Reimplement dynamic frame alignment for frames that are compiled via OSR or have more than 2 double…

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index 2d469da6ed55867d5a32e0cdd6c22253888fc1da..2f1935573224ba27dfc77d07df63e3d7cdff360b 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -79,6 +79,9 @@ bool LCodeGen::GenerateCode() {
   // the frame (that is done in GeneratePrologue).
   FrameScope frame_scope(masm_, StackFrame::MANUAL);
 
+  dynamic_frame_alignment_ = chunk()->num_double_slots() > 2 ||
+                             info()->osr_ast_id() != AstNode::kNoNumber;
+
   return GeneratePrologue() &&
       GenerateBody() &&
       GenerateDeferredCode() &&
@@ -153,6 +156,31 @@ bool LCodeGen::GeneratePrologue() {
     __ bind(&ok);
   }
 
+  // Move state of dynamic frame alignment into edx.
+  __ mov(edx, Immediate(kNoAlignmentPadding));
+
+  if (dynamic_frame_alignment_) {
+     Label do_not_pad, align_loop;
+     STATIC_ASSERT(kDoubleSize == 2 * kPointerSize);
+     // Align esp to a multiple of 2 * kPointerSize.
+     __ test(esp, Immediate(kPointerSize));
+     __ j(zero, &do_not_pad, Label::kNear);
+     __ push(Immediate(0));
+     __ mov(ebx, esp);
+     __ mov(edx, Immediate(kAlignmentPaddingPushed));
+     // Copy arguments, receiver, and return address.
+     __ mov(ecx, Immediate(scope()->num_parameters() + 2));
+
+     __ bind(&align_loop);
+     __ mov(eax, Operand(ebx, 1 * kPointerSize));
+     __ mov(Operand(ebx, 0), eax);
+     __ add(Operand(ebx), Immediate(kPointerSize));
+     __ dec(ecx);
+     __ j(not_zero, &align_loop, Label::kNear);
+     __ mov(Operand(ebx, 0), Immediate(kAlignmentZapValue));
+     __ bind(&do_not_pad);
+  }
+
   __ push(ebp);  // Caller's frame pointer.
   __ mov(ebp, esp);
   __ push(esi);  // Callee's context.
@@ -160,30 +188,32 @@ bool LCodeGen::GeneratePrologue() {
 
   // Reserve space for the stack slots needed by the code.
   int slots = GetStackSlotCount();
-  if (slots > 0) {
-    if (FLAG_debug_code) {
-      __ mov(Operand(eax), Immediate(slots));
-      Label loop;
-      __ bind(&loop);
-      __ push(Immediate(kSlotsZapValue));
-      __ dec(eax);
-      __ j(not_zero, &loop);
-    } else {
-      __ sub(Operand(esp), Immediate(slots * kPointerSize));
+  ASSERT_GE(slots, 1);
+  if (FLAG_debug_code) {
+    __ mov(Operand(eax), Immediate(slots));
+    Label loop;
+    __ bind(&loop);
+    __ push(Immediate(kSlotsZapValue));
+    __ dec(eax);
+    __ j(not_zero, &loop);
+  } else {
+    __ sub(Operand(esp), Immediate(slots * kPointerSize));
 #ifdef _MSC_VER
-      // On windows, you may not access the stack more than one page below
-      // the most recently mapped page. To make the allocated area randomly
-      // accessible, we write to each page in turn (the value is irrelevant).
-      const int kPageSize = 4 * KB;
-      for (int offset = slots * kPointerSize - kPageSize;
-           offset > 0;
-           offset -= kPageSize) {
-        __ mov(Operand(esp, offset), eax);
-      }
-#endif
+    // On windows, you may not access the stack more than one page below
+    // the most recently mapped page. To make the allocated area randomly
+    // accessible, we write to each page in turn (the value is irrelevant).
+    const int kPageSize = 4 * KB;
+    for (int offset = slots * kPointerSize - kPageSize;
+         offset > 0;
+         offset -= kPageSize) {
+      __ mov(Operand(esp, offset), eax);
     }
+#endif
   }
 
+  // Store dynamic frame alignment state in the first local.
+  __ mov(Operand(ebp, JavaScriptFrameConstants::kLocal0Offset), edx);

[danno, 2012/06/11 10:53:14]

To reduce the theoretical expense of the tag in the non-dynamic_frame_alignment_
case, can you do the immediate store in a single instruction?

+
   // Possibly allocate a local context.
   int heap_slots = scope()->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
   if (heap_slots > 0) {
@@ -2098,8 +2128,24 @@ void LCodeGen::DoReturn(LReturn* instr) {
     __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
     __ CallRuntime(Runtime::kTraceExit, 1);
   }
+  if (dynamic_frame_alignment_) {
+    // Fetch the state of the dynamic frame alignment.
+    __ mov(edx, Operand(ebp, JavaScriptFrameConstants::kLocal0Offset));

[danno, 2012/06/11 10:53:14]

Can you alias something like kFrameAlignmentCookieOffset to kLocalOffset and use
it instead?

+  }
   __ mov(esp, ebp);
   __ pop(ebp);
+  if (dynamic_frame_alignment_) {
+    Label no_padding;
+    __ cmp(edx, Immediate(kNoAlignmentPadding));
+    __ j(equal, &no_padding);
+    if (FLAG_debug_code) {
+      __ cmp(Operand(esp, (GetParameterCount() + 2) * kPointerSize),
+             Immediate(kAlignmentZapValue));
+      __ Assert(equal, "expected alignment marker");
+    }
+    __ Ret((GetParameterCount() + 2) * kPointerSize, ecx);
+    __ bind(&no_padding);
+  }
   __ Ret((GetParameterCount() + 1) * kPointerSize, ecx);
 }