[ThinLTO] Fix dead stripping analysis for SamplePGO

Summary:
The fix for dead stripping analysis in the case of SamplePGO indirect
calls to local functions (r313151) introduced the possibility of an
infinite loop.

Make sure we check for the value being already live after we update it
for SamplePGO indirect call handling.

Reviewers: danielcdh

Subscribers: mehdi_amini, inglorion, llvm-commits, eraman

Differential Revision: https://reviews.llvm.org/D38086

llvm-svn: 313766

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/IPO/FunctionImport.cpp b/llvm/lib/Transforms/IPO/FunctionImport.cpp
index 9f20cbc6fed..670a84862e0 100644
--- a/llvm/lib/Transforms/IPO/FunctionImport.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionImport.cpp
@@ -463,9 +463,6 @@ void llvm::computeDeadSymbols(
   // Make value live and add it to the worklist if it was not live before.
   // FIXME: we should only make the prevailing copy live here
   auto visit = [&](ValueInfo VI) {
-    for (auto &S : VI.getSummaryList())
-      if (S->isLive())
-        return;
     // FIXME: If we knew which edges were created for indirect call profiles,
     // we could skip them here. Any that are live should be reached via
     // other edges, e.g. reference edges. Otherwise, using a profile collected
@@ -478,6 +475,9 @@ void llvm::computeDeadSymbols(
     if (!VI)
       return;
     for (auto &S : VI.getSummaryList())
+      if (S->isLive())
+        return;
+    for (auto &S : VI.getSummaryList())
       S->setLive(true);
     ++LiveSymbols;
     Worklist.push_back(VI);