Add tracking of loop nesting to ARM code.

src/arm/codegen-arm.cc

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 115 matching lines @@
 // CodeGenerator implementation
 
 CodeGenerator::CodeGenerator(MacroAssembler* masm)
     : deferred_(8),
       masm_(masm),
       info_(NULL),
       frame_(NULL),
       allocator_(NULL),
       cc_reg_(al),
       state_(NULL),
+      loop_nesting_(0),
       function_return_is_shadowed_(false) {
 }
 
 
 // Calling conventions:
 // fp: caller's frame pointer
 // sp: stack pointer
 // r1: called JS function
 // cp: callee's context
 
 void CodeGenerator::Generate(CompilationInfo* info) {
   // Record the position for debugging purposes.
   CodeForFunctionPosition(info->function());
   Comment cmnt(masm_, "[ function compiled by virtual frame code generator");
 
   // Initialize state.
   info_ = info;
   ASSERT(allocator_ == NULL);
   RegisterAllocator register_allocator(this);
   allocator_ = &register_allocator;
   ASSERT(frame_ == NULL);
   frame_ = new VirtualFrame();
   cc_reg_ = al;
+
+  // Adjust for function-level loop nesting.
+  loop_nesting_ += info->loop_nesting();
+
   {
     CodeGenState state(this);
 
     // Entry:
     // Stack: receiver, arguments
     // lr: return address
     // fp: caller's frame pointer
     // sp: stack pointer
     // r1: called JS function
     // cp: callee's context
@@ skipping 204 matching lines @@
     // Check that the size of the code used for returning matches what is
     // expected by the debugger. The add instruction above is an addressing
     // mode 1 instruction where there are restrictions on which immediate values
     // can be encoded in the instruction and which immediate values requires
     // use of an additional instruction for moving the immediate to a temporary
     // register.
     ASSERT_EQ(return_sequence_length,
               masm_->InstructionsGeneratedSince(&check_exit_codesize));
   }
 
+  // Adjust for function-level loop nesting.
+  loop_nesting_ -= info->loop_nesting();

[Erik Corry, 2010/04/15 12:46:18]

Seems simpler to ASSERT that loop_nesting() == info->loop_nesting and then set
loop_nesting_ to 0.

+
   // Code generation state must be reset.
   ASSERT(!has_cc());
   ASSERT(state_ == NULL);
+  ASSERT(loop_nesting() == 0);
   ASSERT(!function_return_is_shadowed_);
   function_return_.Unuse();
   DeleteFrame();
 
   // Process any deferred code using the register allocator.
   if (!HasStackOverflow()) {
     ProcessDeferred();
   }
 
   allocator_ = NULL;
@@ skipping 1482 matching lines @@
 
 void CodeGenerator::VisitDoWhileStatement(DoWhileStatement* node) {
 #ifdef DEBUG
   int original_height = frame_->height();
 #endif
   VirtualFrame::SpilledScope spilled_scope(frame_);
   Comment cmnt(masm_, "[ DoWhileStatement");
   CodeForStatementPosition(node);
   node->break_target()->set_direction(JumpTarget::FORWARD_ONLY);
   JumpTarget body(JumpTarget::BIDIRECTIONAL);
+  IncrementLoopNesting();
 
   // Label the top of the loop for the backward CFG edge.  If the test
   // is always true we can use the continue target, and if the test is
   // always false there is no need.
   ConditionAnalysis info = AnalyzeCondition(node->cond());
   switch (info) {
     case ALWAYS_TRUE:
       node->continue_target()->set_direction(JumpTarget::BIDIRECTIONAL);
       node->continue_target()->Bind();
       break;
@@ skipping 40 matching lines @@
           // fall out of the test expression.
           Branch(true, &body);
         }
       }
       break;
   }
 
   if (node->break_target()->is_linked()) {
     node->break_target()->Bind();
   }
+  DecrementLoopNesting();
   ASSERT(!has_valid_frame() || frame_->height() == original_height);
 }
 
 
 void CodeGenerator::VisitWhileStatement(WhileStatement* node) {
 #ifdef DEBUG
   int original_height = frame_->height();
 #endif
   VirtualFrame::SpilledScope spilled_scope(frame_);
   Comment cmnt(masm_, "[ WhileStatement");
   CodeForStatementPosition(node);
 
   // If the test is never true and has no side effects there is no need
   // to compile the test or body.
   ConditionAnalysis info = AnalyzeCondition(node->cond());
   if (info == ALWAYS_FALSE) return;
 
   node->break_target()->set_direction(JumpTarget::FORWARD_ONLY);
+  IncrementLoopNesting();
 
   // Label the top of the loop with the continue target for the backward
   // CFG edge.
   node->continue_target()->set_direction(JumpTarget::BIDIRECTIONAL);
   node->continue_target()->Bind();
 
   if (info == DONT_KNOW) {
     JumpTarget body;
     LoadConditionAndSpill(node->cond(), &body, node->break_target(), true);
     if (has_valid_frame()) {
@@ skipping 11 matching lines @@
     VisitAndSpill(node->body());
 
     // If control flow can fall out of the body, jump back to the top.
     if (has_valid_frame()) {
       node->continue_target()->Jump();
     }
   }
   if (node->break_target()->is_linked()) {
     node->break_target()->Bind();
   }
+  DecrementLoopNesting();
   ASSERT(!has_valid_frame() || frame_->height() == original_height);
 }
 
 
 void CodeGenerator::VisitForStatement(ForStatement* node) {
 #ifdef DEBUG
   int original_height = frame_->height();
 #endif
   VirtualFrame::SpilledScope spilled_scope(frame_);
   Comment cmnt(masm_, "[ ForStatement");
   CodeForStatementPosition(node);
   if (node->init() != NULL) {
     VisitAndSpill(node->init());
   }
 
   // If the test is never true there is no need to compile the test or
   // body.
   ConditionAnalysis info = AnalyzeCondition(node->cond());
   if (info == ALWAYS_FALSE) return;
 
   node->break_target()->set_direction(JumpTarget::FORWARD_ONLY);
+  IncrementLoopNesting();
 
   // If there is no update statement, label the top of the loop with the
   // continue target, otherwise with the loop target.
   JumpTarget loop(JumpTarget::BIDIRECTIONAL);
   if (node->next() == NULL) {
     node->continue_target()->set_direction(JumpTarget::BIDIRECTIONAL);
     node->continue_target()->Bind();
   } else {
     node->continue_target()->set_direction(JumpTarget::FORWARD_ONLY);
     loop.Bind();
@@ skipping 34 matching lines @@
         // statement and not the body.
         CodeForStatementPosition(node);
         VisitAndSpill(node->next());
         loop.Jump();
       }
     }
   }
   if (node->break_target()->is_linked()) {
     node->break_target()->Bind();
   }
+  DecrementLoopNesting();
   ASSERT(!has_valid_frame() || frame_->height() == original_height);
 }
 
 
 void CodeGenerator::VisitForInStatement(ForInStatement* node) {

[Erik Corry, 2010/04/15 12:46:18]

Wot no loop nesting?

 #ifdef DEBUG
   int original_height = frame_->height();
 #endif
   VirtualFrame::SpilledScope spilled_scope(frame_);
   Comment cmnt(masm_, "[ ForInStatement");
   CodeForStatementPosition(node);
 
   JumpTarget primitive;
   JumpTarget jsobject;
   JumpTarget fixed_array;
@@ skipping 6852 matching lines @@
 
   // Just jump to runtime to add the two strings.
   __ bind(&string_add_runtime);
   __ TailCallRuntime(Runtime::kStringAdd, 2, 1);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal