[Compiler-rt] Implement AEABI Unaligned Read/Write Helpers in compiler-rt #167913
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…r-rt This patch adds implementations for the __aeabi_uread and __aeabi_uwrite helper functions to compiler-rt..
| // See https://llvm.org/LICENSE.txt for license information. | ||
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | ||
| // | ||
| //===-----------------------------------------------------------------------------===// |
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Probably a good idea to link to the document defining these functions.
https://github.com/ARM-software/abi-aa/blob/main/rtabi32/rtabi32.rst#unaligned-memory-access
| char v[4]; | ||
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| int __aeabi_uread4(void *p) { |
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I was going to say that surely the read functions should take a const void *, but in RTABI, they don't! I suppose because nobody ever calls these functions from C, so the C prototype isn't really important, only the machine-level PCS that it translates into.
| extern long long __aeabi_uread8(void *); | ||
| extern long long __aeabi_uwrite8(long long, void *); | ||
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| #define lenof(x) (sizeof((x)) / sizeof(*(x))) |
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It's 2025, so we can use _Countof for this! \o/
| long long target8; | ||
| int target4; | ||
| const char source[] = "abcdefghijklmno"; | ||
| static char dest1[lenof(source)], dest2[lenof(source)]; |
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Using static is optional. It’s used here mainly to improve reproducibility — since it provides a stable address from which we can repeatably test unaligned writes.
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✅ With the latest revision this PR passed the C/C++ code formatter. |
🐧 Linux x64 Test Results
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…compiler-rt Apply clang-format to address style issues in the previous patch.
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This patch adds implementations for the __aeabi_uread and __aeabi_uwrite helper functions to compiler-rt..