Add info about the fast generator.
above. Rewrite: Transform MIR according to the assign using reserved hard regs. Only for -O1 and
above. Combine (code selection): Merging data-depended insns into one. Only for -O1 and above.
Dead code elimination: Removing insns with unused outputs. Only for -O1 and above.
- Fast Generator: Only for -O0.
+ Fast Generator: Code generation about 4-5 times faster than one with -O1. The generated code
+ performance is approximately on par with -O0 GCC/Clang. Only for -O0.
Generate machine insns: Machine-dependent code (e.g. in
mir-gen-x86_64.c) creating machine insns. Always.
