Add dynamic stack frame alignment to optimized functions with untagged doubles on the stack.

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 46d80506edd887ce2f1b4915a3f6e04e0248fad0..092e5d01d644dcd31cb8d11db0115e02abff6cd7 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -78,6 +78,9 @@ bool LCodeGen::GenerateCode() {
   // the frame (that is done in GeneratePrologue).
   FrameScope frame_scope(masm_, StackFrame::MANUAL);
 
+  set_dynamic_frame_alignment(chunk()->num_double_slots() > 2 ||
+                              info()->osr_ast_id() != AstNode::kNoNumber);
+
   return GeneratePrologue() &&
       GenerateBody() &&
       GenerateDeferredCode() &&
@@ -152,6 +155,27 @@ bool LCodeGen::GeneratePrologue() {
     __ bind(&ok);
   }
 
+  if (dynamic_frame_alignment()) {
+    Label do_not_pad, align_loop;
+    __ mov(ebx, esp);

[Kevin Millikin (Chromium), 2011/09/23 09:38:49]

Can you test(esp, 4)?

[William Hesse, 2011/09/23 12:50:11]

Done.

+    __ and_(ebx, Immediate(0x4));

[Kevin Millikin (Chromium), 2011/09/23 09:38:49]

Is this better (kDoubleSize - 1) or (kDoubleSize >> 1) or some other named
constant?

[William Hesse, 2011/09/23 12:50:11]

Done.

+    __ j(zero, &do_not_pad, Label::kNear);
+    __ mov(ebx, esp);

[Kevin Millikin (Chromium), 2011/09/23 09:38:49]

The last move after the loop might be slightly more obvious if you make ebx be
the address you're copying to, rather than from.

[William Hesse, 2011/09/23 12:50:11]

Done.

+    __ push(Immediate(0));
+    __ mov(ecx, Immediate(scope()->num_parameters() + 2));

[Kevin Millikin (Chromium), 2011/09/23 09:38:49]

Comment should say 2 is receiver + return address.

[William Hesse, 2011/09/23 12:50:11]

Done.

+
+    __ bind(&align_loop);
+    __ mov(eax, Operand(ebx, 0));
+    __ mov(Operand(ebx, -1 * kPointerSize), eax);
+    __ add(Operand(ebx), Immediate(kPointerSize));
+    __ dec(ecx);
+    __ j(not_zero, &align_loop, Label::kNear);
+    __ mov(Operand(ebx, -1 * kPointerSize),
+           Immediate(isolate()->factory()->frame_alignment_marker()));
+
+    __ bind(&do_not_pad);
+  }
+
   __ push(ebp);  // Caller's frame pointer.
   __ mov(ebp, esp);
   __ push(esi);  // Callee's context.
@@ -2016,6 +2040,16 @@ void LCodeGen::DoReturn(LReturn* instr) {
     __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
     __ CallRuntime(Runtime::kTraceExit, 1);
   }
+  if (dynamic_frame_alignment()) {
+    Label aligned;
+    __ cmp(Operand(ebp, (GetParameterCount() + 3) * kPointerSize),

[Kevin Millikin (Chromium), 2011/09/23 09:38:49]

3 ~ caller's fp, return address, receiver.

[William Hesse, 2011/09/23 12:50:11]

Done.

+           Immediate(factory()->frame_alignment_marker()));
+    __ j(not_equal, &aligned);
+    __ mov(esp, ebp);
+    __ pop(ebp);

[Kevin Millikin (Chromium), 2011/09/23 09:38:49]

Slightly more compact is:

__ mov(esp, ebp);
__ pop(ebp);
__ cmp(Operand(esp, (param_count + 2) * kPointerSize), marker);
__ j(not_equal, &aligned);
__ Ret(parameter_count + 2);
__ bind(&aligned);
__ Ret(parameter_count + 1);

[William Hesse, 2011/09/23 12:50:11]

Done.

+    __ Ret((GetParameterCount() + 2) * kPointerSize, ecx);
+    __ bind(&aligned);
+  }
   __ mov(esp, ebp);
   __ pop(ebp);
   __ Ret((GetParameterCount() + 1) * kPointerSize, ecx);