Do stack checks while pushing locals

src/ia32/full-codegen-ia32.cc

 // Copyright 2012 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 83 matching lines @@
   }
 
   MacroAssembler* masm_;
   Label patch_site_;
 #ifdef DEBUG
   bool info_emitted_;
 #endif
 };
 
 
+static void EmitStackCheck(MacroAssembler* masm_) {
+    Label ok;
+    Isolate* isolate = masm_->isolate();
+    ExternalReference stack_limit =
+        ExternalReference::address_of_stack_limit(isolate);
+    __ cmp(esp, Operand::StaticVariable(stack_limit));
+    __ j(above_equal, &ok, Label::kNear);
+    __ call(isolate->builtins()->StackCheck(), RelocInfo::CODE_TARGET);
+    __ bind(&ok);
+}
+
+
 // Generate code for a JS function.  On entry to the function the receiver
 // and arguments have been pushed on the stack left to right, with the
 // return address on top of them.  The actual argument count matches the
 // formal parameter count expected by the function.
 //
 // The live registers are:
 //   o edi: the JS function object being called (i.e. ourselves)
 //   o esi: our context
 //   o ebp: our caller's frame pointer
 //   o esp: stack pointer (pointing to return address)
@@ skipping 51 matching lines @@
   info->AddNoFrameRange(0, masm_->pc_offset());
 
   { Comment cmnt(masm_, "[ Allocate locals");
     int locals_count = info->scope()->num_stack_slots();
     // Generators allocate locals, if any, in context slots.
     ASSERT(!info->function()->is_generator() || locals_count == 0);
     if (locals_count == 1) {
       __ push(Immediate(isolate()->factory()->undefined_value()));
     } else if (locals_count > 1) {
       __ mov(eax, Immediate(isolate()->factory()->undefined_value()));
-      for (int i = 0; i < locals_count; i++) {
+      const int kTriggerStackLimitCheckCount = 128;
+      // Create a loop that pushes kTriggerStackLimitCheckCount undefines
+      // and performs a stack check.
+      if (locals_count >= kTriggerStackLimitCheckCount) {
+        PrepareForBailoutForId(BailoutId::FunctionEntry(), NO_REGISTERS);

[dcarney, 2014/03/21 09:43:28]

no idea what this does, whether it's the right bailout id, or whether i can call
it twice

[Yang, 2014/03/21 09:52:22]

I don't think we need this. I don't expect optimized code to somehow deoptimize
and end up here. (At least I think that's what this is for).

+        int loop_iterations = locals_count / kTriggerStackLimitCheckCount;
+        __ mov(ecx, loop_iterations);
+        Label loop_header;
+        __ bind(&loop_header);
+        // Do pushes.
+        for (int i = 0; i < kTriggerStackLimitCheckCount; i++) {
+          __ push(eax);
+        }
+        // Do stack check.
+        EmitStackCheck(masm_);
+        // Continue loop if not done.
+        __ dec(ecx);
+        __ cmp(ecx, Immediate(Smi::FromInt(0)));

[Yang, 2014/03/21 09:52:22]

No need for this cmp. dec also sets the flags. Just do a j(not_zero,
&loop_header) later. (not_zero is actually the same flag as not_equal).

+        __ j(not_equal, &loop_header, Label::kNear);
+      }
+      int remaining = locals_count % kTriggerStackLimitCheckCount;
+      // Emit the remaining pushes.
+      for (int i  = 0; i < remaining; i++) {
         __ push(eax);
       }
     }
   }
 
   bool function_in_register = true;
 
   // Possibly allocate a local context.
   int heap_slots = info->scope()->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
   if (heap_slots > 0) {
@@ skipping 92 matching lines @@
         ASSERT(function->proxy()->var()->mode() == CONST ||
                function->proxy()->var()->mode() == CONST_LEGACY);
         ASSERT(function->proxy()->var()->location() != Variable::UNALLOCATED);
         VisitVariableDeclaration(function);
       }
       VisitDeclarations(scope()->declarations());
     }
 
     { Comment cmnt(masm_, "[ Stack check");
       PrepareForBailoutForId(BailoutId::Declarations(), NO_REGISTERS);
-      Label ok;
-      ExternalReference stack_limit =
-          ExternalReference::address_of_stack_limit(isolate());
-      __ cmp(esp, Operand::StaticVariable(stack_limit));
-      __ j(above_equal, &ok, Label::kNear);
-      __ call(isolate()->builtins()->StackCheck(), RelocInfo::CODE_TARGET);
-      __ bind(&ok);
+      EmitStackCheck(masm_);
     }
 
     { Comment cmnt(masm_, "[ Body");
       ASSERT(loop_depth() == 0);
       VisitStatements(function()->body());
       ASSERT(loop_depth() == 0);
     }
   }
 
   // Always emit a 'return undefined' in case control fell off the end of
@@ skipping 4598 matching lines @@
   ASSERT_EQ(isolate->builtins()->OsrAfterStackCheck()->entry(),
             Assembler::target_address_at(call_target_address,
                                          unoptimized_code));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32