/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2023 Google LLC.
*/
#ifndef __UNROLL_H
#define __UNROLL_H
#include <linux/args.h>
#ifdef CONFIG_CC_IS_CLANG
#define __pick_unrolled(x, y) _Pragma(#x)
#else
#define __pick_unrolled(x, y) _Pragma(#y)
#endif
/**
* unrolled - loop attributes to ask the compiler to unroll it
*
* Usage:
*
* #define BATCH 8
*
* unrolled_count(BATCH)
* for (u32 i = 0; i < BATCH; i++)
* // loop body without cross-iteration dependencies
*
* This is only a hint and the compiler is free to disable unrolling if it
* thinks the count is suboptimal and may hurt performance and/or hugely
* increase object code size.
* Not having any cross-iteration dependencies (i.e. when iter x + 1 depends
* on what iter x will do with variables) is not a strict requirement, but
* provides best performance and object code size.
* Available only on Clang and GCC 8.x onwards.
*/
/* Ask the compiler to pick an optimal unroll count, Clang only */
#define unrolled \
__pick_unrolled(clang loop unroll(enable), /* nothing */)
/* Unroll each @n iterations of the loop */
#define unrolled_count(n) \
__pick_unrolled(clang loop unroll_count(n), GCC unroll n)
/* Unroll the whole loop */
#define unrolled_full \
__pick_unrolled(clang loop unroll(full), GCC unroll 65534)
/* Never unroll the loop */
#define unrolled_none \
__pick_unrolled(clang loop unroll(disable), GCC unroll 1)
#define UNROLL(N, MACRO, args...) CONCATENATE(__UNROLL_, N)(MACRO, args)
#define __UNROLL_0(MACRO, args...)
#define __UNROLL_1(MACRO, args...) __UNROLL_0(MACRO, args) MACRO(0, args)
#define __UNROLL_2(MACRO, args...) __UNROLL_1(MACRO, args) MACRO(1, args)
#define __UNROLL_3(MACRO, args...) __UNROLL_2(MACRO, args) MACRO(2, args)
#define __UNROLL_4(MACRO, args...) __UNROLL_3(MACRO, args) MACRO(3, args)
#define __UNROLL_5(MACRO, args...) __UNROLL_4(MACRO, args) MACRO(4, args)
#define __UNROLL_6(MACRO, args...) __UNROLL_5(MACRO, args) MACRO(5, args)
#define __UNROLL_7(MACRO, args...) __UNROLL_6(MACRO, args) MACRO(6, args)
#define __UNROLL_8(MACRO, args...) __UNROLL_7(MACRO, args) MACRO(7, args)
#define __UNROLL_9(MACRO, args...) __UNROLL_8(MACRO, args) MACRO(8, args)
#define __UNROLL_10(MACRO, args...) __UNROLL_9(MACRO, args) MACRO(9, args)
#define __UNROLL_11(MACRO, args...) __UNROLL_10(MACRO, args) MACRO(10, args)
#define __UNROLL_12(MACRO, args...) __UNROLL_11(MACRO, args) MACRO(11, args)
#define __UNROLL_13(MACRO, args...) __UNROLL_12(MACRO, args) MACRO(12, args)
#define __UNROLL_14(MACRO, args...) __UNROLL_13(MACRO, args) MACRO(13, args)
#define __UNROLL_15(MACRO, args...) __UNROLL_14(MACRO, args) MACRO(14, args)
#define __UNROLL_16(MACRO, args...) __UNROLL_15(MACRO, args) MACRO(15, args)
#define __UNROLL_17(MACRO, args...) __UNROLL_16(MACRO, args) MACRO(16, args)
#define __UNROLL_18(MACRO, args...) __UNROLL_17(MACRO, args) MACRO(17, args)
#define __UNROLL_19(MACRO, args...) __UNROLL_18(MACRO, args) MACRO(18, args)
#define __UNROLL_20(MACRO, args...) __UNROLL_19(MACRO, args) MACRO(19, args)
#endif /* __UNROLL_H */
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