Hello, I am working on performance analysis tools. For instrumenting applications we use the compiler instrumentation flags -finstrument-functions. The inserted function calls to __cyg_profile_func_enter and __cyg_profile_func_exit normally provide a function pointer. With libbfd we lookup debug information for this function using this address. This worked fine for many years on different machines, Recently, I tried to port our code to an ARM architecture (dual Cortex A9 processor) running Ubuntu. Here, I discovered that the function addresses that are passed to __cyg_profile_func_enter and __cyg_profile_func_exit do not match the address of the function that we get from libbfd. Although the difference might be caused by libbfd or in the way we interface libbfd, I am wondering that __cyg_profile_func_enter and __cyg_profile_func_exit provide odd function addresses, even if I specify -falign-functions=4. I appended a small test case that shows the addresses that we get from function instrumentation and from libbfd. The output on the ARM system looks like this: Function: foo, Address: 34960 Function: main, Address: 35008 In __cyg_profile_func_enter. Function address: 35009 In __cyg_profile_func_enter. Function address: 34961 in foo In __cyg_profile_func_exit. Function address: 34961 In __cyg_profile_func_exit. Function address: 35009 I tested it on two different machines: 1. dual-core ARM Cortex-A9 Tegar2 SoC with gcc (Ubuntu/Linaro 4.4.4-14ubuntu5) 4.4.5, and 2. Snowball – Cortex A9 board, Nova A9500 dual Cortex A9 with gcc (Ubuntu/Linaro 4.6.1-9ubuntu3) 4.6.1. I performed several builds and test runs and it seems that the address difference is always 1. Is the function adress passed to __cyg_profile_func_enter and __cyg_profile_func_exit intenionally odd on ARM, even when specifing -falign-function=4? Best Regards, Daniel Lorenz ------------------------------------------------------------------------------- ------------------------------------------------------------------------------- Forschungszentrum Juelich GmbH 52425 Juelich Sitz der Gesellschaft: Juelich Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498 Vorsitzender des Aufsichtsrats: MinDir Dr. Karl Eugen Huthmacher Geschaeftsfuehrung: Prof. Dr. Achim Bachem (Vorsitzender), Karsten Beneke (stellv. Vorsitzender), Prof. Dr.-Ing. Harald Bolt, Prof. Dr. Sebastian M. Schmidt ------------------------------------------------------------------------------- ------------------------------------------------------------------------------- Kennen Sie schon unsere app? http://www.fz-juelich.de/app
