Recent questions tagged X86

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x86 - SSE multiplication of 4 32-bit integers

How to multiply four 32-bit integers by another 4 integers? I didn't find any instruction which can do it. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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x86 - Memory alignment on a 32-bit Intel processor

Intel's 32-bit processors such as Pentium have 64-bit wide data bus and therefore fetch 8 bytes per access. ... they be justified in doing so? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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x86 - What's the relative speed of floating point add vs. floating point multiply

A decade or two ago, it was worthwhile to write numerical code to avoid using multiplies and divides and use ... to get a useful intuition. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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x86 Assembly pushl/popl don't work with "Error: suffix or operands invalid"

I'm a newbie to assembly programming, working through Programming Ground Up on an Ubuntu x86_64 desktop with GNU ... Or is it my assembler? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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x86 - Assembly bubble sort swap

I'm trying to do a bubble sort in x86 assembly (yes it has to be bubble, as I'm not concerned about ... into the specific address. Any help? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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x86 - Sum reduction of unsigned bytes without overflow, using SSE2 on Intel

I am trying to find sum reduction of 32 elements (each 1 byte data) on an Intel i3 processor. I did this: s=0 ... . Not sure how it works on SSE See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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x86 64 - Assembly registers in 64-bit architecture

Following the answer about assembly registers' sizes: First, what sizes are eax, ax, ah and their counterparts, ... the new calling convention? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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x86 - Why do virtual memory addresses for linux binaries start at 0x8048000?

Disassembling an ELF binary on a Ubuntu x86 system I couldn't help but notice that the code(.text) section ... it just an arbitrary choice? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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x86 - How to disassemble, modify and then reassemble a Linux executable?

Is there anyway this can be done? I've used objdump but that doesn't produce assembly output that will be ... and then test it afterwards. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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x86 - Is LFENCE serializing on AMD processors?

In recent Intel ISA documents the lfence instruction has been defined as serializing the instruction stream ( ... the instruction stream? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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x86 - int 13h 42h doesn't load anything in Bochs

I changed my bootloader from CHS to LBA, so I replaced int 13h 02h with int 13h 42h. It works ... display_library: x, options="gui_debug" See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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x86 - Why can't my ultraportable laptop CPU maintain peak performance in HPC

I have developed a high performance Cholesky factorization routine, which should have peak performance at around ... the overall measurement. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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621 views

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x86 - Why Linux/gnu linker chose address 0x400000?

I'm experimenting with ELF executables and the gnu toolchain on Linux x86_64: I've linked and stripped (by hand) ... to map the file to? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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803 views

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x86 - Addressing Modes in Assembly Language (IA-32 NASM)

As the web-resources on this is sparse, I will, for the benefit of future searches, begin by listing the address ... the end, not MY_TABLE[1]? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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752 views

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x86 - Fastest way to unpack 32 bits to a 32 byte SIMD vector

Having 32 bits stored in a uint32_t in memory, what's the fastest way to unpack each bit to a separate byte ... .com/en-us/forums/topic/283382 See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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471 views

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x86 - How has CPU architecture evolution affected virtual function call performance?

Years ago I was learning about x86 assembler, CPU pipelining, cache misses, branch prediction, and all that ... bad branch predictions, etc? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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