From 5c9213f4014c236be1b75ed8f0889d5a4810594c Mon Sep 17 00:00:00 2001 From: Tanya Lattner Date: Tue, 15 May 2007 05:00:54 +0000 Subject: Merge from mainline. git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_20@37076 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Support/APInt.cpp | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'lib/Support/APInt.cpp') diff --git a/lib/Support/APInt.cpp b/lib/Support/APInt.cpp index 4142c6ec8b..2a35aa057e 100644 --- a/lib/Support/APInt.cpp +++ b/lib/Support/APInt.cpp @@ -1199,6 +1199,12 @@ APInt APInt::shl(uint32_t shiftAmt) const { if (shiftAmt == BitWidth) return APInt(BitWidth, 0); + // If none of the bits are shifted out, the result is *this. This avoids a + // lshr by the words size in the loop below which can produce incorrect + // results. It also avoids the expensive computation below for a common case. + if (shiftAmt == 0) + return *this; + // Create some space for the result. uint64_t * val = new uint64_t[getNumWords()]; -- cgit v1.2.3-70-g09d2