Change store buffer overflow check to not rely on the store buffer being (2*Size) aligned.

This reduces the reserved virtual memory size needed for the store buffer.

BUG=chromium:578883
LOG=NO

Review URL: https://codereview.chromium.org/1851473002

Cr-Commit-Position: refs/heads/master@{#35174}

src/arm/macro-assembler-arm.cc

@@ -738,12 +738,12 @@ void MacroAssembler::RememberedSetHelper(Register object,  // For debug tests.
   str(scratch, MemOperand(ip));
   // Call stub on end of buffer.
   // Check for end of buffer.
-  tst(scratch, Operand(StoreBuffer::kStoreBufferOverflowBit));
+  tst(scratch, Operand(StoreBuffer::kStoreBufferMask));
   if (and_then == kFallThroughAtEnd) {
-    b(eq, &done);
+    b(ne, &done);
   } else {
     DCHECK(and_then == kReturnAtEnd);
-    Ret(eq);
+    Ret(ne);
   }
   push(lr);
   StoreBufferOverflowStub store_buffer_overflow(isolate(), fp_mode);

src/arm64/macro-assembler-arm64.cc

@@ -4032,13 +4032,12 @@ void MacroAssembler::RememberedSetHelper(Register object,  // For debug tests.
   Str(scratch1, MemOperand(scratch2));
   // Call stub on end of buffer.
   // Check for end of buffer.
-  DCHECK(StoreBuffer::kStoreBufferOverflowBit ==
-         (1 << (14 + kPointerSizeLog2)));
+  Tst(scratch1, StoreBuffer::kStoreBufferMask);
   if (and_then == kFallThroughAtEnd) {
-    Tbz(scratch1, (14 + kPointerSizeLog2), &done);
+    B(ne, &done);
   } else {
     DCHECK(and_then == kReturnAtEnd);
-    Tbnz(scratch1, (14 + kPointerSizeLog2), &store_buffer_overflow);
+    B(eq, &store_buffer_overflow);
     Ret();
   }
 

src/heap/store-buffer.cc

@@ -26,11 +26,10 @@ void StoreBuffer::SetUp() {
   // Allocate 3x the buffer size, so that we can start the new store buffer
   // aligned to 2x the size.  This lets us use a bit test to detect the end of
   // the area.
-  virtual_memory_ = new base::VirtualMemory(kStoreBufferSize * 3);
+  virtual_memory_ = new base::VirtualMemory(kStoreBufferSize * 2);
   uintptr_t start_as_int =
       reinterpret_cast<uintptr_t>(virtual_memory_->address());
-  start_ =
-      reinterpret_cast<Address*>(RoundUp(start_as_int, kStoreBufferSize * 2));
+  start_ = reinterpret_cast<Address*>(RoundUp(start_as_int, kStoreBufferSize));
   limit_ = start_ + (kStoreBufferSize / kPointerSize);
 
   DCHECK(reinterpret_cast<Address>(start_) >= virtual_memory_->address());
@@ -41,9 +40,7 @@ void StoreBuffer::SetUp() {
   DCHECK(start_ <= vm_limit);
   DCHECK(limit_ <= vm_limit);
   USE(vm_limit);
-  DCHECK((reinterpret_cast<uintptr_t>(limit_) & kStoreBufferOverflowBit) != 0);
-  DCHECK((reinterpret_cast<uintptr_t>(limit_ - 1) & kStoreBufferOverflowBit) ==
-         0);
+  DCHECK((reinterpret_cast<uintptr_t>(limit_) & kStoreBufferMask) == 0);
 
   if (!virtual_memory_->Commit(reinterpret_cast<Address>(start_),
                                kStoreBufferSize,

src/heap/store-buffer.h

@@ -18,9 +18,8 @@ namespace internal {
 // code. On buffer overflow the slots are moved to the remembered set.
 class StoreBuffer {
  public:
-  static const int kStoreBufferOverflowBit = 1 << (14 + kPointerSizeLog2);
-  static const int kStoreBufferSize = kStoreBufferOverflowBit;
-  static const int kStoreBufferLength = kStoreBufferSize / sizeof(Address);
+  static const int kStoreBufferSize = 1 << (14 + kPointerSizeLog2);
+  static const int kStoreBufferMask = kStoreBufferSize - 1;
 
   static void StoreBufferOverflow(Isolate* isolate);
 

src/ia32/macro-assembler-ia32.cc

@@ -204,15 +204,15 @@ void MacroAssembler::RememberedSetHelper(
   mov(Operand::StaticVariable(store_buffer), scratch);
   // Call stub on end of buffer.
   // Check for end of buffer.
-  test(scratch, Immediate(StoreBuffer::kStoreBufferOverflowBit));
+  test(scratch, Immediate(StoreBuffer::kStoreBufferMask));
   if (and_then == kReturnAtEnd) {
     Label buffer_overflowed;
-    j(not_equal, &buffer_overflowed, Label::kNear);
+    j(equal, &buffer_overflowed, Label::kNear);
     ret(0);
     bind(&buffer_overflowed);
   } else {
     DCHECK(and_then == kFallThroughAtEnd);
-    j(equal, &done, Label::kNear);
+    j(not_equal, &done, Label::kNear);
   }
   StoreBufferOverflowStub store_buffer_overflow(isolate(), save_fp);
   CallStub(&store_buffer_overflow);

src/mips/macro-assembler-mips.cc

@@ -482,12 +482,12 @@ void MacroAssembler::RememberedSetHelper(Register object,  // For debug tests.
   sw(scratch, MemOperand(t8));
   // Call stub on end of buffer.
   // Check for end of buffer.
-  And(t8, scratch, Operand(StoreBuffer::kStoreBufferOverflowBit));
+  And(t8, scratch, Operand(StoreBuffer::kStoreBufferMask));
   if (and_then == kFallThroughAtEnd) {
-    Branch(&done, eq, t8, Operand(zero_reg));
+    Branch(&done, ne, t8, Operand(zero_reg));
   } else {
     DCHECK(and_then == kReturnAtEnd);
-    Ret(eq, t8, Operand(zero_reg));
+    Ret(ne, t8, Operand(zero_reg));
   }
   push(ra);
   StoreBufferOverflowStub store_buffer_overflow(isolate(), fp_mode);

src/mips64/macro-assembler-mips64.cc

@@ -485,13 +485,13 @@ void MacroAssembler::RememberedSetHelper(Register object,  // For debug tests.
   sd(scratch, MemOperand(t8));
   // Call stub on end of buffer.
   // Check for end of buffer.
-  And(t8, scratch, Operand(StoreBuffer::kStoreBufferOverflowBit));
+  And(t8, scratch, Operand(StoreBuffer::kStoreBufferMask));
   DCHECK(!scratch.is(t8));
   if (and_then == kFallThroughAtEnd) {
-    Branch(&done, eq, t8, Operand(zero_reg));
+    Branch(&done, ne, t8, Operand(zero_reg));
   } else {
     DCHECK(and_then == kReturnAtEnd);
-    Ret(eq, t8, Operand(zero_reg));
+    Ret(ne, t8, Operand(zero_reg));
   }
   push(ra);
   StoreBufferOverflowStub store_buffer_overflow(isolate(), fp_mode);

src/ppc/macro-assembler-ppc.cc

@@ -570,14 +570,14 @@ void MacroAssembler::RememberedSetHelper(Register object,  // For debug tests.
   StoreP(scratch, MemOperand(ip));
   // Call stub on end of buffer.
   // Check for end of buffer.
-  mov(r0, Operand(StoreBuffer::kStoreBufferOverflowBit));
+  mov(r0, Operand(StoreBuffer::kStoreBufferMask));
   and_(r0, scratch, r0, SetRC);
 
   if (and_then == kFallThroughAtEnd) {
-    beq(&done, cr0);
+    bne(&done, cr0);
   } else {
     DCHECK(and_then == kReturnAtEnd);
-    Ret(eq, cr0);
+    Ret(ne, cr0);
   }
   mflr(r0);
   push(r0);

src/s390/macro-assembler-s390.cc

@@ -540,13 +540,13 @@ void MacroAssembler::RememberedSetHelper(Register object,  // For debug tests.
   StoreP(scratch, MemOperand(ip));
   // Call stub on end of buffer.
   // Check for end of buffer.
-  AndP(scratch, Operand(StoreBuffer::kStoreBufferOverflowBit));
+  AndP(scratch, Operand(StoreBuffer::kStoreBufferMask));
 
   if (and_then == kFallThroughAtEnd) {
-    beq(&done, Label::kNear);
+    bne(&done, Label::kNear);
   } else {
     DCHECK(and_then == kReturnAtEnd);
-    beq(&done, Label::kNear);
+    bne(&done, Label::kNear);
   }
   push(r14);
   StoreBufferOverflowStub store_buffer_overflow(isolate(), fp_mode);

src/x64/macro-assembler-x64.cc

@@ -227,15 +227,15 @@ void MacroAssembler::RememberedSetHelper(Register object,  // For debug tests.
   // Call stub on end of buffer.
   Label done;
   // Check for end of buffer.
-  testp(scratch, Immediate(StoreBuffer::kStoreBufferOverflowBit));
+  testp(scratch, Immediate(StoreBuffer::kStoreBufferMask));
   if (and_then == kReturnAtEnd) {
     Label buffer_overflowed;
-    j(not_equal, &buffer_overflowed, Label::kNear);
+    j(equal, &buffer_overflowed, Label::kNear);
     ret(0);
     bind(&buffer_overflowed);
   } else {
     DCHECK(and_then == kFallThroughAtEnd);
-    j(equal, &done, Label::kNear);
+    j(not_equal, &done, Label::kNear);
   }
   StoreBufferOverflowStub store_buffer_overflow(isolate(), save_fp);
   CallStub(&store_buffer_overflow);

src/x87/macro-assembler-x87.cc

@@ -196,15 +196,15 @@ void MacroAssembler::RememberedSetHelper(
   mov(Operand::StaticVariable(store_buffer), scratch);
   // Call stub on end of buffer.
   // Check for end of buffer.
-  test(scratch, Immediate(StoreBuffer::kStoreBufferOverflowBit));
+  test(scratch, Immediate(StoreBuffer::kStoreBufferMask));
   if (and_then == kReturnAtEnd) {
     Label buffer_overflowed;
-    j(not_equal, &buffer_overflowed, Label::kNear);
+    j(equal, &buffer_overflowed, Label::kNear);
     ret(0);
     bind(&buffer_overflowed);
   } else {
     DCHECK(and_then == kFallThroughAtEnd);
-    j(equal, &done, Label::kNear);
+    j(not_equal, &done, Label::kNear);
   }
   StoreBufferOverflowStub store_buffer_overflow(isolate(), save_fp);
   CallStub(&store_buffer_overflow);