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Saveload: Improve codegen in WriteBytesFromHandler

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-fno-strict-aliasing is enabled, so don't rely on the compiler
being able to elide obvious accesses
This commit is contained in:
Jonathan G Rennison 2024-08-08 01:17:48 +01:00
parent f66521e62e
commit b16db11e02
1 changed files with 49 additions and 28 deletions
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77
src/sl/saveload_buffer.h
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@ -220,6 +220,44 @@ struct MemoryDumper {
uint8_t *saved_buf = nullptr;
uint8_t *saved_bufe = nullptr;
static inline void RawWriteUint16At(uint8_t *b, uint16_t v)
{
#if OTTD_ALIGNMENT == 0
*((unaligned_uint16 *)b) = TO_BE16(v);
#else
b[0] = GB(v, 8, 8);
b[1] = GB(v, 0, 8);
#endif
}
static inline void RawWriteUint32At(uint8_t *b, uint32_t v)
{
#if OTTD_ALIGNMENT == 0
*((unaligned_uint32 *)b) = TO_BE32(v);
#else
b[0] = GB(v, 24, 8);
b[1] = GB(v, 16, 8);
b[2] = GB(v, 8, 8);
b[3] = GB(v, 0, 8);
#endif
}
static inline void RawWriteUint64At(uint8_t *b, uint64_t v)
{
#if OTTD_ALIGNMENT == 0
*((unaligned_uint64 *)b) = TO_BE64(v);
#else
b[0] = GB(v, 56, 8);
b[1] = GB(v, 48, 8);
b[2] = GB(v, 40, 8);
b[3] = GB(v, 32, 8);
b[4] = GB(v, 24, 8);
b[5] = GB(v, 16, 8);
b[6] = GB(v, 8, 8);
b[7] = GB(v, 0, 8);
#endif
}
MemoryDumper()
{
const size_t size = 8192;
@ -288,42 +326,19 @@ struct MemoryDumper {
inline void RawWriteUint16(uint16_t v)
{
#if OTTD_ALIGNMENT == 0
*((unaligned_uint16 *) this->buf) = TO_BE16(v);
#else
this->buf[0] = GB(v, 8, 8);
this->buf[1] = GB(v, 0, 8);
#endif
RawWriteUint16At(this->buf, v);
this->buf += 2;
}
inline void RawWriteUint32(uint32_t v)
{
#if OTTD_ALIGNMENT == 0
*((unaligned_uint32 *) this->buf) = TO_BE32(v);
#else
this->buf[0] = GB(v, 24, 8);
this->buf[1] = GB(v, 16, 8);
this->buf[2] = GB(v, 8, 8);
this->buf[3] = GB(v, 0, 8);
#endif
RawWriteUint32At(this->buf, v);
this->buf += 4;
}
inline void RawWriteUint64(uint64_t v)
{
#if OTTD_ALIGNMENT == 0
*((unaligned_uint64 *) this->buf) = TO_BE64(v);
#else
this->buf[0] = GB(v, 56, 8);
this->buf[1] = GB(v, 48, 8);
this->buf[2] = GB(v, 40, 8);
this->buf[3] = GB(v, 32, 8);
this->buf[4] = GB(v, 24, 8);
this->buf[5] = GB(v, 16, 8);
this->buf[6] = GB(v, 8, 8);
this->buf[7] = GB(v, 0, 8);
#endif
RawWriteUint64At(this->buf, v);
this->buf += 8;
}
@ -333,9 +348,12 @@ struct MemoryDumper {
while (length) {
this->CheckBytes(1);
size_t to_copy = std::min<size_t>(this->bufe - this->buf, length);
uint8_t *b = this->buf;
for (size_t i = 0; i < to_copy; i++) {
this->RawWriteByte(handler());
*b = handler();
b++;
}
this->buf = b;
length -= to_copy;
}
}
@ -346,9 +364,12 @@ struct MemoryDumper {
while (length) {
this->CheckBytes(2);
size_t to_copy = std::min<size_t>((this->bufe - this->buf) / 2, length);
uint8_t *b = this->buf;
for (size_t i = 0; i < to_copy; i++) {
this->RawWriteUint16(handler());
RawWriteUint16At(b, handler());
b += 2;
}
this->buf = b;
length -= to_copy;
}
}