Even I'm confused about the errors. when remove the clobber list
"r0", "r1", "r2", "r3", I get undefined reference to r1, r3 and r2.
Here is the generated assembly code
1: when the asm is called directly ... this seems to work
ldr r2, =8 /* number of register */
ldr r1, =#-536813312 /* load the nvic_iser* register */
read_nvic_iser:
sub r2, r2, #1
ldr r0, [r1]
add r1, r1, #4 /* go to the next register */
cmp r0, #0
beq read_nvic_iser_ok
ldr r3, =#-1163018018
str r3, [r4] /* update status flag */
read_nvic_iser_ok:
cmp r2, #0
bne read_nvic_iser
ldr r3, =#1611514078
str r3, [r4] /* update status flag */
2: when the asm gets called through another function ... this is
having the compilation error ...
.thumb_func
.type check_reset_value, %function
check_reset_value:
@ args = 0, pretend = 0, frame = 16
@ frame_needed = 1, uses_anonymous_args = 0
@ link register save eliminated.
push {r4, r5, r6, r7, r8}
sub sp, sp, #20
add r7, sp, #0
str r0, [r7, #12]
str r1, [r7, #8]
str r2, [r7, #4]
ldr r6, [r7, #12]
ldr ip, [r7, #8]
movw r4, #49374
movt r4, 47789
movw r5, #49374
movt r5, 24589
ldr r8, [r7, #4]
@ 24 "nvic_reg_read.c" 1
ldr r2, =8 /* number of register */
ldr r1, =r6 /* load the nvic_iser* register */ <------
read_reg:
sub r2, r2, #1
ldr r0, [r1]
add r1, r1, #4 /* go to the next register */
cmp r0, ip
beq read_reg_ok
ldr r3, =r4 <----------
str r3, [r8] /* update status flag */
read_reg_ok:
cmp r2, #0
bne read_reg
ldr r3, =r5 <--------------
str r3, [r8] /* update status flag */
the lines marked with the arrows are where the errors occur.
On Mon, Jun 10, 2013 at 3:51 PM, Ian Lance Taylor <iant@xxxxxxxxxx> wrote:
> On Mon, Jun 10, 2013 at 2:41 PM, Kalai Rajah N <kalairajah@xxxxxxxxx> wrote:
>
>> I'm trying to do a simple register read through ARM inline assembly.
>> If I embed the asm in the function directly, it works ...
>
> ...
>
>> I see the following errors:
>> /tmp/ccYu7aUS.ltrans0.ltrans.o: In function `read_reg_ok':
>> ccYu7aUS.ltrans0.o:(.text.check_reset_value.4010+0x60): undefined
>> reference to `r6'
>> ccYu7aUS.ltrans0.o:(.text.check_reset_value.4010+0x64): undefined
>> reference to `r4'
>> ccYu7aUS.ltrans0.o:(.text.check_reset_value.4010+0x68): undefined
>> reference to `r5'
>> collect2: error: ld returned 1 exit status
>>
>> What am I doing wrong?
>
>
> Your test case has no mention of r4, r5, or r6. It always helps to
> show a complete standalone test case.
>
> The error messages indicate some confusion: there are references to
> symbols using the names of registers. But I don't know where those
> are coming from.
>
> Ian
