b/src/tools/moc/preprocessor.cpp index 590f17c24f..a47896d722 100644 --- a/src/tools/moc/preprocessor.cpp +++ b/src/tools/moc/preprocessor.cpp @@ -1222,6 +1222,10 @@ Symbols Preprocessor::preprocessed(const QByteArray &filename, QFile *file) // phase 3: preprocess conditions and substitute macros Symbols result; + // Preallocate some space to speed up the code below. + // The magic value was found by logging the final size + // and calculating an average when running moc over FOSS projects. + result.reserve(file->size() / 300000); preprocess(filename, result); mergeStringLiterals(&result);