MIPS: Refactor and improve inlined double-aligned allocations

src/mips/macro-assembler-mips.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 2905 matching lines @@
       AllocationUtils::GetAllocationLimitReference(isolate(), flags);
 
   intptr_t top   =
       reinterpret_cast<intptr_t>(allocation_top.address());
   intptr_t limit =
       reinterpret_cast<intptr_t>(allocation_limit.address());
   ASSERT((limit - top) == kPointerSize);
 
   // 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) {
     // Load allocation top into result and allocation limit into t9.
     lw(result, MemOperand(topaddr));
     lw(t9, MemOperand(topaddr, kPointerSize));
   } else {
     if (emit_debug_code()) {
       // Assert that result actually contains top on entry. t9 is used
       // immediately below so this use of t9 does not cause difference with
       // respect to register content between debug and release mode.
       lw(t9, MemOperand(topaddr));
       Check(eq, kUnexpectedAllocationTop, result, Operand(t9));
     }
     // Load allocation limit into t9. Result already contains allocation top.
     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));
 
   // Tag object if requested.
   if ((flags & TAG_OBJECT) != 0) {
     Addu(result, result, Operand(kHeapObjectTag));
   }
 }
 
 
@@ skipping 47 matching lines @@
       // Assert that result actually contains top on entry. t9 is used
       // immediately below so this use of t9 does not cause difference with
       // respect to register content between debug and release mode.
       lw(t9, MemOperand(topaddr));
       Check(eq, kUnexpectedAllocationTop, result, Operand(t9));
     }
     // Load allocation limit into t9. Result already contains allocation top.
     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.
   if ((flags & SIZE_IN_WORDS) != 0) {
     sll(scratch2, object_size, kPointerSizeLog2);
     Addu(scratch2, result, scratch2);
   } else {
     Addu(scratch2, result, Operand(object_size));
   }
   Branch(gc_required, Ugreater, scratch2, Operand(t9));
@@ skipping 2542 matching lines @@
        opcode == BGTZL);
   opcode = (cond == eq) ? BEQ : BNE;
   instr = (instr & ~kOpcodeMask) | opcode;
   masm_.emit(instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS