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https://github.com/c64scene-ar/llvm-6502.git
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5e4931b489
This code was casting regions of a memory buffer to a couple of different structs. This is wrong in a few ways: 1. It breaks aliasing rules. 2. If the buffer isn't aligned, it hits undefined behaviour. 3. It completely ignores endianness differences. 4. The structs being defined for this aren't specifying their padding properly, so this doesn't even represent the data properly on some platforms. This commit is mostly NFC, except that it fixes reading coverage for 32 bit binaries as a side effect of getting rid of the mispadded structs. I've included a test for that. I've also baked in that we only handle little endian more explicitly, since that was true in practice already. I'll fix this to handle endianness properly in a followup commit. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232346 91177308-0d34-0410-b5e6-96231b3b80d8
219 lines
7.9 KiB
C++
219 lines
7.9 KiB
C++
//===- Endian.h - Utilities for IO with endian specific data ----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file declares generic functions to read and write endian specific data.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_ENDIAN_H
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#define LLVM_SUPPORT_ENDIAN_H
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#include "llvm/Support/AlignOf.h"
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#include "llvm/Support/Host.h"
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#include "llvm/Support/SwapByteOrder.h"
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namespace llvm {
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namespace support {
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enum endianness {big, little, native};
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// These are named values for common alignments.
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enum {aligned = 0, unaligned = 1};
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namespace detail {
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/// \brief ::value is either alignment, or alignof(T) if alignment is 0.
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template<class T, int alignment>
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struct PickAlignment {
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enum {value = alignment == 0 ? AlignOf<T>::Alignment : alignment};
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};
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} // end namespace detail
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namespace endian {
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/// Swap the bytes of value to match the given endianness.
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template<typename value_type, endianness endian>
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inline value_type byte_swap(value_type value) {
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if (endian != native && sys::IsBigEndianHost != (endian == big))
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sys::swapByteOrder(value);
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return value;
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}
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/// Read a value of a particular endianness from memory.
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template<typename value_type,
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endianness endian,
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std::size_t alignment>
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inline value_type read(const void *memory) {
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value_type ret;
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memcpy(&ret,
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LLVM_ASSUME_ALIGNED(memory,
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(detail::PickAlignment<value_type, alignment>::value)),
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sizeof(value_type));
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return byte_swap<value_type, endian>(ret);
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}
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/// Read a value of a particular endianness from a buffer, and increment the
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/// buffer past that value.
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template<typename value_type, endianness endian, std::size_t alignment,
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typename CharT>
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inline value_type readNext(const CharT *&memory) {
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value_type ret = read<value_type, endian, alignment>(memory);
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memory += sizeof(value_type);
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return ret;
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}
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/// Write a value to memory with a particular endianness.
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template<typename value_type,
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endianness endian,
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std::size_t alignment>
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inline void write(void *memory, value_type value) {
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value = byte_swap<value_type, endian>(value);
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memcpy(LLVM_ASSUME_ALIGNED(memory,
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(detail::PickAlignment<value_type, alignment>::value)),
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&value,
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sizeof(value_type));
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}
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} // end namespace endian
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namespace detail {
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template<typename value_type,
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endianness endian,
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std::size_t alignment>
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struct packed_endian_specific_integral {
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operator value_type() const {
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return endian::read<value_type, endian, alignment>(
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(const void*)Value.buffer);
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}
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void operator=(value_type newValue) {
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endian::write<value_type, endian, alignment>(
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(void*)Value.buffer, newValue);
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}
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packed_endian_specific_integral &operator+=(value_type newValue) {
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*this = *this + newValue;
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return *this;
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}
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packed_endian_specific_integral &operator-=(value_type newValue) {
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*this = *this - newValue;
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return *this;
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}
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private:
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AlignedCharArray<PickAlignment<value_type, alignment>::value,
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sizeof(value_type)> Value;
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public:
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struct ref {
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explicit ref(void *Ptr) : Ptr(Ptr) {}
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operator value_type() const {
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return endian::read<value_type, endian, alignment>(Ptr);
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}
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void operator=(value_type NewValue) {
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endian::write<value_type, endian, alignment>(Ptr, NewValue);
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}
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private:
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void *Ptr;
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};
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};
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} // end namespace detail
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typedef detail::packed_endian_specific_integral
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<uint16_t, little, unaligned> ulittle16_t;
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typedef detail::packed_endian_specific_integral
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<uint32_t, little, unaligned> ulittle32_t;
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typedef detail::packed_endian_specific_integral
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<uint64_t, little, unaligned> ulittle64_t;
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typedef detail::packed_endian_specific_integral
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<int16_t, little, unaligned> little16_t;
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typedef detail::packed_endian_specific_integral
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<int32_t, little, unaligned> little32_t;
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typedef detail::packed_endian_specific_integral
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<int64_t, little, unaligned> little64_t;
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typedef detail::packed_endian_specific_integral
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<uint16_t, little, aligned> aligned_ulittle16_t;
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typedef detail::packed_endian_specific_integral
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<uint32_t, little, aligned> aligned_ulittle32_t;
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typedef detail::packed_endian_specific_integral
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<uint64_t, little, aligned> aligned_ulittle64_t;
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typedef detail::packed_endian_specific_integral
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<int16_t, little, aligned> aligned_little16_t;
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typedef detail::packed_endian_specific_integral
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<int32_t, little, aligned> aligned_little32_t;
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typedef detail::packed_endian_specific_integral
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<int64_t, little, aligned> aligned_little64_t;
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typedef detail::packed_endian_specific_integral
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<uint16_t, big, unaligned> ubig16_t;
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typedef detail::packed_endian_specific_integral
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<uint32_t, big, unaligned> ubig32_t;
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typedef detail::packed_endian_specific_integral
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<uint64_t, big, unaligned> ubig64_t;
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typedef detail::packed_endian_specific_integral
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<int16_t, big, unaligned> big16_t;
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typedef detail::packed_endian_specific_integral
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<int32_t, big, unaligned> big32_t;
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typedef detail::packed_endian_specific_integral
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<int64_t, big, unaligned> big64_t;
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typedef detail::packed_endian_specific_integral
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<uint16_t, big, aligned> aligned_ubig16_t;
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typedef detail::packed_endian_specific_integral
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<uint32_t, big, aligned> aligned_ubig32_t;
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typedef detail::packed_endian_specific_integral
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<uint64_t, big, aligned> aligned_ubig64_t;
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typedef detail::packed_endian_specific_integral
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<int16_t, big, aligned> aligned_big16_t;
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typedef detail::packed_endian_specific_integral
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<int32_t, big, aligned> aligned_big32_t;
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typedef detail::packed_endian_specific_integral
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<int64_t, big, aligned> aligned_big64_t;
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typedef detail::packed_endian_specific_integral
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<uint16_t, native, unaligned> unaligned_uint16_t;
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typedef detail::packed_endian_specific_integral
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<uint32_t, native, unaligned> unaligned_uint32_t;
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typedef detail::packed_endian_specific_integral
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<uint64_t, native, unaligned> unaligned_uint64_t;
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typedef detail::packed_endian_specific_integral
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<int16_t, native, unaligned> unaligned_int16_t;
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typedef detail::packed_endian_specific_integral
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<int32_t, native, unaligned> unaligned_int32_t;
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typedef detail::packed_endian_specific_integral
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<int64_t, native, unaligned> unaligned_int64_t;
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namespace endian {
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inline uint16_t read16le(const void *p) { return *(const ulittle16_t *)p; }
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inline uint32_t read32le(const void *p) { return *(const ulittle32_t *)p; }
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inline uint64_t read64le(const void *p) { return *(const ulittle64_t *)p; }
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inline uint16_t read16be(const void *p) { return *(const ubig16_t *)p; }
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inline uint32_t read32be(const void *p) { return *(const ubig32_t *)p; }
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inline uint64_t read64be(const void *p) { return *(const ubig64_t *)p; }
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inline void write16le(void *p, uint16_t v) { *(ulittle16_t *)p = v; }
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inline void write32le(void *p, uint32_t v) { *(ulittle32_t *)p = v; }
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inline void write64le(void *p, uint64_t v) { *(ulittle64_t *)p = v; }
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inline void write16be(void *p, uint16_t v) { *(ubig16_t *)p = v; }
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inline void write32be(void *p, uint32_t v) { *(ubig32_t *)p = v; }
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inline void write64be(void *p, uint64_t v) { *(ubig64_t *)p = v; }
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} // end namespace endian
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} // end namespace support
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} // end namespace llvm
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#endif
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