> I have found an issue related with the condition register usage, while > migrating to GCC from DIAB compiler. The RTOS used is AMX and the platform > is PowerPC. > 1. The comparison result of expression "(argVal < MACRO_VALUE)" is stored > in > CR4 initially (exp-1). Since the same expression is used again (exp-2) and > the 'argVal' is not modified in between these expressions, GCC does not > re-evaluate the expression, instead uses the already evaluated result from > CR4 for branch decision. > But in between these two comparison statements, there is a system call > where > the CR4 register is used for expression evaluation. So when the CR4 > register > is reused in the second if statement (exp-2), the evaluation result goes > wrong. CR4 is non-volatile. If the system calls modify it, your OS is not compliant to the ABI; you'd need a different ABI. Maybe you can force GCC to avoid CR4 by using -ffixed-reg=cr4 . Segher
