From cc1c702f628d93f9d84b681059e16652ad09d595 Mon Sep 17 00:00:00 2001 From: Daniel Dunbar Date: Mon, 21 Sep 2009 03:56:00 +0000 Subject: [PATCH] Don't allow formatted_ostream to be unbuffered, even if its underlying buffer is. - The problem is that formatted_ostream forces its underlying buffer to be unbuffered, so if some client happens to wrap a formatted_ostream around something, but still use the underlying stream, then we can end up writing on a fully unbuffered output (which was never intended to be unbuffered). - This makes clang (and presumably llvm-gcc) -emit-llvm -S a mere 10x faster. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82434 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Support/FormattedStream.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/include/llvm/Support/FormattedStream.h b/include/llvm/Support/FormattedStream.h index 24a3546200a..6b51144e9ef 100644 --- a/include/llvm/Support/FormattedStream.h +++ b/include/llvm/Support/FormattedStream.h @@ -105,10 +105,15 @@ namespace llvm // own buffering, and it doesn't need or want TheStream to do another // layer of buffering underneath. Resize the buffer to what TheStream // had been using, and tell TheStream not to do its own buffering. + // + // If the underlying stream is unbuffered, just use its preferred buffer + // size. We can't treat this as an honest wish for unbuffered output, + // because it could very well be a stream we previously forced to be + // unbuffered. if (size_t BufferSize = TheStream->GetBufferSize()) SetBufferSize(BufferSize); else - SetUnbuffered(); + SetBuffered(); TheStream->SetUnbuffered(); Scanned = 0; -- 2.11.0