Arch86

Opcode	Encoding	16-bit	32-bit	64-bit	`CPUID` Feature Flag(s)	Description
`F3 0F 1A /r` `BNDCL bnd, r/m32`	`rm`	Valid	Valid	N/E	`mpx`	Raise a `#BR` exception if the address in r/m32 is lower than the lower bound of bnd.
Opcode: `F3 0F 1A /r` Mnemonic: `BNDCL bnd, r/m32` Encoding: `rm` Validity (16/32/64 bit): valid, valid, N/E `CPUID` Feature Flag(s): `mpx` Raise a `#BR` exception if the address in r/m32 is lower than the lower bound of bnd.
`F3 0F 1A /r` `BNDCL bnd, r/m64`	`rm`	N/E	N/E	Valid	`mpx`	Raise a `#BR` exception if the address in r/m64 is lower than the lower bound of bnd.
Opcode: `F3 0F 1A /r` Mnemonic: `BNDCL bnd, r/m64` Encoding: `rm` Validity (16/32/64 bit): N/E, N/E, valid `CPUID` Feature Flag(s): `mpx` Raise a `#BR` exception if the address in r/m64 is lower than the lower bound of bnd.

Encoding

Encoding	Operand 1	Operand 2
`rm`	`ModRM.reg[r]`	`ModRM.r/m[r]`

Description

The BNDCL instruction compares the address in the second source operand against the lower bound in the first source operand. If the second source is lower (outside the bounds), a #BR exception is raised and BNDSTATUS is set to 1.

If the second source operand is a general purpose register, the value contained in it is treated as the address to compare against. If, however, it is a memory location, the effective address is calculated (see LEA - Load Effective Address) and used in the comparison. At no time is memory accessed.

Which instruction form is used depends on the operating mode of the processor. In 16-bit and 32-bit modes, the 32-bit form is used. In 64-bit mode, the 64-bit form is used.

Operation

public void BNDCL(Bound bnd, IntPtr addr)
{
    if (addr < bnd.Lower)
    {
        BNDSTATUS.Abd = 0;
        BNDSTATUS.EC = 1; // bounds violation
        #BR;
    }
}

Flags Affected

None.

Intrinsics

void _bnd_chk_ptr_lbounds(const void *address)

Exceptions

Real-Address Mode

#BR

If the bounds test fails.

#UD

If the LOCK prefix is used.
If 16 bit addressing is used, or 32 or 64 bit addressing is used, but without an SIB byte (rm is not 100b).
If a register operand encodes BND4 through BND7.

Virtual-8086 Mode

#BR

If the bounds test fails.

#UD

If the LOCK prefix is used.
If 16 bit addressing is used, or 32 or 64 bit addressing is used, but without an SIB byte (rm is not 100b).
If a register operand encodes BND4 through BND7.

Protected Mode

#BR

If the bounds test fails.

#UD

If the LOCK prefix is used.
If 16 bit addressing is used, or 32 or 64 bit addressing is used, but without an SIB byte (rm is not 100b).
If a register operand encodes BND4 through BND7.

Compatibility Mode

#BR

If the bounds test fails.

#UD

If the LOCK prefix is used.
If 16 bit addressing is used, or 32 or 64 bit addressing is used, but without an SIB byte (rm is not 100b).
If a register operand encodes BND4 through BND7.

Long Mode

#BR

If the bounds test fails.

#UD

If the LOCK prefix is used.
If 16 bit addressing is used, or 32 or 64 bit addressing is used, but without an SIB byte (rm is not 100b).
If a register operand encodes BND4 through BND7.