Hi, I am debugging gcc-4.5.0 source code, built for C compiler only, using gdb. My question is why we can not keep break points on any of the back end functions(functions defined in libbackend.a library)??? I am explaining my question in detail: I downloaded gcc-4.5.0 and build it in objdir=OBJDIR and installed into BIN directory. when I run make install, it is copying xgcc file from OBJDIR to BIN/usr/local/gcc. This is the command by which xgcc is built: gcc -g -fkeep-inline-functions -DIN_GCC -W -Wall -Wwrite-strings -Wcast-qual -Wstrict-prototypes -Wmissin g-prototypes -Wmissing-format-attribute -pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-string s -Wold-style-definition -Wc++-compat -fno-common -DHAVE_CONFIG_H -o xgcc gcc.o opts-common.o gcc-options. o gccspec.o intl.o prefix.o version.o driver-i386.o ../libcpp/libcpp.a ../libiberty/libiberty.a . ./libdecnumber/libdecnumber.a So in building xgcc it is not using libbackend.a library. I think this is the reason why I am unable to keep breakpoints on any of the back end's functions.right? But why xgcc is not built by using libbackend.a library? From where xgcc/gcc is getting the backend functions definitions? Also what are cc,cc1-dummy files? They are built using libbackend.a library. Thanks in advance.