1 /* 2 * Copyright 2017 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #ifndef SkJumper_misc_DEFINED 9 #define SkJumper_misc_DEFINED 10 11 #include "SkJumper.h" // for memcpy() 12 13 // Miscellany used by SkJumper_stages.cpp and SkJumper_vectors.h. 14 15 // Every function in this file should be marked static and inline using SI. 16 #if defined(JUMPER) 17 #define SI __attribute__((always_inline)) static inline 18 #else 19 #define SI static inline 20 #endif 21 22 23 template <typename T, typename P> 24 SI T unaligned_load(const P* p) { // const void* would work too, but const P* helps ARMv7 codegen. 25 T v; 26 memcpy(&v, p, sizeof(v)); 27 return v; 28 } 29 30 template <typename T, typename P> 31 SI void unaligned_store(P* p, T v) { 32 memcpy(p, &v, sizeof(v)); 33 } 34 35 template <typename Dst, typename Src> 36 SI Dst bit_cast(const Src& src) { 37 static_assert(sizeof(Dst) == sizeof(Src), ""); 38 return unaligned_load<Dst>(&src); 39 } 40 41 template <typename Dst, typename Src> 42 SI Dst widen_cast(const Src& src) { 43 static_assert(sizeof(Dst) > sizeof(Src), ""); 44 Dst dst; 45 memcpy(&dst, &src, sizeof(Src)); 46 return dst; 47 } 48 49 // Our program is an array of void*, either 50 // - 1 void* per stage with no context pointer, the next stage; 51 // - 2 void* per stage with a context pointer, first the context pointer, then the next stage. 52 53 // load_and_inc() steps the program forward by 1 void*, returning that pointer. 54 SI void* load_and_inc(void**& program) { 55 #if defined(__GNUC__) && defined(__x86_64__) 56 // If program is in %rsi (we try to make this likely) then this is a single instruction. 57 void* rax; 58 asm("lodsq" : "=a"(rax), "+S"(program)); // Write-only %rax, read-write %rsi. 59 return rax; 60 #else 61 // On ARM *program++ compiles into pretty ideal code without any handholding. 62 return *program++; 63 #endif 64 } 65 66 // LazyCtx doesn't do anything unless you call operator T*(), encapsulating the logic 67 // from above that stages without a context pointer are represented by just 1 void*. 68 struct LazyCtx { 69 void* ptr; 70 void**& program; 71 72 explicit LazyCtx(void**& p) : ptr(nullptr), program(p) {} 73 74 template <typename T> 75 operator T*() { 76 if (!ptr) { ptr = load_and_inc(program); } 77 return (T*)ptr; 78 } 79 }; 80 81 #endif//SkJumper_misc_DEFINED 82
