Improvements for x87 stack handling

src/ia32/lithium-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 73 matching lines @@
            operand->IsUsedAtStart());
   }
   for (TempIterator it(this); !it.Done(); it.Advance()) {
     LUnallocated* operand = LUnallocated::cast(it.Current());
     ASSERT(operand->HasFixedPolicy() ||!operand->HasRegisterPolicy());
   }
 }
 #endif
 
 
+bool LInstruction::HasDoubleRegisterResult() {
+  return HasResult() && result()->IsDoubleRegister();
+}
+
+
 void LInstruction::PrintTo(StringStream* stream) {
   stream->Add("%s ", this->Mnemonic());
 
   PrintOutputOperandTo(stream);
 
   PrintDataTo(stream);
 
   if (HasEnvironment()) {
     stream->Add(" ");
     environment()->PrintTo(stream);
@@ skipping 431 matching lines @@
 LOperand* LChunkBuilder::UseFixed(HValue* value, Register fixed_register) {
   return Use(value, ToUnallocated(fixed_register));
 }
 
 
 LOperand* LChunkBuilder::UseFixedDouble(HValue* value, XMMRegister reg) {
   return Use(value, ToUnallocated(reg));
 }
 
 
+LOperand* LChunkBuilder::UseX87TopOfStack(HValue* value) {
+  return Use(value, ToUnallocated(x87tos));
+}
+
+
 LOperand* LChunkBuilder::UseRegister(HValue* value) {
   return Use(value, new(zone()) LUnallocated(LUnallocated::MUST_HAVE_REGISTER));
 }
 
 
 LOperand* LChunkBuilder::UseRegisterAtStart(HValue* value) {
   return Use(value,
              new(zone()) LUnallocated(LUnallocated::MUST_HAVE_REGISTER,
                                       LUnallocated::USED_AT_START));
 }
@@ skipping 1299 matching lines @@
   // building a stack frame.
   if (from.IsTagged()) {
     if (to.IsDouble()) {
       info()->MarkAsDeferredCalling();
       LOperand* value = UseRegister(instr->value());
       // Temp register only necessary for minus zero check.
       LOperand* temp = instr->deoptimize_on_minus_zero()
                        ? TempRegister()
                        : NULL;
       LNumberUntagD* res = new(zone()) LNumberUntagD(value, temp);
-      return AssignEnvironment(DefineAsRegister(res));
+      if (CpuFeatures::IsSafeForSnapshot(SSE2)) {
+        return AssignEnvironment(DefineAsRegister(res));
+      } else {
+        return AssignEnvironment(DefineX87TOS(res));
+      }
     } else {
       ASSERT(to.IsInteger32());
-      LOperand* value = UseRegister(instr->value());
       if (instr->value()->type().IsSmi()) {
+        LOperand* value = UseRegister(instr->value());
         return DefineSameAsFirst(new(zone()) LSmiUntag(value, false));
       } else {
         bool truncating = instr->CanTruncateToInt32();
-        LOperand* xmm_temp =
-            (truncating && CpuFeatures::IsSupported(SSE3))
-            ? NULL
-            : FixedTemp(xmm1);
-        LTaggedToI* res = new(zone()) LTaggedToI(value, xmm_temp);
-        return AssignEnvironment(DefineSameAsFirst(res));
+        if (CpuFeatures::IsSafeForSnapshot(SSE2)) {
+          LOperand* value = UseRegister(instr->value());
+          LOperand* xmm_temp =
+              (truncating && CpuFeatures::IsSupported(SSE3))
+              ? NULL
+              : FixedTemp(xmm1);
+          LTaggedToI* res = new(zone()) LTaggedToI(value, xmm_temp);
+          return AssignEnvironment(DefineSameAsFirst(res));
+        } else {
+          LOperand* value = UseFixed(instr->value(), ecx);
+          LTaggedToINoSSE2* res =
+              new(zone()) LTaggedToINoSSE2(value, TempRegister(),
+                                           TempRegister(), TempRegister());
+          return AssignEnvironment(DefineFixed(res, ecx));
+        }
       }
     }
   } else if (from.IsDouble()) {
     if (to.IsTagged()) {
       info()->MarkAsDeferredCalling();
       LOperand* value = CpuFeatures::IsSupported(SSE2)
           ? UseRegisterAtStart(instr->value())
           : UseAtStart(instr->value());
       LOperand* temp = FLAG_inline_new ? TempRegister() : NULL;
 
@@ skipping 97 matching lines @@
   HValue* value = instr->value();
   Representation input_rep = value->representation();
   if (input_rep.IsDouble()) {
     LOperand* reg = UseRegister(value);
     return DefineFixed(new(zone()) LClampDToUint8(reg), eax);
   } else if (input_rep.IsInteger32()) {
     LOperand* reg = UseFixed(value, eax);
     return DefineFixed(new(zone()) LClampIToUint8(reg), eax);
   } else {
     ASSERT(input_rep.IsTagged());
-    LOperand* reg = UseFixed(value, eax);
-    // Register allocator doesn't (yet) support allocation of double
-    // temps. Reserve xmm1 explicitly.
-    LOperand* temp = FixedTemp(xmm1);
-    LClampTToUint8* result = new(zone()) LClampTToUint8(reg, temp);
-    return AssignEnvironment(DefineFixed(result, eax));
+    if (CpuFeatures::IsSupported(SSE2)) {
+      LOperand* reg = UseFixed(value, eax);
+      // Register allocator doesn't (yet) support allocation of double
+      // temps. Reserve xmm1 explicitly.
+      LOperand* temp = FixedTemp(xmm1);
+      LClampTToUint8* result = new(zone()) LClampTToUint8(reg, temp);
+      return AssignEnvironment(DefineFixed(result, eax));
+    } else {
+      LOperand* value = UseRegister(instr->value());
+      LClampTToUint8NoSSE2* res =
+          new(zone()) LClampTToUint8NoSSE2(value, TempRegister(),
+                                           TempRegister(), TempRegister());
+      return AssignEnvironment(DefineFixed(res, ecx));
+    }
   }
 }
 
 
 LInstruction* LChunkBuilder::DoReturn(HReturn* instr) {
   LOperand* context = info()->IsStub()
       ? UseFixed(instr->context(), esi)
       : NULL;
   LOperand* parameter_count = UseRegisterOrConstant(instr->parameter_count());
   return new(zone()) LReturn(UseFixed(instr->value(), eax), context,
                              parameter_count);
 }
 
 
 LInstruction* LChunkBuilder::DoConstant(HConstant* instr) {
   Representation r = instr->representation();
   if (r.IsInteger32()) {
     return DefineAsRegister(new(zone()) LConstantI);
   } else if (r.IsDouble()) {
     double value = instr->DoubleValue();
-    LOperand* temp = (BitCast<uint64_t, double>(value) != 0)
-        ? TempRegister()
-        : NULL;
-    return DefineAsRegister(new(zone()) LConstantD(temp));
+    bool value_is_zero = BitCast<uint64_t, double>(value) == 0;
+    if (CpuFeatures::IsSafeForSnapshot(SSE2)) {
+      LOperand* temp = value_is_zero ? NULL : TempRegister();
+      return DefineAsRegister(new(zone()) LConstantD(temp));
+    } else {
+      return DefineX87TOS(new(zone()) LConstantD(NULL));
+    }
   } else if (r.IsTagged()) {
     return DefineAsRegister(new(zone()) LConstantT);
   } else {
     UNREACHABLE();
     return NULL;
   }
 }
 
 
 LInstruction* LChunkBuilder::DoLoadGlobalCell(HLoadGlobalCell* instr) {
@@ skipping 148 matching lines @@
   LOperand* context = UseFixed(instr->context(), esi);
   LOperand* object = UseFixed(instr->object(), edx);
   LOperand* key = UseFixed(instr->key(), ecx);
 
   LLoadKeyedGeneric* result =
       new(zone()) LLoadKeyedGeneric(context, object, key);
   return MarkAsCall(DefineFixed(result, eax), instr);
 }
 
 
+LOperand* LChunkBuilder::GetStoreKeyedValueOperand(HStoreKeyed* instr) {

[danno, 2013/04/08 12:57:27]

Is this change related?

[mvstanton, 2013/04/08 16:10:14]

Nope, removed

+  ElementsKind elements_kind = instr->elements_kind();
+
+  // Determine if we need a byte register in this case for the value.
+  bool val_is_fixed_register =
+      elements_kind == EXTERNAL_BYTE_ELEMENTS ||
+      elements_kind == EXTERNAL_UNSIGNED_BYTE_ELEMENTS ||
+      elements_kind == EXTERNAL_PIXEL_ELEMENTS;
+  if (val_is_fixed_register) {
+    return UseFixed(instr->value(), eax);
+  }
+
+  if (!CpuFeatures::IsSafeForSnapshot(SSE2) &&
+      IsDoubleOrFloatElementsKind(elements_kind)) {
+    return UseRegisterAtStart(instr->value());
+  }
+
+  return UseRegister(instr->value());
+}
+
+
 LInstruction* LChunkBuilder::DoStoreKeyed(HStoreKeyed* instr) {
   if (!instr->is_external()) {
     ASSERT(instr->elements()->representation().IsTagged());
     ASSERT(instr->key()->representation().IsInteger32() ||
            instr->key()->representation().IsTagged());
 
     if (instr->value()->representation().IsDouble()) {
       LOperand* object = UseRegisterAtStart(instr->elements());
-      LOperand* val = UseTempRegister(instr->value());
+      LOperand* val = NULL;
+      if (CpuFeatures::IsSafeForSnapshot(SSE2)) {
+        val = UseRegisterAtStart(instr->value());
+      } else {
+        if (!instr->IsConstantHoleStore()) {
+          val = UseX87TopOfStack(instr->value());
+        }
+      }
       LOperand* key = UseRegisterOrConstantAtStart(instr->key());
-
       return new(zone()) LStoreKeyed(object, key, val);
     } else {
       ASSERT(instr->value()->representation().IsTagged());
       bool needs_write_barrier = instr->NeedsWriteBarrier();
 
       LOperand* obj = UseRegister(instr->elements());
-      LOperand* val = needs_write_barrier
-          ? UseTempRegister(instr->value())
-          : UseRegisterAtStart(instr->value());
-      LOperand* key = needs_write_barrier
-          ? UseTempRegister(instr->key())
-          : UseRegisterOrConstantAtStart(instr->key());
+      LOperand* val;
+      LOperand* key;
+      if (needs_write_barrier) {
+        val = UseTempRegister(instr->value());

[mvstanton, 2013/04/08 16:10:14]

This change is unrelated, removing.

+        key = UseTempRegister(instr->key());
+      } else {
+        val = UseRegisterOrConstantAtStart(instr->value());
+        key = UseRegisterOrConstantAtStart(instr->key());
+      }
       return new(zone()) LStoreKeyed(obj, key, val);
     }
   }
 
   ElementsKind elements_kind = instr->elements_kind();
   ASSERT(
       (instr->value()->representation().IsInteger32() &&
        (elements_kind != EXTERNAL_FLOAT_ELEMENTS) &&
        (elements_kind != EXTERNAL_DOUBLE_ELEMENTS)) ||
       (instr->value()->representation().IsDouble() &&
        ((elements_kind == EXTERNAL_FLOAT_ELEMENTS) ||
         (elements_kind == EXTERNAL_DOUBLE_ELEMENTS))));
   ASSERT(instr->elements()->representation().IsExternal());
 
   LOperand* external_pointer = UseRegister(instr->elements());
-  // Determine if we need a byte register in this case for the value.
-  bool val_is_fixed_register =
-      elements_kind == EXTERNAL_BYTE_ELEMENTS ||
-      elements_kind == EXTERNAL_UNSIGNED_BYTE_ELEMENTS ||
-      elements_kind == EXTERNAL_PIXEL_ELEMENTS;
-
-  LOperand* val = val_is_fixed_register
-      ? UseFixed(instr->value(), eax)
-      : UseRegister(instr->value());
+  LOperand* val = GetStoreKeyedValueOperand(instr);
   bool clobbers_key = ExternalArrayOpRequiresTemp(
       instr->key()->representation(), elements_kind);
   LOperand* key = clobbers_key
       ? UseTempRegister(instr->key())
       : UseRegisterOrConstantAtStart(instr->key());
   return new(zone()) LStoreKeyed(external_pointer,
                                  key,
                                  val);
 }
 
@@ skipping 65 matching lines @@
         ? UseRegister(instr->object())
         : UseTempRegister(instr->object());
   } else {
     obj = needs_write_barrier_for_map
         ? UseRegister(instr->object())
         : UseRegisterAtStart(instr->object());
   }
 
   LOperand* val = needs_write_barrier
       ? UseTempRegister(instr->value())
-      : UseRegister(instr->value());
+      : UseRegisterOrConstant(instr->value());

[danno, 2013/04/08 12:57:27]

Is this change related?

[mvstanton, 2013/04/08 16:10:14]

Nope, removed.

 
   // We only need a scratch register if we have a write barrier or we
   // have a store into the properties array (not in-object-property).
   LOperand* temp = (!instr->is_in_object() || needs_write_barrier ||
       needs_write_barrier_for_map) ? TempRegister() : NULL;
 
   // We need a temporary register for write barrier of the map field.
   LOperand* temp_map = needs_write_barrier_for_map ? TempRegister() : NULL;
 
   return new(zone()) LStoreNamedField(obj, val, temp, temp_map);
@@ skipping 118 matching lines @@
 
 LInstruction* LChunkBuilder::DoParameter(HParameter* instr) {
   LParameter* result = new(zone()) LParameter;
   if (instr->kind() == HParameter::STACK_PARAMETER) {
     int spill_index = chunk()->GetParameterStackSlot(instr->index());
     return DefineAsSpilled(result, spill_index);
   } else {
     ASSERT(info()->IsStub());
     CodeStubInterfaceDescriptor* descriptor =
         info()->code_stub()->GetInterfaceDescriptor(info()->isolate());
-    Register reg = descriptor->register_params_[instr->index()];
+    Register reg;

[danno, 2013/04/08 12:57:27]

unrelated change?

[mvstanton, 2013/04/08 16:10:14]

Yep, removed

+    if (static_cast<int>(instr->index()) == descriptor->register_param_count_) {
+      reg = *(descriptor->stack_parameter_count_);
+    } else {
+      reg = descriptor->register_params_[instr->index()];
+    }
     return DefineFixed(result, reg);
   }
 }
 
 
 LInstruction* LChunkBuilder::DoUnknownOSRValue(HUnknownOSRValue* instr) {
   int spill_index = chunk()->GetNextSpillIndex(false);  // Not double-width.
   if (spill_index > LUnallocated::kMaxFixedIndex) {
     Abort("Too many spill slots needed for OSR");
     spill_index = 0;
@@ skipping 14 matching lines @@
   // There are no real uses of the arguments object.
   // arguments.length and element access are supported directly on
   // stack arguments, and any real arguments object use causes a bailout.
   // So this value is never used.
   return NULL;
 }
 
 
 LInstruction* LChunkBuilder::DoAccessArgumentsAt(HAccessArgumentsAt* instr) {
   LOperand* args = UseRegister(instr->arguments());
-  LOperand* length = UseTempRegister(instr->length());
-  LOperand* index = Use(instr->index());
+  LOperand* length;

[danno, 2013/04/08 12:57:27]

unrelated change?

[mvstanton, 2013/04/08 16:10:14]

Indeed, thx.

+  LOperand* index;
+  if (instr->length()->IsConstant() && instr->index()->IsConstant()) {
+    length = UseRegisterOrConstant(instr->length());
+    index = UseOrConstant(instr->index());
+  } else {
+    length = UseTempRegister(instr->length());
+    index = Use(instr->index());
+  }
   return DefineAsRegister(new(zone()) LAccessArgumentsAt(args, length, index));
 }
 
 
 LInstruction* LChunkBuilder::DoToFastProperties(HToFastProperties* instr) {
   LOperand* object = UseFixed(instr->value(), eax);
   LToFastProperties* result = new(zone()) LToFastProperties(object);
   return MarkAsCall(DefineFixed(result, eax), instr);
 }
 
@@ skipping 137 matching lines @@
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseTempRegister(instr->index());
   return DefineSameAsFirst(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32