From: Dinesh Dwivedi <dinesh.d@samsung.com>
Date: Tue, 17 Jun 2014 14:34:19 +0000 (+0000)
Subject: Fixed jump threading going to infinite loop.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=199da600f3afd6804af2077203a2d4086d7242a9;p=oota-llvm.git

Fixed jump threading going to infinite loop.

This patch add code to remove unreachable blocks from function
as they may cause jump threading to stuck in infinite loop.

Differential Revision: http://reviews.llvm.org/D3991



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211103 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp
index 230a381593e..e501ff29d03 100644
--- a/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/lib/Transforms/Scalar/JumpThreading.cpp
@@ -158,6 +158,9 @@ bool JumpThreading::runOnFunction(Function &F) {
   TLI = &getAnalysis<TargetLibraryInfo>();
   LVI = &getAnalysis<LazyValueInfo>();
 
+  // Remove unreachable blocks from function as they may result in infinite loop.
+  removeUnreachableBlocks(F);
+
   FindLoopHeaders(F);
 
   bool Changed, EverChanged = false;
diff --git a/test/Transforms/JumpThreading/pr15851_hang.ll b/test/Transforms/JumpThreading/pr15851_hang.ll
new file mode 100644
index 00000000000..0484bc9f9dc
--- /dev/null
+++ b/test/Transforms/JumpThreading/pr15851_hang.ll
@@ -0,0 +1,22 @@
+; RUN: opt -S -jump-threading < %s | FileCheck %s
+
+; CHECK-LABEL: @f(
+; CHECK-LABEL: entry
+; CHECK: ret void
+; CHECK-NOT: for.cond1
+; CHECK-NOT: for.body
+
+define void @f() {
+entry:
+  ret void
+
+for.cond1:
+  %i.025 = phi i32 [ %inc, %for.body ], [ %inc, %for.body ], [ 1, %for.cond1 ]
+  %cmp = icmp slt i32 %i.025, 2
+  br i1 %cmp, label %for.body, label %for.cond1
+
+for.body:
+  %inc = add nsw i32 %i.025, 0
+  %a = icmp ugt i32 %inc, 2
+  br i1 %a, label %for.cond1, label %for.cond1
+}
diff --git a/test/Transforms/JumpThreading/select.ll b/test/Transforms/JumpThreading/select.ll
index 201e604e0c5..545e86c082f 100644
--- a/test/Transforms/JumpThreading/select.ll
+++ b/test/Transforms/JumpThreading/select.ll
@@ -127,7 +127,7 @@ L4:
 ; CHECK: test_switch_default
 ; CHECK: entry:
 ; CHECK: load
-; CHECK: switch
+; CHECK: icmp
 ; CHECK: [[THREADED:[A-Za-z.0-9]+]]:
 ; CHECK: store
 ; CHECK: br