From: Andrew Trick <atrick@apple.com>
Date: Wed, 31 Jul 2013 02:43:40 +0000 (+0000)
Subject: Fix a severe compile time problem when forming large SCEV expressions.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d832d32f57bc6d2bebf60e0befebc955d84aae12;p=oota-llvm.git

Fix a severe compile time problem when forming large SCEV expressions.

This fix is very lightweight. The same fix already existed for AddRec
but was missing for NAry expressions.

This is obviously an improvement and I'm unsure how to test compile
time problems.

Patch by Xiaoyi Guo!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187475 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 85290d6e1b8..f5d095b9781 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -585,6 +585,9 @@ namespace {
 
         // Lexicographically compare n-ary expressions.
         unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands();
+        if (LNumOps != RNumOps)
+          return (int)LNumOps - (int)RNumOps;
+
         for (unsigned i = 0; i != LNumOps; ++i) {
           if (i >= RNumOps)
             return 1;