Disable DCE when there are irreducible loops.

Also ensure an instruction that requires an environment
does have one.

Change-Id: I41a8460e05ef320f872197d3be7847e7ffaa6ee8

1 files changed, 20 insertions, 0 deletions

diff --git a/compiler/optimizing/graph_checker.cc b/compiler/optimizing/graph_checker.cc
index 9439ba0c8d..31136772c7 100644
--- a/compiler/optimizing/graph_checker.cc
+++ b/compiler/optimizing/graph_checker.cc
@@ -484,6 +484,18 @@ void SSAChecker::CheckLoop(HBasicBlock* loop_header) {
         loop_information->GetPreHeader()->GetSuccessors().size()));
   }
 
+  if (loop_information->GetSuspendCheck() == nullptr) {
+    AddError(StringPrintf(
+        "Loop with header %d does not have a suspend check.",
+        loop_header->GetBlockId()));
+  }
+
+  if (loop_information->GetSuspendCheck() != loop_header->GetFirstInstructionDisregardMoves()) {
+    AddError(StringPrintf(
+        "Loop header %d does not have the loop suspend check as the first instruction.",
+        loop_header->GetBlockId()));
+  }
+
   // Ensure the loop header has only one incoming branch and the remaining
   // predecessors are back edges.
   size_t num_preds = loop_header->GetPredecessors().size();
@@ -589,6 +601,14 @@ void SSAChecker::VisitInstruction(HInstruction* instruction) {
     }
   }
 
+  if (instruction->NeedsEnvironment() && !instruction->HasEnvironment()) {
+    AddError(StringPrintf("Instruction %s:%d in block %d requires an environment "
+                          "but does not have one.",
+                          instruction->DebugName(),
+                          instruction->GetId(),
+                          current_block_->GetBlockId()));
+  }
+
   // Ensure an instruction having an environment is dominated by the
   // instructions contained in the environment.
   for (HEnvironment* environment = instruction->GetEnvironment();