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Diffstat (limited to 'boost/atomic/detail/ops_gcc_arm.hpp')
| -rw-r--r-- | boost/atomic/detail/ops_gcc_arm.hpp | 971 |
1 files changed, 971 insertions, 0 deletions
diff --git a/boost/atomic/detail/ops_gcc_arm.hpp b/boost/atomic/detail/ops_gcc_arm.hpp new file mode 100644 index 0000000000..29e1e5a319 --- /dev/null +++ b/boost/atomic/detail/ops_gcc_arm.hpp @@ -0,0 +1,971 @@ +/* + * Distributed under the Boost Software License, Version 1.0. + * (See accompanying file LICENSE_1_0.txt or copy at + * http://www.boost.org/LICENSE_1_0.txt) + * + * Copyright (c) 2009 Helge Bahmann + * Copyright (c) 2013 Tim Blechmann + * Copyright (c) 2014 Andrey Semashev + */ +/*! + * \file atomic/detail/ops_gcc_arm.hpp + * + * This header contains implementation of the \c operations template. + */ + +#ifndef BOOST_ATOMIC_DETAIL_OPS_GCC_ARM_HPP_INCLUDED_ +#define BOOST_ATOMIC_DETAIL_OPS_GCC_ARM_HPP_INCLUDED_ + +#include <boost/cstdint.hpp> +#include <boost/memory_order.hpp> +#include <boost/atomic/detail/config.hpp> +#include <boost/atomic/detail/storage_type.hpp> +#include <boost/atomic/detail/operations_fwd.hpp> +#include <boost/atomic/detail/ops_extending_cas_based.hpp> +#include <boost/atomic/capabilities.hpp> + +#ifdef BOOST_HAS_PRAGMA_ONCE +#pragma once +#endif + +namespace boost { +namespace atomics { +namespace detail { + +// From the ARM Architecture Reference Manual for architecture v6: +// +// LDREX{<cond>} <Rd>, [<Rn>] +// <Rd> Specifies the destination register for the memory word addressed by <Rd> +// <Rn> Specifies the register containing the address. +// +// STREX{<cond>} <Rd>, <Rm>, [<Rn>] +// <Rd> Specifies the destination register for the returned status value. +// 0 if the operation updates memory +// 1 if the operation fails to update memory +// <Rm> Specifies the register containing the word to be stored to memory. +// <Rn> Specifies the register containing the address. +// Rd must not be the same register as Rm or Rn. +// +// ARM v7 is like ARM v6 plus: +// There are half-word and byte versions of the LDREX and STREX instructions, +// LDREXH, LDREXB, STREXH and STREXB. +// There are also double-word versions, LDREXD and STREXD. +// (Actually it looks like these are available from version 6k onwards.) +// FIXME these are not yet used; should be mostly a matter of copy-and-paste. +// I think you can supply an immediate offset to the address. +// +// A memory barrier is effected using a "co-processor 15" instruction, +// though a separate assembler mnemonic is available for it in v7. +// +// "Thumb 1" is a subset of the ARM instruction set that uses a 16-bit encoding. It +// doesn't include all instructions and in particular it doesn't include the co-processor +// instruction used for the memory barrier or the load-locked/store-conditional +// instructions. So, if we're compiling in "Thumb 1" mode, we need to wrap all of our +// asm blocks with code to temporarily change to ARM mode. +// +// You can only change between ARM and Thumb modes when branching using the bx instruction. +// bx takes an address specified in a register. The least significant bit of the address +// indicates the mode, so 1 is added to indicate that the destination code is Thumb. +// A temporary register is needed for the address and is passed as an argument to these +// macros. It must be one of the "low" registers accessible to Thumb code, specified +// using the "l" attribute in the asm statement. +// +// Architecture v7 introduces "Thumb 2", which does include (almost?) all of the ARM +// instruction set. (Actually, there was an extension of v6 called v6T2 which supported +// "Thumb 2" mode, but its architecture manual is no longer available, referring to v7.) +// So in v7 we don't need to change to ARM mode; we can write "universal +// assembler" which will assemble to Thumb 2 or ARM code as appropriate. The only thing +// we need to do to make this "universal" assembler mode work is to insert "IT" instructions +// to annotate the conditional instructions. These are ignored in other modes (e.g. v6), +// so they can always be present. + +// A note about memory_order_consume. Technically, this architecture allows to avoid +// unnecessary memory barrier after consume load since it supports data dependency ordering. +// However, some compiler optimizations may break a seemingly valid code relying on data +// dependency tracking by injecting bogus branches to aid out of order execution. +// This may happen not only in Boost.Atomic code but also in user's code, which we have no +// control of. See this thread: http://lists.boost.org/Archives/boost/2014/06/213890.php. +// For this reason we promote memory_order_consume to memory_order_acquire. + +#if defined(__thumb__) && !defined(__thumb2__) +#define BOOST_ATOMIC_DETAIL_ARM_ASM_START(TMPREG) "adr " #TMPREG ", 8f\n" "bx " #TMPREG "\n" ".arm\n" ".align 4\n" "8:\n" +#define BOOST_ATOMIC_DETAIL_ARM_ASM_END(TMPREG) "adr " #TMPREG ", 9f + 1\n" "bx " #TMPREG "\n" ".thumb\n" ".align 2\n" "9:\n" +#define BOOST_ATOMIC_DETAIL_ARM_ASM_TMPREG_CONSTRAINT(var) "=&l" (var) +#else +// The tmpreg may be wasted in this case, which is non-optimal. +#define BOOST_ATOMIC_DETAIL_ARM_ASM_START(TMPREG) +#define BOOST_ATOMIC_DETAIL_ARM_ASM_END(TMPREG) +#define BOOST_ATOMIC_DETAIL_ARM_ASM_TMPREG_CONSTRAINT(var) "=&r" (var) +#endif + +struct gcc_arm_operations_base +{ + static BOOST_FORCEINLINE void fence_before(memory_order order) BOOST_NOEXCEPT + { + if ((order & memory_order_release) != 0) + hardware_full_fence(); + } + + static BOOST_FORCEINLINE void fence_after(memory_order order) BOOST_NOEXCEPT + { + if ((order & (memory_order_consume | memory_order_acquire)) != 0) + hardware_full_fence(); + } + + static BOOST_FORCEINLINE void fence_after_store(memory_order order) BOOST_NOEXCEPT + { + if (order == memory_order_seq_cst) + hardware_full_fence(); + } + + static BOOST_FORCEINLINE void hardware_full_fence() BOOST_NOEXCEPT + { +#if defined(BOOST_ATOMIC_DETAIL_ARM_HAS_DMB) + // Older binutils (supposedly, older than 2.21.1) didn't support symbolic or numeric arguments of the "dmb" instruction such as "ish" or "#11". + // As a workaround we have to inject encoded bytes of the instruction. There are two encodings for the instruction: ARM and Thumb. See ARM Architecture Reference Manual, A8.8.43. + // Since we cannot detect binutils version at compile time, we'll have to always use this hack. + __asm__ __volatile__ + ( +#if defined(__thumb2__) + ".short 0xF3BF, 0x8F5B\n" // dmb ish +#else + ".word 0xF57FF05B\n" // dmb ish +#endif + : + : + : "memory" + ); +#else + int tmp; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%0) + "mcr\tp15, 0, r0, c7, c10, 5\n" + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%0) + : "=&l" (tmp) + : + : "memory" + ); +#endif + } +}; + + +template< bool Signed > +struct operations< 4u, Signed > : + public gcc_arm_operations_base +{ + typedef typename make_storage_type< 4u, Signed >::type storage_type; + + static BOOST_FORCEINLINE void store(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + storage = v; + fence_after_store(order); + } + + static BOOST_FORCEINLINE storage_type load(storage_type const volatile& storage, memory_order order) BOOST_NOEXCEPT + { + storage_type v = storage; + fence_after(order); + return v; + } + + static BOOST_FORCEINLINE storage_type exchange(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + storage_type original; + fence_before(order); + uint32_t tmp; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "1:\n" + "ldrex %[original], %[storage]\n" // load the original value + "strex %[tmp], %[value], %[storage]\n" // store the replacement, tmp = store failed + "teq %[tmp], #0\n" // check if store succeeded + "bne 1b\n" + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [tmp] "=&l" (tmp), [original] "=&r" (original), [storage] "+Q" (storage) + : [value] "r" (v) + : "cc" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE bool compare_exchange_weak( + storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order success_order, memory_order failure_order) BOOST_NOEXCEPT + { + fence_before(success_order); + uint32_t success; + uint32_t tmp; + storage_type original; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "mov %[success], #0\n" // success = 0 + "ldrex %[original], %[storage]\n" // original = *(&storage) + "cmp %[original], %[expected]\n" // flags = original==expected + "itt eq\n" // [hint that the following 2 instructions are conditional on flags.equal] + "strexeq %[success], %[desired], %[storage]\n" // if (flags.equal) *(&storage) = desired, success = store failed + "eoreq %[success], %[success], #1\n" // if (flags.equal) success ^= 1 (i.e. make it 1 if store succeeded) + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [original] "=&r" (original), // %0 + [success] "=&r" (success), // %1 + [tmp] "=&l" (tmp), // %2 + [storage] "+Q" (storage) // %3 + : [expected] "r" (expected), // %4 + [desired] "r" (desired) // %5 + : "cc" + ); + if (success) + fence_after(success_order); + else + fence_after(failure_order); + expected = original; + return !!success; + } + + static BOOST_FORCEINLINE bool compare_exchange_strong( + storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order success_order, memory_order failure_order) BOOST_NOEXCEPT + { + fence_before(success_order); + uint32_t success; + uint32_t tmp; + storage_type original; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "mov %[success], #0\n" // success = 0 + "1:\n" + "ldrex %[original], %[storage]\n" // original = *(&storage) + "cmp %[original], %[expected]\n" // flags = original==expected + "bne 2f\n" // if (!flags.equal) goto end + "strex %[success], %[desired], %[storage]\n" // *(&storage) = desired, success = store failed + "eors %[success], %[success], #1\n" // success ^= 1 (i.e. make it 1 if store succeeded); flags.equal = success == 0 + "beq 1b\n" // if (flags.equal) goto retry + "2:\n" + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [original] "=&r" (original), // %0 + [success] "=&r" (success), // %1 + [tmp] "=&l" (tmp), // %2 + [storage] "+Q" (storage) // %3 + : [expected] "r" (expected), // %4 + [desired] "r" (desired) // %5 + : "cc" + ); + if (success) + fence_after(success_order); + else + fence_after(failure_order); + expected = original; + return !!success; + } + + static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + uint32_t tmp; + storage_type original, result; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "1:\n" + "ldrex %[original], %[storage]\n" // original = *(&storage) + "add %[result], %[original], %[value]\n" // result = original + value + "strex %[tmp], %[result], %[storage]\n" // *(&storage) = result, tmp = store failed + "teq %[tmp], #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [original] "=&r" (original), // %0 + [result] "=&r" (result), // %1 + [tmp] "=&l" (tmp), // %2 + [storage] "+Q" (storage) // %3 + : [value] "r" (v) // %4 + : "cc" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE storage_type fetch_sub(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + uint32_t tmp; + storage_type original, result; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "1:\n" + "ldrex %[original], %[storage]\n" // original = *(&storage) + "sub %[result], %[original], %[value]\n" // result = original - value + "strex %[tmp], %[result], %[storage]\n" // *(&storage) = result, tmp = store failed + "teq %[tmp], #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [original] "=&r" (original), // %0 + [result] "=&r" (result), // %1 + [tmp] "=&l" (tmp), // %2 + [storage] "+Q" (storage) // %3 + : [value] "r" (v) // %4 + : "cc" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE storage_type fetch_and(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + uint32_t tmp; + storage_type original, result; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "1:\n" + "ldrex %[original], %[storage]\n" // original = *(&storage) + "and %[result], %[original], %[value]\n" // result = original & value + "strex %[tmp], %[result], %[storage]\n" // *(&storage) = result, tmp = store failed + "teq %[tmp], #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [original] "=&r" (original), // %0 + [result] "=&r" (result), // %1 + [tmp] "=&l" (tmp), // %2 + [storage] "+Q" (storage) // %3 + : [value] "r" (v) // %4 + : "cc" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE storage_type fetch_or(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + uint32_t tmp; + storage_type original, result; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "1:\n" + "ldrex %[original], %[storage]\n" // original = *(&storage) + "orr %[result], %[original], %[value]\n" // result = original | value + "strex %[tmp], %[result], %[storage]\n" // *(&storage) = result, tmp = store failed + "teq %[tmp], #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [original] "=&r" (original), // %0 + [result] "=&r" (result), // %1 + [tmp] "=&l" (tmp), // %2 + [storage] "+Q" (storage) // %3 + : [value] "r" (v) // %4 + : "cc" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE storage_type fetch_xor(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + uint32_t tmp; + storage_type original, result; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "1:\n" + "ldrex %[original], %[storage]\n" // original = *(&storage) + "eor %[result], %[original], %[value]\n" // result = original ^ value + "strex %[tmp], %[result], %[storage]\n" // *(&storage) = result, tmp = store failed + "teq %[tmp], #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [original] "=&r" (original), // %0 + [result] "=&r" (result), // %1 + [tmp] "=&l" (tmp), // %2 + [storage] "+Q" (storage) // %3 + : [value] "r" (v) // %4 + : "cc" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE bool test_and_set(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT + { + return !!exchange(storage, (storage_type)1, order); + } + + static BOOST_FORCEINLINE void clear(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT + { + store(storage, 0, order); + } + + static BOOST_FORCEINLINE bool is_lock_free(storage_type const volatile&) BOOST_NOEXCEPT + { + return true; + } +}; + + +template< > +struct operations< 1u, false > : + public operations< 4u, false > +{ + typedef operations< 4u, false > base_type; + typedef base_type::storage_type storage_type; + + static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + uint32_t tmp; + storage_type original, result; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "1:\n" + "ldrex %[original], %[storage]\n" // original = *(&storage) + "add %[result], %[original], %[value]\n" // result = original + value + "uxtb %[result], %[result]\n" // zero extend result from 8 to 32 bits + "strex %[tmp], %[result], %[storage]\n" // *(&storage) = result, tmp = store failed + "teq %[tmp], #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [original] "=&r" (original), // %0 + [result] "=&r" (result), // %1 + [tmp] "=&l" (tmp), // %2 + [storage] "+Q" (storage) // %3 + : [value] "r" (v) // %4 + : "cc" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE storage_type fetch_sub(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + uint32_t tmp; + storage_type original, result; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "1:\n" + "ldrex %[original], %[storage]\n" // original = *(&storage) + "sub %[result], %[original], %[value]\n" // result = original - value + "uxtb %[result], %[result]\n" // zero extend result from 8 to 32 bits + "strex %[tmp], %[result], %[storage]\n" // *(&storage) = result, tmp = store failed + "teq %[tmp], #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [original] "=&r" (original), // %0 + [result] "=&r" (result), // %1 + [tmp] "=&l" (tmp), // %2 + [storage] "+Q" (storage) // %3 + : [value] "r" (v) // %4 + : "cc" + ); + fence_after(order); + return original; + } +}; + +template< > +struct operations< 1u, true > : + public operations< 4u, true > +{ + typedef operations< 4u, true > base_type; + typedef base_type::storage_type storage_type; + + static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + uint32_t tmp; + storage_type original, result; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "1:\n" + "ldrex %[original], %[storage]\n" // original = *(&storage) + "add %[result], %[original], %[value]\n" // result = original + value + "sxtb %[result], %[result]\n" // sign extend result from 8 to 32 bits + "strex %[tmp], %[result], %[storage]\n" // *(&storage) = result, tmp = store failed + "teq %[tmp], #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [original] "=&r" (original), // %0 + [result] "=&r" (result), // %1 + [tmp] "=&l" (tmp), // %2 + [storage] "+Q" (storage) // %3 + : [value] "r" (v) // %4 + : "cc" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE storage_type fetch_sub(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + uint32_t tmp; + storage_type original, result; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "1:\n" + "ldrex %[original], %[storage]\n" // original = *(&storage) + "sub %[result], %[original], %[value]\n" // result = original - value + "sxtb %[result], %[result]\n" // sign extend result from 8 to 32 bits + "strex %[tmp], %[result], %[storage]\n" // *(&storage) = result, tmp = store failed + "teq %[tmp], #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [original] "=&r" (original), // %0 + [result] "=&r" (result), // %1 + [tmp] "=&l" (tmp), // %2 + [storage] "+Q" (storage) // %3 + : [value] "r" (v) // %4 + : "cc" + ); + fence_after(order); + return original; + } +}; + + +template< > +struct operations< 2u, false > : + public operations< 4u, false > +{ + typedef operations< 4u, false > base_type; + typedef base_type::storage_type storage_type; + + static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + uint32_t tmp; + storage_type original, result; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "1:\n" + "ldrex %[original], %[storage]\n" // original = *(&storage) + "add %[result], %[original], %[value]\n" // result = original + value + "uxth %[result], %[result]\n" // zero extend result from 16 to 32 bits + "strex %[tmp], %[result], %[storage]\n" // *(&storage) = result, tmp = store failed + "teq %[tmp], #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [original] "=&r" (original), // %0 + [result] "=&r" (result), // %1 + [tmp] "=&l" (tmp), // %2 + [storage] "+Q" (storage) // %3 + : [value] "r" (v) // %4 + : "cc" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE storage_type fetch_sub(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + uint32_t tmp; + storage_type original, result; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "1:\n" + "ldrex %[original], %[storage]\n" // original = *(&storage) + "sub %[result], %[original], %[value]\n" // result = original - value + "uxth %[result], %[result]\n" // zero extend result from 16 to 32 bits + "strex %[tmp], %[result], %[storage]\n" // *(&storage) = result, tmp = store failed + "teq %[tmp], #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [original] "=&r" (original), // %0 + [result] "=&r" (result), // %1 + [tmp] "=&l" (tmp), // %2 + [storage] "+Q" (storage) // %3 + : [value] "r" (v) // %4 + : "cc" + ); + fence_after(order); + return original; + } +}; + +template< > +struct operations< 2u, true > : + public operations< 4u, true > +{ + typedef operations< 4u, true > base_type; + typedef base_type::storage_type storage_type; + + static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + uint32_t tmp; + storage_type original, result; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "1:\n" + "ldrex %[original], %[storage]\n" // original = *(&storage) + "add %[result], %[original], %[value]\n" // result = original + value + "sxth %[result], %[result]\n" // sign extend result from 16 to 32 bits + "strex %[tmp], %[result], %[storage]\n" // *(&storage) = result, tmp = store failed + "teq %[tmp], #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [original] "=&r" (original), // %0 + [result] "=&r" (result), // %1 + [tmp] "=&l" (tmp), // %2 + [storage] "+Q" (storage) // %3 + : [value] "r" (v) // %4 + : "cc" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE storage_type fetch_sub(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + uint32_t tmp; + storage_type original, result; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%[tmp]) + "1:\n" + "ldrex %[original], %[storage]\n" // original = *(&storage) + "sub %[result], %[original], %[value]\n" // result = original - value + "sxth %[result], %[result]\n" // sign extend result from 16 to 32 bits + "strex %[tmp], %[result], %[storage]\n" // *(&storage) = result, tmp = store failed + "teq %[tmp], #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%[tmp]) + : [original] "=&r" (original), // %0 + [result] "=&r" (result), // %1 + [tmp] "=&l" (tmp), // %2 + [storage] "+Q" (storage) // %3 + : [value] "r" (v) // %4 + : "cc" + ); + fence_after(order); + return original; + } +}; + + +#if defined(BOOST_ATOMIC_DETAIL_ARM_HAS_LDREXD_STREXD) + +// Unlike 32-bit operations, for 64-bit loads and stores we must use ldrexd/strexd. +// Any other instructions result in a non-atomic sequence of 32-bit accesses. +// See "ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition", +// Section A3.5.3 "Atomicity in the ARM architecture". + +// In the asm blocks below we have to use 32-bit register pairs to compose 64-bit values. +// In order to pass the 64-bit operands to/from asm blocks, we use undocumented gcc feature: +// the lower half (Rt) of the operand is accessible normally, via the numbered placeholder (e.g. %0), +// and the upper half (Rt2) - via the same placeholder with an 'H' after the '%' sign (e.g. %H0). +// See: http://hardwarebug.org/2010/07/06/arm-inline-asm-secrets/ + +template< bool Signed > +struct operations< 8u, Signed > : + public gcc_arm_operations_base +{ + typedef typename make_storage_type< 8u, Signed >::type storage_type; + + static BOOST_FORCEINLINE void store(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + exchange(storage, v, order); + } + + static BOOST_FORCEINLINE storage_type load(storage_type const volatile& storage, memory_order order) BOOST_NOEXCEPT + { + storage_type original; + uint32_t tmp; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%0) + "ldrexd %1, %H1, [%2]\n" + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%0) + : BOOST_ATOMIC_DETAIL_ARM_ASM_TMPREG_CONSTRAINT(tmp), // %0 + "=&r" (original) // %1 + : "r" (&storage) // %2 + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE storage_type exchange(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + storage_type original; + fence_before(order); + uint32_t tmp; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%0) + "1:\n" + "ldrexd %1, %H1, [%3]\n" // load the original value + "strexd %0, %2, %H2, [%3]\n" // store the replacement, tmp = store failed + "teq %0, #0\n" // check if store succeeded + "bne 1b\n" + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%0) + : BOOST_ATOMIC_DETAIL_ARM_ASM_TMPREG_CONSTRAINT(tmp), // %0 + "=&r" (original) // %1 + : "r" (v), // %2 + "r" (&storage) // %3 + : "cc", "memory" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE bool compare_exchange_weak( + storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order success_order, memory_order failure_order) BOOST_NOEXCEPT + { + fence_before(success_order); + uint32_t tmp; + storage_type original, old_val = expected; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%0) + "ldrexd %1, %H1, [%3]\n" // original = *(&storage) + "cmp %1, %2\n" // flags = original.lo==old_val.lo + "ittt eq\n" // [hint that the following 3 instructions are conditional on flags.equal] + "cmpeq %H1, %H2\n" // if (flags.equal) flags = original.hi==old_val.hi + "strexdeq %0, %4, %H4, [%3]\n" // if (flags.equal) *(&storage) = desired, tmp = store failed + "teqeq %0, #0\n" // if (flags.equal) flags = tmp==0 + "ite eq\n" // [hint that the following 2 instructions are conditional on flags.equal] + "moveq %2, #1\n" // if (flags.equal) old_val.lo = 1 + "movne %2, #0\n" // if (!flags.equal) old_val.lo = 0 + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%0) + : BOOST_ATOMIC_DETAIL_ARM_ASM_TMPREG_CONSTRAINT(tmp), // %0 + "=&r" (original), // %1 + "+r" (old_val) // %2 + : "r" (&storage), // %3 + "r" (desired) // %4 + : "cc", "memory" + ); + const uint32_t success = (uint32_t)old_val; + if (success) + fence_after(success_order); + else + fence_after(failure_order); + expected = original; + return !!success; + } + + static BOOST_FORCEINLINE bool compare_exchange_strong( + storage_type volatile& storage, storage_type& expected, storage_type desired, memory_order success_order, memory_order failure_order) BOOST_NOEXCEPT + { + fence_before(success_order); + uint32_t tmp; + storage_type original, old_val = expected; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%0) + "1:\n" + "ldrexd %1, %H1, [%3]\n" // original = *(&storage) + "cmp %1, %2\n" // flags = original.lo==old_val.lo + "it eq\n" // [hint that the following instruction is conditional on flags.equal] + "cmpeq %H1, %H2\n" // if (flags.equal) flags = original.hi==old_val.hi + "bne 2f\n" // if (!flags.equal) goto end + "strexd %0, %4, %H4, [%3]\n" // *(&storage) = desired, tmp = store failed + "teq %0, #0\n" // flags.equal = tmp == 0 + "bne 1b\n" // if (flags.equal) goto retry + "2:\n" + "ite eq\n" // [hint that the following 2 instructions are conditional on flags.equal] + "moveq %2, #1\n" // if (flags.equal) old_val.lo = 1 + "movne %2, #0\n" // if (!flags.equal) old_val.lo = 0 + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%0) + : BOOST_ATOMIC_DETAIL_ARM_ASM_TMPREG_CONSTRAINT(tmp), // %0 + "=&r" (original), // %1 + "+r" (old_val) // %2 + : "r" (&storage), // %3 + "r" (desired) // %4 + : "cc", "memory" + ); + const uint32_t success = (uint32_t)old_val; + if (success) + fence_after(success_order); + else + fence_after(failure_order); + expected = original; + return !!success; + } + + static BOOST_FORCEINLINE storage_type fetch_add(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + storage_type original, result; + uint32_t tmp; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%0) + "1:\n" + "ldrexd %1, %H1, [%3]\n" // original = *(&storage) + "adds %2, %1, %4\n" // result = original + value + "adc %H2, %H1, %H4\n" + "strexd %0, %2, %H2, [%3]\n" // *(&storage) = result, tmp = store failed + "teq %0, #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%0) + : BOOST_ATOMIC_DETAIL_ARM_ASM_TMPREG_CONSTRAINT(tmp), // %0 + "=&r" (original), // %1 + "=&r" (result) // %2 + : "r" (&storage), // %3 + "r" (v) // %4 + : "cc", "memory" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE storage_type fetch_sub(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + storage_type original, result; + uint32_t tmp; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%0) + "1:\n" + "ldrexd %1, %H1, [%3]\n" // original = *(&storage) + "subs %2, %1, %4\n" // result = original - value + "sbc %H2, %H1, %H4\n" + "strexd %0, %2, %H2, [%3]\n" // *(&storage) = result, tmp = store failed + "teq %0, #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%0) + : BOOST_ATOMIC_DETAIL_ARM_ASM_TMPREG_CONSTRAINT(tmp), // %0 + "=&r" (original), // %1 + "=&r" (result) // %2 + : "r" (&storage), // %3 + "r" (v) // %4 + : "cc", "memory" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE storage_type fetch_and(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + storage_type original, result; + uint32_t tmp; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%0) + "1:\n" + "ldrexd %1, %H1, [%3]\n" // original = *(&storage) + "and %2, %1, %4\n" // result = original & value + "and %H2, %H1, %H4\n" + "strexd %0, %2, %H2, [%3]\n" // *(&storage) = result, tmp = store failed + "teq %0, #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%0) + : BOOST_ATOMIC_DETAIL_ARM_ASM_TMPREG_CONSTRAINT(tmp), // %0 + "=&r" (original), // %1 + "=&r" (result) // %2 + : "r" (&storage), // %3 + "r" (v) // %4 + : "cc", "memory" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE storage_type fetch_or(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + storage_type original, result; + uint32_t tmp; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%0) + "1:\n" + "ldrexd %1, %H1, [%3]\n" // original = *(&storage) + "orr %2, %1, %4\n" // result = original | value + "orr %H2, %H1, %H4\n" + "strexd %0, %2, %H2, [%3]\n" // *(&storage) = result, tmp = store failed + "teq %0, #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%0) + : BOOST_ATOMIC_DETAIL_ARM_ASM_TMPREG_CONSTRAINT(tmp), // %0 + "=&r" (original), // %1 + "=&r" (result) // %2 + : "r" (&storage), // %3 + "r" (v) // %4 + : "cc", "memory" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE storage_type fetch_xor(storage_type volatile& storage, storage_type v, memory_order order) BOOST_NOEXCEPT + { + fence_before(order); + storage_type original, result; + uint32_t tmp; + __asm__ __volatile__ + ( + BOOST_ATOMIC_DETAIL_ARM_ASM_START(%0) + "1:\n" + "ldrexd %1, %H1, [%3]\n" // original = *(&storage) + "eor %2, %1, %4\n" // result = original ^ value + "eor %H2, %H1, %H4\n" + "strexd %0, %2, %H2, [%3]\n" // *(&storage) = result, tmp = store failed + "teq %0, #0\n" // flags = tmp==0 + "bne 1b\n" // if (!flags.equal) goto retry + BOOST_ATOMIC_DETAIL_ARM_ASM_END(%0) + : BOOST_ATOMIC_DETAIL_ARM_ASM_TMPREG_CONSTRAINT(tmp), // %0 + "=&r" (original), // %1 + "=&r" (result) // %2 + : "r" (&storage), // %3 + "r" (v) // %4 + : "cc", "memory" + ); + fence_after(order); + return original; + } + + static BOOST_FORCEINLINE bool test_and_set(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT + { + return !!exchange(storage, (storage_type)1, order); + } + + static BOOST_FORCEINLINE void clear(storage_type volatile& storage, memory_order order) BOOST_NOEXCEPT + { + store(storage, 0, order); + } + + static BOOST_FORCEINLINE bool is_lock_free(storage_type const volatile&) BOOST_NOEXCEPT + { + return true; + } +}; + +#endif // defined(BOOST_ATOMIC_DETAIL_ARM_HAS_LDREXD_STREXD) + + +BOOST_FORCEINLINE void thread_fence(memory_order order) BOOST_NOEXCEPT +{ + if (order != memory_order_relaxed) + gcc_arm_operations_base::hardware_full_fence(); +} + +BOOST_FORCEINLINE void signal_fence(memory_order order) BOOST_NOEXCEPT +{ + if (order != memory_order_relaxed) + __asm__ __volatile__ ("" ::: "memory"); +} + +} // namespace detail +} // namespace atomics +} // namespace boost + +#endif // BOOST_ATOMIC_DETAIL_OPS_GCC_ARM_HPP_INCLUDED_ |