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x86: use effective address size for the loop counter register #3025

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x86: use effective address size for the loop counter register #3025

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18 changes: 12 additions & 6 deletions arch/X86/X86Mapping.c
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Original file line number Diff line number Diff line change
Expand Up @@ -957,6 +957,7 @@ void X86_get_insn_id(cs_struct *h, cs_insn *insn, unsigned int id)
case X86_INS_LOOP:
case X86_INS_LOOPE:
case X86_INS_LOOPNE:
// The instruction pointer register follows the mode.
switch (h->mode) {
default:
break;
Expand All @@ -969,24 +970,30 @@ void X86_get_insn_id(cs_struct *h, cs_insn *insn, unsigned int id)
insn->detail->regs_write,
insn->detail->regs_write_count,
X86_REG_EIP, X86_REG_IP);
break;
case CS_MODE_64:
arr_replace(
insn->detail->regs_read,
insn->detail->regs_read_count,
X86_REG_ECX, X86_REG_CX);
X86_REG_EIP, X86_REG_RIP);
arr_replace(
insn->detail->regs_write,
insn->detail->regs_write_count,
X86_REG_ECX, X86_REG_CX);
X86_REG_EIP, X86_REG_RIP);
break;
case CS_MODE_64:
}
// The loop counter register follows the effective address
// size, which a 0x67 address-size prefix can override.
if (insn->detail->x86.addr_size == 2) {
arr_replace(
insn->detail->regs_read,
insn->detail->regs_read_count,
X86_REG_EIP, X86_REG_RIP);
X86_REG_ECX, X86_REG_CX);
arr_replace(
insn->detail->regs_write,
insn->detail->regs_write_count,
X86_REG_EIP, X86_REG_RIP);
X86_REG_ECX, X86_REG_CX);
} else if (insn->detail->x86.addr_size == 8) {
arr_replace(
insn->detail->regs_read,
insn->detail->regs_read_count,
Expand All @@ -995,7 +1002,6 @@ void X86_get_insn_id(cs_struct *h, cs_insn *insn, unsigned int id)
insn->detail->regs_write,
insn->detail->regs_write_count,
X86_REG_ECX, X86_REG_RCX);
break;
}
}

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12 changes: 6 additions & 6 deletions tests/details/x86.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -6053,8 +6053,8 @@ test_cases:
x86:
prefix: [ X86_PREFIX_0, X86_PREFIX_0, X86_PREFIX_0, X86_PREFIX_ADDRSIZE ]
opcode: [ 0xe2, 0x00, 0x00, 0x00 ]
regs_read: [ rip, rcx ]
regs_write: [ rip, rcx ] # BUG: should be ecx
regs_read: [ rip, ecx ]
regs_write: [ rip, ecx ]
-
asm_text: "loope 0x34"
details:
Expand All @@ -6081,8 +6081,8 @@ test_cases:
prefix: [ X86_PREFIX_0, X86_PREFIX_0, X86_PREFIX_0, X86_PREFIX_ADDRSIZE ]
opcode: [ 0xe1, 0x00, 0x00, 0x00 ]
eflags: [ X86_EFLAGS_TEST_ZF ]
regs_read: [ rip, rcx, rflags ]
regs_write: [ rip, rcx ] # BUG: should be ecx
regs_read: [ rip, ecx, rflags ]
regs_write: [ rip, ecx ]
-
asm_text: "loopne 0x34"
details:
Expand All @@ -6109,8 +6109,8 @@ test_cases:
prefix: [ X86_PREFIX_0, X86_PREFIX_0, X86_PREFIX_0, X86_PREFIX_ADDRSIZE ]
opcode: [ 0xe0, 0x00, 0x00, 0x00 ]
eflags: [ X86_EFLAGS_TEST_ZF ]
regs_read: [ rip, rcx, rflags ]
regs_write: [ rip, rcx ] # BUG: should be ecx
regs_read: [ rip, ecx, rflags ]
regs_write: [ rip, ecx ]

-
input:
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