MIPS: Reland and fix r21225 and r21226.

Port r21232 (5681b0b)

BUG=
R=plind44@gmail.com

Review URL: https://codereview.chromium.org/275973002

Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21240 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/full-codegen-mips.cc

@@ -3039,7 +3039,7 @@ void FullCodeGenerator::EmitIsStringWrapperSafeForDefaultValueOf(
   __ Addu(t0, t0, Operand(DescriptorArray::kFirstOffset - kHeapObjectTag));
   // Calculate the end of the descriptor array.
   __ mov(a2, t0);
-  __ sll(t1, a3, kPointerSizeLog2 - kSmiTagSize);
+  __ sll(t1, a3, kPointerSizeLog2);
   __ Addu(a2, a2, t1);
 
   // Loop through all the keys in the descriptor array. If one of these is the

src/mips/macro-assembler-mips.cc

@@ -5236,7 +5236,7 @@ void MacroAssembler::CheckMapDeprecated(Handle<Map> map,
   if (map->CanBeDeprecated()) {
     li(scratch, Operand(map));
     lw(scratch, FieldMemOperand(scratch, Map::kBitField3Offset));
-    And(scratch, scratch, Operand(Smi::FromInt(Map::Deprecated::kMask)));
+    And(scratch, scratch, Operand(Map::Deprecated::kMask));
     Branch(if_deprecated, ne, scratch, Operand(zero_reg));
   }
 }
@@ -5493,7 +5493,8 @@ void MacroAssembler::NumberOfOwnDescriptors(Register dst, Register map) {
 void MacroAssembler::EnumLength(Register dst, Register map) {
   STATIC_ASSERT(Map::EnumLengthBits::kShift == 0);
   lw(dst, FieldMemOperand(map, Map::kBitField3Offset));
-  And(dst, dst, Operand(Smi::FromInt(Map::EnumLengthBits::kMask)));
+  And(dst, dst, Operand(Map::EnumLengthBits::kMask));
+  SmiTag(dst);
 }
 
 

src/mips/macro-assembler-mips.h

@@ -1486,7 +1486,7 @@ const Operand& rt = Operand(zero_reg), BranchDelaySlot bd = PROTECT
   template<typename Field>
   void DecodeField(Register reg) {
     static const int shift = Field::kShift;
-    static const int mask = (Field::kMask >> shift) << kSmiTagSize;
+    static const int mask = Field::kMask >> shift;
     srl(reg, reg, shift);
     And(reg, reg, Operand(mask));
   }