Remove HNativeDebugInfo from start of basic blocks.

We do not require full environment at the start of basic block.
The dex pc contained in basic block is sufficient for line mapping.

Change-Id: I5ba9e5f5acbc4a783ad544769f9a73bb33e2bafa

1 files changed, 16 insertions, 1 deletions

diff --git a/compiler/optimizing/code_generator.cc b/compiler/optimizing/code_generator.cc
index c2c8ccfc56..c67efc06c1 100644
--- a/compiler/optimizing/code_generator.cc
+++ b/compiler/optimizing/code_generator.cc
@@ -226,6 +226,10 @@ void CodeGenerator::Compile(CodeAllocator* allocator) {
     // errors where we reference that label.
     if (block->IsSingleJump()) continue;
     Bind(block);
+    // This ensures that we have correct native line mapping for all native instructions.
+    // It is necessary to make stepping over a statement work. Otherwise, any initial
+    // instructions (e.g. moves) would be assumed to be the start of next statement.
+    MaybeRecordNativeDebugInfo(nullptr /* instruction */, block->GetDexPc());
     for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) {
       HInstruction* current = it.Current();
       DisassemblyScope disassembly_scope(current, *this);
@@ -733,7 +737,8 @@ void CodeGenerator::RecordPcInfo(HInstruction* instruction,
   uint32_t native_pc = GetAssembler()->CodeSize();
 
   if (instruction == nullptr) {
-    // For stack overflow checks.
+    // For stack overflow checks and native-debug-info entries without dex register
+    // mapping (i.e. start of basic block or start of slow path).
     stack_map_stream_.BeginStackMapEntry(outer_dex_pc, native_pc, 0, 0, 0, 0);
     stack_map_stream_.EndStackMapEntry();
     return;
@@ -808,6 +813,16 @@ bool CodeGenerator::HasStackMapAtCurrentPc() {
   return count > 0 && stack_map_stream_.GetStackMap(count - 1).native_pc_offset == pc;
 }
 
+void CodeGenerator::MaybeRecordNativeDebugInfo(HInstruction* instruction, uint32_t dex_pc) {
+  if (GetCompilerOptions().GetNativeDebuggable() && dex_pc != kNoDexPc) {
+    if (HasStackMapAtCurrentPc()) {
+      // Ensure that we do not collide with the stack map of the previous instruction.
+      GenerateNop();
+    }
+    RecordPcInfo(instruction, dex_pc);
+  }
+}
+
 void CodeGenerator::RecordCatchBlockInfo() {
   ArenaAllocator* arena = graph_->GetArena();