Intel® Extended Memory 64 Technology Software Developer's Guide

LOOP/LOOPcc—Loop According to ECX CounterOpcode Instruction 64-Bit Mode Compat/Leg DescriptionModeE2 cb LOOP rel8 Valid Valid Decrement count; jump short if count ≠ 0REX.W + E2 cb LOOP rel8 Valid N.E. Decrement count; jump short if count ≠ 0. JMP Shortis RIP = RIP + 8-bit offset sign-extended to 64-bits.E1 cb LOOPE rel8 Valid Valid Decrement count; jump short if count ≠ 0 and ZF=1REX.W + E1 cb LOOPE rel8 Valid N.E. Decrement count; jump short if count ≠ 0 and ZF=1.JMP Short is RIP = RIP + 8-bit offset sign-extended to64-bits.E0 cb LOOPNE rel8 Valid Valid Decrement count; jump short if count ≠ 0 and ZF=0REX.W + E0 cb LOOPNZ rel8 Valid N.E. Decrement count; jump short if count ≠ 0 and ZF=0.JMP Short is RIP = RIP + 8-bit offset sign-extended to64-bits.Flags AffectedNone.IA-32e Mode OperationPromoted to 64 bits.Operand size at 64 bits.JMP Short is RIP = RIP + 8-bit offset sign extended to 64 bits.Protected Mode Exceptions#GP(0)If the offset being jumped to is beyond the limits of the CS segment.Real-Address Mode Exceptions#GPIf the offset being jumped to is beyond the limits of the CS segment or is outside of theeffective address space from 0 to FFFFH. This condition can occur if a 32-bit address sizeoverride prefix is used.Virtual-8086 Mode ExceptionsSame exceptions as in Real Address ModeCompatibility Mode ExceptionsSame as for protected mode exceptions.64-Bit Mode Exceptions#GP(0)If the memory address is in a non-canonical form.Vol. 1 2-297