[x86] Faster/shorter code for stack checks.

src/compiler/ia32/instruction-selector-ia32.cc

Index: src/compiler/ia32/instruction-selector-ia32.cc
diff --git a/src/compiler/ia32/instruction-selector-ia32.cc b/src/compiler/ia32/instruction-selector-ia32.cc
index 54184302c565db287a13f5e7f80e1ea46cc433fb..5797becfcb1fdf509d6ac158418d487ddb5e4495 100644
--- a/src/compiler/ia32/instruction-selector-ia32.cc
+++ b/src/compiler/ia32/instruction-selector-ia32.cc
@@ -841,6 +841,26 @@ void VisitWordCompare(InstructionSelector* selector, Node* node,
 
 void VisitWordCompare(InstructionSelector* selector, Node* node,
                       FlagsContinuation* cont) {
+  IA32OperandGenerator g(selector);
+  Int32BinopMatcher m(node);
+  if (m.left().IsLoad() && m.right().IsLoadStackPointer()) {
+    LoadMatcher<ExternalReferenceMatcher> mleft(m.left().node());
+    ExternalReference js_stack_limit =
+        ExternalReference::address_of_stack_limit(selector->isolate());
+    if (mleft.object().Is(js_stack_limit) && mleft.index().Is(0)) {
+      // Compare(Load(js_stack_limit), LoadStackPointer)
+      if (!node->op()->HasProperty(Operator::kCommutative)) cont->Commute();
+      InstructionCode opcode = cont->Encode(kIA32StackCheck);
+      if (cont->IsBranch()) {
+        selector->Emit(opcode, g.NoOutput(), g.Label(cont->true_block()),
+                       g.Label(cont->false_block()))->MarkAsControl();
+      } else {
+        DCHECK(cont->IsSet());
+        selector->Emit(opcode, g.DefineAsRegister(cont->result()));
+      }
+      return;
+    }
+  }
   VisitWordCompare(selector, node, kIA32Cmp, cont);
 }