| Compiler | Code size | Cycle count per iteration | |----------|-----------|----------------------------| | GCC -O2 | 14.2 KB | 128 cycles | | Keil AC6 -Oz | 10.8 KB | 112 cycles | | Keil AC6 -O3 | 12.1 KB | 96 cycles |
For or tight memory systems, Keil often wins. You pay for predictability. 3. Three features you shouldn’t ignore a) Microlib A lightweight C library for deeply embedded systems. Reduces code size by ~50% compared to standard Arm libc—perfect for Cortex‑M0/M0+. b) Linker feedback files (.arf) Keil’s linker can generate feedback to the compiler, enabling link-time optimization (LTO) and unused-section elimination. GCC can do this too, but Keil makes it effortless. c) Event Recorder Not strictly a compiler feature, but tightly integrated: real-time software tracing without extra hardware. Great for debugging timing or logic issues. 4. Real-world performance example We benchmarked a control loop on a Cortex-M4 (STM32F4) – FIR filter + PID. keil arm compiler
Have you migrated from AC5 to AC6? Or switched from GCC to Keil? Let me know in the comments – I’d love to hear your performance numbers. Want more embedded toolchain deep dives? Subscribe to the newsletter. | Compiler | Code size | Cycle count