1 // Copyright 2014 the V8 project authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef V8_RUNTIME_RUNTIME_UTILS_H_ 6 #define V8_RUNTIME_RUNTIME_UTILS_H_ 7 8 #include "src/base/logging.h" 9 #include "src/common/globals.h" 10 #include "src/objects/objects.h" 11 #include "src/runtime/runtime.h" 12 13 namespace v8 { 14 namespace internal { 15 16 // A mechanism to return a pair of Object pointers in registers (if possible). 17 // How this is achieved is calling convention-dependent. 18 // All currently supported x86 compiles uses calling conventions that are cdecl 19 // variants where a 64-bit value is returned in two 32-bit registers 20 // (edx:eax on ia32, r1:r0 on ARM). 21 // In AMD-64 calling convention a struct of two pointers is returned in rdx:rax. 22 // In Win64 calling convention, a struct of two pointers is returned in memory, 23 // allocated by the caller, and passed as a pointer in a hidden first parameter. 24 #ifdef V8_HOST_ARCH_64_BIT 25 struct ObjectPair { 26 Address x; 27 Address y; 28 }; 29 MakePair(Object x, Object y)30static inline ObjectPair MakePair(Object x, Object y) { 31 ObjectPair result = {x.ptr(), y.ptr()}; 32 // Pointers x and y returned in rax and rdx, in AMD-x64-abi. 33 // In Win64 they are assigned to a hidden first argument. 34 return result; 35 } 36 #else 37 using ObjectPair = uint64_t; 38 static inline ObjectPair MakePair(Object x, Object y) { 39 #if defined(V8_TARGET_LITTLE_ENDIAN) 40 return x.ptr() | (static_cast<ObjectPair>(y.ptr()) << 32); 41 #elif defined(V8_TARGET_BIG_ENDIAN) 42 return y->ptr() | (static_cast<ObjectPair>(x->ptr()) << 32); 43 #else 44 #error Unknown endianness 45 #endif 46 } 47 #endif 48 49 } // namespace internal 50 } // namespace v8 51 52 #endif // V8_RUNTIME_RUNTIME_UTILS_H_ 53