- godbolt Compiler Explorer
- Use this to see the assembly generated for various languages using various compilers. Very useful tool.
- uops table
- See instruction latency, throughput, # uops, and port usage across different architectures.
- Intel Intrinsics Guide
- A table of all Intel intrinsics
- Float Toy
- Flat Assembler (FASM)
- My personal choice for writing assembly. Has a cool macro system.
- gpfault.net x86-64 assembly tutorials using FASM
- Agner Fog's Optimization manuals
- Lots of good info contained in these manuals that will assist you in writing fast code.
- Intel 64 and IA-32 Architectures Software Developer’s Manual Combined Volumes
- Most of the things you need to know about the Intel platform. Good to know this if writing code X86/X64 code.
- Intel 64 and IA-32 Architectures Optimization Reference Manual