1 /* SPDX-License-Identifier: GPL-2.0 */ 2 3 /* 4 * Copyright (C) 2023 Google LLC. 5 */ 6 7 #ifndef __UNROLL_H 8 #define __UNROLL_H 9 10 #include <linux/args.h> 11 12 #ifdef CONFIG_CC_IS_CLANG 13 #define __pick_unrolled(x, y) _Pragma(#x) 14 #else 15 #define __pick_unrolled(x, y) _Pragma(#y) 16 #endif 17 18 /** 19 * unrolled - loop attributes to ask the compiler to unroll it 20 * 21 * Usage: 22 * 23 * #define BATCH 8 24 * 25 * unrolled_count(BATCH) 26 * for (u32 i = 0; i < BATCH; i++) 27 * // loop body without cross-iteration dependencies 28 * 29 * This is only a hint and the compiler is free to disable unrolling if it 30 * thinks the count is suboptimal and may hurt performance and/or hugely 31 * increase object code size. 32 * Not having any cross-iteration dependencies (i.e. when iter x + 1 depends 33 * on what iter x will do with variables) is not a strict requirement, but 34 * provides best performance and object code size. 35 * Available only on Clang and GCC 8.x onwards. 36 */ 37 38 /* Ask the compiler to pick an optimal unroll count, Clang only */ 39 #define unrolled \ 40 __pick_unrolled(clang loop unroll(enable), /* nothing */) 41 42 /* Unroll each @n iterations of the loop */ 43 #define unrolled_count(n) \ 44 __pick_unrolled(clang loop unroll_count(n), GCC unroll n) 45 46 /* Unroll the whole loop */ 47 #define unrolled_full \ 48 __pick_unrolled(clang loop unroll(full), GCC unroll 65534) 49 50 /* Never unroll the loop */ 51 #define unrolled_none \ 52 __pick_unrolled(clang loop unroll(disable), GCC unroll 1) 53 54 #define UNROLL(N, MACRO, args...) CONCATENATE(__UNROLL_, N)(MACRO, args) 55 56 #define __UNROLL_0(MACRO, args...) 57 #define __UNROLL_1(MACRO, args...) __UNROLL_0(MACRO, args) MACRO(0, args) 58 #define __UNROLL_2(MACRO, args...) __UNROLL_1(MACRO, args) MACRO(1, args) 59 #define __UNROLL_3(MACRO, args...) __UNROLL_2(MACRO, args) MACRO(2, args) 60 #define __UNROLL_4(MACRO, args...) __UNROLL_3(MACRO, args) MACRO(3, args) 61 #define __UNROLL_5(MACRO, args...) __UNROLL_4(MACRO, args) MACRO(4, args) 62 #define __UNROLL_6(MACRO, args...) __UNROLL_5(MACRO, args) MACRO(5, args) 63 #define __UNROLL_7(MACRO, args...) __UNROLL_6(MACRO, args) MACRO(6, args) 64 #define __UNROLL_8(MACRO, args...) __UNROLL_7(MACRO, args) MACRO(7, args) 65 #define __UNROLL_9(MACRO, args...) __UNROLL_8(MACRO, args) MACRO(8, args) 66 #define __UNROLL_10(MACRO, args...) __UNROLL_9(MACRO, args) MACRO(9, args) 67 #define __UNROLL_11(MACRO, args...) __UNROLL_10(MACRO, args) MACRO(10, args) 68 #define __UNROLL_12(MACRO, args...) __UNROLL_11(MACRO, args) MACRO(11, args) 69 #define __UNROLL_13(MACRO, args...) __UNROLL_12(MACRO, args) MACRO(12, args) 70 #define __UNROLL_14(MACRO, args...) __UNROLL_13(MACRO, args) MACRO(13, args) 71 #define __UNROLL_15(MACRO, args...) __UNROLL_14(MACRO, args) MACRO(14, args) 72 #define __UNROLL_16(MACRO, args...) __UNROLL_15(MACRO, args) MACRO(15, args) 73 #define __UNROLL_17(MACRO, args...) __UNROLL_16(MACRO, args) MACRO(16, args) 74 #define __UNROLL_18(MACRO, args...) __UNROLL_17(MACRO, args) MACRO(17, args) 75 #define __UNROLL_19(MACRO, args...) __UNROLL_18(MACRO, args) MACRO(18, args) 76 #define __UNROLL_20(MACRO, args...) __UNROLL_19(MACRO, args) MACRO(19, args) 77 78 #endif /* __UNROLL_H */ 79