From: Peter Johnson <peter@tortall.net>
Date: Tue, 4 Dec 2007 05:58:54 +0000 (-0000)
Subject: Fix #124: Fully simplify out sym-sym in values (e.g. a symbol minus itself).
X-Git-Tag: v0.7.0~39
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=f938cbd21d4df71780620d620b79dfe4ae353928;p=yasm

Fix #124: Fully simplify out sym-sym in values (e.g. a symbol minus itself).
This could particularly cause false errors if sym is external.

svn path=/trunk/yasm/; revision=2018
---

diff --git a/libyasm/tests/Makefile.inc b/libyasm/tests/Makefile.inc
index e0e3d951..4b9eb1d6 100644
--- a/libyasm/tests/Makefile.inc
+++ b/libyasm/tests/Makefile.inc
@@ -75,6 +75,9 @@ EXTRA_DIST += libyasm/tests/unary.asm
 EXTRA_DIST += libyasm/tests/unary.hex
 EXTRA_DIST += libyasm/tests/value-err.asm
 EXTRA_DIST += libyasm/tests/value-err.errwarn
+EXTRA_DIST += libyasm/tests/value-samesym.asm
+EXTRA_DIST += libyasm/tests/value-samesym.errwarn
+EXTRA_DIST += libyasm/tests/value-samesym.hex
 
 check_PROGRAMS += bitvect_test
 check_PROGRAMS += floatnum_test
diff --git a/libyasm/tests/value-samesym.asm b/libyasm/tests/value-samesym.asm
new file mode 100644
index 00000000..da325992
--- /dev/null
+++ b/libyasm/tests/value-samesym.asm
@@ -0,0 +1,2 @@
+extern RW
+mov [eax + (RW + 22032) - (RW + 23056)], eax
diff --git a/libyasm/tests/value-samesym.errwarn b/libyasm/tests/value-samesym.errwarn
new file mode 100644
index 00000000..58c850b3
--- /dev/null
+++ b/libyasm/tests/value-samesym.errwarn
@@ -0,0 +1 @@
+-:1: warning: binary object format does not support extern variables
diff --git a/libyasm/tests/value-samesym.hex b/libyasm/tests/value-samesym.hex
new file mode 100644
index 00000000..4bab16b8
--- /dev/null
+++ b/libyasm/tests/value-samesym.hex
@@ -0,0 +1,8 @@
+67 
+66 
+89 
+80 
+00 
+fc 
+ff 
+ff 
diff --git a/libyasm/value.c b/libyasm/value.c
index e3eda5fd..74b793bc 100644
--- a/libyasm/value.c
+++ b/libyasm/value.c
@@ -208,6 +208,29 @@ value_finalize_scan(yasm_value *value, yasm_expr *e,
                     continue;
                 }
 
+                /* Look for the same symrec term; even if both are external,
+                 * they should cancel out.
+                 */
+                for (j=0; j<e->numterms; j++) {
+                    if (e->terms[j].type == YASM_EXPR_SYM
+                        && e->terms[j].data.sym == sym
+                        && (used & (1<<j)) == 0) {
+                        /* Mark as used */
+                        used |= 1<<j;
+
+                        /* Replace both symrec portions with 0 */
+                        yasm_expr_destroy(sube);
+                        e->terms[i].type = YASM_EXPR_INT;
+                        e->terms[i].data.intn = yasm_intnum_create_uint(0);
+                        e->terms[j].type = YASM_EXPR_INT;
+                        e->terms[j].data.intn = yasm_intnum_create_uint(0);
+
+                        break;  /* stop looking */
+                    }
+                }
+                if (j != e->numterms)
+                    continue;
+
                 if (!yasm_symrec_get_label(sym, &precbc)) {
                     if (value_finalize_scan(value, sube, expr_precbc,
                                             ssym_not_ok))