BNDMK—Make Bounds

Opcode/

Op/En

64/32

CPUID

Description

Instruction bit Mode Support Feature Flag
F3 0F 1B /r BNDMK bnd, m32 RM NE/V MPX Make lower and upper bounds from m32 and store them in bnd.
F3 0F 1B /r BNDMK bnd, m64 RM V/NE MPX Make lower and upper bounds from m64 and store them in bnd.

Instruction Operand Encoding

Op/En Operand 1 Operand 2 Operand 3
RM ModRM:reg (w) ModRM:r/m (r) NA

Description

Makes bounds from the second operand and stores the lower and upper bounds in the bound register bnd. The second operand must be a memory operand. The content of the base register from the memory operand is stored in the lower bound bnd.LB. The 1's complement of the effective address of m32/m64 is stored in the upper bound b.UB. Computation of m32/m64 has identical behavior to LEA.

This instruction does not cause any memory access, and does not read or write any flags.

If the instruction did not specify base register, the lower bound will be zero. The reg-reg form of this instruction retains legacy behavior (NOP).

The instruction causes an invalid-opcode exception (#UD) if executed in 64-bit mode with RIP-relative addressing.

Operation

BND.LB := SRCMEM.base;
IF 64-bit mode Then
    BND.UB := NOT(LEA.64_bits(SRCMEM));
ELSE
    BND.UB := Zero_Extend.64_bits(NOT(LEA.32_bits(SRCMEM)));
FI;

Intel C/C++ Compiler Intrinsic Equivalent

BNDMKvoid * _bnd_set_ptr_bounds(const void * q, size_t size);

Flags Affected

None

Protected Mode Exceptions

#UD

If the LOCK prefix is used.

If ModRM.r/m encodes BND4-BND7 when Intel MPX is enabled.

If 67H prefix is not used and CS.D=0.

If 67H prefix is used and CS.D=1.

Real-Address Mode Exceptions

#UD

If the LOCK prefix is used.

If ModRM.r/m encodes BND4-BND7 when Intel MPX is enabled.

If 16-bit addressing is used.

Virtual-8086 Mode Exceptions

#UD

If the LOCK prefix is used.

If ModRM.r/m encodes BND4-BND7 when Intel MPX is enabled.

If 16-bit addressing is used.

Compatibility Mode Exceptions

Same exceptions as in protected mode.

64-Bit Mode Exceptions

#UD

If the LOCK prefix is used.

If ModRM.r/m and REX encodes BND4-BND15 when Intel MPX is enabled.

If RIP-relative addressing is used.

#SS(0) If the memory address referencing the SS segment is in a non-canonical form.
#GP(0) If the memory address is in a non-canonical form.

Same exceptions as in protected mode.