mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-17 18:31:04 +00:00
fc1a161d76
Refactor the TableGen'erated fixed length disassemblmer to use a table-driven state machine rather than a massive set of nested switch() statements. As a result, the ARM Disassembler (ARMDisassembler.cpp) builds much more quickly and generates a smaller end result. For a Release+Asserts build on a 16GB 3.4GHz i7 iMac w/ SSD: Time to compile at -O2 (averaged w/ hot caches): Previous: 35.5s New: 8.9s TEXT size: Previous: 447,251 New: 297,661 Builds in 25% of the time previously required and generates code 66% of the size. Execution time of the disassembler is only slightly slower (7% disassembling 10 million ARM instructions, 19.6s vs 21.0s). The new implementation has not yet been tuned, however, so the performance should almost certainly be recoverable should it become a concern. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161888 91177308-0d34-0410-b5e6-96231b3b80d8
96 lines
2.7 KiB
C++
96 lines
2.7 KiB
C++
//===- llvm/Support/LEB128.h - [SU]LEB128 utility functions -----*- C++ -*-===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file declares some utility functions for encoding SLEB128 and
|
|
// ULEB128 values.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_SYSTEM_LEB128_H
|
|
#define LLVM_SYSTEM_LEB128_H
|
|
|
|
#include <llvm/Support/raw_ostream.h>
|
|
|
|
namespace llvm {
|
|
|
|
/// Utility function to encode a SLEB128 value to an output stream.
|
|
static inline void encodeSLEB128(int64_t Value, raw_ostream &OS) {
|
|
bool More;
|
|
do {
|
|
uint8_t Byte = Value & 0x7f;
|
|
// NOTE: this assumes that this signed shift is an arithmetic right shift.
|
|
Value >>= 7;
|
|
More = !((((Value == 0 ) && ((Byte & 0x40) == 0)) ||
|
|
((Value == -1) && ((Byte & 0x40) != 0))));
|
|
if (More)
|
|
Byte |= 0x80; // Mark this byte that that more bytes will follow.
|
|
OS << char(Byte);
|
|
} while (More);
|
|
}
|
|
|
|
/// Utility function to encode a ULEB128 value to an output stream.
|
|
static inline void encodeULEB128(uint64_t Value, raw_ostream &OS,
|
|
unsigned Padding = 0) {
|
|
do {
|
|
uint8_t Byte = Value & 0x7f;
|
|
Value >>= 7;
|
|
if (Value != 0 || Padding != 0)
|
|
Byte |= 0x80; // Mark this byte that that more bytes will follow.
|
|
OS << char(Byte);
|
|
} while (Value != 0);
|
|
|
|
// Pad with 0x80 and emit a null byte at the end.
|
|
if (Padding != 0) {
|
|
for (; Padding != 1; --Padding)
|
|
OS << '\x80';
|
|
OS << '\x00';
|
|
}
|
|
}
|
|
|
|
/// Utility function to encode a ULEB128 value to a buffer. Returns
|
|
/// the length in bytes of the encoded value.
|
|
static inline unsigned encodeULEB128(uint64_t Value, uint8_t *p,
|
|
unsigned Padding = 0) {
|
|
uint8_t *orig_p = p;
|
|
do {
|
|
uint8_t Byte = Value & 0x7f;
|
|
Value >>= 7;
|
|
if (Value != 0 || Padding != 0)
|
|
Byte |= 0x80; // Mark this byte that that more bytes will follow.
|
|
*p++ = Byte;
|
|
} while (Value != 0);
|
|
|
|
// Pad with 0x80 and emit a null byte at the end.
|
|
if (Padding != 0) {
|
|
for (; Padding != 1; --Padding)
|
|
*p++ = '\x80';
|
|
*p++ = '\x00';
|
|
}
|
|
return (unsigned)(p - orig_p);
|
|
}
|
|
|
|
|
|
/// Utility function to decode a ULEB128 value.
|
|
static inline uint64_t decodeULEB128(const uint8_t *p, unsigned *n = 0) {
|
|
const uint8_t *orig_p = p;
|
|
uint64_t Value = 0;
|
|
unsigned Shift = 0;
|
|
do {
|
|
Value += (*p & 0x7f) << Shift;
|
|
Shift += 7;
|
|
} while (*p++ >= 128);
|
|
if (n)
|
|
*n = (unsigned)(p - orig_p);
|
|
return Value;
|
|
}
|
|
|
|
} // namespace llvm
|
|
|
|
#endif // LLVM_SYSTEM_LEB128_H
|