llvm-reduce: Add pass to reduce instructions

Patch by Diego TreviƱo!

Differential Revision: https://reviews.llvm.org/D66263

llvm-svn: 372282
diff --git a/llvm/test/Reduce/Inputs/remove-global-vars.py b/llvm/test/Reduce/Inputs/remove-global-vars.py
index 81fbea9..1ae8b0e 100755
--- a/llvm/test/Reduce/Inputs/remove-global-vars.py
+++ b/llvm/test/Reduce/Inputs/remove-global-vars.py
@@ -2,9 +2,17 @@
 
 import sys
 
+InterestingVar = 0
+
 input = open(sys.argv[1], "r")
 for line in input:
-  if "@interesting = global" in line:
-    sys.exit(0)
+  i = line.find(';')
+  if i >= 0:
+    line = line[:i]
+  if line.startswith("@interesting = global") or "@interesting" in line:
+    InterestingVar += 1
 
-sys.exit(1) # IR isn't interesting
+if InterestingVar == 4:
+  sys.exit(0) # interesting!
+
+sys.exit(1)