2017年5月23日 · The best solution (especially if you want to stick to SSE2 - i.e. to avoid using AVX) to initialize two registers (say, xmm0 and xmm1) with the two 64-bit halves of your immediate value, do MOVLHPS xmm0,xmm1 In order to initialize a 64-bit value, the easiest solution is to use a general-purpose register (say, AX), and then use MOVQ to transfer its value to the XMM register.

2017年10月23日 · Well, my learning of assembly was mostly incidental... what I know of x86 assembly comes most from profiling, post-mortem debugging and reverse engineering of C/C++ applications, plus some fun with code golf challenges, that I usually solve in 16-bit x86 assembly.

2013年12月19日 · The final store to resVal "unties" the xmm0 register to allow the register to be freely "renamed", which allows more of the loops to be run in parallel. This is a typical case of "unless you are absolutely sure, leave writing code to the compiler".

2018年1月8日 · xmm0 is the low half of ymm0, exactly like eax is the low half of rax. Writing to xmm0 (with a VEX-coded instruction like vaddps xmm , not legacy SSE addps xmm ) zeros the upper lane of ymm0 , just like writing to eax zeros the …

2018年9月7日 · I'm trying to convert some x86 assembly back into C++, and I cannot figure out how this set of instructions was originally written. movd xmm0,eax ; byte read from device '0x04' cvtdq2pd xmm0,xmm0 ;

2023年8月6日 · Store/reload is necessary to transfer from XMM to st0.Even though MMX registers alias the x87 registers, there's no way to use MOVDQ2Q mm0, xmm0 to get an 80-bit FP bit-pattern into st0, even apart from the problem of switching back from MMX to x87 state without clearing the registers.

2012年12月30日 · movsd xmm0,[_1] addsd xmm1,xmm0 If you are on x64, you can do this: mov rax,1.0 movq xmm0,rax addsd xmm1,xmm0 or use the stack if the type mismatch bothers you: mov rax,1.0 push rax movsd xmm0,[rsp] pop rax addsd xmm1,xmm0 As for the x87 code, doubles are qwords, not dwords.

How can I view the XMM0-XMM7 registers within OllyDbg? I can right click on the registers window and go to view MMX registers, but I'm not exactly sure that these are the same. I see an instruction: MOVSS DWORD PTR DS:[ESI+8],XMM0 and as step through that instruction, the value shown in MM0 on the register window does not become the value ...

2014年3月13日 · After xor-ing into xmm0, the wrapper copies the result to xmm2 only to then copy it back to the stack. Overall, not terribly efficient. MOVQ copies 8 bytes at a time, and expects (under some circumstances), an 8-byte aligned address .

2021年12月1日 · Swapping xmm0 beside movdqa requires stores/loads from memory - 7 xmm registers are used per buffer: two for states and five for msgtmps. For two buffers I need 14 registers + 1 xmm0. The last register might be used either for SHUF_MASK or as a scratch for xmm0. In either case there is a register spilling. –