From f3b8a3c8a893113d9851b71bb4a036de3624dcc3 Mon Sep 17 00:00:00 2001
From: "mvstanton@chromium.org"
 <mvstanton@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Tue, 12 Mar 2013 09:06:23 +0000
Subject: [PATCH] MIPS: To fully support hydrogen code stubs which accept a
 variable number of arguments, the HReturn/LReturn instruction needs to be
 able to determine argument count from a stack evaluation rather than as a
 constant from scope.

Port r13888 (33905114)

BUG=

Review URL: https://codereview.chromium.org/12414011

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13910 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/mips/lithium-codegen-mips.cc | 15 ++++++++++++---
 src/mips/lithium-codegen-mips.h  |  1 -
 src/mips/lithium-mips.cc         |  4 +++-
 src/mips/lithium-mips.h          | 14 ++++++++++++--
 4 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/src/mips/lithium-codegen-mips.cc b/src/mips/lithium-codegen-mips.cc
index ab08399..3cd89b8 100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -2558,11 +2558,20 @@ void LCodeGen::DoReturn(LReturn* instr) {
     }
   }
   if (NeedsEagerFrame()) {
-    int32_t sp_delta = (GetParameterCount() + 1) * kPointerSize;
     __ mov(sp, fp);
     __ Pop(ra, fp);
-    if (!info()->IsStub()) {
-      __ Addu(sp, sp, Operand(sp_delta));
+
+    if (instr->has_constant_parameter_count()) {
+      int parameter_count = ToInteger32(instr->constant_parameter_count());
+      int32_t sp_delta = (parameter_count + 1) * kPointerSize;
+      if (sp_delta != 0) {
+        __ Addu(sp, sp, Operand(sp_delta));
+      }
+    } else {
+      Register reg = ToRegister(instr->parameter_count());
+      __ Addu(reg, reg, Operand(1));
+      __ sll(at, reg, kPointerSizeLog2);
+      __ Addu(sp, sp, at);
     }
   }
   __ Jump(ra);
diff --git a/src/mips/lithium-codegen-mips.h b/src/mips/lithium-codegen-mips.h
index b4476c4..1d2a659 100644
--- a/src/mips/lithium-codegen-mips.h
+++ b/src/mips/lithium-codegen-mips.h
@@ -201,7 +201,6 @@ class LCodeGen BASE_EMBEDDED {
                        Register temporary2);
 
   int GetStackSlotCount() const { return chunk()->spill_slot_count(); }
-  int GetParameterCount() const { return info()->num_parameters(); }
 
   void Abort(const char* reason);
   void Comment(const char* format, ...);
diff --git a/src/mips/lithium-mips.cc b/src/mips/lithium-mips.cc
index 533207c..b233d51 100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -1804,7 +1804,9 @@ LInstruction* LChunkBuilder::DoClampToUint8(HClampToUint8* instr) {
 
 
 LInstruction* LChunkBuilder::DoReturn(HReturn* instr) {
-  return new(zone()) LReturn(UseFixed(instr->value(), v0));
+  LOperand* parameter_count = UseRegisterOrConstant(instr->parameter_count());
+  return new(zone()) LReturn(UseFixed(instr->value(), v0),
+                             parameter_count);
 }
 
 
diff --git a/src/mips/lithium-mips.h b/src/mips/lithium-mips.h
index c5a00d7..ccaad71 100644
--- a/src/mips/lithium-mips.h
+++ b/src/mips/lithium-mips.h
@@ -1343,14 +1343,24 @@ class LArithmeticT: public LTemplateInstruction<1, 2, 0> {
 };
 
 
-class LReturn: public LTemplateInstruction<0, 1, 0> {
+class LReturn: public LTemplateInstruction<0, 2, 0> {
  public:
-  explicit LReturn(LOperand* value) {
+  explicit LReturn(LOperand* value, LOperand* parameter_count) {
     inputs_[0] = value;
+    inputs_[1] = parameter_count;
   }
 
   LOperand* value() { return inputs_[0]; }
 
+  bool has_constant_parameter_count() {
+    return parameter_count()->IsConstantOperand();
+  }
+  LConstantOperand* constant_parameter_count() {
+    ASSERT(has_constant_parameter_count());
+    return LConstantOperand::cast(parameter_count());
+  }
+  LOperand* parameter_count() { return inputs_[1]; }
+
   DECLARE_CONCRETE_INSTRUCTION(Return, "return")
 };
 
-- 
2.7.4