Aneesh V <ane...@ti.com> wrote on 03/16/2011 10:32:50 AM:
> Can you try this sequence:
>
> arm-linux-gnueabi-gcc -march=armv7-a -mthumb -mthumb-interwork -o foo1.o
> foo1.c -c
> arm-linux-gnueabi-gcc -march=armv7-a -mthumb -mthumb-interwork -o foo2.o
> foo2.S -c
> arm-linux-gnueabi-ld -r foo1.o foo2.o
> arm-linux-gnueabi-objdump -S a.out
>
> With this sequence I get the following output:
> 0000000c <main>:
> c: b580 push {r7, lr}
> e: af00 add r7, sp, #0
> 10: f7ff fffe bl 18 <foo>
> 14: 4618 mov r0, r3
> 16: bd80 pop {r7, pc}
>
> 00000018 <foo>:
> 18: e92d0080 push {r7}
> 1c: e28d7000 add r7, sp, #0
> 20: e1a0d007 mov sp, r7
> 24: e8bd0080 pop {r7}
> 28: e12fff1e bx lr
Well, sure, but the result of "ld -r" is not a final executable, but just
another relocatable object file. In particular, it will still carry
relocation records. In fact, if you add --reloc to the objdump line,
you should see:
0000000c <main>:
c: b580 push {r7, lr}
e: af00 add r7, sp, #0
10: f7ff fffe bl 18 <foo>
10: R_ARM_THM_CALL foo
14: 4618 mov r0, r3
16: bd80 pop {r7, pc}
The R_ARM_THM_CALL marks the branch instruction as still to be processed
by the final link step. And once you actually *perform* the final link,
e.g. via "gcc -o final a.out", the branch gets indeed converted to a blx
by the linker for me:
0000836c <main>:
836c: b580 push {r7, lr}
836e: af00 add r7, sp, #0
8370: f000 e802 blx 8378 <foo>
8374: 4618 mov r0, r3
8376: bd80 pop {r7, pc}
00008378 <foo>:
8378: e92d0080 push {r7}
837c: e28d7000 add r7, sp, #0
8380: e1a0d007 mov sp, r7
8384: e8bd0080 pop {r7}
8388: e12fff1e bx lr
Mit freundlichen Gruessen / Best Regards
Ulrich Weigand
--
Dr. Ulrich Weigand | Phone: +49-7031/16-3727
STSM, GNU compiler and toolchain for Linux on System z and Cell/B.E.
IBM Deutschland Research & Development GmbH
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Wittkopp
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