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Theodosius/dependencies/asmjit/core/codewriter.cpp

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// AsmJit - Machine code generation for C++
//
// * Official AsmJit Home Page: https://asmjit.com
// * Official Github Repository: https://github.com/asmjit/asmjit
//
// Copyright (c) 2008-2020 The AsmJit Authors
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software. If you use this software
// in a product, an acknowledgment in the product documentation would be
// appreciated but is not required.
// 2. Altered source versions must be plainly marked as such, and must not be
// misrepresented as being the original software.
// 3. This notice may not be removed or altered from any source distribution.
#include "../core/api-build_p.h"
#include "../core/codeholder.h"
#include "../core/codewriter_p.h"
ASMJIT_BEGIN_NAMESPACE
bool CodeWriterUtils::encodeOffset32(uint32_t* dst, int64_t offset64, const OffsetFormat& format) noexcept {
uint32_t bitCount = format.immBitCount();
uint32_t bitShift = format.immBitShift();
uint32_t discardLsb = format.immDiscardLsb();
if (!bitCount || bitCount > format.valueSize() * 8u)
return false;
if (discardLsb) {
ASMJIT_ASSERT(discardLsb <= 32);
if ((offset64 & Support::lsbMask<uint32_t>(discardLsb)) != 0)
return false;
offset64 >>= discardLsb;
}
if (!Support::isInt32(offset64))
return false;
int32_t offset32 = int32_t(offset64);
if (!Support::isEncodableOffset32(offset32, bitCount))
return false;
switch (format.type()) {
case OffsetFormat::kTypeCommon: {
*dst = (uint32_t(offset32) & Support::lsbMask<uint32_t>(bitCount)) << bitShift;
return true;
}
case OffsetFormat::kTypeAArch64_ADR:
case OffsetFormat::kTypeAArch64_ADRP: {
// Sanity checks.
if (format.valueSize() != 4 || bitCount != 21 || bitShift != 5)
return false;
uint32_t immLo = uint32_t(offset32) & 0x3u;
uint32_t immHi = uint32_t(offset32 >> 2) & Support::lsbMask<uint32_t>(19);
*dst = (immLo << 29) | (immHi << 5);
return true;
}
default:
return false;
}
}
bool CodeWriterUtils::encodeOffset64(uint64_t* dst, int64_t offset64, const OffsetFormat& format) noexcept {
uint32_t bitCount = format.immBitCount();
uint32_t discardLsb = format.immDiscardLsb();
if (!bitCount || bitCount > format.valueSize() * 8u)
return false;
if (discardLsb) {
ASMJIT_ASSERT(discardLsb <= 32);
if ((offset64 & Support::lsbMask<uint32_t>(discardLsb)) != 0)
return false;
offset64 >>= discardLsb;
}
if (!Support::isEncodableOffset64(offset64, bitCount))
return false;
switch (format.type()) {
case OffsetFormat::kTypeCommon: {
*dst = (uint64_t(offset64) & Support::lsbMask<uint64_t>(bitCount)) << format.immBitShift();
return true;
}
default:
return false;
}
}
bool CodeWriterUtils::writeOffset(void* dst, int64_t offset64, const OffsetFormat& format) noexcept {
// Offset the destination by ValueOffset so the `dst` points to the
// patched word instead of the beginning of the patched region.
dst = static_cast<char*>(dst) + format.valueOffset();
switch (format.valueSize()) {
case 1: {
uint32_t mask;
if (!encodeOffset32(&mask, offset64, format))
return false;
Support::writeU8(dst, Support::readU8(dst) | mask);
return true;
}
case 2: {
uint32_t mask;
if (!encodeOffset32(&mask, offset64, format))
return false;
Support::writeU16uLE(dst, Support::readU16uLE(dst) | mask);
return true;
}
case 4: {
uint32_t mask;
if (!encodeOffset32(&mask, offset64, format))
return false;
Support::writeU32uLE(dst, Support::readU32uLE(dst) | mask);
return true;
}
case 8: {
uint64_t mask;
if (!encodeOffset64(&mask, offset64, format))
return false;
Support::writeU64uLE(dst, Support::readU64uLE(dst) | mask);
return true;
}
default:
return false;
}
}
ASMJIT_END_NAMESPACE