From e7a3875bb4a7e5ab23fab46b31757cd47286ebfb Mon Sep 17 00:00:00 2001
From: "whesse@chromium.org"
 <whesse@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Fri, 30 Apr 2010 08:40:31 +0000
Subject: [PATCH] Cut-and-paste port from ia32 to x64: Delay load of trivial
 left operand of binary operation until after right operand loaded. Review
 URL: http://codereview.chromium.org/1736023

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4552 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/x64/codegen-x64.cc       | 11 +++++++++--
 src/x64/virtual-frame-x64.cc | 25 +++++++++++++++++++++++++
 src/x64/virtual-frame-x64.h  |  4 ++++
 3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/src/x64/codegen-x64.cc b/src/x64/codegen-x64.cc
index 9f53ec4..9575a29 100644
--- a/src/x64/codegen-x64.cc
+++ b/src/x64/codegen-x64.cc
@@ -3531,8 +3531,15 @@ void CodeGenerator::VisitBinaryOperation(BinaryOperation* node) {
       overwrite_mode = OVERWRITE_RIGHT;
     }
 
-    Load(node->left());
-    Load(node->right());
+    if (node->left()->IsTrivial()) {
+      Load(node->right());
+      Result right = frame_->Pop();
+      frame_->Push(node->left());
+      frame_->Push(&right);
+    } else {
+      Load(node->left());
+      Load(node->right());
+    }
     GenericBinaryOperation(node->op(), node->type(), overwrite_mode);
   }
 }
diff --git a/src/x64/virtual-frame-x64.cc b/src/x64/virtual-frame-x64.cc
index f612051..1e4374b 100644
--- a/src/x64/virtual-frame-x64.cc
+++ b/src/x64/virtual-frame-x64.cc
@@ -226,6 +226,31 @@ void VirtualFrame::EmitPush(Heap::RootListIndex index, TypeInfo info) {
 }
 
 
+void VirtualFrame::Push(Expression* expr) {
+  ASSERT(expr->IsTrivial());
+
+  Literal* lit = expr->AsLiteral();
+  if (lit != NULL) {
+    Push(lit->handle());
+    return;
+  }
+
+  VariableProxy* proxy = expr->AsVariableProxy();
+  if (proxy != NULL) {
+    Slot* slot = proxy->var()->slot();
+    if (slot->type() == Slot::LOCAL) {
+      PushLocalAt(slot->index());
+      return;
+    }
+    if (slot->type() == Slot::PARAMETER) {
+      PushParameterAt(slot->index());
+      return;
+    }
+  }
+  UNREACHABLE();
+}
+
+
 void VirtualFrame::Drop(int count) {
   ASSERT(count >= 0);
   ASSERT(height() >= count);
diff --git a/src/x64/virtual-frame-x64.h b/src/x64/virtual-frame-x64.h
index eba9047..7cda181 100644
--- a/src/x64/virtual-frame-x64.h
+++ b/src/x64/virtual-frame-x64.h
@@ -415,6 +415,10 @@ class VirtualFrame : public ZoneObject {
     result->Unuse();
   }
 
+  // Pushing an expression expects that the expression is trivial (according
+  // to Expression::IsTrivial).
+  void Push(Expression* expr);
+
   // Nip removes zero or more elements from immediately below the top
   // of the frame, leaving the previous top-of-frame value on top of
   // the frame.  Nip(k) is equivalent to x = Pop(), Drop(k), Push(x).
-- 
2.7.4