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 <string.h> // for memcpy() 12 13// Miscellany used by SkJumper_stages.cpp and SkJumper_stages_lowp.cpp. 14 15// Every function in this file should be marked static and inline using SI. 16#if defined(__clang__) 17 #define SI __attribute__((always_inline)) static inline 18#else 19 #define SI static inline 20#endif 21 22 23template <typename T, typename P> 24SI 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 30template <typename T, typename P> 31SI void unaligned_store(P* p, T v) { 32 memcpy(p, &v, sizeof(v)); 33} 34 35template <typename Dst, typename Src> 36SI Dst bit_cast(const Src& src) { 37 static_assert(sizeof(Dst) == sizeof(Src), ""); 38 return unaligned_load<Dst>(&src); 39} 40 41template <typename Dst, typename Src> 42SI 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. 54SI 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// Lazily resolved on first cast. Does nothing if cast to Ctx::None. 67struct Ctx { 68 struct None {}; 69 70 void* ptr; 71 void**& program; 72 73 explicit Ctx(void**& p) : ptr(nullptr), program(p) {} 74 75 template <typename T> 76 operator T*() { 77 if (!ptr) { ptr = load_and_inc(program); } 78 return (T*)ptr; 79 } 80 operator None() { return None{}; } 81}; 82 83#endif//SkJumper_misc_DEFINED 84