Revert "Fix phis for non-sse2 double values"

Need to investigate box2d regression.

BUG=
TBR=verwaest@chromium.org

Review URL: https://codereview.chromium.org/23437028

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16680 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/ia32/lithium-codegen-ia32.cc

@@ -382,13 +382,9 @@ bool LCodeGen::GenerateBody() {
 
     instr->CompileToNative(this);
 
-    if (!CpuFeatures::IsSupported(SSE2)) {
-      if (instr->IsGoto()) {
-        x87_stack_.LeavingBlock(current_block_, LGoto::cast(instr));
-      } else if (FLAG_debug_code && FLAG_enable_slow_asserts &&
-                 !instr->IsGap() && !instr->IsReturn()) {
+    if (!CpuFeatures::IsSupported(SSE2) &&
+        FLAG_debug_code && FLAG_enable_slow_asserts) {
         __ VerifyX87StackDepth(x87_stack_.depth());
-      }
     }
   }
   EnsureSpaceForLazyDeopt();
@@ -686,21 +682,6 @@ void LCodeGen::X87Stack::FlushIfNecessary(LInstruction* instr, LCodeGen* cgen) {
       __ fstp(0);
       stack_depth_--;
     }
-    __ VerifyX87StackDepth(0);
-  }
-}
-
-
-void LCodeGen::X87Stack::LeavingBlock(int current_block_id, LGoto* goto_instr) {
-  ASSERT(stack_depth_ <= 1);
-  // If ever used for new stubs producing two pairs of doubles joined into two
-  // phis this assert hits. That situation is not handled, since the two stacks
-  // might have st0 and st1 swapped.
-  if (current_block_id + 1 != goto_instr->block_id()) {
-    // If we have a value on the x87 stack on leaving a block, it must be a
-    // phi input. If the next block we compile is not the join block, we have
-    // to discard the stack state.
-    stack_depth_ = 0;
   }
 }
 
@@ -2505,10 +2486,6 @@ void LCodeGen::EmitGoto(int block) {
 }
 
 
-void LCodeGen::DoClobberDoubles(LClobberDoubles* instr) {
-}
-
-
 void LCodeGen::DoGoto(LGoto* instr) {
   EmitGoto(instr->block_id());
 }

src/ia32/lithium-codegen-ia32.h

@@ -471,7 +471,6 @@ class LCodeGen V8_FINAL BASE_EMBEDDED {
     void PrepareToWrite(X87Register reg);
     void CommitWrite(X87Register reg);
     void FlushIfNecessary(LInstruction* instr, LCodeGen* cgen);
-    void LeavingBlock(int current_block_id, LGoto* goto_instr);
     int depth() const { return stack_depth_; }
     void pop() {
       ASSERT(is_mutable_);

src/ia32/lithium-ia32.cc

@@ -954,16 +954,6 @@ void LChunkBuilder::VisitInstruction(HInstruction* current) {
     if (FLAG_stress_environments && !instr->HasEnvironment()) {
       instr = AssignEnvironment(instr);
     }
-    if (!CpuFeatures::IsSafeForSnapshot(SSE2) && instr->IsGoto() &&
-        LGoto::cast(instr)->jumps_to_join()) {
-      // TODO(olivf) Since phis of spilled values are joined as registers
-      // (not in the stack slot), we need to allow the goto gaps to keep one
-      // x87 register alive. To ensure all other values are still spilled, we
-      // insert a fpu register barrier right before.
-      LClobberDoubles* clobber = new(zone()) LClobberDoubles();
-      clobber->set_hydrogen_value(current);
-      chunk_->AddInstruction(clobber, current_block_);
-    }
     instr->set_hydrogen_value(current);
     chunk_->AddInstruction(instr, current_block_);
   }
@@ -1056,7 +1046,7 @@ LEnvironment* LChunkBuilder::CreateEnvironment(
 
 
 LInstruction* LChunkBuilder::DoGoto(HGoto* instr) {
-  return new(zone()) LGoto(instr->FirstSuccessor());
+  return new(zone()) LGoto(instr->FirstSuccessor()->block_id());
 }
 
 
@@ -1068,7 +1058,7 @@ LInstruction* LChunkBuilder::DoBranch(HBranch* instr) {
     HBasicBlock* successor = HConstant::cast(value)->BooleanValue()
         ? instr->FirstSuccessor()
         : instr->SecondSuccessor();
-    return new(zone()) LGoto(successor);
+    return new(zone()) LGoto(successor->block_id());
   }
 
   ToBooleanStub::Types expected = instr->expected_input_types();

src/ia32/lithium-ia32.h

@@ -73,7 +73,6 @@ class LCodeGen;
   V(ClampTToUint8)                              \
   V(ClampTToUint8NoSSE2)                        \
   V(ClassOfTestAndBranch)                       \
-  V(ClobberDoubles)                             \
   V(CompareNumericAndBranch)                    \
   V(CmpObjectEqAndBranch)                       \
   V(CmpHoleAndBranch)                           \
@@ -407,32 +406,19 @@ class LInstructionGap V8_FINAL : public LGap {
 };
 
 
-class LClobberDoubles V8_FINAL : public LTemplateInstruction<0, 0, 0> {
- public:
-  LClobberDoubles() { ASSERT(!CpuFeatures::IsSafeForSnapshot(SSE2)); }
-
-  virtual bool ClobbersDoubleRegisters() const { return true; }
-
-  DECLARE_CONCRETE_INSTRUCTION(ClobberDoubles, "clobber-d")
-};
-
-
 class LGoto V8_FINAL : public LTemplateInstruction<0, 0, 0> {
  public:
-  explicit LGoto(HBasicBlock* block) : block_(block) { }
+  explicit LGoto(int block_id) : block_id_(block_id) { }
 
   virtual bool HasInterestingComment(LCodeGen* gen) const V8_OVERRIDE;
   DECLARE_CONCRETE_INSTRUCTION(Goto, "goto")
   virtual void PrintDataTo(StringStream* stream) V8_OVERRIDE;
   virtual bool IsControl() const V8_OVERRIDE { return true; }
 
-  int block_id() const { return block_->block_id(); }
-  virtual bool ClobbersDoubleRegisters() const { return false; }
-
-  bool jumps_to_join() const { return block_->predecessors()->length() > 1; }
+  int block_id() const { return block_id_; }
 
  private:
-  HBasicBlock* block_;
+  int block_id_;
 };