ART: Hide unreachable basic blocks in the compiler

Unreachable blocks are not handled uniformly in the optimization
passes. Uniformly hide them to avoid initialization errors.

Bug: 15573463
Change-Id: Ia9e89fa357d5672a6cd8389f28a06ff618fe60ee

4 files changed, 15 insertions, 5 deletions

diff --git a/compiler/dex/frontend.cc b/compiler/dex/frontend.cc
index d45379712b..ca15964b92 100644
--- a/compiler/dex/frontend.cc
+++ b/compiler/dex/frontend.cc
@@ -756,7 +756,7 @@ static bool CanCompileMethod(uint32_t method_idx, const DexFile& dex_file,
       support_list_size = arraysize(x86_64_support_list);
     }
 
-    for (int idx = 0; idx < cu.mir_graph->GetNumBlocks(); idx++) {
+    for (unsigned int idx = 0; idx < cu.mir_graph->GetNumBlocks(); idx++) {
       BasicBlock* bb = cu.mir_graph->GetBasicBlock(idx);
       if (bb == NULL) continue;
       if (bb->block_type == kDead) continue;
diff --git a/compiler/dex/mir_graph.cc b/compiler/dex/mir_graph.cc
index a2676c82ca..63a55707e5 100644
--- a/compiler/dex/mir_graph.cc
+++ b/compiler/dex/mir_graph.cc
@@ -586,7 +586,7 @@ void MIRGraph::InlineMethod(const DexFile::CodeItem* code_item, uint32_t access_
   if (current_method_ == 0) {
     DCHECK(entry_block_ == NULL);
     DCHECK(exit_block_ == NULL);
-    DCHECK_EQ(num_blocks_, 0);
+    DCHECK_EQ(num_blocks_, 0U);
     // Use id 0 to represent a null block.
     BasicBlock* null_block = NewMemBB(kNullBlock, num_blocks_++);
     DCHECK_EQ(null_block->id, NullBasicBlockId);
diff --git a/compiler/dex/mir_graph.h b/compiler/dex/mir_graph.h
index b6cec662c3..27b8ca43aa 100644
--- a/compiler/dex/mir_graph.h
+++ b/compiler/dex/mir_graph.h
@@ -587,7 +587,7 @@ class MIRGraph {
     return m_units_[m_unit_index]->GetCodeItem()->insns_;
   }
 
-  int GetNumBlocks() const {
+  unsigned int GetNumBlocks() const {
     return num_blocks_;
   }
 
@@ -607,7 +607,7 @@ class MIRGraph {
     return exit_block_;
   }
 
-  BasicBlock* GetBasicBlock(int block_id) const {
+  BasicBlock* GetBasicBlock(unsigned int block_id) const {
     return (block_id == NullBasicBlockId) ? NULL : block_list_.Get(block_id);
   }
 
@@ -1149,7 +1149,7 @@ class MIRGraph {
   ArenaBitVector* try_block_addr_;
   BasicBlock* entry_block_;
   BasicBlock* exit_block_;
-  int num_blocks_;
+  unsigned int num_blocks_;
   const DexFile::CodeItem* current_code_item_;
   GrowableArray<uint16_t> dex_pc_to_block_map_;  // FindBlock lookup cache.
   std::vector<DexCompilationUnit*> m_units_;     // List of methods included in this graph
diff --git a/compiler/dex/ssa_transformation.cc b/compiler/dex/ssa_transformation.cc
index 43243254f1..e26745ad5e 100644
--- a/compiler/dex/ssa_transformation.cc
+++ b/compiler/dex/ssa_transformation.cc
@@ -117,6 +117,16 @@ void MIRGraph::ComputeDFSOrders() {
   RecordDFSOrders(GetEntryBlock());
 
   num_reachable_blocks_ = dfs_order_->Size();
+
+  if (num_reachable_blocks_ != num_blocks_) {
+    // Hide all unreachable blocks.
+    AllNodesIterator iter(this);
+    for (BasicBlock* bb = iter.Next(); bb != NULL; bb = iter.Next()) {
+      if (!bb->visited) {
+        bb->Hide(cu_);
+      }
+    }
+  }
 }
 
 /*