From: Chris Lattner <sabre@nondot.org>
Date: Tue, 15 Mar 2005 21:36:50 +0000 (+0000)
Subject: Fix a crash that happens when mapping something like this:
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=4d5af8e894e97eeb6268120f4b7ab464c8a9aeee;p=oota-llvm.git

Fix a crash that happens when mapping something like this:

 { short, short }

to
  short

where the second short maps onto the second field of the first struct.  In
this case, the struct index is not aligned, so we should avoid calling
getLink(2), which asserts out.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@20626 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Analysis/DataStructure/DataStructure.cpp b/lib/Analysis/DataStructure/DataStructure.cpp
index 21e18a6b74d..69b3da43dfc 100644
--- a/lib/Analysis/DataStructure/DataStructure.cpp
+++ b/lib/Analysis/DataStructure/DataStructure.cpp
@@ -2077,12 +2077,18 @@ void DSGraph::computeNodeMapping(const DSNodeHandle &NH1,
   unsigned N2Size = N2->getSize();
   if (N2Size == 0) return;   // No edges to map to.
 
-  for (unsigned i = 0, e = N1->getSize(); i < e; i += DS::PointerSize)
-    if (unsigned(N2Idx)+i < N2Size)
-      computeNodeMapping(N1->getLink(i), N2->getLink(N2Idx+i), NodeMap);
-    else
-      computeNodeMapping(N1->getLink(i),
-                         N2->getLink(unsigned(N2Idx+i) % N2Size), NodeMap);
+  for (unsigned i = 0, e = N1->getSize(); i < e; i += DS::PointerSize) {
+    const DSNodeHandle &N1NH = N1->getLink(i);
+    // Don't call N2->getLink if not needed (avoiding crash if N2Idx is not
+    // aligned right).
+    if (!N1NH.isNull()) {
+      if (unsigned(N2Idx)+i < N2Size)
+        computeNodeMapping(N1NH, N2->getLink(N2Idx+i), NodeMap);
+      else
+        computeNodeMapping(N1NH,
+                           N2->getLink(unsigned(N2Idx+i) % N2Size), NodeMap);
+    }
+  }
 }