From 212afb9fd9c24e9f2e32d77deb7c456bee49193f Mon Sep 17 00:00:00 2001
From: Florian Hahn <florian.hahn@arm.com>
Date: Fri, 26 Jan 2018 10:36:50 +0000
Subject: [PATCH] [CallSiteSplitting] Fix infinite loop when recording
 conditions.

Fix infinite loop when recording conditions by correctly marking basic
blocks as visited.

Fixes https://bugs.llvm.org/show_bug.cgi?id=36105

llvm-svn: 323515
---
 .../Transforms/Scalar/CallSiteSplitting.cpp   |  3 ++-
 .../callsite-no-splitting.ll                  | 24 +++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/Transforms/Scalar/CallSiteSplitting.cpp b/llvm/lib/Transforms/Scalar/CallSiteSplitting.cpp
index 3243731f07db..76358a040d9b 100644
--- a/llvm/lib/Transforms/Scalar/CallSiteSplitting.cpp
+++ b/llvm/lib/Transforms/Scalar/CallSiteSplitting.cpp
@@ -140,10 +140,11 @@ static void recordConditions(CallSite CS, BasicBlock *Pred,
   recordCondition(CS, Pred, CS.getInstruction()->getParent(), Conditions);
   BasicBlock *From = Pred;
   BasicBlock *To = Pred;
-  SmallPtrSet<BasicBlock *, 4> Visited = {From};
+  SmallPtrSet<BasicBlock *, 4> Visited;
   while (!Visited.count(From->getSinglePredecessor()) &&
          (From = From->getSinglePredecessor())) {
     recordCondition(CS, From, To, Conditions);
+    Visited.insert(From);
     To = From;
   }
 }
diff --git a/llvm/test/Transforms/CallSiteSplitting/callsite-no-splitting.ll b/llvm/test/Transforms/CallSiteSplitting/callsite-no-splitting.ll
index ca41bd6fc5e1..25b4cb23be60 100644
--- a/llvm/test/Transforms/CallSiteSplitting/callsite-no-splitting.ll
+++ b/llvm/test/Transforms/CallSiteSplitting/callsite-no-splitting.ll
@@ -16,3 +16,27 @@ Tail:
   %r = call i32 @callee(i32* %a, i32 %v, i32 %p)
   ret i32 %r
 }
+
+define void @fn1(i16 %p1) {
+entry:
+  ret void
+}
+
+define void @fn2() {
+  ret void
+
+; Unreachable code below
+
+for.inc:                                          ; preds = %for.inc
+  br i1 undef, label %for.end6, label %for.inc
+
+for.end6:                                         ; preds = %for.inc
+  br i1 undef, label %lor.rhs, label %lor.end
+
+lor.rhs:                                          ; preds = %for.end6
+  br label %lor.end
+
+lor.end:                                          ; preds = %for.end6, %lor.rhs
+  call void @fn1(i16 0)
+  ret void
+}