| // Copyright 2018 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. |
| |
| #ifndef V8_COMMON_PTR_COMPR_INL_H_ |
| #define V8_COMMON_PTR_COMPR_INL_H_ |
| |
| #include "include/v8-internal.h" |
| #include "src/common/ptr-compr.h" |
| #include "src/execution/isolate.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| #if V8_TARGET_ARCH_64_BIT |
| // Compresses full-pointer representation of a tagged value to on-heap |
| // representation. |
| V8_INLINE Tagged_t CompressTagged(Address tagged) { |
| return static_cast<Tagged_t>(static_cast<uint32_t>(tagged)); |
| } |
| |
| // Calculates isolate root value from any on-heap address. |
| template <typename TOnHeapAddress> |
| V8_INLINE Address GetIsolateRoot(TOnHeapAddress on_heap_addr); |
| |
| template <> |
| V8_INLINE Address GetIsolateRoot<Address>(Address on_heap_addr) { |
| // We subtract 1 here in order to let the compiler generate addition of 32-bit |
| // signed constant instead of 64-bit constant (the problem is that 2Gb looks |
| // like a negative 32-bit value). It's correct because we will never use |
| // leftmost address of V8 heap as |on_heap_addr|. |
| return RoundDown<kPtrComprIsolateRootAlignment>(on_heap_addr + |
| kPtrComprIsolateRootBias - 1); |
| } |
| |
| template <> |
| V8_INLINE Address GetIsolateRoot<Isolate*>(Isolate* isolate) { |
| return isolate->isolate_root(); |
| } |
| |
| // Decompresses smi value. |
| V8_INLINE Address DecompressTaggedSigned(Tagged_t raw_value) { |
| // For runtime code the upper 32-bits of the Smi value do not matter. |
| return static_cast<Address>(raw_value); |
| } |
| |
| // Decompresses weak or strong heap object pointer or forwarding pointer, |
| // preserving both weak- and smi- tags. |
| template <typename TOnHeapAddress> |
| V8_INLINE Address DecompressTaggedPointer(TOnHeapAddress on_heap_addr, |
| Tagged_t raw_value) { |
| // Current compression scheme requires |raw_value| to be sign-extended |
| // from int32_t to intptr_t. |
| intptr_t value = static_cast<intptr_t>(static_cast<int32_t>(raw_value)); |
| Address root = GetIsolateRoot(on_heap_addr); |
| return root + static_cast<Address>(value); |
| } |
| |
| // Decompresses any tagged value, preserving both weak- and smi- tags. |
| template <typename TOnHeapAddress> |
| V8_INLINE Address DecompressTaggedAny(TOnHeapAddress on_heap_addr, |
| Tagged_t raw_value) { |
| if (kUseBranchlessPtrDecompressionInRuntime) { |
| // Current compression scheme requires |raw_value| to be sign-extended |
| // from int32_t to intptr_t. |
| intptr_t value = static_cast<intptr_t>(static_cast<int32_t>(raw_value)); |
| // |root_mask| is 0 if the |value| was a smi or -1 otherwise. |
| Address root_mask = static_cast<Address>(-(value & kSmiTagMask)); |
| Address root_or_zero = root_mask & GetIsolateRoot(on_heap_addr); |
| return root_or_zero + static_cast<Address>(value); |
| } else { |
| return HAS_SMI_TAG(raw_value) |
| ? DecompressTaggedSigned(raw_value) |
| : DecompressTaggedPointer(on_heap_addr, raw_value); |
| } |
| } |
| |
| #ifdef V8_COMPRESS_POINTERS |
| |
| STATIC_ASSERT(kPtrComprHeapReservationSize == |
| Internals::kPtrComprHeapReservationSize); |
| STATIC_ASSERT(kPtrComprIsolateRootBias == Internals::kPtrComprIsolateRootBias); |
| STATIC_ASSERT(kPtrComprIsolateRootAlignment == |
| Internals::kPtrComprIsolateRootAlignment); |
| |
| #endif // V8_COMPRESS_POINTERS |
| |
| #else |
| |
| V8_INLINE Tagged_t CompressTagged(Address tagged) { UNREACHABLE(); } |
| |
| V8_INLINE Address DecompressTaggedSigned(Tagged_t raw_value) { UNREACHABLE(); } |
| |
| template <typename TOnHeapAddress> |
| V8_INLINE Address DecompressTaggedPointer(TOnHeapAddress on_heap_addr, |
| Tagged_t raw_value) { |
| UNREACHABLE(); |
| } |
| |
| template <typename TOnHeapAddress> |
| V8_INLINE Address DecompressTaggedAny(TOnHeapAddress on_heap_addr, |
| Tagged_t raw_value) { |
| UNREACHABLE(); |
| } |
| |
| #endif // V8_TARGET_ARCH_64_BIT |
| } // namespace internal |
| } // namespace v8 |
| |
| #endif // V8_COMMON_PTR_COMPR_INL_H_ |