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

llvm-svn: 211103

2 files changed, 23 insertions, 1 deletions

diff --git a/llvm/test/Transforms/JumpThreading/pr15851_hang.ll b/llvm/test/Transforms/JumpThreading/pr15851_hang.ll
new file mode 100644
index 00000000000..0484bc9f9dc
--- /dev/null
+++ b/llvm/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/llvm/test/Transforms/JumpThreading/select.ll b/llvm/test/Transforms/JumpThreading/select.ll
index 201e604e0c5..545e86c082f 100644
--- a/llvm/test/Transforms/JumpThreading/select.ll
+++ b/llvm/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