[crankshaft] Fragmentation-free allocation folding.

src/mips64/macro-assembler-mips64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <limits.h>  // For LONG_MIN, LONG_MAX.
 
 #if V8_TARGET_ARCH_MIPS64
 
 #include "src/base/division-by-constant.h"
 #include "src/bootstrapper.h"
@@ skipping 4312 matching lines @@
 
   if (emit_debug_code()) {
     And(at, result, Operand(kDoubleAlignmentMask));
     Check(eq, kAllocationIsNotDoubleAligned, at, Operand(zero_reg));
   }
 
   // Calculate new top and bail out if new space is exhausted. Use result
   // to calculate the new top.
   Daddu(result_end, result, Operand(object_size));
   Branch(gc_required, Ugreater, result_end, Operand(alloc_limit));
-  sd(result_end, MemOperand(top_address));
+
+  if ((flags & ALLOCATION_FOLDING_DOMINATOR) == 0) {
+    // The top pointer is not updated for allocation folding dominators.
+    sd(result_end, MemOperand(top_address));
+  }
 
   // Tag object.
   Daddu(result, result, Operand(kHeapObjectTag));
 }
 
 
 void MacroAssembler::Allocate(Register object_size, Register result,
                               Register result_end, Register scratch,
                               Label* gc_required, AllocationFlags flags) {
   if (!FLAG_inline_new) {
@@ skipping 52 matching lines @@
   }
 
   // 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) {
     Dlsa(result_end, result, object_size, kPointerSizeLog2);
   } else {
     Daddu(result_end, result, Operand(object_size));
   }
+
   Branch(gc_required, Ugreater, result_end, Operand(alloc_limit));
 
   // Update allocation top. result temporarily holds the new top.
   if (emit_debug_code()) {
     And(at, result_end, Operand(kObjectAlignmentMask));
     Check(eq, kUnalignedAllocationInNewSpace, at, Operand(zero_reg));
   }
-  sd(result_end, MemOperand(top_address));
+
+  if ((flags & ALLOCATION_FOLDING_DOMINATOR) == 0) {
+    // The top pointer is not updated for allocation folding dominators.
+    sd(result_end, MemOperand(top_address));
+  }
 
   // Tag object if.
   Daddu(result, result, Operand(kHeapObjectTag));
 }
 
+void MacroAssembler::FastAllocate(int object_size, Register result,
+                                  Register scratch1, Register scratch2,
+                                  AllocationFlags flags) {
+  DCHECK(object_size <= Page::kMaxRegularHeapObjectSize);
+  DCHECK(!AreAliased(result, scratch1, scratch2, at));
+
+  // Make object size into bytes.
+  if ((flags & SIZE_IN_WORDS) != 0) {
+    object_size *= kPointerSize;
+  }
+  DCHECK(0 == (object_size & kObjectAlignmentMask));
+
+  ExternalReference allocation_top =
+      AllocationUtils::GetAllocationTopReference(isolate(), flags);
+
+  Register top_address = scratch1;
+  Register result_end = scratch2;
+  li(top_address, Operand(allocation_top));
+  ld(result, MemOperand(top_address));
+
+  // We can ignore DOUBLE_ALIGNMENT flags here because doubles and pointers have
+  // the same alignment on ARM64.

[Michael Lippautz, 2016/05/10 09:04:10]

s/ARM64/MIPS64/

[Hannes Payer (out of office), 2016/05/10 09:10:59]

Done.

+  STATIC_ASSERT(kPointerAlignment == kDoubleAlignment);
+
+  if (emit_debug_code()) {
+    And(at, result, Operand(kDoubleAlignmentMask));
+    Check(eq, kAllocationIsNotDoubleAligned, at, Operand(zero_reg));
+  }
+
+  // Calculate new top and write it back.
+  Daddu(result_end, result, Operand(object_size));
+  sd(result_end, MemOperand(top_address));
+
+  Daddu(result, result, Operand(kHeapObjectTag));
+}
+
+void MacroAssembler::FastAllocate(Register object_size, Register result,
+                                  Register result_end, Register scratch,
+                                  AllocationFlags flags) {
+  // |object_size| and |result_end| may overlap, other registers must not.
+  DCHECK(!AreAliased(object_size, result, scratch, at));
+  DCHECK(!AreAliased(result_end, result, scratch, at));
+
+  ExternalReference allocation_top =
+      AllocationUtils::GetAllocationTopReference(isolate(), flags);
+
+  // Set up allocation top address and object size registers.
+  Register top_address = scratch;
+  li(top_address, Operand(allocation_top));
+  ld(result, MemOperand(top_address));
+
+  // We can ignore DOUBLE_ALIGNMENT flags here because doubles and pointers have
+  // the same alignment on ARM64.

[Michael Lippautz, 2016/05/10 09:04:10]

s/ARM64/MIPS64/

[Hannes Payer (out of office), 2016/05/10 09:10:59]

Done.

+  STATIC_ASSERT(kPointerAlignment == kDoubleAlignment);
+
+  if (emit_debug_code()) {
+    And(at, result, Operand(kDoubleAlignmentMask));
+    Check(eq, kAllocationIsNotDoubleAligned, at, Operand(zero_reg));
+  }
+
+  // Calculate new top and write it back
+  if ((flags & SIZE_IN_WORDS) != 0) {
+    Dlsa(result_end, result, object_size, kPointerSizeLog2);
+  } else {
+    Daddu(result_end, result, Operand(object_size));
+  }
+
+  // Update allocation top. result temporarily holds the new top.
+  if (emit_debug_code()) {
+    And(at, result_end, Operand(kObjectAlignmentMask));
+    Check(eq, kUnalignedAllocationInNewSpace, at, Operand(zero_reg));
+  }
+
+  Daddu(result, result, Operand(kHeapObjectTag));
+}
 
 void MacroAssembler::AllocateTwoByteString(Register result,
                                            Register length,
                                            Register scratch1,
                                            Register scratch2,
                                            Register scratch3,
                                            Label* gc_required) {
   // Calculate the number of bytes needed for the characters in the string while
   // observing object alignment.
   DCHECK((SeqTwoByteString::kHeaderSize & kObjectAlignmentMask) == 0);
@@ skipping 2628 matching lines @@
   if (mag.shift > 0) sra(result, result, mag.shift);
   srl(at, dividend, 31);
   Addu(result, result, Operand(at));
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS64