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187 lines
4.8 KiB
C
187 lines
4.8 KiB
C
/* Bra86.c -- Branch converter for X86 code (BCJ)
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2023-04-02 : Igor Pavlov : Public domain */
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#include "Precomp.h"
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#include "Bra.h"
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#include "CpuArch.h"
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#if defined(MY_CPU_SIZEOF_POINTER) \
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&& ( MY_CPU_SIZEOF_POINTER == 4 \
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|| MY_CPU_SIZEOF_POINTER == 8)
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#define BR_CONV_USE_OPT_PC_PTR
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#endif
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#ifdef BR_CONV_USE_OPT_PC_PTR
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#define BR_PC_INIT pc -= (UInt32)(SizeT)p; // (MY_uintptr_t)
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#define BR_PC_GET (pc + (UInt32)(SizeT)p)
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#else
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#define BR_PC_INIT pc += (UInt32)size;
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#define BR_PC_GET (pc - (UInt32)(SizeT)(lim - p))
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// #define BR_PC_INIT
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// #define BR_PC_GET (pc + (UInt32)(SizeT)(p - data))
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#endif
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#define BR_CONVERT_VAL(v, c) if (encoding) v += c; else v -= c;
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// #define BR_CONVERT_VAL(v, c) if (!encoding) c = (UInt32)0 - c; v += c;
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#define Z7_BRANCH_CONV_ST(name) z7_BranchConvSt_ ## name
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#define BR86_NEED_CONV_FOR_MS_BYTE(b) ((((b) + 1) & 0xfe) == 0)
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#ifdef MY_CPU_LE_UNALIGN
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#define BR86_PREPARE_BCJ_SCAN const UInt32 v = GetUi32(p) ^ 0xe8e8e8e8;
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#define BR86_IS_BCJ_BYTE(n) ((v & ((UInt32)0xfe << (n) * 8)) == 0)
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#else
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#define BR86_PREPARE_BCJ_SCAN
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// bad for MSVC X86 (partial write to byte reg):
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#define BR86_IS_BCJ_BYTE(n) ((p[n - 4] & 0xfe) == 0xe8)
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// bad for old MSVC (partial write to byte reg):
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// #define BR86_IS_BCJ_BYTE(n) (((*p ^ 0xe8) & 0xfe) == 0)
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#endif
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static
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Z7_FORCE_INLINE
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Z7_ATTRIB_NO_VECTOR
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Byte *Z7_BRANCH_CONV_ST(X86)(Byte *p, SizeT size, UInt32 pc, UInt32 *state, int encoding)
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{
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if (size < 5)
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return p;
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{
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// Byte *p = data;
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const Byte *lim = p + size - 4;
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unsigned mask = (unsigned)*state; // & 7;
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#ifdef BR_CONV_USE_OPT_PC_PTR
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/* if BR_CONV_USE_OPT_PC_PTR is defined: we need to adjust (pc) for (+4),
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because call/jump offset is relative to the next instruction.
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if BR_CONV_USE_OPT_PC_PTR is not defined : we don't need to adjust (pc) for (+4),
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because BR_PC_GET uses (pc - (lim - p)), and lim was adjusted for (-4) before.
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*/
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pc += 4;
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#endif
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BR_PC_INIT
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goto start;
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for (;; mask |= 4)
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{
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// cont: mask |= 4;
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start:
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if (p >= lim)
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goto fin;
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{
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BR86_PREPARE_BCJ_SCAN
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p += 4;
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if (BR86_IS_BCJ_BYTE(0)) { goto m0; } mask >>= 1;
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if (BR86_IS_BCJ_BYTE(1)) { goto m1; } mask >>= 1;
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if (BR86_IS_BCJ_BYTE(2)) { goto m2; } mask = 0;
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if (BR86_IS_BCJ_BYTE(3)) { goto a3; }
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}
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goto main_loop;
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m0: p--;
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m1: p--;
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m2: p--;
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if (mask == 0)
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goto a3;
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if (p > lim)
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goto fin_p;
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// if (((0x17u >> mask) & 1) == 0)
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if (mask > 4 || mask == 3)
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{
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mask >>= 1;
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continue; // goto cont;
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}
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mask >>= 1;
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if (BR86_NEED_CONV_FOR_MS_BYTE(p[mask]))
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continue; // goto cont;
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// if (!BR86_NEED_CONV_FOR_MS_BYTE(p[3])) continue; // goto cont;
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{
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UInt32 v = GetUi32(p);
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UInt32 c;
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v += (1 << 24); if (v & 0xfe000000) continue; // goto cont;
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c = BR_PC_GET;
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BR_CONVERT_VAL(v, c)
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{
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mask <<= 3;
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if (BR86_NEED_CONV_FOR_MS_BYTE(v >> mask))
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{
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v ^= (((UInt32)0x100 << mask) - 1);
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#ifdef MY_CPU_X86
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// for X86 : we can recalculate (c) to reduce register pressure
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c = BR_PC_GET;
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#endif
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BR_CONVERT_VAL(v, c)
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}
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mask = 0;
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}
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// v = (v & ((1 << 24) - 1)) - (v & (1 << 24));
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v &= (1 << 25) - 1; v -= (1 << 24);
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SetUi32(p, v)
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p += 4;
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goto main_loop;
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}
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main_loop:
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if (p >= lim)
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goto fin;
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for (;;)
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{
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BR86_PREPARE_BCJ_SCAN
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p += 4;
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if (BR86_IS_BCJ_BYTE(0)) { goto a0; }
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if (BR86_IS_BCJ_BYTE(1)) { goto a1; }
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if (BR86_IS_BCJ_BYTE(2)) { goto a2; }
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if (BR86_IS_BCJ_BYTE(3)) { goto a3; }
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if (p >= lim)
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goto fin;
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}
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a0: p--;
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a1: p--;
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a2: p--;
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a3:
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if (p > lim)
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goto fin_p;
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// if (!BR86_NEED_CONV_FOR_MS_BYTE(p[3])) continue; // goto cont;
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{
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UInt32 v = GetUi32(p);
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UInt32 c;
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v += (1 << 24); if (v & 0xfe000000) continue; // goto cont;
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c = BR_PC_GET;
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BR_CONVERT_VAL(v, c)
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// v = (v & ((1 << 24) - 1)) - (v & (1 << 24));
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v &= (1 << 25) - 1; v -= (1 << 24);
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SetUi32(p, v)
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p += 4;
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goto main_loop;
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}
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}
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fin_p:
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p--;
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fin:
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// the following processing for tail is optional and can be commented
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/*
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lim += 4;
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for (; p < lim; p++, mask >>= 1)
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if ((*p & 0xfe) == 0xe8)
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break;
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*/
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*state = (UInt32)mask;
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return p;
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}
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}
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#define Z7_BRANCH_CONV_ST_FUNC_IMP(name, m, encoding) \
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Z7_NO_INLINE \
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Z7_ATTRIB_NO_VECTOR \
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Byte *m(name)(Byte *data, SizeT size, UInt32 pc, UInt32 *state) \
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{ return Z7_BRANCH_CONV_ST(name)(data, size, pc, state, encoding); }
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Z7_BRANCH_CONV_ST_FUNC_IMP(X86, Z7_BRANCH_CONV_ST_DEC, 0)
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#ifndef Z7_EXTRACT_ONLY
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Z7_BRANCH_CONV_ST_FUNC_IMP(X86, Z7_BRANCH_CONV_ST_ENC, 1)
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#endif
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