mirror of
https://github.com/netwide-assembler/nasm.git
synced 2025-03-31 18:20:22 +08:00
Allow relative references to external symbols in data
Allow constructs like:
dd foo - $
... where foo is an external symbol. Currently this is only
implemented for extops, i.e. dx opcodes.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin
parent
6600eb1188
commit
472a7c1d17
@ -322,12 +322,15 @@ static void out(struct out_data *data)
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if (!data->size)
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return; /* Nothing to do */
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/*
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* Convert addresses to RAWDATA if possible
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* XXX: not all backends want this for global symbols!!!!
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*/
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switch (data->type) {
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case OUT_ADDRESS:
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asize = data->size;
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nasm_assert(asize <= 8);
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if (data->tsegment == NO_SEG && data->twrt == NO_SEG) {
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/* Convert to RAWDATA */
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/* XXX: check for overflow */
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uint8_t *q = xdata.b;
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@ -342,7 +345,6 @@ static void out(struct out_data *data)
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asize = data->size;
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nasm_assert(asize <= 8);
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if (data->tsegment == data->segment && data->twrt == NO_SEG) {
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/* Convert to RAWDATA */
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uint8_t *q = xdata.b;
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int64_t delta = data->toffset - data->offset
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- (data->inslen - data->insoffs);
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@ -535,7 +537,7 @@ int64_t assemble(int32_t segment, int64_t start, int bits, iflag_t cp,
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" instruction");
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} else {
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data.insoffs = 0;
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data.type = OUT_ADDRESS;
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data.type = e->relative ? OUT_RELADDR : OUT_ADDRESS;
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data.inslen = data.size = wsize;
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data.toffset = e->offset;
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data.tsegment = e->segment;
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72
asm/parser.c
72
asm/parser.c
@ -1,6 +1,6 @@
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/* ----------------------------------------------------------------------- *
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*
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* Copyright 1996-2013 The NASM Authors - All Rights Reserved
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* Copyright 1996-2016 The NASM Authors - All Rights Reserved
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* See the file AUTHORS included with the NASM distribution for
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* the specific copyright holders.
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*
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@ -254,7 +254,7 @@ static int parse_mref(operand *op, const expr *e)
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if (is_gpr && e->value == 1)
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b = e->type; /* It can be basereg */
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else /* No, it has to be indexreg */
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else /* No, it has to be indexreg */
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i = e->type, s = e->value;
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e++;
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}
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@ -375,6 +375,59 @@ static void mref_set_optype(operand *op)
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}
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}
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/*
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* Convert an expression vector returned from evaluate() into an
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* extop structure. Return zero on success.
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*/
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static int value_to_extop(expr * vect, extop *eop, int32_t myseg)
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{
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eop->type = EOT_DB_NUMBER;
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eop->offset = 0;
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eop->segment = eop->wrt = NO_SEG;
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eop->relative = false;
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for (; vect->type; vect++) {
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if (!vect->value) /* zero term, safe to ignore */
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continue;
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if (vect->type < EXPR_SIMPLE) /* false if a register is present */
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return -1;
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if (vect->type == EXPR_UNKNOWN) /* something we can't resolve yet */
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return 0;
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if (vect->type == EXPR_SIMPLE) {
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/* Simple number expression */
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eop->offset += vect->value;
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continue;
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}
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if (eop->wrt == NO_SEG && !eop->relative && vect->type == EXPR_WRT) {
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/* WRT term */
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eop->wrt = vect->value;
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continue;
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}
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if (eop->wrt == NO_SEG && !eop->relative &&
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vect->type == EXPR_SEGBASE + myseg && vect->value == -1) {
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/* Expression of the form: foo - $ */
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eop->relative = true;
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continue;
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}
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if (eop->segment == NO_SEG && vect->type >= EXPR_SEGBASE &&
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vect->value == 1) {
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eop->segment = vect->type - EXPR_SEGBASE;
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continue;
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}
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/* Otherwise, badness */
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return -1;
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}
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/* We got to the end and it was all okay */
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return 0;
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}
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insn *parse_line(int pass, char *buffer, insn *result, ldfunc ldef)
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{
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bool insn_is_label = false;
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@ -652,19 +705,10 @@ is_expression:
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i = tokval.t_type;
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if (!value) /* Error in evaluator */
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goto fail;
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if (is_unknown(value)) {
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eop->type = EOT_DB_NUMBER;
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eop->offset = 0; /* doesn't matter what we put */
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eop->segment = eop->wrt = NO_SEG; /* likewise */
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} else if (is_reloc(value)) {
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eop->type = EOT_DB_NUMBER;
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eop->offset = reloc_value(value);
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eop->segment = reloc_seg(value);
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eop->wrt = reloc_wrt(value);
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} else {
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if (value_to_extop(value, eop, location.segment)) {
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nasm_error(ERR_NONFATAL,
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"operand %d: expression is not simple"
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" or relocatable", oper_num);
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"operand %d: expression is not simple or relocatable",
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oper_num);
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}
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}
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@ -1,5 +1,5 @@
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/* ----------------------------------------------------------------------- *
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*
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*
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* Copyright 1996-2016 The NASM Authors - All Rights Reserved
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* See the file AUTHORS included with the NASM distribution for
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* the specific copyright holders.
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@ -14,7 +14,7 @@
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials provided
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* with the distribution.
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*
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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@ -31,7 +31,7 @@
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*
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* ----------------------------------------------------------------------- */
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/*
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/*
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* nasm.h main header file for the Netwide Assembler: inter-module interface
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*/
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@ -575,6 +575,7 @@ typedef struct operand { /* operand to an instruction */
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int32_t segment; /* immediate segment, if needed */
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int64_t offset; /* any immediate number */
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int32_t wrt; /* segment base it's relative to */
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bool relative; /* self-relative expression */
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int eaflags; /* special EA flags */
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int opflags; /* see OPFLAG_* defines below */
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decoflags_t decoflags; /* decorator flags such as {...} */
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@ -582,7 +583,7 @@ typedef struct operand { /* operand to an instruction */
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#define OPFLAG_FORWARD 1 /* operand is a forward reference */
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#define OPFLAG_EXTERN 2 /* operand is an external reference */
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#define OPFLAG_UNKNOWN 4 /* operand is an unknown reference
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#define OPFLAG_UNKNOWN 4 /* operand is an unknown reference
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* (always a forward reference also)
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*/
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@ -593,6 +594,7 @@ typedef struct extop { /* extended operand */
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int64_t offset; /* ... it's given here ... */
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int32_t segment; /* if it's a number/address, then... */
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int32_t wrt; /* ... and here */
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bool relative; /* self-relative expression */
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enum extop_type type; /* defined above */
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} extop;
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@ -707,7 +709,7 @@ struct ofmt {
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/*
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* Output format flags.
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*/
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#define OFMT_TEXT 1 /* Text file format */
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#define OFMT_TEXT 1 /* Text file format */
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unsigned int flags;
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int maxbits; /* Maximum segment bits supported */
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11
test/imm.asm
Normal file
11
test/imm.asm
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@ -0,0 +1,11 @@
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bits 64
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mov eax,1
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mov eax,-1
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mov eax,0x11111111
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mov ecx,2
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add ecx,-6
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add ecx,strict dword -6
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add ecx,4
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add ecx,strict dword 4
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add ecx,10000
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9
test/reldef.asm
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9
test/reldef.asm
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@ -0,0 +1,9 @@
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bits 64
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extern bar
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section .data
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foo: dd bar
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dd foo - $
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; dd foo*2
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dd bar - $
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