X86 INSTRUCTIONS:::CONTROL FLOW::: comparison instruction

Performs a bit-wise logical AND on arg1 and arg2 the result of which we will refer to as Temp and sets the ZF(zero), SF(sign) and PF(parity) flags based on Temp. Temp is then discarded. Syntax test arg1, arg2 #GAS Syntax test arg2, arg1 #Intel syntax Operands arg1 Register Immediate arg2 AL/AX/EAX (only if arg1 is immediate) Register Memory Modified flags SF <- MostSignificantBit(Temp) If Temp == 0 ZF <- 1 else ZF <- 0 PF <- BitWiseXorNor(Temp[Max-1:0]) CF <- 0 OF <- 0 AF is undefined Performs a comparison operation between arg1 and arg2. The comparison is performed by a (signed) subtraction of arg2 from arg1, the results of which can be called Temp. Temp is then discarded. If arg2 is an immediate value it will be sign extended to the length of arg1. The EFLAGS register is set in the same manner as a sub instruction. Syntax cmp arg2, arg1 #GAS Syntax cmp arg1, arg2 #Intel syntax the GAS/AT&T syntax can be rather confusing, as for example cmp $0, %rax followed by jl branch will branch if %rax < 0 (and not the opposite as might be expected from the order of the operands). Operands arg1 AL/AX/EAX (only if arg2 is immediate) Register Memory arg2 Register Immediate Memory Modified flags SF <- MostSignificantBit(Temp) If Temp == 0 ZF <- 1 else ZF <- 0 PF <- BitWiseXorNor(Temp[Max-1:0]) CF, OF and AF<- 0