Hello,
I have some code generating the following assembly:
{OnReset}:
8000010: b508 push {r3, lr}
8000012: 20ff movs r0, #255 ; 0xff
8000014: f000 f828 bl 8000068 <{MyFunction}>
8000018: e7fe b.n 8000018 <{OnReset}+0x8>
800001a: bf00 nop
08000068
{MyFunction}:
8000068: f44f 5380 mov.w r3, #4096 ; 0x1000
800006c: f2c2 0300 movt r3, #8192 ; 0x2000
8000070: 7018 strb r0, [r3, #0]
8000072: 4770 bx lr
"MyFunction" and "OnReset" are in different source files and
therefore compiled to different object files. I would like to
get "MyFunction" fully inlined to "OnReset" to remove the extra
branch instructions (bl and bx).
It's my understanding that because the two functions are compiled
into separate object files, this must be done using LTO. If I
compile them into the same object file, I get the full inlining
I'm looking for, but that's not going to scale well for my
project.
** Beautiful, isn't it? **
{OnReset}:
8000010: f44f 5380 mov.w r3, #4096 ; 0x1000
8000014: f2c2 0300 movt r3, #8192 ; 0x2000
8000018: 22ff movs r2, #255 ; 0xff
800001a: 701a strb r2, [r3, #0]
800001c: e7fe b.n 800001c <{OnReset}+0xc>
800001e: bf00 nop
I've tried adding -flto to my compiler and linker flags and a
number of other things without success. The compiler seems to
generate extra information in my object files, but the linker
doesn't seem to do the optimization. I don't get any ICEs,
however, as stated in Bug 61 and 88. I just don't get the result
I'm after.
Here are my compiler commands:
arm-none-eabi-gdc -mthumb -mcpu=cortex-m4 -fno-emit-moduleinfo
-ffunction-sections -fdata-sections -O3 -c -flto ...
arm-none-eabi-ld -T link/link.ld -Map binary/memory.map
--gc-sections -flto ...
I'm using my arm-none-eabi cross toolchain built from the GDC 4.8
branch. I tried adding --enable-lto to my toolchain's configure,
but that had no effect. It's my understanding that it's enabled
by default anyway.
Does anyone know how I can get this level of inlining without
compiling all my source into one object file?
Thanks for any help,
Mike
