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add support for multibyte nop sequences #54

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merged 1 commit into from Aug 17, 2017
Merged

add support for multibyte nop sequences #54

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30 changes: 30 additions & 0 deletions xbyak/xbyak.h
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Expand Up @@ -2390,6 +2390,36 @@ class CodeGenerator : public CodeArray {
#ifdef XBYAK_UNDEF_JNL
#undef jnl
#endif

void nop(int size = 1)
{
/*
AMD and Intel seem to agree on the same sequences for up to 9 bytes:
https://support.amd.com/TechDocs/55723_SOG_Fam_17h_Processors_3.00.pdf
https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf
*/
static const uint8_t nopSeq[9][9] = {
{0x90},
{0x66, 0x90},
{0x0F, 0x1F, 0x00},
{0x0F, 0x1F, 0x40, 0x00},
{0x0F, 0x1F, 0x44, 0x00, 0x00},
{0x66, 0x0F, 0x1F, 0x44, 0x00, 0x00},
{0x0F, 0x1F, 0x80, 0x00, 0x00, 0x00, 0x00},
{0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00},
{0x66, 0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00},
};
static const int numSeq = sizeof(nopSeq) / sizeof(nopSeq[0]);
while (size) {
int len = size > numSeq ? numSeq : size;
const uint8_t *seq = nopSeq[len - 1];
for (int i = 0; i < len; i++) {
db(seq[i]);
}
size -= len;
}
}

#ifndef XBYAK_DONT_READ_LIST
#include "xbyak_mnemonic.h"
void align(int x = 16)
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1 change: 0 additions & 1 deletion xbyak/xbyak_mnemonic.h
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Expand Up @@ -497,7 +497,6 @@ void mulss(const Xmm& xmm, const Operand& op) { opGen(xmm, op, 0x59, 0xF3, isXMM
void mulx(const Reg32e& r1, const Reg32e& r2, const Operand& op) { opGpr(r1, r2, op, T_F2 | T_0F38, 0xf6, true); }
void mwait() { db(0x0F); db(0x01); db(0xC9); }
void neg(const Operand& op) { opR_ModM(op, 0, 3, 0xF6); }
void nop() { db(0x90); }
void not_(const Operand& op) { opR_ModM(op, 0, 2, 0xF6); }
void or_(const Operand& op, uint32 imm) { opRM_I(op, imm, 0x08, 1); }
void or_(const Operand& op1, const Operand& op2) { opRM_RM(op1, op2, 0x08); }
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