On Tue, May 10, 2011 at 6:23 PM, Richard Guenther <richard.guent...@gmail.com> wrote: > On Tue, May 10, 2011 at 12:08 PM, fanqifei <fanqi...@gmail.com> wrote: >> Hi all, >> >> I am poring gcc 4.3.2 for a micro-controller and use it to compile C >> source code. >> I found that gcc is very sensitive to small changes in C source code >> even if the change doesn't affect any function of the source code. >> For example, a source file foo.c includes a header file foo.h. >> If one macro definition is added to foo.h and the macro is not used in >> foo.c. The assembly file foo.s is still changed and a few instructions >> swapped positions . >> I checked foo.c.129t.final_cleanup and found difference in it. >> >> I am wondering what caused the change in foo.o. Is there any >> randomization in gcc? >> How can I make the assembly file foo.s same no matter foo.h is changed or >> not? > > alias analysis behavior depends on DECL_UIDs for partitioning which > unfortunately shows this behavior in older releases (fixed as of GCC 4.5 > at least). > > Richard. Which file or fucntion should I look into? Maybe I can work around in 4.3.2 What change in 4.5 fixed it?
Thanks. -Qifei Fan
