From 3b3de924f5deccfa651b1e7db01e0be21dcaf1aa Mon Sep 17 00:00:00 2001 From: Daniel Dunbar Date: Tue, 18 Aug 2009 22:24:00 +0000 Subject: [PATCH] Speed up raw_ostream::<<(unsigned long long) for 32-bit systems by doing most div/mods in 32-bits. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79375 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Support/raw_ostream.cpp | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) diff --git a/lib/Support/raw_ostream.cpp b/lib/Support/raw_ostream.cpp index 0c1843c457c..ac9bc6418f4 100644 --- a/lib/Support/raw_ostream.cpp +++ b/lib/Support/raw_ostream.cpp @@ -125,19 +125,24 @@ raw_ostream &raw_ostream::operator<<(long N) { } raw_ostream &raw_ostream::operator<<(unsigned long long N) { - // Output using 32-bit div/mod when possible. + // Handle simple case when value fits in long already. if (N == static_cast(N)) return this->operator<<(static_cast(N)); - char NumberBuffer[20]; - char *EndPtr = NumberBuffer+sizeof(NumberBuffer); - char *CurPtr = EndPtr; - - while (N) { - *--CurPtr = '0' + char(N % 10); - N /= 10; - } - return write(CurPtr, EndPtr-CurPtr); + // Otherwise divide into at two or three 10**9 chunks and write out using + // long div/mod, this is substantially faster on a 32-bit system. + unsigned long Top = 0, Mid = 0, Bot = N % 1000000000; + N /= 1000000000; + if (N > 1000000000) { + Mid = N % 1000000000; + Top = N / 1000000000; + } else + Mid = N; + + if (Top) + this->operator<<(static_cast(Top)); + this->operator<<(static_cast(Mid)); + return this->operator<<(static_cast(Bot)); } raw_ostream &raw_ostream::operator<<(long long N) { -- 2.34.1