Lesson 5.1: Macros, Inline Assembly, and SSE/AVX Overview
Learning Objectives
- Explain how macros expand in assembly and how inline assembly works in high-level languages.
- Recognize SSE and AVX instructions at a high level when reading disassembly.
Prerequisites
- Basic experience with C macros (
#define). - Understanding of vectorization concepts in modern CPUs.
Key Concepts
- Macros: Textual substitution that can produce multiple instructions
- Inline Assembly: Embedding assembly in C/C++ (e.g.,
__asm__blocks) - SSE/AVX: Vector instructions using
xmm/ymmregisters
Detailed Explanation
Macro expansions can generate repetitive assembly patterns.
SSE instructions operate on 128-bit xmm registers, AVX on 256-bit ymm, and AVX-512 on 512-bit zmm.
#define SQUARE(x) ((x)*(x))
int square_inline_asm(int x) {
int result;
__asm__ ("imull %1, %0"
: "=r" (result)
: "r" (x), "0" (x));
return result;
}
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