From: Joseph Tremoulet <jotrem@microsoft.com>
Date: Tue, 17 Jan 2017 19:42:24 +0000 (-0500)
Subject: Fix inter-block heap-live-in calculation
X-Git-Tag: accepted/tizen/base/20180629.140029~2555^2~1
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e1c3cc187b35090318b3338efd5cca420de45999;p=platform%2Fupstream%2Fcoreclr.git

Fix inter-block heap-live-in calculation

Similar to the intra-block case fixed in #8757, without proving that a
heap def completely covers a subsequent heap use, we must propagate heap
liveness up past the heap def.  Fix failure to so propagate liveness in
`LiveVarAnalysis::PerBlockAnalysis`.
---

diff --git a/src/jit/liveness.cpp b/src/jit/liveness.cpp
index 0d47716..569debb 100644
--- a/src/jit/liveness.cpp
+++ b/src/jit/liveness.cpp
@@ -1129,7 +1129,9 @@ class LiveVarAnalysis
         VarSetOps::DiffD(m_compiler, m_liveIn, block->bbVarDef);
         VarSetOps::UnionD(m_compiler, m_liveIn, block->bbVarUse);
 
-        m_heapLiveIn = (m_heapLiveOut && !block->bbHeapDef) || block->bbHeapUse;
+        // Even if m_heapDef is set, we must assume that it doesn't kill heap if m_heapLiveOut, since
+        // (without proof otherwise) the use and def may touch different heap memory at run-time.
+        m_heapLiveIn = m_heapLiveOut || block->bbHeapUse;
 
         /* Can exceptions from this block be handled (in this function)? */