Add loop- and phi-related checks in the optimizing compiler.

- Ensure the pre-header block is first in the list of
  predecessors of a loop header.
- Ensure the loop header has only two predecessors and that
  only the second one is the back edge.
- Ensure there is only one back edge per loop.
- Ensure the first input of a phi is not itself.
- Ensure the number of phi inputs is the same as the number
  of its predecessors.
- Ensure phi input at index I either comes from the Ith
  predecessor or from a block that dominates this
  predecessor.

Change-Id: I4db5c68cfbc9b74d2d03125753d0143ece625378

1 files changed, 4 insertions, 1 deletions

diff --git a/compiler/optimizing/graph_checker.h b/compiler/optimizing/graph_checker.h
index 8ddd399456..34a770b5f3 100644
--- a/compiler/optimizing/graph_checker.h
+++ b/compiler/optimizing/graph_checker.h
@@ -67,9 +67,12 @@ class SSAChecker : public GraphChecker {
 
   // Perform SSA form checks on `block`.
   virtual void VisitBasicBlock(HBasicBlock* block) OVERRIDE;
+  // Loop-related checks from block `loop_header`.
+  void CheckLoop(HBasicBlock* loop_header);
 
-  // Perform SSA form checks on `instruction`.
+  // Perform SSA form checks on instructions.
   virtual void VisitInstruction(HInstruction* instruction) OVERRIDE;
+  virtual void VisitPhi(HPhi* phi) OVERRIDE;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SSAChecker);