Hello, I encountered a problem which seems to be a bug in the assembler 'as': Redefining a symbol with the '.set' directive in connection with the location counter does not work correctly. I am using: GNU assembler 2.14 20030612, configured for `i586-pc-msdosdjgpp', getting to DOS from Windows 98.
I hope that the condensed little program I append (also in the file
'astest.S'), while isolating the supposed bug, contains all necessary
information.
Greetings from Germany, B. Strowitzki
#----- start of sample program ----
.section .data
.p2align 4,,15
somedata: .int 1,2,3,4,5,6,7,8,9,0 /* dummy values */
.set goodval_1, (.-somedata)/4 /* calculate number of entries */
.set badval, (.-somedata)/4
startval: .int badval /* retaining badval for later printing */
/* in real program to be stored into a "C"-defined struct
producing an entry like "datablock.length" */
moredata:
.rept 1024
.byte 32
.endr
.set goodval_2, (.-moredata) /* same procedure again */
.set badval, (.-moredata) /* redefining badval, ok */
midval: .int badval
evenmoredata: .space 200
.set goodval_3, (.-evenmoredata)
.set badval, (.-evenmoredata) /* third definition: doesn't work!
'as' seems to get confused */
# /* shortcut with self-diagnosis by 'as' */
# /* gives an extra error message, but works */
# .if (goodval_3-badval)
# .print "difference encountered"
# .err
# .endif
breakval: .int badval
lastdata:
.space 1200, -1
.set goodval_4, (.-lastdata)/4
.set badval, (.-lastdata)/4 /* doesn't work also */
# further strange behavior
.set dotval_good_1, .
.set dotval_bad, .
firstdot: .int dotval_bad /* no problem so far */
.space 12 /* dummy */
.set dotval_good_2, .
.set dotval_bad, . /* corrupts the value already stored in 'firstdot' */
nextdot: .int dotval_bad
format: .asciz " %i. right val: %i, badval: %i\12\15"
.section .text
.p2align 4,,15
.globl _main
_main:
pushl %ebp
movl %esp,%ebp
movl $startval,%eax
pushl (%eax)
pushl $goodval_1
pushl $1
pushl $format
call _printf /* emits equal numbers, ok */
movl $midval,%eax
pushl (%eax)
pushl $goodval_2
pushl $2
pushl $format
call _printf /* emits equal numbers, ok */
movl $breakval,%eax
pushl (%eax)
pushl $goodval_3
pushl $3
pushl $format
call _printf /* emits two different numbers */
pushl $badval
pushl $goodval_4
pushl $4
pushl $format
call _printf /* different numbers again */
pushl $10 /* newline */
call _putch
movl $firstdot,%eax
pushl (%eax)
pushl $dotval_good_1
pushl $5
pushl $format
call _printf /* emits two different numbers
with last value assigned to 'dotval_bad' */
movl $nextdot,%eax
pushl (%eax)
pushl $dotval_good_2
pushl $6
pushl $format
call _printf /* emits equal numbers, ok */
xorl %eax,%eax /* exit code zero */
movl %ebp,%esp
popl %ebp
ret
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astest.S
Description: Binary data
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