Track side-effect free paths in the graph to allow CSE and LICM for instructions that depend on som…

runtime/vm/compiler.cc

Index: runtime/vm/compiler.cc
diff --git a/runtime/vm/compiler.cc b/runtime/vm/compiler.cc
index 6d0b880b5995eda287fed5420ff66728fed142cb..63f4ca4e6e989710413623109838d298961681b6 100644
--- a/runtime/vm/compiler.cc
+++ b/runtime/vm/compiler.cc
@@ -245,6 +245,11 @@ static bool CompileParsedFunctionHelper(const ParsedFunction& parsed_function,
       optimizer.SelectRepresentations();
       DEBUG_ASSERT(flow_graph->VerifyUseLists());
 
+      if (FLAG_common_subexpression_elimination ||
+          FLAG_loop_invariant_code_motion) {
+        flow_graph->ComputeBlockEffects();
+      }
+
       if (FLAG_common_subexpression_elimination) {
         if (DominatorBasedCSE::Optimize(flow_graph)) {
           DEBUG_ASSERT(flow_graph->VerifyUseLists());