how to use -fomit-frame-pointer for one file only

Question

Hello, 
 I am trying to remove the use of the frame pointers for bootloader_util.c because I am getting the error : "r7 cannot be used in asm here", but I only know how to remove the frame pointers to all files by using -fomit-frame-pointer in CFLAGS. How do I make only one single file omit the frame pointers? 
 Thank you very much for your help!

Håkon Alseth · Accepted Answer

Hi, 
 If you use any optimization except -O0, -fomit-frame-pointer will be used : 
 
 -fomit-frame-pointer 
 Don't keep the frame pointer in a register for
functions that don't need one. This
avoids the instructions to save, set
up and restore frame pointers; it also
makes an extra register available in
many functions. It also makes
debugging impossible on some machines.
On some machines, such as the VAX,
this flag has no effect, because the
standard calling sequence
automatically handles the frame
pointer and nothing is saved by
pretending it doesn't exist. The
machine-description macro
FRAME_POINTER_REQUIRED controls
whether a target machine supports this
flag. See Register Usage. 
 Enabled at levels -O, -O2, -O3, -Os. 
 
 You can use pragma: 
 #pragma GCC push_options
#pragma GCC optimize ("O0")

ret = do_something();

#pragma GCC pop_options
 
 or if you want to set it on the specific function: 
 int some_func(void) __attribute__((optimize("-O0")));
 
 This error is not shown on my end (arm-none-eabi v4.9.3, SDK 10), I even tested with lto set as well. 
 What SDK version are you using? And which version of arm-none-eabi are you using? 
 Cheers,
Håkon