MIPS: Refactor and improve inlined double-aligned allocations

Additionally, fix object size register clobbering in Allocate routine.

Based on 13284 (d42bf80).

BUG=
R=plind44@gmail.com

Review URL: https://codereview.chromium.org/22582002

Patch from Dusan Milosavljevic <Dusan.Milosavljevic@rt-rk.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16112 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/codegen-mips.cc

@@ -205,7 +205,7 @@ void ElementsTransitionGenerator::GenerateSmiToDouble(
   // Allocate new FixedDoubleArray.
   __ sll(scratch, t1, 2);
   __ Addu(scratch, scratch, FixedDoubleArray::kHeaderSize);
-  __ Allocate(scratch, t2, t3, t5, &gc_required, NO_ALLOCATION_FLAGS);
+  __ Allocate(scratch, t2, t3, t5, &gc_required, DOUBLE_ALIGNMENT);
   // t2: destination FixedDoubleArray, not tagged as heap object
 
   // Set destination FixedDoubleArray's length and map.

src/mips/macro-assembler-mips.cc

@@ -2923,9 +2923,7 @@ void MacroAssembler::Allocate(int object_size,
 
   // Set up allocation top address and object size registers.
   Register topaddr = scratch1;
-  Register obj_size_reg = scratch2;
   li(topaddr, Operand(allocation_top));
-  li(obj_size_reg, Operand(object_size));
 
   // This code stores a temporary value in t9.
   if ((flags & RESULT_CONTAINS_TOP) == 0) {
@@ -2944,9 +2942,23 @@ void MacroAssembler::Allocate(int object_size,
     lw(t9, MemOperand(topaddr, limit - top));
   }
 
+  if ((flags & DOUBLE_ALIGNMENT) != 0) {
+    // Align the next allocation. Storing the filler map without checking top is
+    // always safe because the limit of the heap is always aligned.
+    ASSERT((flags & PRETENURE_OLD_POINTER_SPACE) == 0);
+    ASSERT(kPointerAlignment * 2 == kDoubleAlignment);
+    And(scratch2, result, Operand(kDoubleAlignmentMask));
+    Label aligned;
+    Branch(&aligned, eq, scratch2, Operand(zero_reg));
+    li(scratch2, Operand(isolate()->factory()->one_pointer_filler_map()));
+    sw(scratch2, MemOperand(result));
+    Addu(result, result, Operand(kDoubleSize / 2));
+    bind(&aligned);
+  }
+
   // Calculate new top and bail out if new space is exhausted. Use result
   // to calculate the new top.
-  Addu(scratch2, result, Operand(obj_size_reg));
+  Addu(scratch2, result, Operand(object_size));
   Branch(gc_required, Ugreater, scratch2, Operand(t9));
   sw(scratch2, MemOperand(topaddr));
 
@@ -3014,6 +3026,20 @@ void MacroAssembler::Allocate(Register object_size,
     lw(t9, MemOperand(topaddr, limit - top));
   }
 
+  if ((flags & DOUBLE_ALIGNMENT) != 0) {
+    // Align the next allocation. Storing the filler map without checking top is
+    // always safe because the limit of the heap is always aligned.
+    ASSERT((flags & PRETENURE_OLD_POINTER_SPACE) == 0);
+    ASSERT(kPointerAlignment * 2 == kDoubleAlignment);
+    And(scratch2, result, Operand(kDoubleAlignmentMask));
+    Label aligned;
+    Branch(&aligned, eq, scratch2, Operand(zero_reg));
+    li(scratch2, Operand(isolate()->factory()->one_pointer_filler_map()));
+    sw(scratch2, MemOperand(result));
+    Addu(result, result, Operand(kDoubleSize / 2));
+    bind(&aligned);
+  }
+
   // Calculate new top and bail out if new space is exhausted. Use result
   // to calculate the new top. Object size may be in words so a shift is
   // required to get the number of bytes.

src/mips/macro-assembler-mips.h

@@ -51,20 +51,6 @@ class JumpTarget;
 // MIPS generated code calls C code, it must be via t9 register.
 
 
-// Flags used for the AllocateInNewSpace functions.
-enum AllocationFlags {
-  // No special flags.
-  NO_ALLOCATION_FLAGS = 0,
-  // Return the pointer to the allocated already tagged as a heap object.
-  TAG_OBJECT = 1 << 0,
-  // The content of the result register already contains the allocation top in
-  // new space.
-  RESULT_CONTAINS_TOP = 1 << 1,
-  // Specify that the requested size of the space to allocate is specified in
-  // words instead of bytes.
-  SIZE_IN_WORDS = 1 << 2
-};
-
 // Flags used for AllocateHeapNumber
 enum TaggingMode {
   // Tag the result.