Do stack checks while pushing locals

src/ia32/full-codegen-ia32.cc

Index: src/ia32/full-codegen-ia32.cc
diff --git a/src/ia32/full-codegen-ia32.cc b/src/ia32/full-codegen-ia32.cc
index 16c32949146ff60ad01df880ee22ebda4a41cb6b..c105528296d4fb179d7e20c30fb01b5c65ab2e25 100644
--- a/src/ia32/full-codegen-ia32.cc
+++ b/src/ia32/full-codegen-ia32.cc
@@ -101,6 +101,18 @@ class JumpPatchSite BASE_EMBEDDED {
 };
 
 
+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
@@ -172,7 +184,29 @@ void FullCodeGenerator::Generate() {
       __ 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);
       }
     }
@@ -285,13 +319,7 @@ void FullCodeGenerator::Generate() {
 
     { 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");